Bryant T874, Q674 User Manual

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5-8

yrig

T874 Multistage Thermostats

APPLICATION

These thermostats and subbases provide low voltage control of multista pump s

e heating and cooling systems, including heat

stems.

and Q674 Subbases

PRODUCT DATA

FEATURES

• T874 Thermostat has silent, dust-free mercury switches operated by coiled bimetal elements.

• Heat anticipator(s) are adjustable or fixed cooling anticipator(s) are fixed.

• Individual heat and cool levers and scales (most models) for temperature setting located on top of thermostat case.

• Cover thermometer on most T874 Multistage Thermostat models.

• Locking cover and locking lever screws available for T874 Multistage Thermostats.

• Versaguard™ Thermostat Guard or custom key lock thermostat guards available for T874 Multistage Thermostats.

• T874 Thermostat requires a Q674 Subbase.

• Q674 Subbase provides system and fan switching, wiring terminals and mounting base for T874 Multistage Thermostat.

• Adapter plate available for mounting Q674 on wall or

horizontal outlet box.

• Light-emitting diodes (LEDs) located on subbase for

easy reference.

• Up to three stages each of heating and cooling control

possible.

• Models with setpoint restrictions and locking cover

with no thermometer available for Department of Defense (DoD) and other special applications.

• Outdoor reset used on some models to improve

thermal performance.

Contents

Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Checkout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Understanding Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Cross Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

® U.S. Registered Trademark

Cop

60- 248

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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SPECIFICATIONS

IMPORTANT

The specifications given in this publication do not include normal manufacturing tolerances. Therefore, this unit may not exactly match the listed specifications. This product is tested and calibrated under closely controlled conditions, and some minor differences in performance can be expected if those conditions are changed.

Super Tradeline®/Tradeline® Models

SUPER TRADELINE controls offer features not available on TRADELINE or standard models, and are desi a wide range of Honeywell and competitive controls.

TRADELINE models are selected and packa ease of stocking, ease of handling, and maximum replacement value. Specifications of SUPER TRADELINE and TRADELINE controls are the same as those of standard models except as noted below.

Super Tradeline Models

T874 THERMOSTAT

T874D Thermostat. Provides two stages of heating and two

stages of cooling. Use with Q674A-F Subbases.

Y594D

Y594G

Y594R (T874R/Q674L) Thermostat/Subbase package for

T874D/Q674E/TG504A) Thermostat/Subbase/key lock cover packa two stages of cooling. Includes a key lock cover for setpoint protection.

T874G/Q674F) Thermostat/Subbase package for heat pump. Provides two stages of heating and one stage of coolin Available in bei

heat pump. Provides two sta of coolin able in beige or Premier White® color.

. Automatic changeover in heat or cool mode.

. Manual changeover in heat or cool mode. Avail-

e. Provides two stages of heating and

e or Premier White® color.

es of heating and one stage

ned to replace

ed to provide

Tradeline Models

T874 THERMOSTAT

• T874 TRADELINE models provide staged heat and/or cool operation. See Table 1.

Table 1. Heating and Cooling Stages.

Models ABCDEF

Heatin Coolin

• T874A-F are standard models.

TRADELINE FEATURES:

• TRADELINE packa

• T874A,C model available with factor

• T874A,C model available with ad

Q674 SUBBASE

Q674 switchin See Table 2.

Stages 1122— 2

Stages 12122—

e with cross reference label and

special instruction sheet.

stops for DoD

applications.

ustable temperature

locking stops.

subbases provide system and fan switching.

Table 2. System and Fan Switching.

Q674 System Fan

A Heat-Auto-Cool Auto-On B Heat-Off-Cool Auto-On C Off-Auto Auto-On D None None E Off-Heat-Auto-Cool Auto-On F Em. Ht.-Off-Heat-Auto-Cool Auto-On G Off-Auto None

J Em. Ht.-Auto-Off Auto-On

L Em. Ht.-Heat-Off-Cool Auto-On

SUPER TRADELINE FEATURES:

• SUPER TRADELINE packa and special instruction sheet.

• SUPER TRADELINE model supplied with lockin locking cover accessories.

• Includes ad

• T874D replaces T874A-F TRADELINE or standard models.

ustable temperature locking stops.

e with cross reference label

lever and

TRADELINE FEATURE:

• TRADELINE packa special instruction sheet.

• Q674A-E,G are standard Q674F,J,L are heat pump models.

e with cross reference label and

non-heat pump) models.

ORDERING INFORMATION

When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the TRADELINE® Catalo

ou have additional questions, need further information, or would like to comment on our products or services, please write or

If phone:

Your local Home and Buildin

Home and Building Control Customer Relations

well, 1885 Douglas Drive North

Hone

Minneapolis, Minnesota 55422-4386 In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9. International Sales and Service Offices in all principal cities of the world. Manufacturin German

60-2485—82

, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.

or price sheets for complete ordering number.

Control Sales Office (check white pages of your phone directory).

800) 328-5111

in Australia, Canada, Finland, France,

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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)

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)

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Standard Models

T874 THERMOSTATS

Models:

Electrical Rating:

Switching:

Temperature Adjustment:

Dimensions:

Temperature:

See Table 3.

24 to 30 Vac.

Coiled bimetal elements operate mercur

switches.

Heatin

and cooling setting levers, with separate scales located on top of thermostat base. Common lever for heatin one coolin

lever on T874E,V; and one heating lever on

and cooling on T874R;

T874F,Q.

See Fi

dard; optional ran

. 1.

Scale Ran

e: 42° to 88°F (6° to 31°C) stan-

es available.

THERMOSTAT MOUNTED

ON SUBBASE

FRONT

5-5/8 (143)

3/8 (10)

SIDE

Thermometer Range:

Changeover Differential:

and cooling (5°F [3°C] on T874W). Levers can be set

in apart for

reater separation.

42° to 88°F

6 to 31°C

4°F (2°C) minimum between heat-

Interstage Differential:

Standard Models: Mechanical differential is 1°F

0.6°C) between heating or cooling stages; operating differential is approximatel coolin

1.9°F (1°C) between stages in heating or

Special Models: See Table 3.

Finish:

Mounting Means:

Bei

e or Premier White® finish.

T874 Multista

e Thermostat mounts on

Q674 Subbase. Subbase mounts horizontall

on wall or outlet box. Mounts on vertical outlet box with optional 193121A Adapter Plate Assembl

SUBBASE

3-9/32 (83)

HEAT COOL

50 60 70 80

FAN

AUTO ON

50 60 70 80

OFF

EM. HT. HEAT AUTO COOL

1-7/8 (48)

2-3/16 (56)

Fig. 1. T874 Thermostat and Q674 Subbase dimensions in in. (mm).

Optional Specifications (T874 Only):

Temperature scale ran

and 75° to 90°F (24° to 32°C) cooling with stop; 44° to

7° to 20°C) heating, 80° to 86°F (27° to 30°C) cool-

68°F

es are 40° to 75°F (4° to 24°C) heat-

ing; 6° to 29°C (43° to 85°F) Celsius scale; 3° to 22°C (38° to 72°F

Nonad

and 26° to 32°C (78° to 90°F) cooling with stop.

ustable factory-added stop limits heating setpoint to 72°F (22°C) maximum and cooling setpoint to 78°F (26°C) minimum.

OEM customer personalization. Lockin

cover and locking lever (see Thermostat Accesso-

ries

Thermostat cover without thermometer.

ustable locking temperature stops.

e heat anticipation for first or second stage heat or both.

Volta

See Table 3.

cling on heating stage(s) for electric heat applications.

Fast c C815A Outdoor Thermistor for improved performance on

specified models.

1-1/2

(38)

3-1/2

(89)

FAN

AUTO ON

OFF

EM. HT. HEAT AUTO COOL

5-1/8 (130)

3-7/16

Thermostat Accessories:

Lockin

Cover and Locking Lever Assembly: Part no. 194559R with thermometer; 194559S without thermometer. See Fi

. 2. Includes cover, screws, and Allen wrench for locking cover. The screws must be used to assure proper operation.

ustable Lever Stop: Part no. 4074ECK; includes lever stop

and screws.

Universal Versa

plate, rin

uard™ Thermostat Guard: Includes wall-

base, guard cover, tumbler lock, two keys and optional Honeywell logo insert. Double-wall construction provides extra measure of tamper-resistance. Tamperresistant lock; ke locked position. Vents in

cannot be removed without being in

uard base allow airflow for optimum thermostat performance. See form 68-0104 for more information.

— TG511A1000: Clear cover. — TG511B1008: Opa — TG511D1004: Painted steel

ue cover.

off-white) cover. See

Fig. 2.

(87)

M5849

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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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Key Lock Cover: Part no. TG504A replaces existing T874

cover. Mounts on T874 base and covers thermostat set-

levers and subbase switches. Includes LED window

tlin and two ke

s. Should not be used with 193121A Adapter

— TG504A1025: Blank face, internal thermometer. — TG504A1033: External thermometer. See Fi

. 2.

Plate.

194559R Locking Cover

with Thermometer

Allen Wrench

TG504A1033 Key Lock

Cover with External

Thermometer

TG511D1004 Includes

Painted Steel Cover,

Opaque Base and Wallplate

Fig. 2. T874 Thermostat accessories.

Table 3. T874 Thermostat Specifications.

Anticipation

Models and Options Replaces Applications

T874A—Standard and TRADELINE®. — 72°F/78°F

22°C/26°C)setpoint

System Stages

Heat Cool Other Stage 1 Stage 2 Stage 1 Stage 2

T872A Standard 1 1 — 0.1-1.2A — 0-1.5A —

Heating (Adj) Cooling (Fixed)

stops with locking cover.

ustable anticipator set 0.4A.

— Ad

ustable locking temperature

— Ad

stops (TRADELINE®).

— 72°F/78°F

stops with lockin thermometer (for DoD

22°C/26°C) setpoint

cover, no

. T874B—Standard and TRADELINE. T872B Standard 1 2 — 0.1-1.2A — 0-1.2A 0-1.0A T874C—Standard and TRADELINE.

— 72°F/78°F

with lockin

for DoD

— 12°F

H1 and H2 sta

— Fast c

22°C/26°C)set stops cover, no thermometer

7°C) differential between

es (T874C1125).

cling. 0.12-

T874D—Standard and SUPER

T872C Standard 2 1 — 0.1-1.2A 0.1-1.2A 0-1.5A —

0.12-

0.6A

T872D Standard 2 2 — 0.1-1.2A 0.1-1.2A 0-1.2A 0-1.0A

TRADELINE®.

ustable locking temperature

— Ad

SUPER TRADELINE).

stops T874E—Standard and TRADELINE. T872E 2-Stage Cool — 2 —— —0-1.2A 0-1.0A T874F—Standard and TRADELINE.

— Lockin

Department of Defense.

Changeover stage operates with heating.

Fixed voltage type anticipation.

Changeover stage operates with heating; a secondary changeover is provided in cooling switch.

Provides night setback used with standard T874 and timer-operated remote switching.

Manual changeover stage—use Q674B,L subbase.

Changeover stage operates with cooling.

cover.

T872F 2-Sta

Q674 Subbases

e Heat 2 ——0.1-1.2A 0.1-1.2A ——

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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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gray

(89)

(8)

— Fast c

T874G—Heat pump, cool chan

cling. Electric Heat 0.12-

eover, with fast cycling.

T872G Heat Pump or

Standard

0.6A

0-1.0A

0.12-

0.6A

0.1-1.2A 0-1.0A —

— Fixed anticipator for H2. 0.1-1.5A — Fast c

cling. 0.12-

0.6A

T874H—Use with Q674C. T872H Heat Pump or

Standard

T874J—Heat pump. None Heat Pump 2 1 T874K—Heat pump. None Heat Pump 2 1

0-1.0A

— 0-1.0A —

0-1.0Ae0-1.5Ac0-1.0A

0.1-1.2A

0-1.5A

0-1.5A —

—

T874L—Heat pump. None Heat Pump 2 1 — 0.1-1.2A 0.1-1.2A 0-1.5A — T874N—Heat pump, heat

eover.

chan

T872N Heat Pump 2 1

0.1-1.2A 0.1-1.2A 0-1.0A —

T874P—Heat pump. None Heat Pump 2 1 — 0.1-1.2A 0.1-1.2A 0-1.5A — T874Q—Ni

ht setback heating. T872Q Standard T874R—Heat pump. T872R T874S—Two-speed compressor heat

None Heat Pump 2 2

pump.

Heat Pump

21—

——0.1-1.2A ———

0-1.5A 0-1.2Ac0-1.2A

0.1-1.2A 0-1.5A —

0-1.2A 0-1.0A

T874V—Standard. None Standard — 1 —— —0-1.5A — T874W—Heat pump and standard.

ht setback heating.

— Ni

Department of Defense.

Changeover stage operates with heating.

Fixed voltage type anticipation.

Changeover stage operates with heating; a secondary changeover is provided in cooling switch.

Provides night setback used with standard T874 and timer-operated remote switching.

Manual changeover stage—use Q674B,L subbase.

Changeover stage operates with cooling.

T872W Heat Pump or

Standard

Q674 Subbases

32—

0-1.2A

c,d

0-1.2A 0-1.0A

Models:

See Table 4.

Mounting:

Designed to mount horizontally on an outlet box or the wall. Adapter plate assembl on a vertical outlet box

see Subbase Accessory).

available for mounting

Electrical Ratings:

Switch Contacts: 2.5A at 30 Vac LED Li

Switches:

no switches on Q674D

hts (Optional): 30 Vac.

Two slide switches

operated by levers. Switch position

7.5A inrush).

one switch on Q674G and K;

Finish:

Dark brown or

Dimensions in in. (mm):

5/16

depth. See Fig. 1.

3-1/2

height; 5-5/8 (143) width;

is shown on scaleplate.

Table 4. Q674 Subbase Specifications.

Switch Positions

Models and Options Replaces Application

Q674A—Standard and TRADELINE®.

Q672A Standard HEAT-AUTO-COOL AUTO-ON T874A-D

Use WithSystem Fan

— Indicator LEDs. Q674B—Standard and TRADELINE. Q672B Standard HEAT-OFF-COOL AUTO-ON T874A-D — Provision for fan rela

operation from Heat Pump T874G,H,L,R

external fan switch (isolate G terminal). OVERRIDE-HEAT- AUTO-ON T874P — Indicator LEDs. OFF-COOL Q674C—Standard and TRADELINE. Q672C Standard OFF-AUTO AUTO-ON T874A-H,W — Indicator LEDs. Heat Pump OVERRIDE-AUTO- AUTO-ON T874K,L,N

OFF T874P

Q674D—Standard and TRADELINE. — For use when subbase switchin

uired.

is not

Q672D Standard None None T874A-F

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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Q674E—Standard and TRADELINE. Q672E Standard OFF-HEAT-AUTO-

AUTO-ON T874A-D

COOL

Q674F—Two LED models. — EM.HT. li

ht.

— Provision for AUTO fan operation in

EM.HT.

Q672F Heat Pump OFF-EM.HT.-HEAT-

AUTO-COOL

OFF-COOL-AUTO-

HEAT-EM.HT.

AUTO-ON T874C,D,G,N,S

AUTO-ON

Q674G—O and B terminals. Q672G Standard OFF-AUTO None T874A-F Q674J—Provision for AUTO fan operation Q672J Heat Pump EM.HT.-AUTO-OFF AUTO-ON T874A,D,G,J in EM.HT. EM.HT.-ON-OFF AUTO-ON — Provision for outdoor thermistor. SUPL.HT.-ON-OFF AUTO-ON Q674K—Standard. Q672K Standard OFF-HEAT-AUTO-

None T874F

COOL

OFF-WOOD-WOOD/

None

OIL-OIL

Q674L—Provision for AUTO fan operation in EM.HT.

— Indicator LEDs. SUPL.HT.-HEAT-

Q672L Heat Pump EM.HT.-HEAT-OFF-

COOL

AUTO-ON T874R,W

AUTO-ON

OFF-COOL

Q674N—Standard. Q672N Evaporative

Cooler

Q674P—Standard. Q672P Heat Pump SUPL.HT.-HEAT-

EVAP-COOL-OFF-

HEAT

AUTO-ON T874C

AUTO-ON T874G

COOL

Q674Q—Standard. None Fan Coil HEAT-OFF-COOL LO-MED-HI-

T874A

Q674R—Standard. — International s

mbols.

None Fan Coil OFF-COOL LO-HI-

CONT.

T874V

Q674S—Indicator LED. None Standard HEAT-COOL None T874C

Optional Specifications (Q674 Only):

Models available with up to four LEDs; for example, LEDs can

show EM. HT, AUX. HT, SERVICE, CHECK, FILTER, and LOCKOUT. See Fi

stem switching marked HEAT-OFF/RESET-COOL for sys-

. 3.

tems requiring impedance relay reset. Available on Q674B

onl

G terminal isolated on heatin

to provide fan relay operation

from external low voltage fan switch (Q674B only).

Auto fan operation on both heat and cool.

T874 Thermostat with

One Setpoint Lever

T874 Thermostat with

Separate

Heatin

and Cooling Levers

Fig. 3. Heating, cooling levers and system LED indicators.

L terminal is used for s Common R terminal for heatin

stem monitoring devices.

/cooling. Changeover in cool or heat mode for heat pumps. Auto fan in EM.HT. for heat pumps.

Subbase Accessory:

mountin rin

on vertical outlet box. Assembly includes adapter

and cover plate. Use to cover wall marks from

193121A Adapter Plate Assembl

replaced thermostat.

Q674 Subbase

with Four LEDs

for

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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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M6009

VERTICAL OUTLET BOX

ADAPTER RING

COVER PLATE

MOUNTING SCREWS (2)

SUBBASE

SUBBASE MOUNTING SCREWS (2)

HORIZONTAL OUTLET BOX

1 NOT INCLUDED WITH UNIT.

2 ACCESSORY PART AVAILABLE (193121A).

THERMOSTAT

CAPTIVE MOUNTING SCREWS (2)

THERMOSTAT COVER

MERCURY NOTICE

This control contains mercury in a sealed tube. Do place control in the trash at the end of its useful life.

If this control is replacin mercur

in a sealed tube, do

in the trash.

Contact

our local waste management authority for instructions regarding recycling and the proper disposal of this control, or of an old control containin mercur

in a sealed tube. If you have questions, call the Honeywell Customer Response Center at 1-800-468-1502.

INSTALLATION

When Installing this Product…

Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.

Check the ratin product is suitable for your application.

Installer must be a trained, experienced service technician.

After installation is complete, check out product operation as provided in these instructions.

a control that contains

not

place your old control

iven on the product to make sure the

not

— concealed pipes and chimne — unheated

uncooled) areas such as an outside wall behind

the thermostat.

Mount Subbase

The subbase can be mounted on a vertical outlet box, horizontal outlet box or directl

If the subbase is mounted on a vertical outlet box, order

well part no. 193121A Adapter Assembly. See

Hone

. 4. The assembly includes an adapter ring, two

Fi screws and a cover plate to cover marks on the wall. Install the rin

and cover plate on the vertical outlet box.

NOTE: For a wall installation, hold subbase in position and

mark holes for anchors. See Fi must be obtained from local hardware store. Be careful that the wires do not fall back into the wall openin 3/16 in.

. Set aside subbase. Drill four

4.8 mm) holes and gently tap anchors into

the holes until flush with the wall.

Pull wires throu

h the cover plate (if used) and subbase

cable opening. See Fig. 6.

Secure the cover plate screws provided. Do not full screws.

Level the subbase usin

hten subbase mounting screws. The subbase mounting

ti holes provide for minor out-of-level adjustments.

on the wall.

. 5. Wall anchors

if used) and subbase with the

tighten the subbase

a spirit level, see Fig. 7, and firmly

CAUTION

Hazardous Voltage. Can damage heating/cooling system.

1. Disconnect power suppl lation to prevent electrical shock or equipment dama

2. Do

IMPORTANT

Location

Install the thermostat about 5 ft (1.5m) above the floor in an area with

Do not mount the thermostat where it can be affected b — drafts or dead spots behind doors, in corners or under

cabinets.

— hot or cold air from ducts. — radiant heat from the sun, fireplace, or appliances.

can burn out thermostat heat anticipator.

3. To prevent interference with the thermostat linka as close as possible to the subbase.

4. Do screws because dama result.

An incorrectly leveled thermostat will cause the temperature control to deviate from setpoint. It is not a calibration problem.

ood air circulation at average temperature.

before beginning instal-

not

short across coil terminals on relay. This

e, keep wire length to a minimum and run wires

e to subbase threads can

not

overtighten thermostat captive mounting

Fig. 4. Installing Q674 Subbase on outlet box.

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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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WALL

WIRES THROUGH WALL OPENING

WALL ANCHORS (2)

M926

SUBBASE

MOUNTING HOLES

MOUNTING SCREWS (2)

Fig. 5. Installing Q674 Subbase on wall.

All wiring must comply with local electrical codes and ordinances.

IMPORTANT

Use 18 gauge, solid-conductor wire whenever possible. If using 18 gauge stranded wire, no more than 10 wires can be used. Do not use larger than 18 gauge wire.

Follow equipment manufacturer wiring instructions when available. To wire subbase, proceed as follows:

Connect the s the applicable dia each terminal for identification. T

stem wires to the subbase as shown in

ram. A letter code is located near

pical terminal designation and wiring connections are listed in Table 5. The terminal barrier permits strai connection. See Fi

. 7. The subbase can require one or

ht or wraparound wiring

more jumpers that may or may not be factory-supplied. See Fi to be

. 8 and the wiring diagrams for specific terminals

umpered.

SPIRIT LEVEL

POST FOR MOUNTING THERMOSTAT (2)

MOUNTING HOLES (4)

WIRING TERMINAL

THERMOSTAT CABLE OPENING

TO SPRING FINGER CONTACTS ON THE THERMOSTAT

UP TO 12

M927

Fig. 6. Subbase components and leveling procedure.

Wire Subbase

Disconnect power supply before beginning installation to prevent electrical shock or equipment damage.

FOR STRAIGHT INSERTION STRIP 5/16 IN. (8 MM)

–

SUBBASE TERMINAL SCREW

BARRIER

FOR WRAPAROUND–

STRIP 7/16 IN. (11 MM)

Fig. 7. Barrier configuration.

CAUTION

Equipment Damage Hazard.

Never install more than one wire per terminal unless

factory-supplied jumper with spade terminal.

usin

Firml

tighten each terminal screw. Fit wires as close as possible to the subbase. Push excess wire back into the hole.

hole with nonflammable insulation to prevent drafts

Plu from affecting the thermostat.

M928

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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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JUMPER WIRE (SUPPLIED WITH SOME MODELS)

1 TWO ADJACENT TERMINALS SHOWN JUMPERED ARE FOR EXAMPLE ONLY. COMPARE WIRING DIAGRAM AND SUBBASE TO IDENTIFY TERMINALS TO BE JUMPERED.

M5899

Fig. 8. Jumper adjacent terminals for special system hookup using stripped wire 3/4 in. (19 mm).

For nonadjacent terminals and using jumper wire supplied with subbase.

Standard Terminal

Designation

BHeatin EKEmer

Table 5. Terminal Designations

Alternate Designations or

Customer Specials Typical Connection

damper motor; changeover valve

ency heat rela

G F Fan relay coil

LS ORCoolin R V Power connection to transformer

stem monitor

damper motor; changeover valve

internally connected for heating

and coolin RC Power connection to cooling transformer RH Power connection to heating transformer W1 H1, R3 Sta W2 H2, Y, R4 Sta W3

e 1 heating control e 2 heating control

e 3 heating control

Sta

Y1 C1, M Stage 1 cooling control Y2 C2 Sta Y3 Sta

XX1,X2,CClo

e 2 cooling control e 3 cooling control

ed filter switch or common connection

T A Outdoor thermistor

L, C, H HSII control panel

PDefrost

O Momentar

circuit, changeover

A, A1, A2, Z, C, L LEDs

Other terminal designations can be used that are not listed on this table. Refer to the hookup drawing and internal schematic for exact connections.

W3 controls the auxiliary heat like W2, and allows adding additional stages of auxiliary heat with outdoor thermostats while maintaining the proper second stage anticipation.

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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

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Standard Terminal

Designation

Table 5. Terminal Designations

Alternate Designations or

Customer Specials Typical Connection

T External temperature readout, T rela

R1, R2 LO and HI speed fan relays

RS Cooling contactor

Y M Compressor contactor

Other terminal designations can be used that are not listed on this table. Refer to the hookup drawing and internal schematic for exact connections.

W3 controls the auxiliary heat like W2, and allows adding additional stages of auxiliary heat with outdoor thermostats while maintainin

Outdoor Disconnect

The National Electrical Code requires the installation of a disconnect switch w conditioner or heat pump. The switch is for the safet technician working on the unit. The technician can assure that the unit

Install and Adjust Stop Brackets

The stop brackets should be installed only if there is a need to restrict the adjustable range of the heating and cooling temperature setpoint levers. If ad desired, order 4074ECK Envelope Assembl two adjustable lever stop brackets, one brass insert, one

the proper second stage anticipation.

ithin

sight of the outdoor unit of an air

remains

unpowered.

ustable lever stops are

of any

, which contains

mounting screw and two locking screws with insulated heads. When installed, the stop brackets limit the movement of the T874 HEAT and COOL levers.

TO INSTALL:

Remove the thermostat cover b ed

e of the cover upward until it snaps free of the

mountin

Turn to the back of the T874 Thermostat. Locate the

slots.

pulling the bottom

hole for the brass insert in the plastic base below the LED window.

Push the brass insert into the hole with fin

Turn to the front of the T874 Thermostat.

Place the two stop brackets in position with the tabs in

er.

the slot between the HEAT and COOL levers. See

. 9.

HEAT LEVER

ADJUSTABLE LEVER STOP BRACKETS

HOLES FOR INSULATED LOCKING LEVER SCREWS

COOL LEVER

BRACKET SLOTS

ADJUSTABLE STOPS

Fig. 9. Range limiting and lever locking methods.

HOLE WITH BRASS INSERT

BRACKET TABS

MOUNTING SCREW

ADJUSTABLE LOCKING LEVERS

NONADJUSTABLE STOPS WITH LOCKING LEVER SCREWS 75°F (24°C) MAX. HEAT 75°F (24°C) MIN. COOL

NONADJUSTABLE D.O.D. STOPS 72°F (22°C) MAX. HEAT

26°C) MIN. COOL

78°F

M7626

Insert the mountin brackets and attach to the brass insert. Ti screw to pull the brass insert into the back of the ther-

60-2485—810

screw into the two slots in the stop

hten the

mostat.

Loosen the mountin brackets for ad

screw enough to free the stop

ustment.

(

(s)

CAUTION

ALLEN RETAINING SCREWS (2)

M956

Move the HEAT and COOL levers to the maximum temperature desired.

Slide the stop brackets until one rests a lever and the other a

10.

11.

tighten the mounting screw.

Firml If the HEAT and COOL levers are to be locked in place at a specific temperature, use the two insulated head screws supplied instead of the two ad brackets.

ainst the COOL lever.

ainst the HEAT

ustable lever stop

CAUTION

Equipment Damage Hazard.

not

use standard screws that provide metal-to-

Do metal contact with the stop brackets. Short circuit and potential e

uipment damage can result.

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Mount Thermostat

Remove the thermostat cover by pulling the bottom edge of the cover away from the base until it snaps free of the cover clip.

NOTE: The cover is hin

pulling up at the bottom.

Carefull insert that protects the mercur ment. If LED indication with the Q674 Subbase, install the preprinted insert under the thermostat setpoint scale. To install, push both thermostat setpoint levers to the far ends of the thermostat. Use index fin setpoint scale about 1/4 in. (6 mm). Position the desired preprinted insert in the space above the LED li Reposition setpoint levers. Turn over the thermostat base and note the sprin

ers that engage the subbase contacts. Make sure the sprin trical contact with the subbase. Set the heat anticipator indicator current settin pator section. If the thermostat provides optional lockin bl wrench provided. See Fig. 10. Note the two tabs alon mostat base. The tabs fit into correspondin of the subbase. Mount the thermostat on the subbase. Ali base with the posts on the subbase. Ti screws. base posts can result.

remove and discard the polystyrene packing

fingers are

, start the Allen locking screws in the cover with the

n the two captive mounting screws in the thermostat

Do not overtighten screws

ed at the top and must be removed

switches during ship-

EM.HT., CHECK, etc.) is to be used

er to gently pull out the plastic

not

bent flat, preventing proper elec-

of each stage. See Set The Heat Antici-

the top inside edge of the ther-

to the respective

cover assem-

hten both

or damage to sub-

hts.

fin-

slots on top

Fig. 10. Installation of locking cover assembly.

SETTINGS

Equipment Damage Hazard.

stems using a gas valve, never apply a jumper

On s across the valve coil terminals, even temporaril can burn out thermostat heat anticipator(s).

Set the Heat Anticipator

Move the indicator to match the primary control current draw. When usin set each heat anticipator to match its respective primary control current draw. If the primar NOTE and use the following procedure to determine the current draw of each sta

The current draw of each heatin with the thermostat removed and power on to the heatin

stem.

a T874 Thermostat with two stages of heating,

control, or if further adjustment is necessary, see

Connect an ac ammeter of appropriate ran the heatin a. Sta b. Sta c. Sta Move the s After one minute, read the ammeter and record the readin a. Sta b. Sta c. Sta

e 1—between W1 and RH or R; e 2—between W2 and RH or R e 3—between W3 and RH or R.

e 1—__________A; e 2—__________A; e 3—__________A.

ou cannot find the current rating on

stage must be measured

terminals of the subbase:

stem switch to HEAT or AUTO.

. This

e between

NOTE: If e

11 60-2485—8

uipment cycles too fast, set the indicator to a

her current rating, but not more than one-half divi-

hi sion at a time, and recheck the cycle rate. Most conventional two-sta to operate at three c one-stage heating equipment at six cycles per hour, at 50 percent load conditions. When usin Thermostat in heat pump s

e heating equipment is designed

cles per hour per stage, and

the T874

stems, set the heat

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

g sy

anticipator at 140 percent of the actual primary control current draw to reduce the c

cling rate. See Fig.

11.

Most heat pump s

Han the thermostat base and swin

stems should cycle 2-1/2 to 3 times per hour.

the upper edge of the thermostat cover on top of

the cover downward

until it engages with the cover clip.

STAGE ONE

.15

ANTICIPATOR HEATING CONTROL

M5069

STAGE TWO ANTICIPATOR HEATING CONTROL

.12

1.2

.12

.15

1.2

MOVE INDICATOR TO MATCH CURRENT RATING OF PRIMARY CONTROL

Fig. 11. Adjustable heat anticipator scales.

Temperature Setting

Move the heating and cooling levers to the desired comfort positions. See Fig. 12. On some models with two stages of

or cooling, the same lever controls both stages. The

heatin minimum differential between heatin 4°F (2°C) (5°F [3°C]) on T874W.

If model has optional screws to lock temperature control levers, loosen these screws before makin

ustment; tighten the screws when levers are set at desired

ad position.

and cooling setpoints is

temperature

Subbase Setting

The subbase switching positions control the system operation as described below.

SYSTEM SWITCH

OFF—both the heatin

fan switch is at the AUTO position, the cooling fan is also off.

HEAT—heatin

thermostat. Cooling system is off.

AUTO—thermostat automaticall

and cooling system operation, depending on the

in indoor temperature.

COOL—coolin

thermostat. Heatin

EM.HT.—emergency heat relay is automatically controlled

the thermostat. Cooling system is off. Compressor is

b de-ener

SUPL.HT.—supplemental heat relay is energized. Cooling

stem is off. Compressor is de-energized.

WOOD—heatin

burning stage.

OIL—heatin

sta

WOOD/OIL—wood and oil stages operate sequentially;

first the WOOD sta operates if the WOOD sta

EVAP—controls cooling system by water evaporation; see

uipment instructions for further information.

e OVERRIDE—ni ON—heating system is controlled by the thermostat. EM.

HT. or SUPL. HT. rela

FAN SWITCH

ON or CONT.—fan operates continuousl AUTO—fan operates as controlled b

heat pump s

operates as controlled by the plenum switch in conven-

tional heatin LO—fan operates constantl MED—fan operates constantly at medium speed. HI—fan operates constantl

see subbase for positions):

and cooling systems are off. If the

stem is automatically controlled by the

changes between heat-

stem is automatically controlled by the

stem is off.

ized.

stem is operating with only the wood-

stem is operating with only the oil-burning

e operates, then the OIL stage

e cannot handle the load.

ht setback is disabled.

is not energized.

positions control fan operation as follows:

the thermostat in

stems or conventional cooling mode; fan

mode.

at low speed.

at high speed.

STAGE 1 HEATING

STAGE 3 HEATING

HEATING LEVER

COOLING LEVER

STAGE 1 COOLING

To move the subbase switches to the desired control positions, use thumb and index fin

er to slide the lever. The lever must stop over desired function indicator position for proper circuit operation.

return momentary position switching feature is

Sprin available on selected subbase models. On these models, the fan switch is positioned to the ri

the fan switch to the far right and releasing it, the ON

movin position circuit makes. The lever sprin

ht of the system switch. By

s back on release. This

position is not marked on the subbase.

Setting the Adjustable Differential

The adjustable interstage differential feature, on a selected

STAGE 2 HEATING

STAGE 2 COOLING

CAPTIVE MOUNTING SCREWS (2)

M7625

Fig. 12. Internal view of T874W (three stages of

heating, two stages of cooling).

60-2485—812

T874D model only, can be identified by the scale and tension screw near the heatin

. 13. On this model, the number of degrees between the

and cooling mercury switches. See

making of the first and second stage mercury bulbs is

ustable. This feature is especially useful if the first stage

ad controls the comfort temperature, and the second sta controls the energy savings temperature. Timers, such as the S6005, for insertion between the first and second sta control points must be ordered separatel

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

CAUTION

(

CAUTION

(

Each mark on the scale represents 1°F (0.6°C) The differential is factor

set at 2°F (1°C) the differential can be set as high as 12°F (7°C) To set the adjustable interstage differential, loosen the tension screw. See Fi

ustable scale to align with the number of degrees desired

. 13. Slide the

between stages. Use the lower edge of the tension screw bracket as a

wider

apart for a

smaller

larger

for a While supportin

uide for alignment. In heating, slide the lever

larger

differential, or

closer

differential. In cooling, slide the lever

differential, or

wider

apart for a

smaller

the scale with hand, tighten the tension screw.

together for a

closer

together

differential.

IMPORTANT

Support the scale with hand while tightening tension screw. See Fig. 13. Failure to do so can result in twisting and damaging bimetal coil.

HEATING SETPOINT LEVER

TENSION SCREW

SCALE

HEATING

HEAT

50 60

1.2

SECOND STAGE (ADJUSTABLE) SWITCH

70 80

FIRST STAGE SWITCH

Equipment Damage Hazard.

When the thermostat is used to control a two-sta

or cooling system, the second stage mercury

heatin

bulb must never make before the first stage bulb, or severe e this problem, provide at least 2°F

uipment damage could result. To prevent

1°C) differential between stage-one and stage-two make points. Example: in heatin

e-two should make at 68°F (20°C) or lower.

sta

, if stage-one makes at 70°F (21°C)

Verify the Adjustment

Heating

Start with the heating setpoint lever all the way to the left. Slowly move the lever to the right, just until the first stage bulb makes settin ri the temperature scale. The difference between the two temperatures is the the number set on the scale with the tension screw.

Cooling

Start with the cooling setpoint lever all the way to the right. Slowl makes setting on the temperature scale. Slowly move the lever to the left until the second sta temperature scale. The difference between the two temperatures is the the number set on the scale with the tension screw.

mercury rolls to the right side of the bulb). Note the

on the temperature scale. Slowly move the lever to the

ht until the second stage bulb makes. Note the setting on

interstage differential,

which should match

move the lever to the left, just until the first stage bulb

mercury rolls to the left side of the bulb). Note the

e bulb makes. Note the setting on the

interstage differential,

which should match

TENSION SCREW

ALIGN LOWER EDGE WITH SCALE

NOTCH 10°F

SCALE

COOLING

TENSION SCREW

ALIGN LOWER EDGE WITH SCALE

NOTCH 4°F

SCALE

1 EACH MARK ON THE SCALE REPRESENTS 1°F (0.6°C).

SLIDE LEVER WIDER APART FOR LARGER DIFFERENTIAL

SLIDE LEVER CLOSER TOGETHER FOR LARGER DIFFERENTIAL

M937

Fig. 13. Set adjustable interstage differential.

CHECKOUT

Heating

Move the system switch on the Q674 Subbase to HEAT or AUTO. Move the heat lever on the T874 about 10°F above room temperature. See Fi start and the fan should run after a short dela lever about 10°F

uipment should shut off, and the fan should run for a short

6°C) below room temperature. The heating

. 12. Heating system should

. Move the heat

time, then shut off.

In heat pump applications, sometimes time dela involved before the compressor and auxiliary heat are activated. This is due to a minimum-off timer, which prevents the compressor from restartin

for five minutes from when the

thermostat last turned off the compressor, or from when the

stem first received power.

Cooling

Equipment Damage Hazard.

Do not operate cooling if outdoor temperature is below

10°C). Refer to manufacturer recommendations.

50°F

6°C)

s are

13 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

g eq

y by

(

)

Move the system switch on the Q674 Subbase to COOL or AUTO. Move the cool settin

lever on the T874 Multistage

Thermostat about 10°F (6°C) below room temperature. See

. 12. The cooling equipment and fan should start. If the

stem has two stages of cooling, both stages should start.

s Move the cool lever about 10°F (6°C) above room temperature. The coolin

uipment and fan should stop.

Fan

Move the system switch to COOL, OFF, or AUTO. If necessary, position both temperature setting levers so that the

and cooling equipment are off. Move the fan switch to

heatin ON or CONT. The fan should run continuousl

. When the fan switch is in AUTO, LO, MED, or HI position, fan operation is controlled b

the heating or cooling system.

Outdoor Reset Thermistor (Where Applicable)

If the system is supplied with a thermistor, it must be used; if not used, thermostat performance deviates radicall proper operation.

The proper thermistor operation must be verified to ensure the correct operation of the thermostat. Check thermistor operations as follows:

Disconnect the T wire on the subbase.

Use an ohmmeter to measure resistance between the T wire and the A subbase terminal.

Take outdoor temperature at thermistor location and find the correct thermistor resistance on the Fi

If the resistance measured in step 2 and the calculated resistance in step 3 var thermistor re

uires replacement. Contact Honeywell or

more than 15 percent, the

installing dealer for replacement packaged outdoor thermistor, part no. C815A1005.

from

. 14 chart.

Thermometer

The thermometer in your thermostat has been accurately calibrated at the factory. The thermometer should only need

ustment if it has been dropped or shifted due to mishandling.

If the setpoint lever and the thermometer readin

ree, use the following procedure:

Remove the thermostat cover b

pulling up from the bottom edge of the cover away from the base until it snaps free of the cover clip.

Set the thermostat cover on a table near an accurate thermometer.

Allow ten minutes for cover thermometer to sense area temperature; compare the readin

s. Be careful not to

touch thermometer or breathe on it.

If the readin

stem into operation.

If the readings are different, insert a small screwdriver in

s are the same, replace cover and put the

the thermometer slot and turn it until the thermometers have the same readin

Replace thermostat cover and put the system into oper-

. See Fig. 15.

ation.

do not

4600 4400 4200 4000 3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400

THERMISTOR RESISTANCE (ohms)

1200 1000

800 600 400 200

-20 0 20 40 60 80 100 120 140

C815A THERMISTOR RESISTANCE R = 400 ohms ± 10% AT 77°F (25°C)

TEMPERATURE OF THERMISTOR (°F

M1590A

Fig. 14. Thermistor resistance chart.

CALIBRATION

Thermostat

T874 Thermostats are accurately calibrated at the factory.

They do not have provision for field calibration.

M5070

Fig. 15. Thermometer calibration.

UNDERSTANDING CIRCUITS

To understand wiring diagrams, it is important to know what all the symbols mean and how to trace the path of the circuits from the transformer. See Fi

Circuit descriptions and terminolo For standard heatin

Auto chan

-cooling circuits:

eover—refers to the presence of an AUTO position in the system switching (EX: Q674E with OFFHEAT-AUTO-COOL switchin maticall

changes between heat and cool modes as

indoor temperature changes.

Manual chan

to chan

eover—requires a system switch movement

e mode (EX: Q674B with HEAT-OFF-COOL switching). T874D Multistage Thermostats with 2 heat or 2 cool switches are shown on most standard circuits. Most standard or TRADELINE® subbases can be used with T874A-F standard or TRADELINE

. 16 through 25.

are defined as follows:

. The thermostat auto-

Q674A-E,G)

60-2485—814

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

M5848

KEY TO HOOKUP SYMBOLS

TRANSFORMER (24 VAC SECONDARY)

RELAY/CONTACTOR CONTACTS

LED

RELAY OR CONTACTOR COIL

MERCURY SWITCH

FIXED ANTICIPATOR HIGH RESISTANCE (TYPICALLY 5 KILOHMS)

ADJUSTABLE ANTICIPATOR LOW RESISTANCE (TYPICALLY 0 TO 5 OHMS)

TERMINAL

ODT

OUTDOOR THERMOSTAT

EHR

EMERGENCY HEAT RELAY

RTD

TIME DELAY RELAY

DEFROST RELAY

CHP

PRESSURE SWITCH

LACO

LOW AMBIENT CUTOFF

thermostats. The schematics can be field-modified as

uired (EX: if T874C is being used, eliminate second

re stage of heat).

For heat pump circuits:

Cool chan

eover valve—operates on cooling. The reversing valve or relay is activated either by moving the system switch to COOL mercur

switch that makes on a temperature rise (auto

manual changeover) or by a

changeover).

Heat chan

eover valve—operates on heating. The revers-

valve or relay is activated either by moving the system switch to HEAT (manual changeover) or by a mercur chan

switch that makes on a temperature fall (auto

eover).

System monitor relay—optional equipment on some heat

pumps includes an R4222P1065 or e

stem monitor relay detects a malfunction in the com-

uivalent. This

pressor and indicates the malfunction by activating the EMERGENCY HEAT LED on the Q674 Switchin base. The s

stem monitor relay is usually wired into the

L terminal on the Q674.

Each mercur

H1—Sta

switch is identified by function:

e 1 Heating. H2—Stage 2 Heating. H3—Sta C1—Sta

e 3 Heating.

e 1 Cooling. C2—Stage 2 Cooling. C3—Sta C/O—Chan

e 3 Cooling.

eover (heat pumps).

Sub-

perature rise. Fixed anticipation is represented b

line and adjustable anticipation is a zigzag with an

a zig-

arrow. The resistance of the fixed anticipator is so large it limits current so that a s in from a circuit path

stem relay cannot be pulled

oing through the fixed anticipator. The relay can be pulled in through an adjustable anticipator because its resistance is

The center portion

the subbase) contains the switches.

enerally 0 to 5 ohms.

The fan switch is above the system switch. The small circles on the switch represent the maximum possible contacts available on the Q674 Subbase. The lar

er circles represent the switch positions available on this particular Q674, with the solid circle representin is actuall

switched on the diagram.

NOTE: Solid circles are not interconnected electricall

At the ri

ht, the relays and contactors are shown, attached to the proper terminals. The terminals are represented b circles with terminal desi

nations in capital letters. See Table

where it

large

3 for the meaning of each lettered terminal.

Sometimes power for a fixed anticipator is brou

ht through an off system relay like the changeover relay shown in Fig. 20. This current is kept low b anticipator so that rela

the high resistance of the fixed

does not pull in.

Each anticipator is identified and each switch affected is named

All T874 Multista schematic indicates switch operation b open position with an arrow indicating operation with a temperature RISE or FALL.

One circuit has been selected that is t used with heat pumps. This circuit has been traced to illustrate the functions performed b

Tracing Method:

EX: H1 anticipator, C1 anticipator).

e Thermostats use mercury switches. Each

being drawn in the

pical of various models

these control systems.

Alwa

s begin at the system transformer or R terminal. You ma switch position to aid in tracin

want to draw the switch contacts in each

. Colored pencils are helpful when only one copy of the circuit is available. See Fi Fi Completel heat or cool Connections are indicated b intersection. If there is no dot, there is no connection. The left portion of the circuit the mercur temperature fall, and the cool switches make on a tem-

. 16 for a description of the hookup symbols and

. 17 through 25 for typical hookups.

trace only one circuit at a time (for example:

switches. The heat switches make on a

small dots at the point of

the thermostat) contains

Fig. 16. Key to hookup symbols.

15 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT

H1/C1 ANTICIPATOR

FALL

H2 ANTICIPATOR

FALL

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

AUXILIARY HEAT LED AVAILABLE ON SOME MODELS.

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

OFF

COOL

SUBBASE

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

RTD 1 EHR 1

ODT 2

EHR 2 RTD 3

COOL CHANGEOVER VALVE

COMPRESSOR CONTACTOR

(HOT) L1

RTD 2

RTD 1

FAN RELAY

EM. HT. RELAY

CHP

M5072A

Fig. 17. Internal schematic and typical hookup of a T874R Thermostat and Q674L Subbase in a heat pump application.

The thermostat provides two-stage heating and one-stage cooling manual changeover operates on cooling.

60-2485—816

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT

H1/C1

H2 ANTICIPATOR

ANTICIPATOR

FALL

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

SUBBASE SYSTEM COMPONENTS

SYSTEM MONITOR

LACO

RTD 1 EHR 1

RTD 1

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

OFF

COOL

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

ODT 1

ODT 2

EHR 2 RTD 3

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

(HOT)

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

M5840

Fig. 18. Tracing the changeover relay circuit.

THERMOSTAT SUBBASE

H1/ C1 ANTICIPATOR

FALL

H2 ANTICIPATOR

FALL

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

COOL

OFF

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

RTD 1

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

EHR 1

ODT 2

EHR 2 RTD 3

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

L1 (HOT)

M5841

Fig. 19. Tracing the heat 1 and anticipation circuit.

17 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT SUBBASE

H1/ C1 ANTICIPATOR

FALL

H2 ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

OFF

COOL

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

RTD 1 EHR 1

ODT 2

EHR 2 RTD 3

RTD 1

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

L1 (HOT)

M5842

Fig. 20. Tracing the heat 1 anticipation circuit.

THERMOSTAT SUBBASE

H1/C1 ANTICIPATOR

FALL

H2 ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

OFF

COOL

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

RTD 1 EHR 1

ODT 2

EHR 2 RTD 3

RTD 1

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

M5843

L1 (HOT)

Fig. 21. Tracing the heat 2, anticipation and AUX. HT. LED circuit.

60-2485—818

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT SUBBASE

H1/C1 ANTICIPATOR

FALL

H2 ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

OFF

COOL

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

RTD 1 EHR 1

ODT 2

EHR 2 RTD 3

RTD 1

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

M5844

L1 (HOT)

Fig. 22. Tracing the emergency heat and EM. HT. LED circuit.

THERMOSTAT SUBBASE

H1/C1 ANTICIPATOR

FALL

H2 ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

COOL

OFF

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

RTD 1 EHR 1

ODT 2

EHR 2 RTD 3

RTD 1

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

L1 (HOT)

M5845

Fig. 23. Tracing the cooling circuit.

19 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT SUBBASE

H1/C1 ANTICIPATOR

FALL

H2 ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

OFF

COOL

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

RTD 1 EHR 1

ODT 2

EHR 2 RTD 3

RTD 1

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

L1 (HOT)

M5846

Fig. 24. Tracing the auto fan circuit.

THERMOSTAT SUBBASE

H1/C1 ANTICIPATOR

FALL

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

H2 ANTICIPATOR

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

HEAT

COOL

OFF

AUX. HT. LED (GREEN)

EM. HT. LED (RED)

SYSTEM MONITOR

LACO

SYSTEM COMPONENTS

ODT 1

RTD 1 EHR 1

ODT 2

EHR 2 RTD 3

RTD 1

CHANGEOVER VALVE

COMPRESSOR CONTACTOR

RTD 2

FAN RELAY

EM. HT. RELAY

CHP

L1 (HOT)

M5847

Fig. 25. Tracing the fan on circuit.

60-2485—820

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

)

g sy

(

OPERATION

Heat Anticipation/Cool Anticipation

When controlling a heating unit with a thermostat, the temperature does not remain exactl setpoint, but varies within a certain temperature range. Heat anticipation is added to the thermostat to reduce this ran

The anticipator is a small resistive heater in the thermostat that heats when the s

. The heat produced by the anticipator raises the

mode

stem is on (heat mode) or off (cool

internal bimetal temperature slightly faster than the surroundin

room temperature. The thermostat the need to shut off the heatin affected by room temperature only.

There are two t

ustable anticipation is also called

. 26. The heater is in series with the mercury switch and

pes of heat anticipation, adjustable and fixed.

heating primary. The pointer is adjusted to match the current draw of the primar added for proper c

control, and the correct amount of heat is

cle rates.

at the thermostat

anticipates

stem sooner than it would if

current anticipation

L1 (HOT)

. See

Heat anticipators add heat durin

the call for heat. Cooling

anticipators are activated while the air conditioner is off. See

. 28. This heater makes the thermostat think it is warmer than

is, and brings it on sooner than the bimetal alone would.

it reall

(HOT)

RISE

C1 ANTICIPATOR

STAGE 1 COOL RELAY

M5825

Fig. 28. Internal cooling anticipation schematic.

Interstage Differential

The mercury switch of each stage of heat makes at a slightly different temperature; that is, the mercury makes the contacts of the first sta

e bulb at another temperature. The difference between

sta these two temperatures is the

e bulb at one temperature, and the second

interstage differential

H1 ANTICIPATOR

FALL

STAGE 1 HEAT RELAY

M5823

Fig. 26. Adjustable anticipation heater in series with load.

Fixed anticipation is also called

voltage anticipation

. See Fig. 27. The heater is in parallel with the primary control and is not affected b the proper c

the current draw of the primary. It establishes

cle rate for any application.

(HOT)

STAGE 1

FALL

HEAT RELAY

H1 ANTICIPATOR

M5824

Fig. 27. Fixed anticipation heater in parallel with load.

Intersta

e differential is the difference between the two make points when the bulbs are controlled by the heating of the bimetal and the action of the heat anticipator. The intersta differential is 1.9°F

1°C) between the stages of heating or the

stages of cooling for most models.

Mechanical differential is the difference between the make and break points of each switch. The mechanical differential for the T874 is 1°F (0.6°C) between the stages of heating or between the sta

es of cooling for most models.

Droop

The addition of anticipator heat to the bimetal causes a control factor called

As the weather operate lon to the bimetal. The bimetal now thinks it is warmer than it

is, and actual room temperature is controlled at a lower

reall temperature than the setpoint indicates. At 100 percent heat load, this droop can be si

The C815A Outdoor Reset Thermistor is used in heat pump

stems to minimize droop. Without some method of

s countering this situation, the occupant could notice the temperature offset.

droop

rows colder, the heating appliance must

er and more frequently. More heat must be added

nificant.

Outdoor Reset

Some T874/Q674 models are intended for use with the C815A Outdoor Thermistor. The outdoor thermistor provides

nificantly improved thermostat performance when

si compared to conventional multista is usually located in the heat pump condensing unit outdoors.

e thermostats. The C815A

21 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

g sy

(

CAUTION

Equipment Damage Hazard.

Due to calibration techni Thermostats with outdoor reset, the C815A Thermistor must be wired into the s do so will result in serious de

Service and Replacement of C815A Outdoor Thermistor

To check and verify thermistor operation, perform the followin

steps:

Disconnect wire from T terminal on subbase.

Measure resistance with ohmmeter across the T subbase wire and X subbase terminal.

Take outdoor temperature measurement at thermistor location and find correct thermistor resistance on the chart in Fi

Compare resistance on the chart with measured resis-

. 29.

tance. Replace C815A if resistance varies more than 15 percent. Contact installin ment outdoor thermistor.

4600 4400 4200 4000 3800 3600 3400 3200 3000 2800 2600 2400 2200 2000 1800 1600 1400

THERMISTOR RESISTANCE (ohms)

1200 1000

800 600 400 200

-20 0 20 40 60 80 100 120 140

TEMPERATURE OF THERMISTOR (°F)

ues used for T874

stem at all times. Failure to

radation of performance.

dealer for packaged replace-

C815A THERMISTOR RESISTANCE R = 400 ohms ± 10% AT 77°F (25°C)

M1590A

A strip of four inserts is included with TRADELINE T874. Drop a strip into the recessed area behind the scaleplate so selected LEDs show. Make sure insert is completel

seated in recessed area. Let scaleplate pop back; then set levers to desired position.

• FILTER LED li

hts when the filter is clogged and needs

replacement.

• CHECK LED li

hts when something needs to be checked or done to maintain efficient operation of system. See heatin

• EM. HT. LED li

stem instructions for CHECK LED meaning.

hts when the emergency heat is operating.

• SUPL. HT. LED lights when the supplemental heat is operatin

• LOCKOUT LED li

hts when the system is shut down and

needs maintenance.

• AUXILIARY HEAT LED li operatin

hts when the auxiliary heat is

• SERVICE or MALFUNCTION LED can have several meanin

s. Consult heating system instructions.

LEDs cannot be replaced or added in the field.

LEDS

EM. HEAT

FILTER SERV.

AUX HEAT

50 60 70 80

COOL

M5830

Fig. 30. T874/Q674 LED location.

Restricted Setpoint (DoD)

The Department of Defense (DoD) models are equipped with a restricted setpoint feature for fuel efficienc

Fixed stops are factor above 72°F

22°C) on heating, or below 78°F (26°C) on cooling.

-set so setpoint levers cannot be set

Fig. 29. Thermistor resistance chart.

Applications

The T874/Q674 can be applied to standard residential

Features

Two of the features of the T874/Q674 include LED indicators

systems for automatic or manual changeover, to commercial rooftop applications, or to heat pump applications.

and restricted setpoint.

Changeover on Standard Residentia l

LED Indicators

The light-emitting diodes (LED) indicators on the subbase

ht on command when something specific happens in the

li system. See Fig. 30.

Up to four different LEDs are available. The thermostat has a clear lens window for viewin models, a small insert is used so the LED function desired can be selected.

This must be done during installation.

A blank insert is factory-installed in some T874 models. To remove it, push both temperature settin of the thermostat. Use index fingernail to gently pull out the scaleplate a fraction of an inch. Turn thermostat upside-down, and the blank insert falls out.

60-2485—822

each LED. On TRADELINE

levers to the far ends

Systems

In a standard residential heating-cooling circuit, changeover between heatin or manuall

Automatic chan subbase s AUTO position, the thermostat automatically changes between heat and cool modes, dependin

and cooling can be done either automatically

eover is done by an AUTO position on the

stem switch. See Fig. 31. When the switch is in the

on the indoor temperature.

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

OFF EM. HT. HEAT

AUTO COOL

M5828

Fig. 31. System switching for automatic changeover.

Automatic chan

eover is frequently used in areas where there are large temperature differences in 24 hours. Some uses for the automatic chan

eover feature are in the southern states

cool in the morning and hot in the afternoon) and in

commercial applications.

Manual chan

eover requires a system switch movement to change the mode. See Fig. 32. Most manual changeover switches consist of HEAT-OFF-COOL choices. For heatin switch to HEAT. For coolin

Manual chan

eover is often used in areas where the

temperature is relativel

, switch to COOL. It is not automatic.

stable between day and night.

When enthalp

is low enough, the thermostat and a sensor tell the economizer damper to open to let in cool air from the outside. When enthalp

is high, the thermostat and sensor tell the damper to close. No more outside air comes in, so the air conditioner is used instead.

Heat Pump Application

A heat pump system operates much like an air conditioner. However, the heat pump is capable of movin directions; from inside the home to outdoors for coolin from outdoors to inside for heating.

The heat pump can be controlled b

separate relay/contactor

components, which are energized or de-energized by the T874.

Chan

eover between heating and cooling for heat pump

circuits can be accomplished either manually or automatically.

Manual chan

eover control requires a system switch movement to change the mode. The reversing valve is activated b to HEAT for heatin

Automatic chan

moving the system switch to COOL for cooling or

operation.

eover is accomplished by one of the mercury bulb switches in the thermostat. On a s changeover on cooling, the changeover valve is energized by a mercur heatin

switch that makes on a temperature rise. On

, the changeover valve is energized by a mercury

switch that makes on a temperature fall.

heat in two

, or

stem with automatic

OFF EM. HT. HEAT

COOL

M5829

Fig. 32. System switching for manual changeover.

Commercial Rooftop Application

The T874 can be used as part of a commercial rooftop application to run mechanical coolin

An economizer is often used as part of a rooftop application to save on air conditionin

OUTDOOR AIR

H205 OR H705 ENTHALPY CONTROL

. See Fig. 33.

RETURN AIR

Fig. 33. Typical commercial rooftop economizer

application.

Enthalpy

accurate anal made b

is the temperature and humidity of the air. A more

sis of the suitability for free cooling can be

monitoring the enthalpy.

DISCHARGE AIR SENSOR DOWNSTREAM FROM THE EVAPORATOR COIL

M5827A

A description of the methods used to control heat pumps follows.

Space Temperature Sensing Low Voltage Controls

Control systems for heat pumps usually utilize low voltage control circuits. The variety of control functions required and the relative complexit

require a versatile and economical method of control. There are several interlocks and indication functions that would be more difficult and expensive to wire in line volta and flexibilit

The thermostat used is a low volta temperature sensitivit switchin

e circuits. Low voltage controls have the precision

needed.

e device that has good

and several manual and automatic

capabilities.

Two-Stage Thermostat

In most installations, the heat pump itself requires auxiliary heat, usuall buildin pump is usuall the heat pump

when necessary—

pump fails. Usuall

balance point

handle heating load by itself).

A two-sta

make sequentially

ree or two between stages so that the second stage (the

in the form of electric strip heaters, to carry the

heating load at design conditions. Since the heat

more efficient, the control strategy is to run

whenever possible

and the auxiliary heat

during very cold weather or if the heat

the auxiliary heat is used only below the

(temperature at which the heat pump cannot

e thermostat makes this possible. The two stages

as the temperature drops. There is a

only

23 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

one controlling the auxiliary heat) makes only when the heat pump alone cannot handle the load. That is how the strate of using the most economical heat first is implemented.

Cycling Rate

Normally, thermostat anticipation is set to cycle a fossil fuel furnace about five or six times an hour This provides a reasonable balance between comfort, stability and econom

A heat pump, bein

cled at a rate of 2-1/2 to 3 times an hour. With a T874,

be c this is accomplished b

a mechanical refrigeration system, should

setting the anticipator at the total current draw of the controlled device (the contactor and possibl

the changeover relay or valve). Most likely, the

compressor operates from the first sta

The second sta

e normally controls the auxiliary heaters. This heat anticipator can be set for the current draw of the electric heat primar

, and produces good control.

at 50 percent load).

e of the thermostat.

Voltage Anticipation

Although not a specific requirement for heat pumps, several models of the T874 have volta current anticipation.

With volta

e anticipation, the amount of heat added to the thermostat is constant no matter which load is connected to it. The anticipator realizes a constant volta constant amount of heat durin cycling rate to be

designed into

pump manufacturer is assured of correct performance independent of later thermostat ad

e heat anticipation instead of

e and produces a the ON cycle. This allows the the thermostat. The heat

ustments.

This is particularly important on the 3-stage T874. The additional sta

e means that more droop is introduced when the system is in operation. That is the reason the TRADELINE T874W is sold in a packa

e with the outdoor sensor and the

correct subbase.

Outdoor Reset—How it Works

The heater in the thermostat is connected in series with a thermistor sensor that measures outdoor temperature. See

. 34. In warm weather, the thermistor has very low

Fi resistance, permitting a large current flow in the heater, which

enerates a relatively large amount of heat in the thermostat.

In cold weather, the outdoor sensor has hi which results in low current flow and little or no heat bein added to the thermostat. This raises the control point, overcomin

the effects of droop and interstage differential.

(HOT)

RESET HEATER

Fig. 34. Location of thermistor.

h resistance,

C815A OUTDOOR THERMISTOR SENSOR

M5826

Outdoor Reset

Outdoor reset, which a C815A Outdoor Thermistor makes possible, is sometimes applied in heat pump s minimize the effect of the differential between sta 2°F (1.1°C) change in temperature to bring on the second

e and full heating. Added to a certain amount of droop

sta under hi

h loads, there can be a large offset between the

setpoint and room temperature.

Without some method to counteract this situation, the temperature offset from the setpoint could be as much as 6°F

3.3°C) under high load conditions. It is not likely that the occupants accept this variation without makin thermostat settin

Outdoor reset has the effect of raisin

changes.

the setpoint at cold outdoor temperatures. Then, even with a few de the space temperature sta

This is done b

calibrating the thermostat high by 5°F (3°C)—

s near the desired setting.

the amount of expected offset. This offset compensates for differential and droop at hi

h load factors so the thermostat switches at the setpoint. At warm temperatures, heat is added to the thermostat to compensate for this offset; at cold temperatures, the extra heat is automaticall effect is the same as raising the setpoint as the outdoor temperature

oes down.

stems to help

es. It takes

frequent

rees droop,

removed. The

Changeover

Changeover between heating and cooing can be accomplished either the application. Changeover can occur in heating or cooling.

The chan

eover valve is energized as long as the subbase

function switch is in the appropriate position when

eover is used. If a system manually changes over on

chan

, the valve energizes whenever the subbase switch is

coolin in the cooling mode.

One of the mercur thermostat has changeover is in cooling, the changeover valve is energized when the first sta switch turns on the compressor.

It is more common with new e changeover occurs with cooling; that is, the changeover valve is ener

Whether

ized to produce cooling.

automatic

whether the reversin

, a heat pump system can be controlled by the

heatin appropriate T874 Multistage Thermostat.

automatically

manually

, depending on

manual

bulb switches is used for control when the

automatic

changeover. When the

automatic

e cooling switch makes. The second stage

uipment to find that

manual

changeover is used and

valve is energized with cooling or with

60-2485—824

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

M5837

COMP. STAGE 2

THERMOSTAT

HEAT 2

HEAT 1

AUXILIARY HEAT

HEAT 3

COMP. STAGE 1

Low Temperature Lockouts

Some manufacturers of heat pumps have previously controlled their units so the compressor was locked out below a specified outdoor temperature. This was done because of the stress placed on the compressor b

the very cold temperatures, and

the fact that efficiency drops off at low temperatures.

Other manufacturers sa

that although efficiency is low at cold temperatures, the problem of starting the cold compressor is the most critical point. It is more important to keep the compressor runnin

than to shut it off and try to restart it when the temperature warms up to +10°F (-12°C). Also the crankcase heater, which can run onl off, compensates for the lower compressor efficienc

when the compressor is

. So, it is equitable to let the heat pump run even with a coefficient of performance

COP) slightly less than one, rather than to turn it

off and have to run the crankcase heater.

NOTE: To determine the COP of a heat pump, use the fol-

formula:

lowin

COP =

Btu Out/Btu we pay for or Btuh Capacit Unit Wattage x 3.413 Btu/Watt

Another factor favoring this control strategy is that newer heat pump desi

ns maintain a level of efficiency even at outdoor

temperatures well below zero. Some brands do not reach

1.0 COP until -25°F

Virtuall

all manufacturers now let the heat pump run

-32°C).

continuously rather than lock it out at cold temperatures.

Heat Pumps with Dual Compressors

Staging residential sized heat pumps is a requirement that developed from the need to make heat pumps as efficient as possible. One of the methods used to improve overall seasonal efficienc machine is operatin is starting and stopping in addition to recovering from defrost. Under li

ht loads, when the heat pump is cycling on and off, this can be a si significant efficiency reduction. Capacity control is one way to reduce the c

is to reduce the amount of time the

in a transitional mode. Transitional mode

nificant amount of time and can result in a

cling rate and improve the efficiency.

THERMOSTAT

HEAT 1

HEAT 2

COMP. STAGE 1

COMP. STAGE 2

OUTDOOR THERMOSTAT

AUXILIARY HEAT

M5838

Fig. 35. Two-stage heat pump with two-stage thermostat.

The outdoor thermostat is set at the balance point with both heat pump sta

load down to +20°F (-7°C), the auxiliary heat comes

heatin on with the second sta

In effect, this control strate second sta

es running. So if the heat pump can control the

e of the compressor.

changes the heat input of the

e, depending on the amount of heat needed. Additional stages of auxiliary heat can be added with or without the control of more outdoor thermostats, See Auxiliar Heat section.

Another wa

e thermostat. The T874W is designed for this application

sta

to control a two stage heat pump is with a three-

as well as others. See Fig. 36.

The advantage of this system is that no auxiliary heat is used until there is an actual demand from the controlled space.

Additional capacit

eration systems (unloading, multiple compressors) are

refri not as likel

With a sin

le-stage heat pump, the compressor is normally controlled b second sta

control methods used on other

to be seen on residential heat pumps.

the first stage and the auxiliary heat by the

e. The T874G, N and R Thermostats are used for

this purpose.

With a two-sta control the individual compressor sta controlled alon

e compressor, the two thermostat switches

es. Auxiliary heat is

with the compressor stage-two, by the

thermostat second stage. It comes on with the compressor

h speed if an outdoor thermostat—wired in series with it—

hi is made. See Fi

. 35.

Fig. 36. Two-stage heat pump with three-stage

thermostat.

Two speed Heat Pump

One way to control capacity is to use a two-speed compressor. The compressor runs at low speed for sta

and cooling. The compressor runs at the low speed

heatin instead of cycling the heat pump on and off under some light load conditions.

h speed is stage-two cooling. The compressor runs on

The hi

h speed when loads increase so the low speed can no

er handle the cooling load. This reduces cycling rate and

lon improves capacit

25 60-2485—8

e-one

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Defrost Control

In some regions, during half or more of the heating season, the outdoor coil operates below 32°F (0°C) Frost or ice builds up on the outdoor coil of a heat pump similarl buildup in a household refri

erator. Eventually, this

to the frost

accumulation of ice interferes with efficient heat transfer from the outdoor air to the coil and refri occasionall

required to remove this ice, and restore the heat

erant. Defrosting is

pump ability to absorb heat from the air.

Defrosting

A heat pump defrosts its outdoor coil by temporarily switching to the coolin compressor to be directed to the outdoor coil instead of to the indoor coil so the heat pump is takin warm up the outdoor coil. Defrostin to heat pump efficiency.

Defrost Control Functions

Besides changing over to the cooling mode, defrosting

uires several more control initiated actions that follow.

OUTDOOR FAN

When defrosting has begun, it is standard practice to turn off the outdoor fan to speed up the melting process. A separate defrost rela contacts can be needed on the defrost rela changeover valve or power part of the auxiliary heat.

mode, which causes hot gas from the

heat from the home to

is the greatest detriment

is required to control that fan. See Fig. 37. Other

to power the

CONTACTOR

COMPRESSOR MOTOR

CONTROLLED BY DEFROST RELAY

OUTDOOR FAN MOTOR

M5839

Fig. 37. Outdoor fan with defrost control.

(HOT)

TRANSFORMER

THERMOSTAT

HEAT 2

HEAT 1

DEFROST RELAY CONTACT

AUXILIARY HEAT RELAY

M5835

Fig. 38. Auxiliary heat with defrost control.

WHEN TO DEFROST

Timel

defrosting is an essential component of effective heat pump operation. Failure to defrost often enou much ice to accumulate on the coil. At the ver

h permits too

least, this hurts efficiency; at worst, it results in compressor damage. Insufficient defrostin

is a condition the heat pump

manufacturer wants very much to avoid.

A 50 percent reduction in outdoor airflow is the maximum that would be tolerated. So the desi select a control point that puts the s airflow throu

h the outdoor coil approaches half its normal

ner of a heat pump would

stem into defrost when

level. Restricted airflow causes a greater load on the compressor; the outdoor coil runs colder, suction pressure is lower and the motor runs hotter.

At the other end of the scale, defrostin overall ener

efficiency of the system. Consider that in terms

too often hurts the

of heating the building, defrosting is a big loss. Not only does

stem stop heating, but it actually moves heat out of the

the s buildin

. If electric strip heat is used, it is a further waste because its COP is 1.0 and not the 2.0 or more COP realized if the heat is provided b

So, concern for e

economy of operation

defrostin defrost c

while cles. Since the equipment manufacturer chooses, the

the heat pump.

quipment safety

suggests fairly frequent

argues for fewer

balance is usually tipped in favor of more frequent defrosting to avoid the possibilit

of damaging the compressor.

AUXILIARY HEAT DURING DEFROST

Most pump manufacturers brin defrost, althou the second sta

h this is not a universal practice. Some rely on

e of the thermostat to call for auxiliary heat as

on some auxiliary heat during

needed. Since the heat pump is operating in the cooling mode to defrost, it is deliverin heat is used to offset this coolin

cold air to the living space. Auxiliary

. It requires another normally

open contact on the defrost relay. See Fig. 38.

Auxiliary Heat

Except in warm climates, all air-to-air heat pump installations re

uire auxiliary heat capability. Electric resistance heaters

can provide this auxiliar

The electric heaters are supplied in 5 kW units or strips

heat.

sometimes called strip heaters) usually

indoor unit of the heat pump is desi various electric heat units so it can be used in variously sized buildin

s in different parts of the country.

Two-Stage Thermostat

The most common heat pump control strategy is for the thermostat first sta second sta

60-2485—826

e to switch the compressor and the

e to switch the auxiliary heat. See Fig. 39.

about 17,000 Btu). The

ned to accommodate

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

ging

(

)

(

THERMOSTAT

HEAT 1

HEAT 2

COMPRESSOR CONTRACTOR

AUXILIARY HEAT RELAY

CONTROLS AT 65°F (18°C)

CONTROLS AT 63°F (17°C)

M5836

Fig. 39. Auxiliary heat in two-stage thermostat.

This method keeps the auxiliar

e enough to demand 100 percent heat pump operation.

is lar That demand is measured b

heat off until the heating load

the thermostat and is the actual

heat requirement of the space. The two-stage thermostat

uires about a 2°F (1.1°C) room temperature drop to bring

re on the second sta

Stage or Time Modulated Control

There are two different ways to control auxiliary heat, staged or time modulated control.

Outdoor thermostats

of electric heat into the thermostat circuit as the outdoor temperature still controlled by stage-two of the thermostat but only if the outdoor temperature re

. 40.

are used to switch additional increments

ets lower. All increments of auxiliary heat are

uires the additional capacity. See

The disadvanta outdoor thermostats. Also, since the unit is operatin

e of this system is that it can require several

most often at nearly full capacity, the thermostat is on longer which results in more droop, with a little more offset from the thermostat setpoint.

In addition, the capacit loss calculations. Normall

is tied to theoretical load, based on heat

this is very close to the actual load,

but there are times where the second stage is switched on too

no harm done) or too late (the building gets cold).

soon

The T874 Thermostat produces

time modulated

is the on time of the thermostat chan the load chan

es. The on time of the heating system is

control, which

during each cycle as

directly proportional to the heating load of the building. As an example of the

pical gas furnace. It can have a capacity of 100,000 Btu

uality of time modulated control, consider the

293 kW), which is controlled On-Off. The output is 100,000 Btu 293 kW) or nothing. A quality thermostat controls so closely that

the occupants rarel

The same is true with 50,000 or 60,000 Btu

178.8 kW

of heat pump auxiliary electric heat. The T874 can

detect changes in room temperature.

146.5 or

provide the same high quality control.

This scheme also eliminates the need for outdoor thermostats and thus offers the manufacturer an opportunit cost. One disadvanta demandin

The method an which ar

more kW of strip heat when chilly.

particular manufacturer selects depends on

uments it finds persuasive and the opinions of its

e is that a

thermostat jiggler

to reduce unit

can be

distributors and dealers.

THERMOSTAT

HEAT 1

HEAT 2

COMPRESSOR CONTACTOR

AUXILIARY

20°F

OUTDOOR THERMOSTATS

(-7°C)

5°F (-15°C)

HEAT RELAY 1

AUXILIARY HEAT RELAY 2

AUXILIARY HEAT RELAY 3

M5834

Fig. 40. Outdoor thermostats for auxiliary heat.

The rationale for this s

stem capacity to the heating load of the building. By

stem is that it very closely matches the

calculating the heat loss of a building, the installing contractor can pick the theoretical outdoor temperature at which to permit each additional unit of electric heat to be operated b the second stage of the room thermostat.

Three-Stage Thermostat

A definite improvement in quality of control and economy can be achieved with a three-sta especially true with heat pumps using dual compressors.

Three-sta

e control permits both the heat pump and the auxiliary heat to be tied directly to the demand of the controlled space. With a two-sta

100 percent) heat pump operation is required before auxiliary

heat is brought on.

e thermostat (T874W), which is

e compressor, maximum

Emergency Heat

Some provision is generally required to back up the compressor in the event of a failure durin

uite common to find that local building codes or electric utilities

uire that a specified percent of the building heating

uirements be available from emergency heat—a source

re other than the heat pump compressor. Almost universall source is electric resistance heaters. T is for 70 or 80 percent of the buildin

the heating season. In fact, it is

pically, the requirement

heating needs.

Switching to Emergency Heat

Conventional heat pump control (thermostat logic) usually includes a manual subbase switch to brin heat.

emergency heat

In one control strate

the EM.HT. selector switch on the thermostat subbase. The

, the

compressor is prevented from running. The electric heaters

cled as they normally would be by the

are c

on the emergency

relay is turned on

second stage

, the

27 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

y by

(

the thermostat. A set of contacts on the emergency heat relay is used to b

pass each outdoor thermostat so that all electric

heat is under immediate thermostat stage-two control. So the

ency heat relay simply bypasses the outdoor

emer thermostats. See Fi

second

In the directl

the thermostat mercury bulb. In this hookup, the

relay is controlled by the thermostat

ency heat relay energizes all of the auxiliary heat relays

emer on a call for heat. See Fi

So the emer thermostat. The emer

. 41.

method, the emergency

heat relay is cycled

first stage

. The

. 42.

ency heat is controlled by the first stage of the

ency heat relay energizes all of the

electric strip heaters so the heat and the indoor fan come on

ether as soon as the first stage calls for heat.

With the first method, the fan remains on the first sta on and off with the second sta

e of the thermostat) and the electric heaters cycle

In either case, a subbase indicator li the function switch is in the emer

THERMOSTAT

FUNCTION SWITCH

HEAT 1

HEAT 2

OUTDOOR THERMOSTAT

EMERGENCY HEAT RELAY CONTACT

ency heat (EM.HT.) position.

being controlled by

ht is turned on whenever

COMPRESSOR

AUXILIARY HEAT RELAY 1

AUXILIARY HEAT RELAY 2

EMERGENCY HEAT RELAY

M5833

Fig. 41. Emergency heat relay that bypasses

the outdoor thermostats.

Crankcase Heat

In any mechanical refrigeration system, refrigerant tends to migrate to the coldest part of the equipment and condense there. In a heat pump, this coldest spot could be the compressor because it is usuall

outdoors. In addition, the oil in the com-

pressor crankcase is capable of absorbing a high concentration

erant. On compressor startup, there are two risks: (1) the

of refri

uid refrigerant, which is noncompressible, can be drawn into

li the cylinder, and (2) considerable oil can be entrained in the

erant and swept out of the crankcase through the

refri

eover valve and dispersed in the piping and coils.

chan

So the mi because it can interfere with s

ration of refrigerant to the crankcase is undesirable

stem lubrication and because the

liquid refrigerant must be kept from going through the compressor.

Addin

a crankcase heater creates enough temperature differential to prevent this migration because the compressor is no lon not mi

er the coldest part of the system so refrigerant does

rate to it.

Compressor Fault Relay

Another very simple method of detecting a compressor failure has been developed. It uses the volta capacitor in a permanent split capacitor compressor motor.

The principle involved is that virtuall reduce the volta

e across the motor capacitor. By carefully selecting the correct coil voltage, the normally closed relay does not pull in unless the proper volta capacitor, which brin

s on the SERVICE LED. See Fig. 43.

Here is how it works:

• On a call for coolin

, the thermostat makes R to Y, the

contactor coil is powered, and the compressor motor turns on.

• At the same time, the indicator li

• As the motor

ets up to speed—about one second, the fault relay sees enough voltage to pull in. Its normally closed contact opens and the indicator li

thing that prevents the motor from running prevents the

• An fault relay from pulling in.

COMPRESSOR MOTOR

e developed across the

all serious problems

e builds up across the

ht is energized.

ht goes out.

FAULT RELAY

24 V

THERMOSTAT

FUNCTION SWITCH

HEAT 2

HEAT 1

EMERGENCY HEAT RELAY CONTACT

COMPRESSOR

AUXILIARY HEAT RELAY

EMERGENCY HEAT RELAY

M5832

Fig. 42. Emergency heat relay that energizes all of the

auxiliary heat relays on a call for heat.

CONTACTOR

RUN

CAP.

START

RISE

THERMOSTATSUBBASE

LED

Fig. 43. Compressor fault relay schematic.

60-2485—828

M5831

L1 (HOT)

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

CROSS REFERENCE

The following section lists the current T874 Trade replacements for T872 and T874 Multistage Thermostats. It also lists the Q674 Trade replacements for Q672 and Q674 Subbases.

All thermostats listed carr otherwise noted.

When usin

the Cross Reference Charts, refer to the following

instructions:

Locate and identif

the Honeywell logo unless

the existing thermostat and subbase

Description

The of the existin

Trade Replacement

The

column identifies certain characteristics

device.

column identifies the correct replacement device. The

Remarks

column lists an

characteristics or adjust-

ments to be made on the Trade replacement model.

Fig. No.

The

column lists the wirin specific model number. The wirin Cross Reference section. Refer to the circuit illustration that corresponds with the appropriate number. This fi

ure illustrates the internal

electric circuit for the desired model number.

model.

Refer to the that matches the existin

Model Number

thermostat and subbase.

column to find the model

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

T872A

1-stage heat, 1-stage cool

T874 Trade

Replacement

Remarks

A1006 Standard OEM T874A1036 A1014 72-78°F

thermometer

22-26°C) stop; locking cover; no

T874A1010 Use T874A1176 for Dept. of

Defense

DoD) application. A1022 Heat anticipator set at 0.45A T874A1036 A1030 0.4A heat anticipator settin

T874A1036 A1048 TRADELINE T874A1036 A1055 AAF lo

o; locking cover T874A1036 A1063 Climatrol logo T874A1036 A1071 Lennox lo

o; 0.5A heat anticipator settin

T874A1036 A1089 Melco logo T874A1036 A1097 Westinghouse logo T874A1036 A1105 Amana lo

o; 1.2A heat anticipator settin

T874A1036 A1113 Trane logo T874A1036 A1121 Airtemp (Chrysler) logo T874A1036 A1139 Sin

er logo; no. 02005384 T874A1036 A1147 American Standard logo T874A1036 A1154 Carrier lo A1162 General Electric lo

o and color; no. HH07AT074 T874A1036

o; no. AY28X097 T874A1036 A1170 Sears logo; no. 4291441 T874A1036 A1188 Command-Aire logo T874A1036 A1196 Sin

er logo; Celsius scale; no. 02005521 T874A1036 A1204 Carteret logo T874A1036 A1212 General Electric; no. AY28X114; 72-78°F

22-26°C) stop

T874A1010 Use T874A1176 for Dept. of

Defense (DoD) application. A1220 Singer logo; no. 050240-01 T874A1036 A1238 Celsius scale T874A1036 A1246 TRADELINE; lockin

cover and adjustable locking

T874A1150

lever stops A1253 Trane Comfort Corp T874A1036 A1261 TRADELINE; 72-78°F

22-26°C) stop; locking

T874A1176

cover; no thermometer; meets DoD specs

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

hookup used for the

diagrams follow the

29 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

A1279 General Electric logo; no. AY28X114A; 75°F stop;

cover; no thermometer.

lockin

A1287 General Electric; no. AY28X097A; fan current

shunt for auto fan in heatin

; heat anticipator set at

0.4A.

T874 Trade

Replacement

T874A1010 Use T874A1176 for Dept. of

T874A1036/ Q674B1018

Defense (DoD) application. Set thermostat sta

anticipator for total of fan and sta 1 primar

control current draw. A1295 Lennox; Celsius scale T874A1036 A1303 Lennox logo; no. 64A0601; meets DoD specs T874A1176 A1311 Envirotron special; Celsius scale T874A1010 A1329 Carrier lo

o; Celsius scale; no. HH07AT074C T874A1036 A1337 Square D; no. HCD-3; heat anticipator set at 0.2A T874A1036 A1345 TRADELINE; Celsius scale T874A1010 A1352 Heat anticipator set 1.2A T874A1036 A1360 Friedrich lo A1378 Wesco lo

T872B

1-stage heat, 2-stage cool

o; heat anticipator set at 0.2A T874A1036

o; heat anticipator set at 0.8A T874A1036

B1005 Standard OEM T874B1019 B1013 0.4A heat anticipator settin

T874B1019 B1021 TRADELINE T874B1019 B1039 Westinghouse logo T874B1019 B1047 American Standard lo

o T874B1019 B1054 Climatrol logo T874B1019 B1062 Carrier logo T874B1019 B1070 Trane lo

o T874B1019 B1088 Fedders logo T874B1019 B1096 Climatrol logo T874B1019 B1104 Carteret lo

o T874B1019 B1112 Singer logo; no. 050240-03 T874B1019 B1120 Celsius scale T874B1019 B1138 Sin

er logo; no. 02005711; locking cover and

T874B1019

lever.

B1146 Lennox lo

o; no. P-8-8895 T874B1019

B1153 Lennox logo; Celsius scale T874B1019

T872C

2-stage heat, 1-stage cool C1004 Standard OEM T874C1018 C1012 Heat anticipator set at 0.4A T874C1018 C1020 72-78°F

thermometer; 42-88°F

22-26°C) stop; locking cover; no

6-31°C) setpoint range.

T874C1141 Use T874C1141 for Dept. of

Defense (DoD) application. C1038 TRADELINE T874C1018 C1046 American Standard logo T874C1018 C1053 Friedrich lo

o T874C1018 C1061 Lennox logo; no. P-8-8896 T874C1018 C1079 Westin

0.75A; sta

C1087 Fast c

anticipator ran

C1095 Pa

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

house logo; stage 1 heat anticipator set at

e 2 anticipator set at 1.2A

cle performance on both heat stages;

e 0.12-0.6A

ne logo; no. 0.1-0.175 T874C1018

T874C1018

T874C1018 Ad

performance.

ust anticipator

Remarks

e 1 heat

faster

for correct

60-2485—830

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

T874 Trade

Replacement

Remarks

C1103 Amana logo; anticipator set at 1.2A T874C1018 C1111 Airtem p

Chrysler) logo T874C1018 C1129 Day and Night logo; no. 0.1-0.174 T874C1018 C1137 Fast cycle performance on both heat stages T874C1018 Adjust anticipator

performance. C1145 Rheem lo C1152 Ruud lo

o T874C1018

o T874C1018 C1160 Climatrol logo T874C1018 C1178 Wesco logo T874C1018 C1186 Sears lo

o T874C1018 C1194 First Co. logo T874C1018 C1202 Carrier logo T874C1018 C1210 Carrier lo C1228 0.4A heat anticipator settin

o; Celsius scale T874C1018

T874C1018 C1236 Carrier logo; no. HH07AT070 T874C1018 C1244 Fraser-Johnson lo

o T874C1018 C1251 Trane logo T874C1018 C1269 Fedders logo T874C1018 C1277 Climatrol special T874C1018 C1285 Auto

as logo T874C1018 C1293 Fedders logo T874C1018 C1301 Climatrol lo

o T874C1018 C1319 Command-Aire logo T874C1018 C1327 Melco logo; lock cover and levers T874C1018 C1335 Sin

er logo (Carteret

T874C1018 C1343 Singer logo; no. 050240-04 T874C1018 C1350 Celsius scale T874C1018 C1368 12°F

67°C) differential between heat 1 and

T874C1125

heat 2

C1376 AAF lo

o; locking cover; 72-78°F (22-26°C) stop T874C1018 C1384 Servel logo T874C1018 C1392 TRADELINE; fast cycle performance on both heat

es.

sta

C1400 72-78°F

22-26°C) stop; locking cover; no

T874C1018 Ad

performance.

T874C1141

ust anticipator

thermometer; meets DoD specs

C1418 Solaron lo

o T874C1018 C1426 Lennox logo; no. 42C04; four LEDs None C1434 Carrier lo

o; no. HH07AT070C; Celsius scale T874C1018 C1442 Goettl logo T874C1018 C1459 Goettl logo; used with Q672N1001, N1019 None C1467 Lennox lo

o; Celsius scale T874C1018 C1475 Tappan logo; no. 080-13708-37 T874C1018 C1483 Fasco lo C1491 Lennox lo

o; no. 1230-8161 T874C1018

o; no. 64A0501; locking cover; no

T874C1141

thermometer; meets DoD specs

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

faster

for correct

31 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

T874 Trade

Replacement

Remarks

C1509 Fedders logo; used with Q672L1102 Y594R1425 Wiring differences (old=new): C=X,

K=E; remove Y-W1

umper.

C1517 Climatrol logo; used with Q672L1102 Y594R1425 Wiring differences (old=new): C=X,

K=E; remove Y-W1

umper. C1525 Square D logo; no. HCD-2 T874C1018 C1533 Airtemp lo

o T874C1018

C1541 Airtemp logo; used with Q672L1102 Y594R1425 Wiring differences (old=new): C=X,

K=E; remove Y-W1

umper. C1566 TRADELINE; Celsius scale T874C1018 Replacement has °F scaleplate. C1574 Whalen special; used with Q672B1269 None C1582 Lennox; meets DoD None C1590 Sin

C1608 Sin

er; 8°F (4.4°C) differential between stage

1 and sta

e 2

er logo; no. 02005784 8°F (4.4°C) differential

between sta

e 1 and stage 2

C1616 Celsius scale; stop set at 23°C None Add 4074ECK ad

T874C1125 Replacement has 2°F

differential between H1 and H2.

T874C1125 Replacement has 2°F

differential between H1 and H2.

ustable stop.

1° C)

1°C)

C1624 Heat Wave logo; no. 0360-116 T874C1018 C1632 York lo

o; heat anticipator set at 0.2A T874C1018 C1640 Heat anticipator set at 0.4A T874C1018 C1665 Wesco logo; heat anticipator set at 0.8A T874C1018 C1673 Wards lo

o; used with Q672B1285, B1293 Gas systems:

T874C1018/ Q674B1034

Electric s

stems:

T874C1018/

ust anticipator faster for correct

Ad performance.

Q674B1075 C1681 Lechauffa C1699 Duotherm logo; used with Q672E1068 or

Q672F1000

C1707 Si

ler logo; used with Q672N1027 None

C1715 Westin

T872D

2-stage heat, 2-stage cool

e Urbain logo; Celsius scale T874C1018

T874C1018 See subbase description for

replacement information.

house logo T874C1018

D1003 Standard OEM T874D1165 D1011 TRADELINE T874D1165 D1029 Westin

house logo T874D1165 D1037 Climatrol logo T874D1165 D1045 Lennox lo D1052 York lo

o; no. P-8-8897; used with Q672E1191. T874D1165

o T874D1165 D1060 Singer logo; no. 02005385 T874D1165 D1078 Rheem logo T874D1165 D1086 Rudd lo

o T874D1165 D1094 York logo; locking cover T874D1165 D1102 American Standard lo D1110 ITT lo

o T874D1165

D1128 Carrier logo T874D1165 D1136 No anticipator on sta

e 1 cool; used with

T874D1165

Q672C1029

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

60-2485—832

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

T874 Trade

Replacement

Remarks

D1144 Carrier logo; no. HH07AT072 T874D1165 D1151 General Electric lo

o; no. AY28X098; 0.4 heat

T874D1165

anticipator settin

D1169 Airtemp

D1177 Trane lo

Chrysler) logo; used with Q672E1118 T874D1165/

Q674E1049

o T874D1165

Wiring differences (old=new): A=W1; set H1 anticipator to 1.2A.

D1185 Dunham-Bush logo T874D1165 D1193 Fedders logo T874D1165 D1201 Climatrol lo

o T874D1165 D1219 Command-Aire logo T874D1165 D1227 Singer logo; no. 02005522; Celsius scale T874D1165 D1235 Sin

er logo; (Carteret

T874D1165 D1243 Friedrich logo T874D1165 D1250 Singer logo; no. 050240-02 T874D1165 D1268 Airtemp lo

o T874D1165 D1276 Celsius scale T874D1165 D1284 Solaron T874D1165 D1292 Tok

o Carrier logo; no. HH07AT072C; Celsius

T874D1165

scale D1300 SUPER TRADELINE T874D1165 D1318 General Electric lo

shunt for auto fan in heatin

o; no. AY28X098A; fan current

D1326 General Electric logo; locking cover 72-78°F

T874D1165/ Q674B1075

T874D1165

22-26°C) stop; fan current shunt for auto fan in

heating. D1334 Lennox lo

o; Celsius scale T874D1165 D1342 Tappan logo; no. 080-13708-32 T874D1165 D1359 Singer logo; no. 02005740; Celsius scale; 6.6°C

differential between H1 and H2. D1367 Friedrich lo D1375 Sin

er logo; no. 02005713; Celsius scale; controls

o; no. 600-580-23 T874D1165

T874D1165 Only 2°F (1°C) differential between

H1 and H2.

None 2 separate heat/cool circuits; used with Q674G1017

D1383 TRADELINE; Celsius scale T874D1165 D1391 Sin

er logo; no. 02005712; controls two separate

None heat/cool circuits; used with Q674G1017

D1409 12°F D1417 Fedders lo

7°C) differential between H1 and H2 T874D1165

o T874D1165 D1425 Climatrol logo T874D1165 D1433 Singer logo; no. 02005785; 8°F (4.4°C) differential

T874D1165

between H1 and H2 D1441 American Air Filter T874D1165 D1474 Carrier; no. HH07AT072-03; Celsius scale T874D1165

T872E

2-sta

e cool E1002 Standard OEM T874E1016 E1010 TRADELINE T874E1016 E1028 Westin

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

house logo T874E1016

33 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

T874 Trade

Replacement

E1036 American Standard logo T874E1016 E1044 York lo

o; locking cover T874E1016 E1051 ITT logo T874E1016 E1069 Climatrol logo T874E1016 E1077 Airtemp

Chrysler) logo T874E1016 E1085 Lennox logo T874E1016 E1093 Trane logo T874E1016 E1101 Dunham-Bush lo

o T874E1016 E1119 Fedders logo T874E1016 E1127 Climatrol logo T874E1016 E1135 General Electric lo

o; no. AY28X108 T874E1016 E1143 Lennox logo; Celsius scale T874E1016 E1150 Celsius scale T874E1016 E1168 Airtemp lo

o T874E1016 T872F 2-stage heat F1001 Standard OEM T874F1015 F1019 TRADELINE T874F1015 F1027 Lennox lo F1035 Luxaire logo; fast cycle performance on both heat

sta

o; fast cycle heat anticipator T874C1018

es.

T874C1018 M839 draws 0.72A; set ad

heat anticipator to settin for proper c

cle rate. F1043 York logo; locking cover; used with M839. T874C1018 F1050 Raehco logo T874F1015 F1068 Fast c

cle performance on both heat stages. T874C1018 F1076 Wesco logo T874F1015 F1084 Lennox logo T874F1015 F1092 Auto Gas lo

o T874F1015 F1100 Celsius scale T874F1015 F1118 Lennox logo; Celsius scale T874F1015 F1126 Sta

es 1 and 2 heat electrically isolated; used with

None

Q672D1002

F1134 S

uare D logo; HCD-4 T874F1015 F1159 Wesco logo; heat anticipator set at 0.8A T874F1015 F1167 York logo T874F1015 F1175 Oneida Heater lo

o; no. 30A0287-01; used with

Q672K1012.

T872G

Heat pump models; 2-sta

e cool, 1-stage changeover.

1-sta

e heat,

G1000 Fast cycle performance stage 2 heat; fixed

anticipator sta

; used with Q672F1018.

coolin

G1018 Ad

ustable anticipator stage 2 heat; fixed

anticipator sta

; used with Q672E1027.

coolin

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

e 1 heat and cool; changeover with

T874F1015/ Q674K1026

Y594G1252 Wirin

W=W2, X1=X.

Y594G1393 Wirin

Y1=O, Y2=Y.

differences (old=new):

Remarks

ustable

of 0.9A

60-2485—834

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

G1026 Lennox logo; fast cycle performance; stage 2 heat;

fixed anticipator sta

eover with cooling; used with Q672E1019,

chan

e 1 heat and cool;

T874 Trade

Replacement

None See subbase description for

Remarks

replacement information.

F1067.

G1034 Westin

heat; fixed anticipator stage 1 heat and cool; chan

house logo; adjustable anticipator stage 2

eover with cooling; used with Q672F1091,

Y594G1252 Wirin

differences (old=new):

W=W2.

F1141, F1257 or Q672J1013, J1062.

G1042 York lo

cool; chan

o; fixed anticipator on all stages heat and

eover with cooling; used with

Y594G1567

Q672J1021.

G1059 TRADELINE; no anticipator sta

anticipator stage 1 heat and cool; changeover with

; used with Q672J1039 outdoor reset.

coolin

G1067 Lennox lo

performance; sta 1 heat and cool; chan

o; no. P-8-11222; fast cycle

e 2 heat; fixed anticipator stage

eover with cooling; used

e 2 heat; fixed

Y594G1161 Desi

ned for use on General

Electric heat pumps.

See subbase description for

replacement information.

with Q672E1142, F1083.

G1075 Carrier lo

fixed anticipator stage 1 heat and cool; chan

o; adjustable anticipator stage 2 heat;

eover with cooling; used with Q672J1054,

See subbase description for replacement information.

L1052.

G1083 Ad

ustable anticipator stage 2 heat; fixed

anticipator sta

e 1 heat and cool; changeover with

Y594G1252

cooling; includes shunt to bypass stage 2 anticipator with auxiliar

heat relays; used with

Q672F1158.

G1091 Lennox lo

DoD specs.

G1109 Tappan lo

anticipator sta

o; same as T872G1026 except meets

o; no. 080-13708-52; adjustable

e 1 heat and cool; changeover with

Y594G1252 Wirin

See subbase description for replacement information.

differences (old=new): C=X.

cooling; used with Q672F1117. G1117 C han G1125 Lennox logo; no. 63A0401; Celsius scale; isolated

eover; used with Q672F1125. Y594G1252 Wiring differences (old=new): C=X.

None

auxiliar

heat power circuit; fast cycle anticipator

stage 2 heat. G1133 Rheem lo

anticipator sta

heat and cool; chan

shunt to b

o; no. RXMT-B71; adjustable

e 2 heat; fixed anticipator stage 1

eover with cooling; includes

pass stage 2 anticipator with auxiliary

Y594G1252

heat relays; used with Q672F1158, F1232. G1141 Ruud lo

o; adjustable anticipator stage 2 heat;

Y594G1252

fixed anticipator stage 1 heat and cool;

eover with cooling; includes shunt to bypass

chan

stage 2 anticipator with auxiliary heat relays; used

with Q672F1158. G1158 Carrier lo

ling.

o; same as T872G1075. Except DoD

See subbase description for

replacement information. G1166 BDP used with Q672F1125. Y594G1252 Wiring differences (old=new): C=X. G1174 BDP used with Q672F1125. Y594G1252 Wirin G1182 Carrier; no. HH07AT071C; Celsius scale; used

See subbase description for

with Q672L1052, J1054.

G1190 Tappan; no. B13708-57; used with Q672L1078 for

None

differences (old=new): C=X.

replacement information.

8 and 10 ton heat pumps with 2 compressors.

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

35 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

G1208 Marvair logo; special for Crispaire; used with

T874 Trade

Replacement

Y594G1393

Remarks

Q672F1166, F1323.

G1216 Janitrol lo

o; no. 26G05; stage 2 heat anticipator

Y594G1252 Wiring differences (old=new): C=X.

set at 1.2A; used with Q672F1117.

G1224 TRADELINE; ad

fixed anticipator sta

eover in cool; used with Q672F1208.

chan

ustable anticipator stage 2 heat;

e 1 heat and cool;

Y594G1419

G1232 Heat Wave (Southwest Mfg.) logo; stage 2 heat

anticipator set at 1.2A; used with Q672F1224.

G1240 Lennox; fast c

cle anticipator stage 2 heat; used

None

with Q672F1240.

G1257 Carrier lo

Q672L1169

o; no. HH07AT073; used with

HH93AZ071).

None

G1265 Addison logo; used with Q672F1265. Y594G1252 Wiring differences (old=new): C=X. G1273 Carrier logo; (DoD model); 68°F (20°C) maximum

heatin

; 78°F (26°C) minimum cooling; used with

See subbase description for replacement information.

Q672L1052, J1054 G1281 Wesco lo G1299 York logo; meets DoD specs; used with

o; used with Q672F1265. Y594G1252 Wiring differences (old=new): C=X.

Y594G1567

Q672L1177. G1307 Carrier; no. 38EQ1900; Celsius; used with

Q672J1054, L1052. G1315 Luxaire special; sta

e 2 heat anticipator set to

Y594G1252

See subbase description for replacement information.

1.2A; used with Q672F1281.

G1323 Lennox special; used with Q672L1201 and

None

C815A1013. G1331 York; used with Q672J1021. Y594G1567 Wirin

differences (old=new):

X=X1, L=X2, W=E; Y1-W1 and Y2-

umpers required.

G1356 Westinghouse; used with Q672L1219. T874D1165/

Q674F1022

Wiring differences (old=new): X=X1, L=X2, W=E; Y1-W1 and Y2-

umpers required.

W2 G1364 York; used with Q672D1077. None G1372 Tappan/Janitrol lo

o; no. B-13708-521;

Y594G1252 Wiring differences (old=new): C=X.

used with Q672F1117.

G1398 York lo

T872H

Heat pump model; 1 stage heat, 1 sta

H1009 Command-Aire logo; fixed anticipator stage 1 heat

and cool; chan

o; no. 025-21454C; used with Q672J1021. Y594G1567

e cool, 1 stage changeover.

Y594H1012

eover with cooling; used with

Q672C1086.

H1017 Friedrich lo

o. Y594H1012 H1025 Friedrich logo; Celsius. Y594H1012 T872M 1 stage heat, 1 stage cool with stage 2 heat factory

set at 60°F

M1003 Standard OEM; used with Q672D and external

switchin

16°C).

means.

T874C1125 T874C1125 has 12°F

differential between sta

e 2 heat.

sta

6.7°C) e 1 and

T872N Heat pump model; 2-stage heat, 1-stage cool plus

eover, changeover in heat mode.

chan

N1002 None

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

60-2485—836

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

N1010 Williamson logo; adjustable anticipator stage 1

and 2 heat; fixed anticipator sta

e 1 cool; used

T874 Trade

Replacement

T874N1016/ Q674F1220

Remarks

with Q672F1133 or F1315.

N1028 TRADELINE heat mode chan

eover; used with

T874N1016

Q672F1216.

N1036 Bard; used with Q672F1299. T874N1016/

Q674F1220

N1044 Thermotron lo

mode; used with Q672F1299.

T872Q

1-sta

o; 1st stage changeover heat

e heat; used with another T872 for heating

T874N1016/ Q674F1220

setback. Q1009 Standard OEM T874C1125 Q1017 York lo

o T874C1125 Replacement only good for

e heat and 1-stage cool

1-sta applications.

Q1025 ITT lo

oNone Q1033 Lennox logo; no. P-8-8899. None Q1041 Lennox lo

T872R

Heat pump model; 2-stage heat, 1-stage cool, manual chan

R1008 Fixed anticipator stage 1 heat and cool; no

anticipator sta

o; no. 63A6401. None

eover.

Y594R1425 Wirin

e 2 heat; changeover with cooling;

differences (old=new):

W=W2; W1-Y1

used with Q672B1046.

R1016 Addison same as T872R1008; used with

Q672B1103.

R1024 Lennox lo

o; fast cycle stage 2 heat; fixed

anticipator stage 1 heat and cool; changeover with

; used with Q672B1160 and Q672L1003.

coolin

R1032 York logo; fixed anticipator stage 1 and 2 heat and

e 1 cool; changeover with cooling; used with

sta

Y594R1425 Wirin

Y594R1664

differences (old=new):

W=W2; W1-Y1 jumper required. See subbase description for

replacement information.

Q672L1011.

R1040 Lennox lo

anticipator sta

o; fast cycle stage 2 heat; fixed

e 1 heat and cool; isolated stage 2

See subbase description for

replacement information. heat switch; changeover with cooling; used with Q672B1202 no. P-8-11221, Q672L1029

R1057 TRADELINE; fixed anticipator sta

cool; no anticipator sta

; used with Q672L1037; outdoor reset.

coolin

e 2 heat; changeover on

e 1 heat and

R1065 Adjustable anticipator stage 2 heat; fixed

anticipator sta

e 1 heat and cool; changeover on

Y594R1763 Desi

Y594R1243

ned for use on General Electric heat pumps. Wirin differences

old=new): A=T.

cooling; used with Q672L1045.

R1073 Lennox logo; no. 63A0301; Celsius scale;

separate auxiliar

e 2 heat antic.

sta

heat power circuit; fast cycle

R1081 Ruud logo; same circuit as T872R1065; used with

None

Y594R1243

Q672L1045, L1136.

R1099 Dunham Bush special; used with Q672L1060,

Y594R1243

L1383.

R1107 Rheem; no. RXMT-B70; used with Q672L1045,

Y594R1243

L1136.

R1115 Friedrich lo

o; fixed anticipator; used with

Q672B1244, L1086.

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

See subbase description for replacement information.

umper required.

37 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 6. T872-T874 Thermostat Cross Reference.

Model Number Description

T874 Trade

Replacement

Remarks

R1123 York logo; no. 025-21453C; Celsius scale. Y594R1664 R1131 Lennox lo

o; separate auxiliary heat power circuit;

None fast cycle stage 2 heat anticipator; outdoor reset; used with Q672L1144, C815A1013.

R1149 Westin

anticipator; coolin

e 1 heat and cool; used with Q672L1110,

sta

house logo; adjustable stage 2 heat

changeover; fixed anticipator

Y594R1243 Wirin

differences (old=new):

W=W2.

L1128, L1151.

R1156 Marvair logo; used with Q672L1094, L1250. Y594R1243 Replacement has auto fan in

Emergency Heat mode. R1164 Bard; used with Q672L1185. Y594R1243 R1172 Heil Quaker; used with Q672L1193. Y594R1243 Wirin

differences (old=new): B=X,

W=W2. R1180 York; Celsius; used with Q672L1011. Y594R1664 R1198 TRADELINE; used with Q672L1227 Y594R1243 R1206 For use with W89; used with Q672L1235. None R1214 Intertherm lo

o; used with Q672L1276. Y594R1300 Wiring differences (old=new):

W1=B, Z=L, K=E. R1222 York lo

anticipator sta

o; used with C815A1039; adjustable

e-2 heat; used with Q672L1284

R1230 Amana logo; no. C62397-1; used with

Y594R1672

None

Q672L1300, W89. R1255 Sin R1271 Westinghouse logo; used with Q672L1375 and

er logo; used with Q672L1326 and W89. None

Y594R1664

W89. R1297 York; Celsius scale; used with Q672L1011. None R1305 Used with Q672L1235 and W89. None R1321 Duotherm lo

o; used with Q672L1409, and W89. None

R1339 Williamson; used with Q672L1391. Y594R1243

T872S

Heat pump model; 2-sta

e heat plus changeover,

1-stage cool. S1005 Westin

house logo; adjustable anticipator stage 1

and 2 heat; fixed anticipator stage 1 heat;

eover with heating: used with Q672C1045

chan

T872T

1-heat sta T1004 Trane lo

T872W

3-heat stages, 2-cool stages, manual changeover

e, 1-vent and 2-cool stages.

o; used with Q672B1129. None

W1019 Lennox logo; no. 52C7501; used with Q672L1342

T874C1018/ Q674C1058

None

Wirin

differences (old=new): V=RC-RH, F=G, C=Y1, Z=B, H2=W2; W1-Y1

umper required.

and C815A1013.

W1027 Westin

house logo; used with Q672L1268 and

None

C815A1021.

W1035 TRADELINE; used with C815A1043 and

Y594W1014

Q672B1251.

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and the subbase.

60-2485—838

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 7. Q672-Q674 Subbase Cross Reference.

Model Number Description

Q672A

System: HEAT-AUTO-COOL, Fan: AUTO-ON

Q674 Trade

Replacement

Remarks

A1005 Standard OEM Q674A1019 A1013 TRADELINE Q674A1019 A1021 RC-RH A1039 RC-RH

Q672B

System: HEAT-OFF-COOL, Fan: AUTO-ON

umper Q674A1019 RC-RH jumper required. umper; Chek Lite Q674A1019 RC-RH jumper required.

B1004 Standard OEM Q674B1034 B1012 Isolated G terminal. Q674B1018 B1020 S

stem: HEAT-OFF-RESET-COOL Q674B1034 Used system off as reset position. B1038 TRADELINE Q674B1034 B1046 Heat pump circuit; used with T872R1008. Y594R1425 Wirin

differences (old=new):

W1=Y1, W=W2.

B1053 RC-RH

umper Q674B1034 RC-RH jumper required. B1061 Chek Lite Q674B1034 B1079 Auto fan operation in heat and cool. Q674B1075 B1087 Carrier no. HH93AZ078; RC-RH

umper. Q674B1075 B1095 Carrier no. HH93AZ084; RC-RH jumper. Q674B1034 B1103 Addison; heat pump circuit; used with

T872R1016.

Y594R1425 Wiring differences (old=new):

W=W2; W1-Y1

umper required. B1111 Carrier no. HH93AZ080; isolated G terminal. Q674B1018 B1129 Trane special circuit; used with T872T1004. None B1137 RC-RH

umper; isolated G terminal. Q674B1018 RC-RH jumper required. B1145 Fedders special Q674B1034 RC-RH jumper required. B1152 Fedders special; auto fan operation in heat

Q674B1075

and cool.

B1160 Lennox; heat pump circuit; used with

T872R1024; includes compressor lockout in

Y594R1243 Wirin

differences (old=new):

V-VR=R, M=Y, Y=W2, F=G, R=O.

EM. HT.

B1178 General Electric no. AY28X107; auto fan

Q674B1075

operation in heat and cool. B1186 Trane; isolated G terminal; Filter LED. Q674B1018 B1194 General Electric no. AY28X124; auto fan

operation in heat and cool.

B1202 Lennox no. P-8-11223; heat pump circuit; used

with T872R1040.

Q674B1075 Set T874 sta

combined load of heat rela

rela

Y594R1243 Wiring differences (old=new):

V-VR=R, M=Y, Y=W2, F=G, R=O.

e-1 anticipator for

B1210 None B1228 General Electric no. BAY28X137; isolated

Q674B1018

G terminal. B1236 Carrier no. HH-93AZ079; RC-RH

LOCKOUT LED indicates compressor lockout

umper;

Q674B1034 RC-RH

provided in TRADELINE model.

umper; LED cannot be

switch activated. B1244 Friedrich; heat mode chan

T872R1115.

eover; used with

T874C1018/ Q674B1034

Wiring differences (old=new): C=no connection; RC-RH and W1-Y1

umpers required.

B1251 Used with T872W1035 and C815A1043. Y594W1014

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase.

and fan

39 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 7. Q672-Q674 Subbase Cross Reference.

Model Number Description

B1269 Whalen; Hi-Lo fan switch; constant fan in heat

and cool s

stem switch positions; used with

Q674 Trade

Replacement

None

Remarks

T872C1574. B1277 S B1285 Wards; RC-RH and F-W3 jumpers; used with

uare D no. HCB-5. Q674B1034

Gas Furnace:

T872C1673.

T874C1018/ Q674B1034

Electric Furnace: T874C1018/

ust anticipator

Ad performance.

Q674B1075

B1293 Lennox no. 41C96; used with T872C1673. Same as

Q672B1285

Q672C

stem: OFF-AUTO, Fan: AUTO-ON

S C1003 Standard OEM Q674C1058 C1011 Westinghouse; RC-RH jumper. Q674C1058 RC-RH jumper required. C1029 W1-Y2

umper; for heat pump; used with

T872D1136. C1037 Chr

sler Airtemp; System: COOL-OFF-AUTO. Q674C1058

C1045 Westinghouse; heat pump; used with

T872S1005.

Q674E1049 Replacement has heat/cool system

switching.

T874C1018/ Q674C1058

Wiring differences (old=new): V=RC-RH, F=G, C=Y1, Z=B, H2=W2; W1-Y1

C1052 Isolated sta

relay.

e 2 heat circuit for dc electric heat

Recontrol Use T874G1246/Q674F1212 which

adds HEAT-COOL-EM.HT. system

switch. C1060 Fedders special. Q674C1058 C1078 General Electric no. AY28X109. Q674C1058 C1086 Command-Aire; heat pump; used with

Y594H1012

T872H1009.

C1102 TRADELINE Q674C1058

Q672D

stem: None. Fan: None.

S D1002 Standard OEM; used with T872F1126. Q674D1040 D1010 Lennox special. None D1028 Carrier; RC-RH D1036 Carrier no. HH93AZ070; RC-RH

umper. None

umper. Q674D1040 RC-RH jumper required. D1044 General Electric no. AY-28X100. None D1069 Square D no. HCB-4. None D1077 York; used with T872G1364. None D1085 TRADELINE Q674D1040

Q672E

stem: OFF-HEAT-AUTO-COOL

Fan: AUTO-ON E1001 Standard OEM Q674E1049 E1019 Lennox no. P-8-8892; heat pump; cool mode

eover; used with T872G1026.

chan E1027 Heat pump circuit; W1-Y2

eover; used with T872G1018.

chan E1035 Heat pump circuit; W1-Y2

eover.

chan E1043 Heat pump circuit; heat mode chan

umper; cool mode

eover. Q674E1049 Wiring differences (old=new):

T874D1165/ Q674B1075

Y594G1393 Wirin

Y2=Y.

Y594G1393 Wirin

Y2=Y.

differences (old=new): Y1=O,

W1=B, W2=W1; W1-Y1

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase.

faster

for correct

umper required.

umper.

60-2485—840

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 7. Q672-Q674 Subbase Cross Reference.

Model Number Description

Q674 Trade

Replacement

Remarks

E1050 TRADELINE Q674E1049 E1068 RC-RH

umper; used with T872C1699. Q674E1049 RC-RH jumper required. E1076 RC-RH internal jumper; EM. HT. LED. Q674E1049 RC-RH jumper required. E1084 Carrier no. HH93AZ076; RC-RH jumper. Q674E1049 RC-RH jumper required. E1092 Carrier no. HH93AZ082; RC-RH

umper; B

Q674E1049

terminal; isolated G terminal. E1100 General Electric no. AY28X099. Q674E1049 E1118 Airtemp; heat pump; used with T872D1169. T874D1165/

Q674E1049 E1126 Common R terminal. Q674E1049 RC-RH E1134 ITT Nesbitt; RC-RH jumper; O and B terminals;

Q674E1049

differences (old=new):

Wirin A=W1; set H1 anticipator to 1.2A.

umper required.

isolated G terminal.

E1142 Lennox no. P-8-11224; heat pump;

umper; cool mode changeover; used with

V-VR

Y594G1252 Wirin

differences (old=new):

V-VR=R, Y=W2, R=O, M=Y, F=G.

T872G1067.

E1159 Carrier no. HH93AZ077; RC-RH

LOCKOUT LED indicates activation of

umper;

Q674E1049 RC-RH jumper required; no LED in

TRADELINE model.

compressor lockout switch.

E1167 S

uare D no. HCB-2; Chek Lite. Q674E1049 E1183 Square D no. HCB-3. Q674E1049 E1191 Lennox; HIGH and LOW LEDs; used with

Q674E1049 No LEDs on replacement.

T872D1045.

Q672F

stem: EM. HT.-HEAT-AUTO-COOL-OFF

Fan: AUTO-ON. F1000 With EM. HT. LED; used with T872C1699. Q674F1022 Remove W3-X2 F1018 Heat pump; heat mode chan

eover; Chek Lite;

used with T872G1000. F1026 Chek Lite; W2-X2

umper. Q674F1022

F1034 Airtemp; EM. HT. LED; RC-RH and X2-E

umpers.

Y594G1252 Wiring differences (old=new):

W=W2, X1=X.

Q674F1022 If RC-RH

Q672F1034, Q674F1022 does not

umper to E-X2.

umper removed on

replace.

F1042 W2-X2

umper; Chek Lite. Q674F1022

F1059 Carrier no. HH93AZ074; EM. HT. LED. Q674F1022 Remove W2-X2 jumper to E-X2; X

terminal same as C.

F1067 Lennox; heat pump; cool mode chan

eover;

None

EM. HT. LED; used with T872G1026. F1075 Heat pump circuit; EM. HT. LED; 2 terminal; RC-

umper.

RH F1083 Lennox no. P-8-11225; heat pump;

None

None V-VR jumper; cool mode changeover; EM. HT. LED; used with T872G1067.

F1091 Westin

mode chan

house; heat pump; EM. HT. LED; cool

eover; compressor lockout in

Y594G1252 Wirin

differences (old=new):

W=W2.

EM. HT.; used with T872G1034.

F1109 Airtemp no. 3778567ACC; R-X2

umper;

Q674F1022 R-X2 jumper required. EM. HT. LED.

F1117 Tappan no. 080-13708-53; heat pump; EM. HT.

LED; cool mode chan

eover; compressor

Y594G1252 Wirin

differences (old=new): C=X.

lockout and auto fan in EM. HT.; used with T872G1109, G1216, G1372.

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase.

41 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

(G)

Table 7. Q672-Q674 Subbase Cross Reference.

Model Number Description

F1125 BDP no. 3442DP90; used with T872G1117,

Q674 Trade

Replacement

Y594G1252 Wiring differences (old=new): C=X.

G1166, G1174.

F1133 Williamson; heat pump; EM. HT. LED; heat

mode chan

eover; compressor lockout in

T874N1016/ Q674F1220

EM. HT.; used with T872N1010.

F1141 Westin

house; EM. HT. LED; auto fan in

EM. HT.; used with T872G1034.

F1158 Rheem Ruud; heat pump; EM. HT. LED; cool

mode chan

eover; compressor lockout in

Y594G1252 Wiring differences (old=new):

W=W2.

Y594G1252

EM. HT.; used with T872G1083, G1133, G1141;

auto fan in EM. HT. F1166 Crispaire; EM. HT. LED; used with T872G1208. Y594G1252 F1174 Carrier no. HH93AZ081; EM. HT. LED. Q674F1022 F1182 S

F1190 EM. HT. LED; X2-E and RC-RH

uare D no. HCB-1; Chek Lite; R-X2 jumper; stem: Aux. Heat replaces EM. HT.

umpers. None

F1208 TRADELINE; cool mode changeover; EM. HT.

Q674F1022 R-X2

between X1 and low side of power.

Y594G1419

umper; add monitor switch

LED; used with T872G1224. F1216 TRADELINE; heat mode chan

LED; used with T872N1028. F1224 Heatwave

Southwest Mfg.); compressor

eover; EM. HT.

T874N1016/ Q674F1220

Y594G1252 lockout in EM. HT.; EM. HT. LED; used with T872G1232.

F1232 Rheem; cool mode chan

eover; EM. HT. and

Y594G1252 AUX. HEAT LEDs; compressor lockout in EM. HT.; used with T872G1133.

F1240 Lennox; cool mode chan

eover; EM. HT. and

None SERVICE LEDs; used with T872G1240.

F1257 Westin

EM. HT. and AUX. HEAT LEDs; auto fan in

house; cool mode changeover;

Y594G1252 Wiring differences (old=new):

W=W2.

EM. HT; used with T872G1034.

F1265 Wesco Addison; Chek and EM. HT. LEDs; used

Y594G1252 Wirin

differences (old=new): C=X.

with T872G1281, G1265.

F1273 Southwest special; no. 0361-136; W2-X2

None

umper. F1281 Luxaire special; used with T872G1315. Y594G1252 F1299 Bard special; used with T872N1036, N1044. T874N1016/

Q674F1220

F1315 Williamson special; used with T872N1010. T874N1016/

Q674F1220

F1323 Crispaire special; used with T872G1208. Y594G1252

Q672G

stem: OFF-AUTO. Fan: None.

S G1009 Standard OEM Q674G1070 G1017 Singer; O-B jumper; used with T872D1375. Q674G1070 G1025 Includes O and B terminals. Q674G1070 G1033 General Electric no. AY28X102. Q674G1070 G1041 Sin

er no. 02005649; French wording; O-B

Q674G1070 Less French wordin

umper.

G1066 SLI-Mammoth; heat pump; heat mode

eover.

chan

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase.

Q674G1070 Connect fan

B-O and RC-RH

Remarks

wire to Y1 terminal;

umpers.

60-2485—842

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 7. Q672-Q674 Subbase Cross Reference.

Model Number Description

G1074 Singer no. 02005754; X1 and X2 terminals for

field-added indicator li

hts; used with

Q674 Trade

Replacement

None

Remarks

T872D1375.

G1082 Sin

field-added indicator li

er no. 02005792; X1 and X2 terminals for

hts; used with

None

T872D1375.

G1090 TRADELINE; B and O terminals. Q674G1070

Q672H

stem: OFF-ON

Fan: NIGHT INT.-DAY CONT.

H1008 Used with T872. None

Q672J

stem: EM. HT.-AUTO-OFF

Fan: AUTO-ON. J1005 With EM. HT. LED; used with T872C or D. None J1013 Westin

house; heat pump; EM. HT. LED; cool

Y594G1252 mode changeover; compressor lockout in EM. HT.; used with T872G1034.

J1021 York; heat pump; EM. HT. LED; cool mode

eover; compressor lockout and auto fan in

chan EM. HT.; E-W

umper; used with T872G1042,

Y594G1567

G1331, G1398.

J1039 Heat pump; EM. HT. and AUX. HEAT LEDs;

cool mode chan

eover; compressor lockout and

Y594G1161 Designed for use on General

Electric heat pumps.

auto fan in EM. HT.; used with T872G1059.

J1047 Sin

er no. 02005699; heat pump; EM. HT. LED;

heat mode chan

eover.

J1054 Carrier no. HH93AZ073A; heat pump; EM. HT.

LED; cool mode chan

eover; compressor

Q674F1022

Y594G1252 Wirin

differences (old=new): C=X.

lockout in EM. HT.; used with T872G1075, G1182, G1307.

J1062 Westinghouse; EM. HT. and AUX. HEAT LEDs;

used with T872G1034.

Q672K

stem: OFF-HEAT-AUTO-COOL. Fan: None.

Y594G1252 Wiring differences (old=new):

W=W2.

K1004 Carrier no. HH93AZ072. Q674E1049 Fan switch does not function. K1012 Oneida Heater no. 30A0288-01; System: OFF-

WOOD-WOOD/OIL-OIL; used with T872F1175.

Q672L

stem: EM. HT.-HEAT-OFF-COOL.

T874F1155/

Q674K1026

Fan: ON-AUTO.

L1003 Lennox; heat pump; EM. HT. LED; cool mode

eover; used with T872R1024.

chan

L1011 York; heat pump; EM. HT. LED; cool mode

eover; compressor lockout and auto fan in

chan

Y594R1425

Y594R1664

EM. HT.; used with T872R1032, R1180, R1297.

L1029 Lennox no. P-8-11226; heat pump; EM. HT.

LED; V-VR

umper; cool mode changeover;

Y594R1425 Wirin

differences (old=new):

V-VR=R, M=Y, Y=W2, F=G, R=O. compressor lockout in EM. HT.; used with T872R1040.

L1037 Heat pump; EM. HT. and AUX. HT. LEDs; cool

mode changeover; compressor lockout and auto fan in EM. HT.; used with T872R1057.

L1045 Rheem; heat pump; EM. HT. LED; cool mode

eover; compressor lockout in EM. HT.;

chan

Y594R1763 Wirin

desi

Electric heat pumps.

Y594R1243

differences (old=new): A=T;

ned for used on General

auto fan in EM. HT; used with T872R1065, R1081, R1107.

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase.

43 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 7. Q672-Q674 Subbase Cross Reference.

Model Number Description

L1052 Carrier no. HH93AZ075; heat pump; EM. HT.

LED; cool mode chan

eover; compressor

Q674 Trade

Replacement

Y594R1615 Wirin

differences (old=new): C=X.

lockout in EM. HT.; used with T872G1075, G1182, G1273, G1307.

L1060 Dunham Bush; EM. HT. LED; used with

Y594R1243

T872R1099.

L1078 Tappan no. B13708-58; heat pump; EM. HT.

LED; cool mode chan lockout in EM. HT.; EM. HT. rela

eover; compressor

provides fan

None

operation in EM. HT.; used with T872G1190.

L1086 Friedrich; heat mode chan

eover; EM. HT. LED;

used T872R1115 with L terminal.

L1094 Crispaire; W2-H

umper; EM. HT. LED; used

with T872R1065, R1156.

L1102 Fedders; heat mode changeover; EM. HT. LED;

used with T872C1509, C1517, C1541.

L1110 Wes tinghouse; EM. HT. LED; used with

T872R1149.

L1128 Westin

house; EM. HT. LED; used with

T872R1149.

L1136 Rheem no. 41-20796-07; cool mode

eover; EM. HT. and AUX. HT. LEDs; used

chan

Y594R1243 Wiring differences (old=new): X2=E,

C=X.

Y594R1243 Replacement has auto fan in

ency Heat mode.

Emer

Y594R1425 Wiring differences (old=new): K=E,

C=X; remove Y-W1

Y594R1243 Wiring differences (old=new):

W=W2.

Y594R1243 Wiring differences (old=new):

W=W2.

Y594R1243

with T872R1081, T872R1107.

L1144 Lennox; V-VR

umper; EM. HT. and SERVICE

None LEDs; isolated stage 2 heat; used with T872R1131, C815A1013.

L1151 Westin

house; AUX. HT. and EM. HT. LEDs;

used with T872R1149.

L1169 Carrier no. HH93AZ071; EM. HT. LED; used

with T872G1257

HH07AT073).

Y594R1243 Wiring differences (old=new):

W=W2.

None

L1177 York; DoD; EM. HT. LED; used with T872G1299. Y594G1567 L1185 Bard; used with T872R1164. Y594R1243 L1193 Heil Quaker no. NAXA001TS01; used with

T872R1172.

L1201 Lennox special; no. 1485701; used with

Y594R1243 Wirin

None

differences (old=new): B=X,

W=W2.

T872G1323.

L1219 Westin

house special; used with T872G1356. T874D1165/

Q674F1022

Wiring differences (old=new): X=X1, L=X2, W=E; Y1-W1 and Y2-W2

umpers required. L1227 Heat pump; used with T872R1198. Y594R1243 L1235 Intertherm; used with T872R1206, R1305. None L1250 Crispaire special; used with T872R1156 and

Y594R1243

C815A1021.

L1268 Westin

house special; used with T872W1027

None

and C815A1021.

L1276 Intertherm special; used with T872R1214. Y594R1300 Wirin

differences (old=new):

W1=B, Z=L, K=E. L1284 York special; used with T872R1222. Y594R1672 L1300 Amana special; no. C62345-1; used with

None

T872R1230.

L1326 Sin

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase.

er; used with T872R1255. None

Remarks

umper.

60-2485—844

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 7. Q672-Q674 Subbase Cross Reference.

Model Number Description

L1342 Lennox no. 52C7601; used with T872W1019

Q674 Trade

Replacement

None

and C815A1013.

L1375 Westin

house; used with T872R1271, W89. None L1383 Dunham Bush; used with T872R1099. Y594R1243 L1391 Williamson; used with T872R1339. Y594R1243 L1409 Duotherm special; used with T872R1321, W89. None

Q672N

N1001 Goettl; heat pump; heat mode changeover;

stem: OFF-HEAT-COOL-EVAP.

None

evaporative cooler circuit; Fan: AUTO-ON;

stem: AUTO; used with T872C1459.

N1019 Goettl; heat pump; heat mode chan

eover;

None evaporative cooler circuit; W1-Y1 jumper; used with T872C1459.

N1027 Sie

Q672P

P1009 Carrier special; no. HH93AZ069; used with

When replacing a T872 Thermostat and Q672 Subbase, always replace both the thermostat and subbase.

ler special; used with T872C1707. None

stem: EM. HT.-HEAT-COOL.

T872G1075

HH07AT071).

Y594R1243 Replacement has OFF s

switch position

Remarks

stem

45 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 8. T874 Cross Reference.

Model

Number

T874A

A1002 44, 65 Hone A1010 44 Hone

Fig.

No. Description

e heat, 1-stage cool.

1-sta

well logo; Standard OEM; used with Q674B1331. T874A1036 well logo; includes Allen wrench and screws to

lock cover; non-ad

ustable range stops set at 72°F (max.

heat) and 78°F (min. cool) (22-26°C); field adjustable

levers.

lockin A1028 44 Hone A1036 44 Hone

well logo; heat anticipator factory set at 0.4A. T874A1036 well logo; TRADELINE® model; includes Allen

wrench and screws to lock cover; field adjustable

levers.

lockin A1044 44 Obsolete

. AAF/Snyder General logo; part no. 4ELN-

3006C; °F/°C scaleplate. A1051 44 Lennox lo

o; part no. 12F9901; °F/°C scaleplate; heat

anticipator set at 0.45A. A1069 44 Obsolete A1077 46, 82 Obsolete

. Westinghouse logo; used with Q674A-E,G. T874A1036

. Amana Air Conditioning logo; part no. D68535-1; heat anticipator factory set at 1.2A; used with Q674B1075, E1056; used in Y594A1001, A1019.

A1085 44, 46,

55, 66

Obsolete Q674B1018, B1075, D1008.

A1093 44 Obsolete

. Trane logo; part no. 13510451; used with

. McQuay logo; part no. 02005935; °F/°C scaleplate.

A1101 51, 53 Carrier lo

A1119 82 Obsolete

o; part no. HH07AT174; used with Q674B. Y594C1421 or

. Sears logo; part no. 541. 91441/49. 9144; °F/ °C scaleplate; used with Q674E1007; used in Y594A1068.

A1127 44 Obsolete

. Climate Control logo; part no. 02005936; °C scaleplate.

A1135 44 Fedders multi-lo

o; part no. THTX-110-WCHA,

88-58-00500-001.

A1143 44 Hone

A1150 44 Hone

well logo; °C scaleplate. T874A1036 Replacement has °F

well logo; TRADELINE model; includes Allen

wrench and screws to lock cover; field ad

levers (68°F max. heat, 78°F min. cool).

lockin

A1168 44 Obsolete

. Trane Comfort Corps logo. T874A1036

A1176 44 Honeywell logo; meets DoD specs; includes Allen

wrench and screws to lock cover; no thermometer; non-

ustable range stops set at 72°F (max. heat) and 78°F

min. cool) (22-26°C); field adjustable locking levers.

A1184 51, 53 Trane lo

o; part no. BAY28X182; °F/°C scaleplate; automatic fan in heating and cooling modes; heat anticipator set at 0.4A; used with Q674B1141, E1080.

A1192 44 Obsolete

heat anticipator factor

Both the thermostat and subbase must be replaced.

. Lennox logo; part no. 13F0001; °C scaleplate;

set at .458A.

ustable

Trade Model

Replacement Remarks

T874A1010

T874A1036

T874A1036 Replacement has °F

scaleplate.

T874A1036 Replacement has °F

scaleplate.

T874A1036

T874A1036 Replacement has °F/°C

scaleplate. When using the T874C1036,

T874A1036

set sta

e 1 heat anticipator for

total current draw of fan and

e 1 heat primary.

sta

T874A1036 Replacement has °F

scaleplate.

T874A1036 Replacement has °F

scaleplate.

T874A1036

scaleplate.

T874A1150

T874A1176

T874A1036

When used with Q674E1080, set stage 1 heat anticipator for total current draw of fan and

e 1 heat primary;

sta replacement has °F scaleplate.

T874A1036 Replacement has °F

scaleplate.

60-2485—846

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

A1200 51, 53 Obsolete. Carrier logo; part no. HH07AT164; °C

scaleplate; includes Allen wrench and screws to lock cover; used with Q674B.

A1226 44 Hone

well logo; Honeywell Canada TRADELINE model; °C scaleplate; includes Allen wrench and screws to lock cover.

A1234 44 Obsolete

anticipator factor

A1242 44 Obsolete A1259 44 Obsolete A1267 59 Obsolete A1275 44 Obsolete

. Friedrich Climate Master logo; heat

set 1.2A. . Friedrich Climate Master logo. T874A1036 . Wesco logo; heat anticipator set at 0.8A. T874A1036 . McQuay logo; used with Q674Q1004. T874A1036 . Lennox logo; part no. 13F0101; meets DoD

specifications.

A1283 75 McQua

with Q674C1132 and thermistor to displa

Air Conditioning logo; part no. 03005047; used

outdoor

temperature.

A1291 64 No lo

o; three-speed fan; one setpoint lever for heat and cool setpoints; used with Q674Q1012; used in Y594A1126.

A1309 44 Obsolete

. Arcoaire Air Conditioning and Heating logo; part no. AO2076; includes Allen wrench and screws to lock cover.

A1317 44 Obsolete

. McQuay logo; part no. 60685301; no scaleplate; used with Q674A-E,G.

A1325 75 Obsolete

. McQuay logo; part no. 60685401; no scaleplate; used with Q674C1306 and outdoor thermistor to displa

outdoor temperature.

A1341 44 Obsolete. Trane logo; part no. THT-0577; meets DoD

specifications.

A1358 44 York-Miraco lo A1366 51, 53 Obsolete

A1374 44 American Standard lo

anticipator factor

o. T874A1036

. BDP Multi-logo; part no. HH07AT182.

o; part no. ASYSTAT610; heat

set at 0.4A.

A1390 44 Obsolete. Climate Control logo; part no. 654958804; °F/

°C scaleplate.

A1416 44 Obsolete

. Reznor logo; part no. 654758803; °F/°C scaleplate.

A1424 214 Obsolete

no. HH07AT194; used with Q674B1455

. Carrier Olympia Series Split System logo; part

HH93AZ208).

A1440 91 Obsolete. Simplex System 2000 logo; heat anticipator

set at 1.2A; used with Q674G1005; used in

factor Y594A.

A1465 212 Hone

well Trol-A-Temp™ logo; Premier White® color;

heat anticipator factor

set at 0.10A; used with

Q674E1379.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

T874A1036

Set stage 1 heat anticipator for total current draw of fan and

e 1 heat primary;

sta replacement has °F scaleplate.

T874A1036 Replacement has °F

scaleplate.

T874A1036

T874A1176

T874A1036 Replacement does not have

to display external

abilit temperature or momentar system switch position.

T874A1036/

Q674B1075

Replacement has two levers

and 1 speed fan.

T874A1036

T874A1036 Replacement does not have

ability to display external temperature or momentary

stem switch position.

T874A1176

T874A1036

Set stage 1 heat anticipator for total current draw of fan and

e 1 heat primary.

sta

T874A1036

T874A1036 Replacement has °F

scaleplate.

T874A1036 Replacement has °F

scaleplate.

See OEM for replacement.

T874A1036

None See Trol-A-Temp for

replacement.

47 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 8. T874 Cross Reference.

Model

Number

A1481 44 Obsolete. Honeywell logo; Carrier part no. HH621602;

Fig.

No. Description

Trade Model

Replacement Remarks

T874A1036 includes locking cover and non-adjustable range stops set at 72°F

A1507 44 Obsolete. Climate-Tel logo; includes Allen wrench and

screws to lock cover and non-ad at 72°F

A1523 224,

Obsolete 066804404; °F/°C scaleplate; no coolin

225

max. heat) and 78°F (min. cool).

ustable range stops set

max. heat) and 78°F (min. cool).

. AAF/Snyder General logo; part no.

anticipation;

T874A1176

See OEM for replacement.

used with Q674E1312, C1298.

A1549 224,

Obsolete anticipation; used with Q674E1312, C1298.

225

A1556 51, 53 Carrier lo

. McQuay logo; part no. 066816601; no cooling

o; part no. HH07AT164-W; °C scaleplate;

See OEM for replacement.

T874A1036 Premier White® color; includes Allen wrench and screws to lock cover; used with Q674B.

A1572 224,

Obsolete

225

White® color; °F/°C scaleplate; no coolin

. McQuay logo; part no. 066816611; Premier

anticipation.

A1580 91 California Economizer logo; Premier White® color; heat

set at 1.2A.

A1598 224,

225

anticipator factor McQuay logo; part no. 073319001; Premier White®

color; °F/°C scaleplate; includes Allen wrench, screws to

See OEM for replacement.

T874A1036

See OEM for replacement.

lock cover and AAF insert.

A1614 44 Hone

well logo; TRADELINE® model; °C scaleplate;

T874A1036 Replacement has °F Premier White® color; includes Allen wrench and screws to lock cover; used with Q674B.

A1622 44 Obsolete

. York logo; part no. 2TH04703224A; includes

T874A1010 Allen wrench and screws to lock cover and non-

ustable range stops set at 72°F (max. heat) and 78°F

min. cool).

T874B 1-stage heat, 2-stage cool.

B1001 44 Obsolete. Honeywell logo. T874B1019 B1019 44 Hone

well logo; TRADELINE model; includes Allen

T874B1019 wrench and screws to lock cover.

B1027 44 Obsolete B1035 44, 46 Obsolete. Trane logo; used with Q674B1018, B1075;

. Westinghouse logo. T874B1019

T874B1019 used in Y594B1026, B1034.

B1043 44 Obsolete

B1050 44 Lennox lo

B1068 44 Hone

. Honeywell logo; °C scaleplate. T874B1019 Replacement has °F

o; part no. 13F0201; °F/°C scaleplate. T874B1019 Replacement has °F

well logo; Honeywell Canada TRADELINE model;

T874B1019 Replacement has °F °C scaleplate; includes Allen wrench and screws to lock cover.

B1076 88 Obsolete

. Lennox Power Saver Two-Speed logo; part

T874B1019 Replacement has °F no. 91C7401; °F/°C scaleplate; used with Q674E1155.

B1084 44 Obsolete

. Lennox Two-Speed logo; part no. 13F0301;

T874B1019 Replacement has °F °C scaleplate.

B1092 44 Obsolete

. Honeywell logo; Heil Quaker part no.

T874B1019 HQ521389HW.

B1100 88 Obsolete

. Janitrol logo; part no. CHTS36-60; °F/°C

T874B1019 Replacement has °F scaleplate; used with Q674E1338; used in Y594B1042.

B1118 44 Hone

well logo; °C scaleplate; used with

T874B1019 Replacement has °F Q674A-E, G.

Both the thermostat and subbase must be replaced.

Replacement has °F scaleplate; replacement is

bei

scaleplate; replacement is

bei

scaleplate.

60-2485—848

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

B1134 222 Obsolete. Carrier Synergy 2000 logo; part no.

HH07AT199; °C scaleplate; used with Q674E1395

HH93AZ209).

T874C

C1000 44, 76 Hone

e heat, 1-stage cool.

2-sta

well logo; used with Q674B1075, C1181; used in

Y594C1058.

C1018 60, 61,

81, 92

well logo; TRADELINE model; includes Allen

Hone wrench and screws to lock cover; used with Q674C1074.

C1026 44 Obsolete

wrench and screws to lock cover; non-ad

. AAF logo; °C scaleplate; includes Allen

ustable range

stops set at 23°C (max. heat and min. cool) (73°F).

C1034 44 Lennox lo

C1042 44 Obsolete

o; part no. 13F0401; °F/°C scaleplate. T874C1018 Replacement has °F

. Westinghouse logo; H1 anticipator factory set at.75A; H2 anticipator factory set at 1.2A; used with Q674A-E,G.

C1059 44, 142 Obsolete

D68535-2; H1 anticipator factor

. Amana Air Conditioning logo; part no.

set at 1.2A; used with Q674E1056, Q674B1059, Q674F1022; used in Y594C1009, Y594C1017, Y594C1256, Y594C1330.

C1067 44 Obsolete

. Sears logo; part no. 42. 9297; °F/°C

scaleplate.

C1075 51, 53 Carrier lo

o; part no. HH07AT170; used with

Q674B1166.

C1083 44 Obsolete. Trane logo; used with Q674E1007; used in

Y594C1082.

C1117 44 Hone

C1125 60, 61, 92Obsolete

well logo; °C scaleplate. T874C1018 Replacement has °F

. Honeywell logo; 12°F (6.7°C) differential

between sta

e 1 heat and stage 2 heat; used with

Q674G1047.

C1133 96 Obsolete

. AAF/Snyder General logo; part no. 4ELN7546; no H1 heat anticipation; used with Q674AG,N and Q674C1173.

C1141 44 Obsolete

. Honeywell logo; meets DoD specs; includes Allen wrench and screws to lock cover; no thermometer;

ustable range stops set at 72°F (max. heat) and

non-ad 78°F

min. cool) (22-26°C); field adjustable locking

levers.

C1158 44 Obsolete C1166 51, 53 Obsolete

. Solaron special. T874C1018

. Carrier logo; part no. HH07AT160; °C scaleplate; includes Allen wrench and screws to lock cover; used with Q674B.

C1174 44 Obsolete

. Goettl logo. T874C1018

C1182 60 Obsolete. Goettl logo; H1 anticipator factory set at 0.8A;

used with Q674N1015.

C1190 44 Obsolete

Both the thermostat and subbase must be replaced.

. Lennox logo; part no. 13F0501; °C scaleplate. T874C1018 Replacement has °F

Trade Model

Replacement Remarks

T874B1019/

Q674E1049

Wiring differences (old=new):

W1=W; RC-RH jumper

uired; replacement has no

re LEDs.

T874C1018

T874C1018 Replacement has °F

scaleplate.

T874C1018

T874C1018 Replacement has °F

scaleplate.

Y594C1421 or

T874C1018

When using the T874C1018,

set stage 1 heat anticipator for total current draw of fan and

e 1 heat primary.

sta

T874C1018

scaleplate.

T8611M2025

T874C1018 Must have H1 anticipator set

to maximum value.

T874C1141

T874C1018

Replacement has °F scaleplate; set stage 1 heat anticipator for total current draw of fan and sta

e 1 heat

primary.

T874C1018

scaleplate.

49 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 8. T874 Cross Reference.

Model

Number

Fig.

No. Description

Trade Model

Replacement Remarks

C1216 44 Obsolete. Fasco part no. 1230-8197. T874C1018 C1224 105 Obsolete. Square D logo. T874C1018 C1240 44 Honeywell logo; Honeywell Canada TRADELINE model;

°C scaleplate; includes Allen wrench and screws to lock

T874C1018 Replacement has °F

scaleplate.

cover.

C1257 44 Obsolete

differential between H1 and H2 heat.

. Singer part no. 0200-5931; 8°F (4.4°C)

T874C1125 Replacement has 12°F

differential between H1 and H2 heat.

C1265 44 Obsolete

differential between H1 and H2 heat.

. Singer special; °C scaleplate; 5°C (8°F)

T874C1125 Replacement has 12°F

differential between H1 and H2 heat; replacement has °F scaleplate.

C1273 44 Hone

and screws to lock cover; non-ad

well logo; °C scaleplate; includes Allen wrench

ustable range stops

T874C1018 Replacement has °F

scaleplate.

factory set at 23°C (max. heat and min. cool) (73°F).

C1281 44 Obsolete

. Heat Wave special. T874C1018

C1307 44 Obsolete. Friedrich Climate Master logo. T874C1018 C1315 44 Obsolete. Wesco logo; heat anticipator factory set at

T874C1018

0.8A.

C1323 44 Obsolete

. Le Chauffage Urbain special; °C scaleplate. T874C1018 Replacement has °F

scaleplate. C1331 82, 141 Obsolete C1349 61 Obsolete C1372 52 Obsolete. Honeywell logo; used with Q674B1190. T874C1018/

. Duotherm logo; used with Q674E or Q674F. T874C1018 . Sigler logo; used with Q674N1023. T874C1018

Q674B1034

For systems requiring

automatic fan in coolin

only.

stems requiring

For s

automatic fan in heating and

coolin

Wiring differences (old=new):

K=E, C=X; replacement has °F

C1398 105 Obsolete. Fedders logo; °F/°C scaleplate; used with

Q674L1090.

T874C1018/

Q674B1075

Y594R1425

scaleplate. C1406 105 Obsolete

Q674L1090.

. Climatrol logo; °F/°C scaleplate; used with

Y594R1425

Wiring differences (old=new):

K=E, C=X; replacement has °F

scaleplate. C1414 105 Obsolete

Q674L1090.

. Airtemp logo; °F/°C scaleplate; used with

Y594R1425

Wiring differences (old=new):

K=E, C=X; replacement has °F

scaleplate. C1422 187 Obsolete C1430 49 Obsolete

. Honeywell logo; used with Q674B1208. None . Lennox Zone Master Two-Speed logo; part

T874C1018

no. 25F7201; used with Q674B1224.

C1448 110,

190

Obsolete specifications; re

. Lennox logo; part no. 24F5101; meets DoD

uires outdoor reset; used with

Q674L1165, L1355.

Y594R1763

Wiring differences (new=old):

R=V-VR, Y=M, G=F, B-X,

W=Y, T=A, O=R, X2=E;

ency Heat becomes

Emer

stage 1 heat source. C1455 127 Obsolete

. Williamson logo; used with Q674L1322.

Y594R1243

C1463 82 Obsolete. AAF logo; °C scaleplate. T874C1018 Replacement has °F

scaleplate. C1471 56 Obsolete

. Mammoth logo; part no. 71120102; used with

T874C1018

Q674B1257; used in Y594C1314.

Both the thermostat and subbase must be replaced.

mode

60-2485—850

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

y sy

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

C1489 121 Obsolete. Honeywell logo; non-adjustable range stops

set at 75°F (max. heat and min. cool) (24°C); used with Q674L1157.

C1497 121 Obsolete. Honeywell logo; meets DoD specifications;

used with Q674L1157.

C1513 44 Obsolete. Borg-Warner multi-logo; part no.

6TH11703124A.

C1562 44 Obsolete

. Honeywell logo; Heil Quaker part no.

HQ712001HW.

C1570 45 Obsolete

. Williamson logo; used with Q674B1000; used

in Y594C1280.

C1638 121 Obsolete

. Honeywell logo; meets DoD specifications; includes Allen wrench and screws to lock cover; no thermometer; non-ad

ustable range stops set at 72°F

max. heat) and 78°F (min. cool) (22-26°C); field

ustable locking levers; used with Q674L1561; used in

ad Y594C1322.

C1653 70 Obsolete. Fiberglas Canada; °C scaleplate; no H1, H2,

or C1 anticipation; used with Q674S1000; used in Y594C1348.

C1661 99 Obsolete

. McQuay logo; part no. 61202401; °F/°C scaleplate; includes momentary system switch position with sprin

C1695 45 Obsolete

release; used with Q674C1363.

. Miller logo; used with Q674B1000; used in Y594C1355.

C1703 45 Obsolete

. Intertherm logo; used with Q674B1000; used in Y594C1363.

C1737 44 Obsolete

. Honeywell logo; Carrier part no. HH621603. T874C1018

C1745 44 Obsolete. AAF/Snyder General logo; part no.

4ELN7919.

C1752 219 Obsolete

. McQuay/Snyder General logo; part no. 061202402; 12°F offset between H1 and H2; °F/°C scaleplate; no C1 anticipation; used with Q674C1363.

C1760 44 Bard lo

o. T874C1018

C1778 219 Obsolete. AAF/Snyder General logo; part no.

066804405; 12°F offset between H1 and H2; °F/°C scaleplate; no C1 anticipation; used with Q674C1363.

C1794 53 Obsolete

. Carrier logo; Canada; part no. HH07AT160-W; Premier White® color; °C scaleplate; includes lockin cover.

C1802 246 Obsolete

. California Economizer logo; °F/°C scaleplate;

used with Q674G1005; used in Y594C1371.

C1810 237 Obsolete

. Honeywell logo; TRADELINE model; Premier White® color; used with Q674B1547; used in Y594C1389.

C1844 238 Ener

Night logo; used with Q674F1592; used in

Y594C1413.

C1851 60 Obsolete C1869 219 McQua

. Whalen logo. T874C1018

logo; part no. 0073318801 Premier White®

color; °F/°C scaleplate.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594C1322

T874C1018

Y594C1322

See OEM for replacement.

T874C1125/

Q674B1075

Replacement has HEAT-OFF-

COOL system switching; no momentar position; no LEDs.

T874C1018

T8611M2025

See OEM for replacement.

T874C1018 Set sta

total current draw of fan and

e 1 heat primary.

sta

T874C1018

Y594C1389

Y594R1425 Jumper E-W2; system switch:

EM.HT.-HEAT-OFF-COOL.

See OEM for replacement.

stem switch

e 1 heat anticipator for

51 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

Table 8. T874 Cross Reference.

Model

Number

C1877 53 Obsolete. Honeywell logo; TRADELINE model; used

Fig.

No. Description

with Q674B1554; used in Y594C1421.

Trade Model

Replacement Remarks

Y594D1347 Jumper RC-RH; system

switch: OFF-HEAT-AUTOCOOL

T874D

D1009 166, 82 Obsolete

e heat, 2-stage cool.

2-sta

. Honeywell logo; used with Q674F1337,

T874D1165

E1007; used in Y594D1222, D1339.

D1017 44, 88 Obsolete

. Honeywell logo; TRADELINE model; includes

T874D1165 Allen wrench and screws to lock cover; used with Q674A-G and Q674E1155.

D1025 44 Obsolete

at 0.75A; H2 anticipator factor

D1033 44 Lennox lo

. Westinghouse logo; H1 anticipator factory set

set at 1.2A.

o; part no. 13F0601; °F/°C scaleplate. T874D1165 Replacement has °F

T874D1165

scaleplate.

D1041 53 York lo

o; part no. 2TH04701524A; used with

T874D1165 Q674B1125.

D1058 44 Obsolete D1066 44 Obsolete D1074 51, 53,

Carrier logo; part no. HH07AT172; used with

146

Q674F1030 Q674B.

D1082 44, 46,

48, 72

Trane lo B1133; used in Y594D1024, D1040.

D1090 44 Obsolete

. Shiger special. T874D1165 . ITT logo. T874D1165

T874D1165

HH93AZ174), F1063 (HH93AZ181) or

o; used with Q674B1018, C1009, B1075,

T874D1165

. Dunham-Bush logo. T874D1165

Set H1 anticipator for current draw of fan and sta primary.

D1108 44 Obsolete. Westinghouse logo. T874D1165 D1116 76, 89, 94Obsolete. Comfortmaker logo; part no. 1505-682; °F/°C

scaleplate; used with Q674C1116, E1197, G1104.

D1124 44 Obsolete D1132 44 Hone

. Airtemp special. T874D1165

well logo; °C scaleplate. T874D1165 Replacement has °F

T874D1165 Replacement has °F

scaleplate.

D1140 44 Obsolete

. Solaron special. T874D1165 Replacement has °F

scaleplate.

D1157 51, 53,

146

Carrier lo

o; part no. HH07AT172; °C scaleplate; used

with Q674B or Q674F1030, F1063.

T874D1165

Replacement has °F scaleplate; set H1 anticipator for current draw of fan and

e 1 heat primary.

sta

D1165 82 Hone

D1173 51, 53 Trane lo

well logo; SUPER TRADELINE® model; includes Allen wrench and screws to lock cover, field-ad ran

e stops, field-adjustable locking levers.

o; part no. BAY28X183; heat anticipator factory

ustable

set at 0.4A.

D1181 51, 53 Obsolete. General Electric logo; locking cover includes

Allen wrench and screws to lock cover and ran set at 72°F

max. heat) and 78°F (min. cool).

e stops

T874D1165

Set H1 anticipator for current draw of fan and sta

primar

Set H1 anticipator for current draw of fan and sta

primar

D1199 44 Obsolete. Lennox logo; part no. 13F0701; °C scaleplate. T874D1165 Replacement has °F

scaleplate.

D1207 114 Obsolete

Q674L1199 and C815A1013 or Q674L1389.

. Lennox logo; part no. 24F5201; used with

T8611M2025

programmable

Wiring differences (old=new): V-VR=R, Y=W3, X=C, R=O, M=Y, M2=Y2-W2, F=G;

umper Y2-W2; no outdoor reset needed; use onl system transformer.

Both the thermostat and subbase must be replaced.

e 1 heat

one

60-2485—852

(

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

D1215 44 Obsolete. Friedrich Climate Master logo; part no.

AT5415; °F/°C scaleplate.

D1223 44 Hone

well logo; Honeywell Canada TRADELINE model;

Celsius scale.

D1231 44 Obsolete

. Honeywell logo; 12°F (7°C) differential

between H1 and H2.

D1249 44 Obsolete D1256 44 Obsolete D1264 107 Obsolete

no. HH07AT173; used with Q674L1116

D1272 51, 53 Obsolete

. Fedders special. T874D1165 . Climatrol special. T874D1165 . Carrier Heat Pump System Control logo; part

HH93AZ171).

. Carrier logo; part no. HH07AT162-03; °C

scaleplate; used with Q674B.

D1280 44 Obsolete D1298 90, 232 Obsolete

. Command-Aire logo. T874D1165

. Singer special; °C scaleplate; controls two separate heat/cool circuits; used with Q674D or Q674G1054, G1062.

D1306 90, 186 Obsolete

. Trane special; part no. 02005949; controls two separate heat/cool circuits; used with Q674G1013.

D1314 44 Obsolete

. McQuay logo; part no. 02005941; 12°F

6.6°C) differential between H1 and H2.

D1322 46 Obsolete

. Amana logo; part no. D68535-03; used with Q674B1075; used in Y594D1149.

D1330 44 Obsolete

D1355 44 Obsolete

°C scaleplate; 6°C

. Trane logo; part no. 13080242; °C scaleplate. T874D1165 Replacement has °F

. Climate Control special; part no. 02005942;

11°F) differential between H1 and

H2.

D1363 44 Obsolete

. McQuay logo; part no. 02005943; 12°F

6.6°C) differential between H1 and H2; 6°F (3.3°C)

differential between C1 and C2.

D1405 44 Obsolete

differential between H1 and H2; 6°F

. Trane logo; part no. 02005952; 12°F (6.6°C)

3.3°C) differential

between C1 and C2.

D1413 44 Obsolete

. Trane logo; part no. 02005956; 12°F (6.6°C) differential between H1 and H2.

D1421 44 Obsolete

. Climate Control special; part no. 02005938; °C scaleplate.

D1439 90 McQua

logo; part no. 02005935; used with

Q674G1096.

D1447 90 Obsolete

. Climate Control special; part no. 02005940; °C scaleplate; used with Q674G1096.

D1454 51, 53 Obsolete

D1462 80 Obsolete

. Carrier logo.

. Fedders multi-logo; part no. THTX-220-A0HB, 88-58-00550-001; used with Q674E1205.

Both the thermostat and subbase must be replaced.

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Trade Model

Replacement Remarks

T874D1165 Replacement has °F

scaleplate.

T874D1165 Replacement has °F

scaleplate.

T874D1165 Replacement has 2°F

differential between H1 and H2.

See OEM for replacement.

T874D1165

Replacement thermostat has °F scaleplate; set H1 anticipator for current draw of fan and sta

e 1 heat primary.

See OEM for replacement.

T874D1165 Replacement has °F

scaleplate; 2°F differential between H1 and H2.

T874D1165

scaleplate.

T874D1165 Replacement has 2°F

differential between H1 and H2.

T874D1165 Replacement has 2°F

differential between H1 and H2; 2°F differential between C1 and C2.

T874D1165 Replacement has 2°F

differential between H1 and H2; 2°F differential between C1 and C2.

T874D1165 Replacement has 2°F

differential between H1 and H2.

T874D1165 Replacement has °F

scaleplate.

T874D1165

T874D1165 Replacement has °F

scaleplate.

T874D1165

Set H1 anticipator for current draw of fan and sta

e 1 heat

primary.

T874D1165

53 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 8. T874 Cross Reference.

Model

Number

D1470 44 Obsolete. York logo; part no. 2TH04701624A; includes

Fig.

No. Description

Trade Model

Replacement Remarks

T874D1165 Replacement has °F

Allen wrench and screws to lock cover; °C scaleplate. D1488 44 Obsolete D1496 44 Obsolete

. Risco special. T874D1165 . Borg Warner multi-logo; part no.

T874D1165 6TH04701524A; includes Allen wrench and screws to lock cover.

D1504 82 York lo

o; part no. 025-23321-000; °C scaleplate; used

T874D1165 Replacement has °F with Q674E1007; used in Y594D1180.

D1512 44 Hone D1520 44 Obsolete

well logo; Heil Quaker part no. HQ712002HW. T874D1165

. Bard logo; adjustable lever stops set 68°F

T874D1165

max. heat) and 78°F (min. cool). D1538 44 Obsolete D1553 44 Obsolete

. McQuay logo; part no. 02005937. T874D1165 . Climate Control special; part no. 02005944;

T874D1165 Replacement has 2°F °C scaleplate; 6°C differential between H1 and H2; 3°C differential between C1 and C2.

D1561 44 Obsolete D1587 44 Obsolete

. General Electric logo; used with Q674 A-G. T874D1165 . Stiles Four Seasons logo. T874D1165

D1595 139 Obsolete. Nepco logo; used with Q674F1394. T874D1165/

Q674B1018

D1603 44 Obsolete D1611 44 Obsolete. No logo; Friedrich part no. AT5411; °F/°C

. Arcoaire logo. T874D1165

T874D1165 Replacement has °F scaleplate.

D1629 82 Obsolete

. Reznor logo; °F/°C scaleplate; used with

T874D1165 Replacement has °F Q674E1007; used in Y594D1248.

D1678 44 Obsolete

. Honeywell logo; Saudi Oger special; °C

T874D1165 Replacement has °F scaleplate; one setpoint lever; used with Q674A-K.

D1686 98 Obsolete

. McQuay logo; part no. 60685501; 8°F (4.4°C)

T874D1165 Replacement has 2°F differential between H1 and H2; 6°F (3.3°C) differential between C1 and C2; used with Q674E1312.

D1694 202 Obsolete

Q674G1120.

D1702 44 Obsolete

. McQuay logo; part no. 60685201; used with

. McQuay logo; part no. 60685101. T874D1165

See OEM for replacement.

D1710 44 Trane logo. T874D1165 D1728 44 York-Miraco lo D1744 44 American Standard lo

o. T874D1165

o; heat anticipator factory set at

T874D1165

0.4A.

D1751 44 Obsolete

at 68°F

. Goettl logo; part no. 372080; range stops set

max. heating) and 78°F (min. cooling).

D1769 82 Obsolete. Arcoaire logo; part no. 1506753; °F/°C

T874D1165

T874D1165 Replacement has °F scaleplate; used with Q674E1346; used in Y594D1297.

D1777 44 Obsolete

. Climate Control logo; part no. 65495806; °F/

T874D1165 Replacement has °F °C scaleplate.

D1785 82 Obsolete

. Comfortmaker logo; part no. 1505753; °F/°C

T874D1165 Replacement has °F scaleplate; used with Q674E1346; used in Y594D1305.

D1793 44 Obsolete

. McQuay logo; part no. 65495805; °F/°C

T874D1165 Replacement has °F scaleplate.

Both the thermostat and subbase must be replaced.

scaleplate.

differential between H1 and H2; 2°F differential between C1 and C2; replacement has °F scaleplate.

Replacement has HEAT-OFF-

COOL s

stem switching; no

LEDs.

scaleplate.

scaleplate; separate heatin and cooling setpoint levers.

differential between H1 and H2; 2°F differential between C1 and C2.

scaleplate.

60-2485—854

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 8. T874 Cross Reference.

Model

Number

D1801 45, 208 Trol-A-Temp by Honeywell logo; H1 and H2 anticipators

Fig. No. Description

Trade Model

Replacement Remarks

None See Trol-A-Temp for

set at 0.10A; used with Q674B1463, D1115.

D1819 44 Marv Air Com Stat lo

o; part no. 50059; adjustable

T874D1165 Replacement has a 2°F fixed interstage between H1 and H2 and between C1 and C2; includes Allen wrench and screws to lock cover; field

ustable range stops; °F/°C scaleplate.

D1827 45, 208 Trol-A-Temp b

Honeywell logo; Premier White® color;

None See Trol-A-Temp. H1 and H2 heat anticipators set at 0.10A; used with Q674B1471, D1123.

D1843 45 Obsolete

. Janitrol logo; Goodman part no. CHT 90-120;

T874D1165

used with Q674B1000; used in Y594D1321.

D1850 44 Hone D1868 44 Bard lo

well logo; Carrier part no. HH621606. T874D1165

o; part no. 8405-031; H1 and H2 heat

T874D1165 Replacement has 2°F fixed anticipators factory set at 0.25A; 5°F interstage differential between H1 and H2 and between C1 and C2; includes Allen wrench and screws to lock cover; field

ustable range stops.

D1876 44 Obsolete

. AAF/Snyder General logo; part no.

T874D1165 Replacement has °F 4ELN6981A; °F/°C scaleplate.

D1892 44 Obsolete D1918 224,

Obsolete. AAF/Snyder General logo; °F/°C scaleplate;

225

no coolin

. Climate-Tel logo. T874D1165

See OEM for

anticipation; used with Q674E1312, C1298;

replacement.

66804407.

D1926 226 Obsolete

no cooling anticipation; used with Q674G1120;

. AAF/Snyder General logo; °F/°C scaleplate;

See OEM for replacement.

66804406.

D1934 44 Bard lo D1942 82 Hone

o. T874D1165

well logo; TRADELINE model; used with

Y594D1347 Q674E1403; used in Y594D1347; designed to replace York part no. 2TH04701024.

D1959 44 Rheem part no. 41-21444-01. T874D1165 D1967 44 Obsolete D1975 224,

Obsolete. McQuay part no. 066816603; °F/°C

225

scaleplate; no coolin

D1983 226 Obsolete

scaleplate; no coolin

. Desert Aire logo. T874D1165

See OEM for

anticipation.

. McQuay part no. 066816602; °F/°C

anticipation; used with

replacement. See OEM for

replacement.

Q674G1120.

D1991 51, 53 Carrier lo

D2007 44 Ultra-Zone lo D2023 44 Honeywell logo; TRADELINE model; Premier White®

color; °C scaleplate; includes lockin

o; Premier White® color; °C scaleplate.

T874D1165

o. T874D1165

T874D1165 Replacement has °F

cover; used with

Q674A-K.

D2031 82 Obsolete

. Honeywell logo; no cover; used with

Q674E1049 and TG504A1025; used in Y594D1354.

D2049 45, 72,

55, 66,

Both the thermostat and subbase must be replaced.

Obsolete no. HH07AT236; °F/°C scaleplate; used with Q674B-D, Q674G; used in Y594D.

184

. Carrier Heat Pump System Control logo; part

T874D1165 or

Y594D1354 T874D1165 Replacement has °F

replacement.

intersta

e differential between H1 and H2 and between C1 and C2; replacement has °F scaleplate.

intersta

e differential between H1 and H2 and between C1 and C2.

scaleplate.

Set H1 anticipator for total current draw of fan and sta 1 primar

; replacement has °F

scaleplate.

scaleplate and is bei

scaleplate.

55 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 8. T874 Cross Reference.

Model

Number

D2056 44 Obsolete. ComStat logo; part no. 50056; °F/°C

Fig.

No. Description

Trade Model

Replacement Remarks

T874D1165 Replacement has °F

scaleplate; adjustable interstage on both heating and

; includes locking cover and field-adjustable

coolin

levers.

lockin

D2064 53 Obsolete

e 1 and 2 heat anticipator factory set 0.1A; taupe

sta

. Carrier Weathermaker; part no. HH07AT209;

T874D1165 Set sta

color; used with Q674E1445; used in Y594D1412.

D2072 53 Obsolete

. Carrier Zone Perfect; part no. HH07AT208;

T874D1165 Set stage 1 heat anticipator for

taupe color; used with Q674E1445; used in Y594D1420.

D2080 139 Obsolete

. Hydroheat logo. T874D1165/

Q674B1018

D2098 44 Obsolete

. Honeywell logo; °F scaleplate; one setpoint

T874D1165 Replacement has °F

lever; used with Q674D1008; used in Y594D1438.

D2106 44 Obsolete

. Honeywell logo; °C scaleplate; one setpoint

T874D1165 Replacement has °F

lever; used with Q674D1008; used in Y594D1446.

D2114 44 Obsolete

D2122 224,

Obsolete

. Bard logo; °C scaleplate. T874D1165 Replacement has °F

. McQuay T874D2023 Replacement has °C

225

T874D1165 Replacement has °F

D2130 226 Obsolete

. McQua

See OEM for

replacement. D2148 44 Obsolete D2155 139 Hydroheat logo; Premier White® color; °F/°C scaleplate;

used with Q674F1634.

D2163 208 Obsolete

. Dry Aire Systems logo; °F/°C scaleplate. T874D1165

T874D1165/

Q674B1018

. Amana logo; part no. P1217501F; °F/°C

T874D1165

scaleplate.

D2171 44 Obsolete

. Amana logo; part no. P1217701F; °F/°C

T874D1942

scaleplate.

D2189 44 Armstron

logo; part no. 01142A024; °F/°C scaleplate;

T874D1165

includes Air Ease insert.

D2197 44 Liebert lo

intersta

o; part no. 138968P3; °F/°C scaleplate;

e differential between H1 and H2 and between

T874D1165

C1 and C2; includes Allen wrench and screws to lock

ustable locking levers.

o; Premier White® color; °F/°C scaleplate. T874D1165

D2205 44 Aaon lo

T874E

cover; field-ad

0-stage heat, 2-stage cool. E1008 44 Obsolete. Honeywell logo. T874E1016 E1016 44 Hone

well logo; TRADELINE model; includes Allen

T874E1016

wrench and screws to lock cover; field-adjustable

levers.

lockin E1024 44 Obsolete. Westinghouse logo. T874E1016 E1032 44 Lennox lo

E1040 72 Obsolete

o; part no. 13F0901; °F/°C scaleplate. T874E1016 Replacement has °F

. Trane logo; used with Q674C1009; used in

T874E1016

Y594E1015.

Both the thermostat and subbase must be replaced.

scaleplate and 2°F fixed differential in heatin

coolin

e 1 heat anticipator for

total current draw of fan and

e 1 heat primary.

sta Replacement is bei

total current draw of fan and

e 1 heat primary.

sta Replacement is beige.

Replacement system switch:

HEAT-OFF-COOL; no LEDs.

scaleplate and two setpoint levers

scaleplate and two setpoint levers.

scaleplate.

Replacement system switch:

HEAT-OFF-COOL; no LEDs.

scaleplate.

and

60-2485—856

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

Trade Model

Replacement Remarks

E1081 44 Trane logo; part no. BAY28X186; °F/°C scaleplate. T874E1016 Replacement has °F

scaleplate.

E1099 44 Obsolete

. Lennox logo; part no. 13F1001; °C scaleplate. T874E1016 Replacement has °F

scaleplate.

E1107 44 Hone

well logo; °C scaleplate. T874E1016 Replacement has °F

scaleplate. E1123 44 Obsolete E1149 44 Obsolete E1156 44 Obsolete

. Amana logo; part no. D68535-4. T874E1016 . York logo; part no. 2TH04701724A. T874E1016 . Borg Warner multi-logo; part no.

T874E1016

6TH04701724A. E1164 44 Obsolete E1206 44 Obsolete E1230 44 Obsolete

T874F

2-sta F1007 44 Hone F1015 44 Honeywell logo; TRADELINE model; includes Allen

wrench and screws to lock cover; field-ad

. E. A. Juffali & Bros. logo. T874E1016 . Trane logo. T874E1016 . Climar logo. T874E1016

e heat, 0-stage cool.

well logo. T874F1015

T874F1015

ustable

locking levers. F1023 44 Obsolete F1031 44 Obsolete. Honeywell logo; °C scaleplate; used with

40003440-001 wallplate; used in Y594F1022. F1049 44 Obsolete

. Lennox logo; part no. 13F1101. T874F1015

T874F1015 Replacement has °F

scaleplate.

. Lennox logo; °C scaleplate. T874F1015 Replacement has °F

scaleplate.

F1056 55,66Obsolete

electricall

. Honeywell logo; stages 1 and 2 heat

isolated; used with Q674D1008.

F1072 44 Obsolete. Wesco logo; heat anticipator factory set at

None

T874F1015

0.8A.

F1098 189 Obsolete

. Lennox logo; used with Q674D1008 to control

an M839. F1106 95 Obsolete. Oneida logo; part no. 30A0287-02; used with

T874F1015 Set H1 and H2 anticipators to

lowest settin

T874F1155

Q674K1018 on combination wood and oil applications. F1114 4 4 H one

well logo; Honeywell Canada TRADELINE model; °C scaleplate; includes Allen wrench and screws to lock cover; field-ad

F1122 62 Obsolete

used with Q674B1307.

F1130 72, 91 Obsolete

Q674C, D, or G; used with Q674C1009, G1005; used in

ustable locking levers.

. Honeywell logo; two heat setpoint levers;

. Reznor logo; °F/°C scaleplate; used with

T874F1015 Replacement has °F

scaleplate.

T874F1015/

Replacement has no LED.

Q674D1040

T874F1015 Replacement has °F

scaleplate.

Y594F1048.

F1148 44 Obsolete F1155 95 Hone

. Trane logo; part no. THT 0584. T874F1015

well logo; used with Q674K1026 on combination

T874F1155

wood and oil applications.

T874G

Heat pump models; 2-sta

e heat, 1-stage cool;

1–stage changeover.

G1006 84, 155 Obsolete

. Honeywell logo; used with Q674E1015.

Y594G1252

Wiring differences (old=new): R=O, M=Y, F=G, V=R, Y=W2;

umper required.

E-W2

Both the thermostat and subbase must be replaced.

57 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

Table 8. T874 Cross Reference.

Model

Number

Fig.

No. Description

G1014 86, 150 Obsolete. Lennox logo; part no. 24F5801; °F/°C

scaleplate; H2 anticipator factory set at 0.25A for fast

cle performance; changeover in cooling mode;

c independent heatin

and cooling circuits; used with

Q674E1148, F1113.

G1022 86, 150 Obsolete

. Lennox logo; part no. 24F5701; °F/°C

scaleplate; H2 anticipator factory set at 0.25A for fast

cle performance; changeover in cooling mode;

c independent heatin

and cooling circuits; used with

Q674E1148, F1113.

G1048 153,

Obsolete at 1.2A; used with Q674F1121, J1019.

159

G1055 161 Carrier Heat Pump S

HH07AT171; H2 anticipator factor chan

. Westinghouse logo; H2 anticipator factory set

stem Control logo; part no.

set at 0.8A;

eover in cooling mode; used with Q674J1035

HH93AZ173).

G1071 50, 103,

126,

183

Obsolete meets DoD specifications; H2 anticipator factory set at

0.8A; used with Q674P1005

. Carrier Heat Pump System Control logo;

HH93AZ169), L1041

HH93AZ175), B1158, or J1050.

G1089 154 Obsolete

anticipator factor

. Marvair logo; special for Crispaire; H2

set at 1.2A; used with Q674F1204;

used in Y594G1153.

G1097 155 Obsolete

. Honeywell logo; Rheem part no. ZXMT-B79;

used with Q674F1238 (41-20797-14).

G1105 153 Obsolete. Heat Wave (Southwest Mfg.) logo; H2

anticipator factory set at 1.2A; used with Q674F1170.

G1113 103 O bsol ete. Carrier Heat Pump System Control logo;

meets DoD specifications; H2 anticipator factory set at

0.8A; used with Q674L1041.

G1121 103 Obsolete

. Carrier Heat Pump System Control logo; part

no. HH07AT161; °C scaleplate; H2 anticipator factor set at 0.8A; includes Allen wrench and screws to lock cover.

G1139 143,

G1147 148 Obsolete

234

Obsolete C1108.

. Honeywell logo; used with Q674B1240,

. Honeywell logo; changeover in cooling mode;

used with Q674F1139.

G1154 84, 139 Obsolete

G1162 155 Obsolete

. Lennox logo; used with Q674E1015, F1105.

. Lennox logo; meets DoD specifications; used

with Q674F.

G1170 160 Obsolete

. York logo; part no. 2TH11702424A; H2

anticipator is fixed; used with Q674J1027; used in Y594G1013.

G1188 147 Obsolete. Honeywell logo; Keeprite/Westinghouse

special; H2 anticipator factor

eover in cooling mode; used with Q674F1295.

chan

G1196 160 Obsolete

coolin

. York logo; °C scaleplate; changeover in

mode; used with Q674J1027; used in

set 1.2A; °C scaleplate;

Y594G1138.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594G1252

Wiring differences (old=new): R=O, M=Y, F=G, Y=W2, V-VR=R transformer

Y594G1252

Wiring differences (old=new): R=O, M=Y, F=G, Y=W2, V-VR=R transformer

Y594G1252

Wiring differences when replacing T874G/Q674J1019

old=new): W=W2.

None See subbase description for

replacement information.

Y594G1419 Wirin

differences (old=new):

C=X; jumper Y1-W1.

Y594G1393

Wiring differences (old=new): A=L.

Y594G1252

Y594G1419

Wiring differences (old=new): C=X; jumper Y1 -W1.

Y594G1419

Wiring differences (old=new):

umper Y1-W1.

C=X;

None See subbase description for

replacement information.

Y594G1252

Wiring differences (old=new): C=X.

Y594G1252

See subbase description for replacement information.

Y594G1419

Y594G1567

Y594G1252

W1-Y1 jumper required.

Wiring differences (old=new): S=L.

Y594G1567

must use single

60-2485—858

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

Table 8. T874 Cross Reference.

Model

Number

G1204 162 Honeywell logo; designed for use on Trane heat pumps;

Fig. No. Description

no H2 anticipation; changeover in cooling mode; used

Trade Model

Replacement Remarks

Y594G1161

Designed for use on Trane heat pumps.

with Q674J1043 and C815A1005; used in Y594G1161.

G1212 155 Obsolete

0.2A; chan

pass H2 anticipator with W3 heat relays; used with

. Honeywell logo; H2 anticipator factory set at

eover in cooling mode; includes shunt to

Y594G1252

Q674F1238.

G1220 235 Obsolete. Rheem logo; part no. RXMT-C71; changeover

Y594G1252

in cooling mode; used with Q674F1238.

G1238 155 Obsolete. Ruud logo; part no. UXMT-C71; changeover

Y594G1252

in cooling mode; used with Q674F1238.

G1246 Obsolete. Honeywell logo; changeover in cooling mode.

155 Used with Q674F1212; used in Y594G1195, G1252,

Y594G1252

G1369.

170 Used with Q674F1410; used in Y594G1393.

Y594G1393

G1261 58, 157 Obsolete. Borg-Warner; used with Q674D1032, F1253. None See subbase description for

replacement information.

G1279 58, 157 Obsolete

. Bryant logo; used with Q674D1032, F1253. None See subbase description for

replacement information.

G1287 58, 157 Obsolete

. Wesco logo; used with Q674D1032, F1253. None See subbase description for

replacement information.

G1295 58 Obsolete

Q674D1032.

. York logo; part no. 2TH11702724A; used with

T874D1165/ Q674D1040

Wiring differences (old=new): Y=Y2, O=Y1, W=W2; W1-Y2.

G1345 160 Obsolete

. York logo; part no. 2TH11702624A; °C

Y594G1575

scaleplate; used with Q674J1027.

G1352 73 Obsolete. Command-Aire logo; 12°F differential

between H1 and H2 for night setback; used with Q674C1066.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y, L=R, R=none; R-

umper required; no night

L setback.

T8600D1004

programmable

Wiring differences (old=new): Y1=O, Y2=Y, L=RH; RC-RH

umper required; includes

ht setback.

G1378 79 Obsolete. Mammoth logo; H2 anticipator factory set at

0.8A; 12°F differential between H1 and H2 for ni

setback; °F/°C scaleplate; used with Q674C1124; used

Y594H1012

Wiring differences (old=new): R1=none, R2=L; R-L

uired; no night setback.

in Y594G1294.

T8090A1007/

Q682A1038a

Includes night setback; W-Y

umper required.

programmable

G1402 129 Obsolete. York part no. 2TH11702824A; meets DoD

specifications; used with Q674L1363.

Y594R1425

Wiring differences (old=new): W=W2, X=E, B=X; jumper Y-W1.

G1410 155 Obsolete

. Borg-Warner multi-logo; part

no. 6TH11703024A; used with Q674F1311.

G1428 160 Obsolete. Borg-Warner multi-logo; part no.

6TH11702424A; used with Q674J1027; used in

T874G1246

Y594G1252 Y594G1567

Y594G1229.

G1436 58 Obsolete. Borg-Warner multi-logo; part no.

6TH11702724A.

T874D1165/ Q674D1040

Wiring differences (old=new): Y=Y2, O=Y1, W=W2; W1-Y2.

Both the thermostat and subbase must be replaced.

umper

59 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

)

(

)

Table 8. T874 Cross Reference.

Model

Number

Fig.

No. Description

G1444 160 Obsolete. ROCA logo; °C scaleplate; used with

Q674J1027.

G1451 155 Obsolete

. BDP multi-logo; part no. HH641502; used with

Q674F1212; used in Y594G1245.

G1469 194 Obsolete. No logo; Addison special; used with

Q674F1345; used in Y594G1344.

G1485 163 Obsolete

. AAF logo; part no. 4ELN-7839; °F/°C

scaleplate; 10°F differential between H1 and H2 for ni setback and momentar

RESET system switch position;

used with Q674C1199.

G1493 167 Obsolete

. Honeywell logo; Rheem part no. 41-20797-

18; used with Q674F1360.

G1501 195 Obsolete. Coleman logo; part no. 3600-375; changeover

in cooling mode; used with Q674F1378.

G1535 163 Obsolete. AAF/Snyder General logo; 4ELN7839 °F/°C

scaleplate; 10°F differential between H1 and H2 for ni setback and momentar

RESET system switch position;

used with Q674C1199.

G1543 194 Obsolete

. Addison logo; Weather King part no. 8403-

197; used with Q674F1345; used in Y594G1328.

G1568 160 Obsolete

. Luxaire logo; part no. 026-00068-000; °C

scaleplate; used with Q674J1126; used in Y594G1351.

G1576 169 Obsolete

in heatin

. Coleman logo; part no. 3600-373; changeover

and cooling mode; used with Q674F1402;

used in Y594G1377.

G1584 73 Obsolete. No logo; Friedrich part no. AT5784; 8°F

4.4°C) differential between H1 and H2; used with

Q674C1223.

G1592 155 Obsolete

. Arcoaire logo; used with Q674F1212; used in

Y594G1385.

G1600 199 Obsolete. Honeywell logo; meets DoD specifications;

used with Q674F1428; used in Y594G1401.

G1618 73 Obsolete

. Honeywell logo; 12°F differential between H1

and H2 for night setback; used with Q674C1256.

G1626 167 Hone

well logo; used with Q674F1436; used in

Y594G1526.

G1642 227 Hone

well logo; TRADELINE model; meets DoD specifications; used with Q674F1444; used in Y594G1419.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594G1567

T874G1246

V594G1252 Y594G1252

Replacement has °F scaleplate.

Wiring differences (old=new): Y1=O, C=X, W1=Y1, X=L.

Y594G1393

T8611G1004

programmable

Y594G1526

Y594G1252

No night setback or momentar

Includes night setback; no momentar

Wiring differences (old=new): L1=L; changeover in cooling

onl

Y594G1393

T8611G1004

No night setback or momentar

Includes night setback.

programmable

Y594G1252

Wiring differences (old=new): Y1=O, C=X, W1=Y, X=L.

Y594G1367

Replacement has °F scaleplate.

Y594G1633

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y, L=R, R=none;

umper required; no night

L-R setback.

T8611G1004

Includes night setback.

programmable

T874G1246

Y594G1252 Y594G1419

Wirin

differences (old=new):

umper W1-Y1.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y, L=R, R=none;

umper required; no night

L-R setback.

T8600C1162

programmable

Wiring differences (old=new): L=R, W=O; W-Y jumper

uired; includes night

re setback.

None

Y594G1419

reset switch.

60-2485—860

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

)

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

G1659 177 Obsolete. Mammoth logo; 0.8A maximum current

through B or O terminal; 12°F differential between H1 and H2 for ni

ht setback; used with Q674C1330; used in

Y594G1427.

G1675 174 Obsolete

. American Standard logo; part no. ASYSTAT650; used with Q674J1142; used in Y594G1443.

G1691 176 Obsolete. Command Aire logo; part no. P1013-0060;

6.6°C) differential between H1 and H2 for night

12°F setback; used with Q674C1389, C1397.

G1717 175 Obsolete

. Carrier Heat Pump System Control logo; part no. HH07AT102N; used with Q674J1167; used in Y507J1201.

G1741 227 Hone

well logo; TRADELINE model; includes factory

set range stops at 68°F (max. heat) and 78°F (min.

; Premier White® color; used with Q674F1477;

cool used in Y594G1476.

G1758 211 Trol-A-Temp by Honeywell logo; Premier White® color;

eover is provided by Trol-A-Temp zone panel;

chan used with Q674F1485; used in Y594G1492.

G1774 216 Obsolete

. Comfortmaker logo; part no. 1505756; used with Q674J1175; used in Y594G1500.

G1782 216 Obsolete

. Arcoaire logo; part no. 1506756; used with Q674J1175; used in Y594G1518.

G1790 161 Obsolete

. Carrier logo; Premier White® color; °C scaleplate; includes Allen wrench and screws to lock cover; used with Q674J1191.

G1816 163 Climate Master lo

o; part no. AT5716; °F/°C scaleplate; 10°F differential between H1 and H2 and momentar RESET s

G1824 227 Hone

stem switch position.

well logo; Australian TRADELINE model; Premier White® color; °C scaleplate; used with Q674F1477; used in Y594G1534.

G1832 231 Obsolete. Intertherm logo; used with Q674F1519; used

in Y594G1542.

G1840 231 Obsolete. Miller logo; used with Q674F1519; used in

Y594G1559.

G1857 229 Obsolete

. Lennox logo; °C scaleplate; Premier White®

color; used with Q674F1535; used in Y594G1583.

G1865 160 Hone

well logo; TRADELINE model; designed to replace Y594G1013

York part no. 2TH11702424), Y594G1229 (York part no. 6TH11702424), and York part no. 2TH117704124

; used with Q674J1209; used in

Y594G1567.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594H1012

Wiring differences (old=new): R2=L, R1=none; L-R jumper

uired; no night setback.

T8611G1004

Includes night setback.

programmable

Y594G1161

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y, R=none; L-R

umper required; no night

setback.

T8611G1004

Includes night setback.

programmable

Y594G1252

Wiring differences (old=new): C=X, D=L; replacement has AUX. HEAT and EM. HEAT LEDs.

Y594G1476

None See Trol-A-Temp for

replacement.

Y594G1252

Wiring differences (old=new): E=W2, W1=W3, X=E, C=X.

Y594G1252

Wiring differences (old=new): E=W2, W1=W3, X=E, C=X.

Y594G1252

Wiring differences (old=new): C=X; replacement has °F scaleplate.

Y594G1393

No momentary reset switch.

Y594G1476

Y594G1252

Y594G1161

Replacement has auto chan

eover in cooling mode

onl

Replacement has auto

eover in cooling mode

chan

onl

Wiring differences (old=new): E=X2, C=B, L=F.

Y594G1567

61 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

)

(

)

(

)

Table 8. T874 Cross Reference.

Model

Number

Fig.

No. Description

G1873 160 Obsolete. Honeywell logo; TRADELINE model; Premier

White® color; designed to replace Y594G1013 (York part no. 2TH11702424 6TH11702424

, and York part no. 2TH117704124); used

, Y594G1229 (York part no.

with Q674J1225; used in Y594G1575. G1881 167 Rheem; part no. 41-20797-18. G1899 169 Obsolete. Amana; part no. 10574101; used with

Q674F1550; used in Y594G1591. G1915 155 Econar logo; used with Q674F1212; used in

Y594G1609.

170 Used with Q674F1410.

G1923 176 Trane logo; part no. X13510599010; H2 make 12°F

below H1 make.

G1931 155,

Obsolete

scaleplate; used with Q674F1568.

170

G1949 73 Obsolete

. Honeywell logo; Premier White® color; °C

. Carrier Heat Pump System Control logo; part no. HH07AT204; °F/°C scaleplate; H2 make 8°F below H1 make; used in Y594.

G1956 30, 103,

126,

Obsolete °C scaleplate; includes lockin

. Carrier logo; Canada; Premier White® color;

cover.

183

G1964 160 York lo

o; Canada; Premier White® color; °C scaleplate;

used in Y594G1625.

G1972 169 Hone

well logo; TRADELINE model; used with

Q674F1584; used in Y594G1633.

G1980 169 Obsolete. Amana logo; part no. 10574103; used with

Q674F1600; used in Y594G1641.

G1998 155 Obsolete

. Tempstar logo (Inter-City Products); used in Y594G1658; used with Q674F1212.

G2004 103 Honeywell logo; TRADELINE model; used with Q674L;

used in Y594G.

161 Used with Q674J1274; used in Y594G1674. Y594G1674

G2046 155,

170

WaterFurnace lo color; °F/°C scaleplate; used with Q674F1667; used in

o; part no. TA21H03; Premier White®

Y594G1716.

T874H

Heat pump model; 1-sta

e changeover in cool.

1-sta

e heat, 1-stage cool,

H1005 74 Obsolete. Command Aire logo; used with Q674C1041.

H1013 74 Obsolete

. Friedrich part no. AT5813; °C scaleplate; used with Q674C1041.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594G1567

Y594G1526 Y594G1633

Y594G1252

Y594G1393 Y594H1012

Replacement is beige.

Wiring differences (old=new): Y1=O, Y2=Y, R=none; L-R

umper required; no night

setback.

T8611G1004

Includes night setback.

programmable

None See subbase description for

replacement information.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y, L=R, R=none; R-

umper required; no night

L setback.

T8600D1004

programmable

Wiring differences (old=new): Y1=O, Y2=Y, L=RH; RC-RH

umper required; includes

ht setback.

Y594G1476 Replacement has °F

scaleplate.

Y594G1575

Replacement has °F scaleplate.

Y594G1633

Wiring differences (old=new): W3=W2.

Y594G1252

Y594G1666

Y594G1716

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; L-R required.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; L-R jumper

uired; replacement has °F

re scaleplate.

umper

60-2485—862

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

H1021 74 Obsolete. Friedrich Climate Master logo; part no.

AT5821; °F/°C scaleplate; used with Q674C1041.

H1039 79 Obsolete

. Mammoth logo; °F/°C scaleplate; used with

Q674C1124; used in Y594H1004.

H1054 74 Obsolete

. No logo; Friedrich part no. AT5854; used with

Q674C1041.

H1062 164 Hone

well logo; used with Q674C1249; used in

Y594H1012.

H1070 172,

Obsolete. Carrier Heat Pump System Control logo; part

173

no. HH07AT166; °C scaleplate; used with Q674B1406

HH93AZ200) or Q674C1322 (HH93AZ199).

H1088 172,

H1096 177 Obsolete

Obsolete

173

no. HH07AT167; used with Q674B1406

or Q674C1322

. Carrier Heat Pump System Control logo; part

HH93AZ199).

. Mammoth Water Source Heat Pump logo; °F/

°C scaleplate; chan

eover stage 0.8A maximum; used B

HH93AZ200)

or O terminal; used with Q674C1330.

H1112 74 No lo

o; Friedrich part no. AT5812; used with

Q674C1355.

H1120 205 Obsolete. Command Aire logo; part no. P1013-0055;

used with Q674C1389, C1397.

H1138 221 Obsolete

. Climate Master logo; part no. AT5838; used

with Q674C1470.

H1146 205 Trane logo; part no. X13510598010.

H1153 173 Obsolete

. Carrier Heat Pump System Control logo; part no. HH07AT167; °F/°C scaleplate; used with Q674C1322; used in Y594H1053.

H1161 74 Obsolete

. Carrier Heat Pump System Control logo; part no. HH07AT203; °F/°C scaleplate; used with Q674C1496; used in Y594H1038.

T874J

J1002 124,

J1010 124,

J1028 124,

J1036 124,

J1044 124,

J1051 124,

Both the thermostat and subbase must be replaced.

Heat pump model. 2-stage heat, 1-stage cool. Obsolete

no. HH07AT175; used with Q674J1068

144,

Q674J1159

206,

Q674L1637

207

Obsolete

171

2471; used with Q674J1084, L1371. Obsolete

no. HH07AT165; °C scaleplate; used with Q674J1068

144, 206,

207

HH93AZ183), Q674J1159 (HH93AZ196), Q674L1074 HH93AZ186), Q674L1637 (HH93AZ195).

Obsolete Q674J1217.

171

Obsolete Q674J1217.

171

Obsolete White® color; °C scaleplate.

144

. Carrier Heat Pump System Control logo; part

HH93AZ196), Q674L1074 (HH93AZ186),

HH93AZ195).

. BDP multi logo; part no. 34427DP124/P272-

. Carrier Heat Pump System Control logo; part

. Miller logo; part no. 9132230; used with

. Intertherm logo; part no. 9132240; used with

. Carrier logo; part no. HH07AT165-W; Premier

HH93AZ183),

Trade Model

Replacement Remarks

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; L-R jumper

uired; replacement has °F

re scaleplate.

Y594H1012

Wiring differences (old=new): R1=R, R2=L.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; L-R required.

Y594H1012

None See subbase description for

replacement information.

None See subbase description for

replacement information.

Y594H1012

Wiring differences (old=new): R1=R, R2=L; L-R required.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; L-R jumper

uired.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; replacement has MALFUNCTION LED onl

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y.

None See subbase description for

replacement information.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; L-R jumper

uired.

None See subbase description for

replacement information.

None See subbase description for

replacement information.

None See subbase description for

replacement information.

T8511G1021

None See subbase description for

replacement information.

umper

63 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

Table 8. T874 Cross Reference.

Model

Number

J1069 124,

Fig.

No. Description

Obsolete

144,

with Q674J1282; used in Y594J1019.

. Honeywell logo; TRADELINE model; used

206,

207

J1077 124,

T874K

K1001 77 Obsolete

K1019 181 Obsolete

Obsolete

171

scaleplate. Heat pump model; 2-sta

eover in heat.

chan

. Nordyne logo; part no. 9148300; °F/°C

e heat, 1-stage cool, automatic

. LSI Mammoth logo; used with Q674C1090.

. McQuay/Snyder General logo; part no.

60687301; °F/°C scaleplate; H1 anticipator set at 0.83A; 8°F intersta

e differential between H1 and H2 for night

setback; used with Q674C1280.

K1027 181 Obsolete. AAF/Snyder General logo; part no.

066804403; °F/°C scaleplate; H1 anticipator set at

0.83A; 8°F intersta

e differential between H1 and H2 for

night setback; used with Q674C1280.

T874L

Heat pump model; 2-stage heat, 1-stage cool,

eover in cool.

chan

L1000 198 Obsolete. Carrier logo; part no. HH07AT176; used with

Q674E1270

L1018 138,

Obsolete HH07AT178; used with Q674B1356

165

Q674C1264

L1026 198 Obsolete

HH93AZ189).

. Carrier Multiplex System logo; part no.

HH93AZ192) or

HH93AZ193).

. Honeywell logo; BDP part no. P272-2786;

used with Q674E1304.

L1034 203 Obsolete

scaleplate; H1 anticipator factor

. McQuay logo; part no. 60687201; °F/°C

set at 0.83A; used with

Q674C1280.

L1059 215,

213

Obsolete Q674B1448

. Carrier logo; part no. HH07AT192; used with

HH93A2202) or Q674C1413

HH93AZ204).

L1067 203 Obsolete. AAF/Snyder General logo; part no.

066804402; H1 anticipator factor

set at 0.83A; used

with Q674C1280.

L1075 203 Obsolete

. McQuay logo; part no. 073318601; Premier

White® color; °F/°C scaleplate; includes AAF insert.

T874N

Heat pump model; 2-sta

eover; changeover in heat mode.

chan

e heat; 1-stage cool plus

N1008 178 Obsolete. Williamson logo; used with Q674F1196; used

in Y594N1007.

N1016 178 Hone

well Heat Pump Thermostat logo; used with

Q674F1220.

N1024 179,

Both the thermostat and subbase must be replaced.

217

Bard lo Q674F1261.

o; H1 and C1 anticipation fixed; used with

Trade Model

Replacement Remarks

T8511G1021

Y594G1419

Wiring differences (old=new): RH-RC=R, W1=B, W3=W2, W2=W1; remove Y1-W1

umper.

Y594G1252

Wiring differences (old=new): C=X, W=B, A=L;

ht setback.

T8611G1004

programmable

E-W2; no ni Wiring differences (old=new):

C=X, W=B, A=X2; R; remove external time clock;

ht setback.

Y594G1252

includes ni

Wiring differences (old=new): C=X, W=B, A=L;

ht setback.

T8611G1004

programmable

E-W2; no ni Wiring differences (old=new):

C=X, W=B, A=X2; X2-R; remove external time clock; includes ni

Y594G1419

E-W2 jumper required.

See OEM for replacement.

Y594G1419

E-W2 jumper required.

Wiring differences (old=new): Y=Y1, W=B, A=X1; remove Y1-W1

umper.

See OEM for replacement.

Y594G1419

differences (old=new):

Wirin Y=Y1, W=B, A=X1; remove Y1-W1

umper.

See OEM for replacement.

T874N1016

None See subbase description for

replacement information.

umper

umper X2-

umper

ht setback.

60-2485—864

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

N1040 179 Obsolete. Honeywell logo; H1 and C1 anticipation fixed;

used with Q674F1261; used in Y594N1015.

N1057 178 Obsolete

. Intertherm logo; part no. 9111882; used with Q674F1220; used in Y594N1023.

N1065 178 Obsolete

. Miller logo; Nordyne part no. 9122240; used with Q674F1220; used in Y594N1031.

T874P

Heat pump model; 2-sta

e heat, 1-stage cool, automatic

changeover in cool.

P1006 57, 78 Obsolete

. McQuay logo; part no. 860-442725B-00; 8°F

4.4°C) interstage differential between H1 and H2; used

with Q674B1273, C1140.

P1014 78 Obsolete

scaleplate; 8°F for ni

P1022 97 Obsolete

. Friedrich/Climate Master logo; °F/°C

4.4°C) differential between H1 and H2

ht setback; used with Q674C1207.

. Friedrich/Climate Master logo; part no. AT5922; °F/°C scaleplate; 8°F (4.4°C) differential between H1 and H2 for ni

ht setback; used with

Q674C1215.

P1030 97 Obsolete

. No logo; Friedrich part no. AT5930; 8°F

4.4°C) differential between H1 and H2 for night setback;

used with Q674C1215.

P1055 68, 97 Obsolete

. Carrier Heat Pump System Control logo; part no. HH07AT205; °F/°C scaleplate; heat interstage

4.4°C).

T874Q

Q1005 44 Hone

differential 8°F 1-stage heat; used with another T874 for night setback.

well logo. T874A1036

Q1013 44 Obsolete. Lennox logo; part no. 13F1201; °F/°C

scaleplate.

Q1021 44 Obsolete

T874R

Heat pump model; 2-sta chan

. Lennox logo; part no. 13F1301; °C scaleplate. T874A1036 Replacement has °F

e heat, 1-stage cool, manual

eover.

R1004 47 Obsolete. Honeywell logo; used with Q674B1042; used

in Y594R1029.

R1012 47 Obsolete

. Honeywell logo; Addison heat pump; used with Q674B1109.

R1020 102 Obsolete

. Lennox logo; part no. 24F5401; °F/°C scaleplate; H1 and C1 anticipators are fixed; auxiliar heat circuit powered b

separate transformer; used with

Q674L1025.

R1038 102 Obsolete

anticipators are fixed; auxiliar

. Lennox logo; °C scaleplate; H1 and C1

heat circuit powered by

separate transformer; used with Q674L1025.

R1046 120,

101

Obsolete anticipator is fixed; used with Q674L1272 in Y594R1011

. York logo; part no. 2TH11702224A; H2

or with Q674L1094.

R1053 109 Obsolete. Honeywell logo; H2 anticipator is fixed; used

with Q674L1140; used in Y594R1136.

R1061 104 Obsolete

. Honeywell logo; H2 anticipator is field

ustable; changeover in cooling; used with

Q674L1082.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

None

T874N1016

None See subbase description for

replacement information.

T8600D2028

programmable

Wiring differences (old=new): L=R, W=O; W-Y

uired; includes night

re setback.

None See subbase description for

replacement information.

None See subbase description for

replacement information.

None See subbase description for

replacement information.

T874A1036 Replacement has °F

scaleplate.

Y594R1243

Wiring differences (old=new): W1=W2.

Y594R1243

Wiring differences (old=new): W1=W2.

Y594R1243

differences (old=new):

Wirin M=Y, F=G, V-VR=R, Y=W2, R=O; replacement has °F scaleplate.

Y594R1243

Wiring differences (old=new): M=Y, F=G, V-VR=R, Y=W2, R=O; replacement has °F scaleplate.

Y594R1664

Y594R1763

Designed for use on Trane heat pumps.

Y594R1243

Replacement has auto fan in

ency Heat mode.

Emer

umper

65 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 8. T874 Cross Reference.

Model

Number

Fig.

No. Description

R1079 123 Obsolete. Ruud logo; part no. UXMT-C70; used with

Q674L1157.

R1087 120 Obsolete. Honeywell logo; Special for Dunham Bush;

use with Q674L.

R1095 123 Obsolete. Rheem logo; part no. RXMT-C70; used with

Q674L1157. R1103 104 Obsolete. Westinghouse logo; used with Q674L. R1111 116,

Obsolete. Marvair logo; H2 anticipator factory set at

104

1.2A; used with Q674L1215, L1082; used in

Y594R1128. R1129 113 Bard lo

R1137 108,

Obsolete

HQ711597HW; used with Q674L1132; used in

125

o; used with Q674L1181.

. Honeywell logo; Heil Quaker part no.

Y594R1110. R1145 120 Obsolete. York logo; °C scaleplate; H2 anticipator is

fixed; used with Q674L1272; used in Y594R1102. R1152 115 Honeywell logo; used with Q674L1207, L1033; used in

Y594R1243. R1160 182 Obsolete. Honeywell Advanced Heat Pump System

o; used with Q674L1298 and W89.

lo R1178 110,

Obsolete. Lennox logo; part no. 24F5601; °F/°C

111

scaleplate; auxiliar

transformer; fast c

heat circuit powered by separate

cle stage H2 anticipator; requires outdoor reset and independent circuits; used with Q674L1165, L1355.

R1186 182 Obsolete

. Honeywell Advanced Heat Pump System

o; used with Q674L1231 and W89. R1194 115 Obsolete. Amana logo; used with Q674L1249 and W89. R1202 201 Obsolete. Intertherm logo; part no. 9111871; used with

Q674L1264 or Q674L1595; used in Y594R1185.

R1210 101 Obsolete

. Roca logo; °C scaleplate; used with

Q674L1017.

R1228 120 Obsolete

. York logo; part no. 2TH11702524A; °C scaleplate; used with Q674L1272 and C815A1005; used in Y594R1144.

R1236 115 Obsolete. Williamson logo; includes Allen wrench and

screws to lock cover; used with Q674L1348.

R1244 115 Obsolete

. Westinghouse logo; used with Q674L1314 and W89.

R1251 120 Obsolete. York logo; part no. 2TH11702324A; H2

anticipator is fixed; used with Q674L1272 and C815A1039.

R1269 122 Obsolete. Fedders multi logo; part no.

THTX-120-HEHB 88-58-00540-001; used with Q674L1066; used in Y594R1037.

R1285 123 Obsolete

. Honeywell logo; Rheem part no. 41-2079615; used with Q674L1157.

R1301 113 Obsolete. Comfortmaker logo; part no. 1505-714; used

with Q674L1181; used in Y594R1417.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594R1243

Y594R1664

T874R1152/

Y594R1243 Y594R1243 Y594R1243

Y594R1243

Replacement has auto fan in

ency Heat mode.

Emer

Wiring differences (old=new): X1=X.

Y594R1292

Y594R1664

Y594R1243

None

Y594R1763

Wiring differences (old=new): V-VR=R, M=Y, F=G, X=B, Y=W, A=T, R=O, E=X2.

None

Y594R1243 Y594R1672

Wiring differences (old=new): W2=W, Z=no connection, K=X, W=G, W1=H, X=B.

Y594R1243

Wiring differences (old=new): W=W2, X=L, B=X.

Y594R1672

T874R1152

T874R1152/

Y594R1243 Y594R1672

Y594R1615

Wiring differences (old=new): K=E, C=X, W1=B, Z=L.

Y594R1243

Wiring differences (old=new): X1=X.

60-2485—866

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 8. T874 Cross Reference.

Model

Number

R1319 191 Obsolete. Carrier part no. 42QH400083; used with

R1327 120 Obsolete

Fig. No. Description

Q674B1281 on two speed fan applications.

. Borg-Warner multi-logo; part no.

Trade Model

Replacement Remarks

See OEM for replacement.

Y594R1672 6TH11702224A; used with Q674L1272; used in Y594R1193.

R1335 106 Obsolete. BDP multi-logo; part no. HH641501; H2

anticipator factor

set 1.2A; used with Q674L1405; used

Y594R1243

in Y594R1201.

R1343 133 Obsolete. Fedders multi-logo; part no.

Y594R1425 THTX-120-HEHC 88-58-0056-001; used with Q674L1413; used in Y594R1219.

R1350 113 Obsolete

R1368 125 Obsolete

. Honeywell logo; used with Q674L1181.

. Coleman logo; part no. 3600-368; used with

Y594R1243

Y594R1797 Q674L1421; used in Y594R1235.

R1376 115 Honeywell logo; °C scaleplate; used with Q674L1207. T874R1152 R1384 131,

Obsolete. Carrier Heat Pump System Control logo; part

135

no. HH07AQ170; used with Q674L

HH93AZ187),

Y594G1243

Q674L (HH93AZ197), or Q674L (HH93AZ198).

R1392 128 Obsolete

. Williamson logo; used with Q674L1447; used

Y594R1425 in Y594R1250.

R1400 113 Obsolete

. LSI part no. 104710001; used with

Q674L1181, L1462.

R1426 136 Obsolete

. Trane Weathertron Heat Pump logo; part no.

Y594R1763 BAYSTAT339 (WY28X0112); °F/°C scaleplate; used with Q674L1496; used in Y594R1284.

R1434 134 Ruud logo; part no. 41-20796-32; used with Q674L1504;

Y594R1300 used in Y594R1649.

R1442 134 Rheem logo; part no. 41-20796-28; used with

Y594R1300 Q674L1504; used in Y594R1631.

R1459 134 Obsolete. Honeywell logo; Rheem part no. 41-20796-

Y594R1300 25; used with Q674L1504.

R1467 108 Honeywell logo; used with Q674L1512; used in

Y594R1292 Y594R1292.

R1475 123 Honeywell logo; scale range 42°F to 88°F; used with

Y594R1300 Q674L1520; used in Y594R1300.

R1483 130 Obsolete. Comfortmaker logo; °F/°C scaleplate; used

Y594R1763 with Q674L1538 and C815A1005; used in Y594R1318.

R1491 137 Obsolete

. Honeywell logo; TRADELINE model; used

Y594R1615 with Q674L1553; used in Y594R1326.

R1509 47 Obsolete. Slant/Fin logo; used with Q674B1042; used in

Y594R1243 Y594R1334.

R1517 130 Obsolete

. Arcoaire logo; part no. 150671; used with

Y594R1763 Q674L1538 and C815A1005; used in Y594R1342.

R1525 113 Obsolete

. Arcoaire logo; used with Q674L1181; used in

Y594R1243 Y594R1359.

R1541 67 Obsolete

. Goettl logo; part no. 372071; used with

Y594R1300 Q674B1349.

R1558 134 Obsolete. Universal Parts logo; part no. 41-20796-45;

Y594R1300 used with Q674L1504; used in Y594R1623.

R1566 130 Obsolete. Honeywell logo; used with Q674L1538 and

Y594R1763 C815A1005; used in Y594R1375.

Both the thermostat and subbase must be replaced.

Wiring differences (old=new): K=E, C=X1, Z=L; remove Y1-W1

Wiring differences (old=new):

umper.

X1=X.

Wiring differences (old=new): C=X.

Wiring differences (old=new): A=L.

See subbase description for replacement information.

Wiring differences (old=new): W1=W, E=X2, X=F, C=B.

Wiring differences (old=new): W1=W2.

Wiring differences (old=new): W1=W, E=X2, X=F, C=B.

Wiring differences (old=new): X1=X.

Wiring differences (old=new): W1=W, E=X2, X=F, C=B.

67 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

)

Table 8. T874 Cross Reference.

Model

Number

Fig.

No. Description

R1574 132 Obsolete. Comfortmaker logo; part no. 1505739; used

with Q674L1538; used in Y594R1383.

R1582 132 Obsolete

. Arcoaire logo; part no. 150739; used with

Q674L1538; used in Y594R1391.

R1590 115 Obsolete

R1608 119 Obsolete

. Refac logo; used with Q674L1207. T874R1152/

. Honeywell logo; Intertherm heat pump; used

with Q674L1264; used in Y594R1409.

R1616 168 Hone

well logo; SUPER TRADELINE® model; used

with Q674L1587; used in Y594R1425.

R1624 200 Obsolete. Honeywell logo; used with Q674L1595; used

in Y594R1433.

R1632 134 Obsolete

. Honeywell logo; used with Q674L1603.

R1640 115 Obsolete. Hitecsa logo; °C scaleplate; H2 anticipator

set at 1.2A; used with Q674L1207.

factor

R1657 136 Obsolete

ASYSTAT651; re

. American Standard logo; part no.

uires outdoor reset; used with

Q674L1611; used in Y594R1441.

R1673 108 Heil logo; part no. 1060321, HAXB004TW01; used with

Q674L1132; used in Y594R1466.

R1699 119 Obsolete. Miller logo; used with Q674L1264; used in

Y594R1482.

R1707 209 Trol-A-Temp b

Honeywell logo; Premier White® color;

used with Q674L1678; used in Y594R1490.

R1715 209 Trol-A-Temp b

Honeywell logo; used with Q674L1186;

used in Y594R1508.

R1723 218 Obsolete

. No logo; Snyder General part no. 654958B07;

°F/°C scaleplate; used with Q674L1702 and C815A1005; used in Y594R1516.

R1731 108 Obsolete

. Inter-City Products logo; part no.

HQ11477909HW; used with Q674L1132; used in Y594R1524.

R1749 108 Tempstar logo; part no. 1060322, TAXB004TW01; used

with Q674L1132; used in Y594R1532.

R1814 108 Obsolete. Honeywell logo; Keeprite part no. THPC; °C

scaleplate; used with Q674L1132; used in Y594R1607.

R1822 230 Hone

well logo; TRADELINE model; used with

Q674L1710; used in Y594R1615.

R1830 134 Obsolete. Addison logo; WeatherKing part no. 41-

20796-61; used with Q674L1504; used in Y594R1656.

R1855 228 Obsolete. Lennox logo; Premier White® color; °C

scaleplate; outdoor reset re

uired (use C815A1005);

used with Q674L1728; used in Y594R1714.

R1871 120 Hone

well logo; designed to replace Y594R1011 (Yor k

part no. 2TH11702224

; used with Q674L1736; used in

Y594R1664.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594R1243

Wiring differences (old=new): C=X, X=L, W=W2.

Y594R1243

Wiring differences (old=new): C=X, X=L, W=W2.

Replacement has °F

Y594R1243 Y594R1763

scaleplate.

Wiring differences (old=new): W2=W, X=B, Z=F, K=X2, W1=O.

Y594R1425

Y594R1243

Wiring differences (old=new): X=B, Z=F, W2=W, K=X2, W1=O.

Y594R1243 Y594R1243

Replacement has °F scaleplate.

Y594R1763

Y594R1292

Y594R1763

Wiring differences (old=new): W2=W, X=B, Z=F, K=X2, W1=O.

None See Trol-A-Temp for

replacement.

None See Trol-A-Temp for

replacement.

Y594R1672

Wiring differences (old=new): W1=W, X=X2, C=B.

Y594R1292

Replacement has °F scaleplate.

Y594R1615

Y594R1300

Y594R1763

Wiring differences (old=new): Y1=Y, L=F, W1=W, E=X2, C=B; replacement has °F scaleplate.

Y594R1664

60-2485—868

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

)

go (

(

Table 8. T874 Cross Reference.

Model

Number

Fig. No. Description

R1889 120 Honeywell logo; designed to replace Y594R1151 (Yor k

part no. 2TH11702324), Y594R1193 (York part no. 6TH11702224

, and York part no. 2TH11704024; used

with Q674L1736 and C815A1054; used in Y594R1672.

R1897 230 Honeywell logo; Premier White® color; used with

Q674L1751; used in Y594R1680.

R1905 120 Obsolete. Honeywell logo; Premier White® color;

ned to replace Y594R1151 (York part no.

desi 2TH11702324), Y594R1193 (York part no. 6TH11702224

, and York part no. 2TH11704024; used

with Q674L1777 and C815A1054; used in Y594R1698.

R1913 120 Obsolete. Honeywell logo; Premier White® color;

ned to replace Y594R1011 (York part no.

desi 2TH11702224); used with Q674L1777; used in Y594R1706.

R1921 115 Obsolete

. Econar logo; used with Q674L1207; used in

Y594R1722.

R1939 197 American Standard logo (Trane); part no.

ASYSTAT651A; includes outdoor reset; used with Q7674L1801; used in Y594R1748.

R1947 168 Obsolete. Inter-City Products logo; part no.

HQ1149406HW; used with Q674L1819; used in Y594R1755.

R1954 197 Honeywell logo; TRADELINE model; includes outdoor

reset; used with Q674L1827; used in Y594R1763.

R1962 115 Obsolete. Consolidated Industries logo; part no.

9036100; Premier White® color; used with Q674L1843; used in Y594R1771.

R1970 120 York lo

o; Canada; Premier White® color; °C scaleplate;

used in Y594R1789; used with C815A1039.

R1988 125 Hone

well logo; TRADELINE model; used with

Q674L1868; used in Y594R1797.

R2002 245 Obsolete

. Amana Air Conditioning logo; part no.

10574102; used in Y594R1805.

R2010 245 Obsolete

. Amana Air Conditioning logo; part no.

10574104.

R2028 209 Obsolete

. York logo; part no. 2TH11703424A; used with

Q674L1918 in Y594R1821.

R2036 134 Ruud lo

T874S

2-sta

S1001 223 Obsolete

o; °C scaleplate; used with Q674L1504. See OEM for

e heat, 3-stage cool.

. Carrier Synergy 2000 Heat Pump System

Control logo; used with Q674F1501.

T874V

1-stage cool.

V1008 69 Obsolete. No logo; Carrier part no. HH07AT177; used

with Q674R1003.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement Remarks

Y594R1672

Y594R1680

Y594R1672

Y594R1664

Y594R1243

Y594R1763

Y594R1425

Y594R1763

Replacement is beige.

Direct replacement for Y594R1748 (T874R1939/ Q674L1801 Standard lo

American

ASYSTAT

651A) and Y594R1136

T874R1053/Q674L1140).

Y594R1680

Y594R1672

Includes CHECK LED.

Replacement has °F scaleplate.

Y594R1797 Direct replacement for

Y594R1235

T874R1368/ Q674L1421) Evcon/Coleman part no. 3600-368.

Y594R1797 Wiring differences (old=new):

C/X=X.

Y594R1797 Wiring differences (old=new):

C/X=X, W3=W2.

Y594R1797

replacement.

T8611M2025

Includes ni

ht setback.

programmable)

or see OEM for

direct

replacement.

T874A1036

69 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

)

(

)

(

Table 8. T874 Cross Reference.

Model

Number

T874W

Fig.

No. Description

3-stage heat, 2-stage cool, manual changeover.

W1007 118 Obsolete. Honeywell logo; Westinghouse special; used

with Q674L1256.

W1015 54 Hone

well logo; used with Q674B1216 and C815A1005;

used in Y594W1014.

W1023 233 Obsolete

. Lennox Advanced Heat Pump System logo;

used with Q674L1280 and W89.

W1031 140 Obsolete

. No logo; Rheem part no. 41-20797-20; used

with Q674L1546 and C815A1005; used in Y594W1022.

W1049 100 Obsolete

intersta

. McQuay logo; part no. 61202501; 12°F

e differential between H2 and H3 for night

setback; used with Q674C1363.

W1056 220 Obsolete

. McQuay/Snyder General logo; part no. 1202501; 12°F differential between H2 and H3 for night setback; used with Q674C1363

W1064 220 Obsolete

. AAF/Snyder General logo; part no.

61202502).

066804408; 12°F differential between H2 and H3 for

ht setback; used with Q674C1363 (66804408).

W1072 140 Obsolete

. Honeywell logo (Inter-City Products); used in Y594W1030.

W1080 220 McQua

logo; part no. 073318901; Premier White® color; 12°F differential between H2 and H3 for ni setback.

W1106 247 Obsolete

. Addison logo; part no. 843-277; °F/°C

scaleplate; used with Q674L1934 in Y594W1055.

T874Y

Heat pump model; 2-sta

e heat, 2-stage cool, heat or

cool auto changeover.

Y1005 210 Obsolete

. Mammoth Water Source Heat Pump logo;

used with Q674E1353; used in Y594Y1004.

Y1013 248 Obsolete

. WaterFurnace logo; part no. TA21H03; Premier White® color; °F/°C scaleplate; used with Q674F1675

Both the thermostat and subbase must be replaced.

32003081).

Trade Model

Replacement Remarks

T8611M2025

Includes night setback.

programmable

T874W1015

T8611M2025

Includes night setback.

programmable

T8611M2025

Includes night setback.

programmable

See OEM for replacement.

T8611M2025

Includes night setback.

programmable

None

T8611M2025

See OEM for replacement.

60-2485—870

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 9. Q674 Subbase Cross Reference.

Model

Number

Q674A

Fig.

No. Description

stem: HEAT-AUTO-COOL; Fan: AUTO-ON

Q674 Trade

Replacement Remarks

A1001 71 Standard OEM. Q674A1019 A1019 71 TRADELINE® model; used with T874A-D. Q674A1019 A1035 71 Obsolete A1043 71 Hone A1050 71 Obsolete

Q674B

B1000 45 Standard OEM; used with T874C1570, C1695, C1703,

. Trane part no. BAS-0435; used with T874A-D. Q674A1019

well logo; TRADELINE model; Q674A1019

. Standard OEM. Q674A1043

stem: HEAT-OFF-COOL; Fan: AUTO-ON

Q674B1034

D1843; used in Y594C1363.

B1018 44 Standard OEM; used with T874B1035, D1082; used in

Q674B1018

Y594B1026, D1016.

B1026 45 Obsolete

. System: HEAT-OFF-RESET-COOL. Q674B1034 B1034 45 TRADELINE Q674B1034 B1042 47 Obsolete. Used with T874R1004, R1509; used in

Y594R1243

Y594R1029, R1334.

B1059 45 Obsolete

. Factory installed RC-RH jumper; used with

Q674B1034 Field wire RC-RH.

T874C1059; used in Y594C1256.

B1075 46 Auto fan in heatin

and cooling mode; used with

Q674B1075

T874B1035, C1000, D1082; used in Y594D1040.

B1083 51 Obsolete

installed RC-RH

B1091 45 Obsolete

installed RC-RH

B1109 47 Obsolete. Addison heat pump; used with T874R1012.

B1117 44 Obsolete

installed RC-RH

B1125 53 Obsolete. York part no. 2TB04700324A; used with

. Carrier part no. HH93AZ178; factory

umper.

. Carrier part no. HH93AZ184; factory

umper.

. Carrier part no. HH93AZ180; factory

umper.

Q674B1075

Q674B1034

Y594R1243

Q674B1018

Q674B1075

T874D1041.

B1133 48 Obsolete

. Includes FILTER LED; used with

Q674B1018

T874D1082; used in Y594D1156.

B1141 51 Trane part no. BAY28X185; automatic fan operation in

Q674B1075 Set T874 H1 anticipator for

heat and cool mode.

B1158 50 Obsolete. Used with T874G1071. T874C1018/

Q674B1018

B1166 249 Carrier part no. HH93AZ179; factor

umper; LOCKOUT LED; used with T874C1075

installed RC-RH

Y594C1421 or

Q674B1075

HH07AT170).

B1190 52 Obsolete

umpers; used with T874C1372.

F-W3

. Wards special; factory installed RH-RC and

Gas Furnace:

Q674B1034

Electric Furnace:

Q674B1075 B1208 187 Obsolete B1216 54 Used with T874W1015 and C815A1005; used in

. Used with T874C1422. None

Q674B1216

Y594W1014.

B1224 49 Obsolete

. Lennox part no. 25F7301; four LEDs; used

Q674B1034 Replacement has no LEDs.

with T874C1430.

Both the thermostat and subbase must be replaced.

Wiring differences (old=new): W1=W2.

One system transformer only.

Wiring differences (old=new): W1=W2.

Jumper RC-RH; replacement has no LOCKOUT LED.

combined load of heat rela and fan rela

W1-Y1 and RH-RC jumpers

uired.

re Replacement only requires

one transformer and has no

LOCKOUT LED.

71 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

gray

Table 9. Q674 Subbase Cross Reference.

Model

Number

B1240 234 Obsolete. Northrup heat pump; AUX HEAT LED; used

Fig.

No. Description

with T874G1139.

Q674 Trade

Replacement Remarks

Y594G1252

Wiring differences (old=new): Y1=Y2, W1=W2; EM HT

stem switch position is not

s operational.

B1257 56 Obsolete

. LSI-Mammoth; RESET LED; automatic fan

Q674B1075 Replacement has no LED. operation in heat and cool modes; used with T874C1471; used in Y594C1314.

B1273 57 Obsolete

OVERRIDE-HEAT-OFF-COOL; used with T874P1006.

B1281 191 Obsolete

OFF-COOL; Fan: LOW-HI-CONT; international s

B1299 46 Obsolete B1307 62 Obsolete. Includes two LEDs; used with T874F1122. T874F1015/

B1315 68 Obsolete. Friedrich part no. AQ5215; OVERRIDE and

SERVICE LEDs; used with T874P1022, P1030.

. McQuay part no. 860-442727B-00; System:

. Carrier no. 42QH400103; System: HEAT-

mbols on switches; used with T874R1319.

. Heil Quaker part no. HQ521714HW. Q674B1075

T874A1036/

Q674B1075

T8600D2028

programmable

See OEM for replacement.

Q674D1040

T8600D2028

programmable

Wiring differences (old=new):

Y=Y1, L=R, W=O; jumper Y1W1; no ni

ht setback.

Wiring differences (old=new): L=R, W=O; W-Y

uired; night setback.

Replacement has no LEDs.

umper

Wiring differences (old=new): L=R, W=O; W-Y jumper

uired; set dual fuel switch

to electric heat; ni B1331 65 Obsolete. Includes two LEDs; used with T874A1002. Q674B1034 Replacement has no LEDs. B1349 67 Obsolete. Goettl part no. 372072; used with

Y594R1300

T874R1541.

B1356 138 Obsolete. Carrier part no. HH93AZ192; used with

T874L1018

HH07AT178).

See OEM for

replacement. B1372 44 Obsolete. Trane part no. BAS-0427; used with T874A-D. Q674B1018 B1380 46 Obsolete B1398 48 Obsolete. Trane part no. BAS-0431; FILTER LED;

. Trane part no. BAS-0426; used with T874A-D. Q674B1075

Q674B1034 Replacement has no LEDs.

used with T874A-D.

B1406 172 Obsolete

. Carrier part no. HH93AZ200; FAULT and

CHECK FILTER LEDs; used with T874H1070

HH07AT166), T874H1088 (HH07AT167) or

T874H1153

HH07AT167); used in Y594H1046. B1414 51 American Standard B1448 215 Obsolete

. Carrier part no. HH93A2202; Fan: Lo-Med-

High-On; used with T874L1059.

B1455 214 Obsolete

. Carrier part no. HH93AZ208; Fan: Lo-Med-

High-On; used with T874A1424 (HH07AT194).

T874A1150/

Q674B1075

Trane) part no. ASYSTAT1617. Q674B1075

See OEM for replacement.

Wiring differences (old=new):

Y=Y1;

umper W1-Y1;

replacement has no LEDs.

B1463 45 Trol-A-Temp; used with T874D1801. None See Trol-A-Temp. B1471 45 Trol-A-Temp; used with T874D1827. None See Trol-A-Temp. B1513 53 Obsolete

Q674B1125

. TRADELINE; exact replacement for

York part no. 2TB04700324).

B1521 53 Obsolete. Carrier Canada part no. HH93AZ179-W;

color; includes LOCKOUT LED and removable

umpers between RC and RH terminals.

B1539 45 Obsolete

. Carrier part no. HH93AZ139; used with

Q674B1075 Jumper RC-RH; replacement

has no LOCKOUT LED.

Q674B1075 Jumper RC-RH; replacement

has no LOCKOUT LED; bei color.

Q674B1034

T874D2049; used in Y594D1370.

B1547 237 Obsolete

. TRADELINE; gray color; used with

Y594C1389

T874C1810; used in Y594C1389.

Both the thermostat and subbase must be replaced.

ht setback.

60-2485—872

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

y sy

(

)

Table 9. Q674 Subbase Cross Reference.

Model

Number

B1554 82 Obsolete. TRADELINE; includes LOCKOUT LED and

Fig.

No. Description

Q674 Trade

Replacement Remarks

Y594D1347 Jumper RH-RC; system removable jumpers between RC and RH terminals; used with T874C1877; used in Y594C1421.

B1562 45 Obsolete

removable

B1570 45 Obsolete B1588 45 Obsolete

Q674C

. Amana logo; part no. P1217701F;

umpers between RC and RH terminals. . Armstrong logo; part no. 03299A18. Q674B1034 Replacement is beige. . Standard OEM. Q674B1034 Replacement is beige.

stem: OFF-AUTO; Fan: AUTO-ON

C1009 72 Standard OEM; used with T874D1082; used in

Q674B1034

Q674C1058

Y594D1024.

C1017 Obsolete

. Includes factory-installed RC-RH jumper;

Q674C1058

used with T874A,F,Q. C1033 72 Trane part no. BAY28X187. Q674C1058 C1041 74 Obsolete

. Command Aire heat pump; used with

Y594H1012

T874H1005, H1054.

C1058 72 TRADELINE Q674C1058 C1066 73 Obsolete

. Command Aire heat pump; used with

Y594H1012

T874G1352.

T8600D2028

programmable

C1074 81 Obsolete C1090 77 Obsolete

. Used with T874C1018. Q674C1058 Jumper W2-Y1 and RH-RC. . LSI-Mammoth heat pump; used with

Y594R1419

T874K1001.

C1108 143 Obsolete. Northrup special; AUX HEAT LED; used with

Y594R1243

T874G1139. C1116 76 Obsolete

. McQuay part no. 02005959; two LEDs; used

Q674C1058 Replacement has no LEDs.

with T874D1116. C1124 79 Obsolete

used with T874G-H; used in Y594G-H. C1132 75 Obsolete

momentar

. LSI-Mammoth heat pump; RESET LED;

. McQuay part no. 03005049; spring return

stem switch position; used with

Y594G1294

T8600D2028 See OEM for

replacement.

T874A1283. C1140 78 Obsolete

OVERRIDE-AUTO-OFF; used with T874P1006.

. McQuay no. 860-442728B-00; System:

T8600D2028

programmable

C1157 72 Obsolete. York part no. 2TB04700124A. Q674C1058 C1165 192 Obsolete

momentary system switch position. C1173 96 Obsolete

. McQuay part no. 03005050; spring return

. American Air Filter part no. 4ELN-8787;

See OEM for replacement.

Q674C1058 Replacement has no LEDs.

used with T874C1133. C1181 76 Obsolete C1199 163 Obsolete. American Air Filter part no. 4ELN-8788; two

LEDs; sprin

. California heat pump; used with T874C1000. Q674C1058

T8600D2028

return momentary system switch position;

used with T874G1485, G1535.

Both the thermostat and subbase must be replaced.

switch: Off-HEAT-AUTOCOOL.

Wiring differences (old=new): Y1=O, Y2=Y; W-Y jumper

uired.

Wiring differences (old=new): Y1=O, Y2=Y, L=R, R=none; R-

umper required; no night

L setback.

Wiring differences (old=new): Y1=O, Y2=Y, L=R; W-Y

umper required; night

setback.

Wiring differences (old=new): RH-RC=R, W1=B, W3=W2, W2=W1; remove Y1-W1

umper.

Wiring differences (old=new): Y1=Y, W1=W2, C=X.

Wiring differences (old=new): L=R, W=O; W-Y

uired; night setback.

No momentar

umper

reset switch.

73 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

)

(

)

(

)

Table 9. Q674 Subbase Cross Reference.

Model

Number

C1207 78 Obsolete. Friedrich; System: OVERRIDE-AUTO-OFF;

C1215 97 Obsolete. Friedrich part no. AQ5315; System:

Fig.

No. Description

used with T874P1014.

OVERRIDE-AUTO-OFF; OVERRIDE and SERVICE

Q674 Trade

Replacement Remarks

T8600D2028

programmable

T8600D2028

programmable

LEDs; used with T874P1022, P1030.

C1223 73 Obsolete

. Friedrich part no. AQ5323; used on systems

uiring night setback contacts; used with

Y594H1012

T874G1584.

T8600D2028

programmable

C1249 164 Includes MALFUNCTION LED; used with T874H1062;

Y594H1012

used in Y594H1012.

C1256 73 Obsolete. Used with T874G1618.

Y594H1012

T8600D2028

programmable

C1264 165 Obsolete. Carrier part no. HH93AZ193; used with

T874L1018

C1280 181,

C1298 76,

Obsolete. McQuay heat pump; part no. 60687401;

203

COMP FAULT LED; used with T874K1019, L1034. Obsolete

used with T874A1523, A1549, D1918.

225

C1306 75 Obsolete

sprin

HH07AT178).

. McQuay part no. 60684801; SERVICE LED;

. McQuay part no. 60685001; SERVICE LED;

return momentary system switch position; used

See OEM for replacement.

T8600D2028 See thermostat description for

See OEM for replacement.

with T874A1325. C1314 72 Obsolete C1322 173 Obsolete. Carrier part no. HH93AZ199; FAULT and CK

FILTER LEDs; used with T874H1070

. Trane part no. BAS-0429; used with T874A-F. Q674C1058

Y594H1012

HH07AT166),

T874H1088 (HH07AT167) or T874H1153

HH07AT167); used in Y594H1053.

C1330 177 Obsolete

LED; used on s

. LSI-Mammoth part no. 71115201; RESET

stems with night setback contacts;

Y594H1012

used with T874G1659, H1096; used in Y594G1427,

H1020. C1355 74 Friedrich part no. AQ355; SERVICE LED; used with

Y594H1012

T874H1112.

C1363 99 Obsolete. McQuay part no. 61202601; SERVICE LED;

auto fan in heat and cool mode; used with T874C.

T874C1125/

Q674B1075

219 Obsolete. Used with T874C. See OEM for

replacement.

220 Obsolete

. Used with T874W. See OEM for

replacement.

100 Obsolete

. Used with T874W. T8611M2025

programmable

C1371 72 American Standard part no. ASYSTAT616. Q674C1058

Both the thermostat and subbase must be replaced.

Wiring differences (old=new): L=R, W=O; W-Y jumper

uired; night setback.

re Wiring differences (old=new):

L=R, W=O; W-Y

uired; night setback.

Wiring differences (old=new):

umper

Y1=O, Y2=Y, L=R, R=none; R-

umper required; no night

L setback.

Wiring differences (old=new): L=R, W=O; W-Y

uired; night setback.

Wiring differences (old=new):

umper

Y1=O, Y2=Y, L=R, R=none; R-

umper required; no night

L setback.

Wiring differences (old=new): L=R, W=O; W-Y

uired; night setback.

umper

replacement information.

Wiring differences (old=new): 2=X.

Wiring differences (old=new): R1=R; R2=L.

Wiring differences (old=new): Y1=O, Y2=Y; L-R

uired.

re Replacement has HEAT-OFF-

COOL.

umper

Includes night setback.

60-2485—874

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

Table 9. Q674 Subbase Cross Reference.

Model

Number

C1389 205,

C1397 205,

C1413 213 Obsolete

C1439 217 Obsolete

C1454 163 Obsolete

Fig.

No. Description

Obsolete. Command Aire part no. P1099-0021; two

176

LEDs; used with T874G-H.

. Command Aire part no. P1099-0023; used

171

Obsolete with T874G-H.

. Carrier part no. HH93AZ204; Fan: Lo-Med-

High-On; used with T874L1059.

. Bard part no. 8404-016; used with

T874N1024.

. Climate Master part no. AQ5354; two LEDs;

Q674 Trade

Replacement Remarks

None See thermostat description for

replacement information.

None See thermostat description for

replacement information.

See OEM for replacement.

Y594G1393

No momentary reset switch.

spring return momentary system switch position. C1462 25 Climate Master Special. Q674C1058 Replacement has no LEDs. C1470 221 Obsolete

T874H1138.

. Climate Master part no. RQ5370; used with

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; replacement has MALFUNCTION LED onl

C1496 74 Obsolete

. Carrier part no. HH93AZ213; includes SERVICE LED; used with T874H1161; used in Y594H1038.

C1504 83 Obsolete. Carrier part no. HH93AZ214; used in Y594.

Y594H1012

Wiring differences (old=new): Y1=O, Y2=Y; L-R jumper

uired.

Wiring differences (old=new): Y1=O, Y2=Y, L=R, R=none; R-

umper required; no night

L setback.

T8600D2028

programmable

Wiring differences (old=new): Y1=O, Y2=Y, L=R; W-Y

umper required; night

setback.

C1512 97 Obsolete

Override-Auto-Off; includes two LEDs; used in Y594.

. Carrier part no. HH93AZ216; System:

T8600D2028

programmable

Wiring differences (old=new): L=R, W=O; W-Y

umper

required; night setback.

C1520 72 Obsolete

. Carrier part no. HH93AZ210; used with

Q674C1058

T874D2049; used in Y594D1388.

C1538 163 Climate Master part no. AQ5354; S

stem: Off-Auto-

Y594G1393 No momentary reset switch. Override; includes two LEDs and momentary spring position.

C1546 76,

C1553 181,

Obsolete includes one LED.

225

Obsolete. McQuay logo; part no. 073319901; includes

203

one LED.

C1561 76 McQua

. McQuay part no. 060684802; gray color;

logo; part no. 073319701; includes one LED. See OEM for

Q674C1058 Replacement has no LEDs;

e color

bei

Q674C1058 Replacement is beige.

replacement.

C1579 99,

McQua

100

C1595 72 Obsolete

Q674D

D1008 55, 66 Obsolete. Used with T874D1082, F1056; used in

logo; part no. 073320001; includes one LED. See OEM for

replacement.

. Standard OEM. Q674C1058

stem: None; Fan: None

Q674D1040 Y594D1057.

D1016 55 Obsolete D1032 58 Obsolete. Borg-Warner; used with T874G. T874D1165/

. Carrier part no. HH93AZ170; RC-RH jumper. Q674D1040 RC-RH jumper required.

Wiring differences (old=new):

Q674D1040

Y=Y2, O=Y1, W=W2; W1-Y2 re

uired. D1040 55 TRADELINE Q674D1040 D1057 55, 66 Obsolete. York part no. 2TB04700424A. Q674D1040

Both the thermostat and subbase must be replaced.

umper

75 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

gray

Table 9. Q674 Subbase Cross Reference.

Model

Number

D1065 63 Obsolete. Includes two LEDs; used with T874F1122. T874F1015/

D1099 55, 66 Obsolete D1107 55, 66 Obsolete

Fig.

No. Description

. Trane part no. BAS-0430; used with T874A-F. Q674D1040

. Snyder General part nos. 654958801/

Q674 Trade

Replacement Remarks

Replacement has no LEDs.

Q674D1040

Q674F1040.

1520503/ 4ELN30070. D1115 208 Trol-A-Temp; used with T874D1801. None See Trol-A-Temp. D1123 208 Trol-A-Temp; D1156 55 Obsolete. Gray color; includes removable jumper

color; used with T874D1827. None See Trol-A-Temp.

Q674D1040 Replacement is beige color.

between RC and RH terminals. D1164 66 Obsolete

. Carrier part no. HH93AZ211; used in

Q674D1040

Y594D1440. D1172 208 Obsolete

. Amana logo; part no. P121501F; removable

Q674D1040

umpers between RC and RH terminals. D1180 55 Obsolete D1198 55, 66 Obsolete

. York logo; part no. 2TH04703224A. Q674D1040 . Standard OEM. T874D1165/

Replacement is beige color.

Q674D1040

Q674E

stem: OFF-HEAT-AUTO-COOL; Fan: AUTO-ON

S E1007 82 Used with T874D1504; used in Y594D1180. Q674E1049 E1015 84 Obsolete. Lennox heat pump; used with T874G1006,

G1154.

E1049 193 TRADELINE; used with T874D2031 and TG504A1025;

Y594G1252

Q674E1049

Wiring differences (old=new): R=O, M=Y, F=G, V=R, Y=W2;

umper required.

E-W2

used in Y594D1354. E1056 82 Obsolete

. Amana part no. D68535-7; used with

Q674E1049 RC-RH jumper required.

T874C1059, C1331; used in Y594C1009. E1064 83 Obsolete E1072 82 Carrier part no. HH93AZ176; RC-RH jumpered

internall

. RC-RH jumpered internally; EM HEAT LED. Q674E1049

Q674E1049 RC-RH

umper required.

E1080 82 Trane part no. BAY28X184. Q674E1049 E1098 85 Obsolete

. Used with T874A-D. Q674E1049 RC-RH jumper required.

E1106 185 Obsolete. ITT Nesbitt. See OEM for

replacement.

E1114 87 Carrier part no. HH93AZ177; RC-RH

LOCKOUT LED to indicate compressor lockout; used

umper;

Q674E1049 RC-RH jumper required;

replacement has no LED.

with HH07AT series thermostats. E1122 83 Obsolete

. Square D part no. 63600-002-10; CHECK

Q674E1049 Replacement has no LED.

LED. E1148 86 Obsolete

G1022.

. Lennox heat pump; used with T874G1014,

Y594G1252

Wiring differences (old=new): R=O, M=Y, F=G, Y=W2, V-VR=R; must use sin transformer.

E1155 88 Obsolete

. Lennox part no. 91C7501; HIGH and LOW

Q674E1049 Replacement has no LEDs.

LEDs; used with T874B1076, D1017. E1197 89 Obsolete

with T874D1116.

. McQuay part no. 02005961; two LEDs; used

Q674E1049 Wiring differences (old=new):

D=O; replacement has no LEDs.

E1205 80 Obsolete

. Fedders special; SERVICE LED; used with

Q674E1049 Replacement has no LEDs.

T874D1462. E1213 82 York part no. 2TB04700224A. Q674E1403 E1221 82 Heil Quaker part no. HQ712003HW. Q674E1049

Both the thermostat and subbase must be replaced.

60-2485—876

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

gray

(

Table 9. Q674 Subbase Cross Reference.

Model

Number

Fig.

No. Description

Q674 Trade

Replacement Remarks

E1262 82 Lennox part no. 13F1701. Q674E1049 E1270 198 Obsolete. Carrier part no. HH93AZ189; used with

T874L1000

E1304 82 Obsolete

HH07AT176).

. BDP part no. P272-1887; used with

Y594G1419

E-W2 jumper required.

T874L1026.

E1312 224 Obsolete

. McQuay part no. 60684901; one LED; used

Q674E1049 Replacement has no LEDs.

with T874A1523, A1549, D1686, D1918. E1320 82 Obsolete E1338 88 Obsolete

. Trane part no. BAS-0434. Q674E1049 . Goodman part no. CHTS36-60; HIGH and

Q674E1049 Replacement has no LEDs. LOW LEDs; used with T874B1100; used in Y594B1042.

E1346 82 Obsolete

. Snyder General part nos. 1505753/1506753/

Q674E1049 654958B02; used with T874D1769; used in Y594D1297.

E1353 210 Obsolete

. Mammoth; used with T874Y1005; used in

T8611M2025

Y594Y1004.

E1379 212 Trol-A-Temp b E1395 222 Obsolete. Carrier part no. HH93AZ209; used with

T874B1134

Honeywell; used with T874A1465. None See Trol-A-Temp.

HH07AT199).

T874B1019/

Q674E1049

Wiring differences (old=new):

W1 =W; RC-RH required; replacement has no LEDs.

E1403 82 TRADELINE; desi

ned to replace York 2TH04701024;

Y594D1347

used with T874D1942; used in Y594D1347.

E1411 82 Obsolete. Carrier Canada part no. HH93AZ176-W;

color; removable jumper between RC and RH

Q674E1049 RC-RH

Replacement is bei

umper required.

terminals.

E1429 87 Carrier Canada part no. HH93AZ177-W;

includes LOCKOUT LED; removable

umper between

RC and RH terminals.

E1445 82 Obsolete

. Carrier part no. HH93AZ217-W; gray color;

removable jumper between RC and RH terminals.

E1460 224 McQua

logo; part no. 073319801; includes one LED.

color;

Q674E1049 RC-RH

umper required. Replacement has no LOCKOUT LED and is bei

Q674E1049 RC-RH jumper required.

Replacement is beige color.

E1478 82 Obsolete. Armstrong logo; part no. 03299A19. Q674E1049 RC-R jumper required.

Replacement is bei

E1486 82 Obsolete

. Standard OEM. Q674E1049 RC-R jumper required.

Replacement is bei

Q674F

System: EM.HT.-HEAT-AUTO-COOL-OFF; Fan: AUTO-ON

F1006 141 Obsolete

. Includes EM HEAT LED; used with

Q674F1022 Jumper E-X2.

T874C1331.

F1022 142 Includes LED and field selectable inserts; used with

Q674F1022

T874C1059; used in Y594C1017, C1330.

F1030 146 Carrier part no. HH93AZ174; SUPL HEAT LED; used

with T874D1074

F1048 149 Obsolete

. Includes EM HEAT LED and auxiliary power

HH07AT172).

terminal Z.

Q674F1022 Wirin

Q674F1022 Replacement does not include

differences (old=new):

C=X1, X=X2.

Z terminal and onl one transformer.

F1063 146 Obsolete

LED; used with T874D1074 (HH07AT172).

F1071 142 Obsolete

. Carrier part no. HH93AZ181; SUPL HEAT

. Square D part no. 63600-002-11; CHECK

Q674F1022 Wiring differences (old=new):

C=X1, X=X2.

Q674F1022

LED.

Both the thermostat and subbase must be replaced.

umper

e color.

requires

77 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 9. Q674 Subbase Cross Reference.

Model

Number

F1089 152 Obsolete. Includes EM HEAT LED; X2-E and RC-RH

Fig.

No. Description

Q674 Trade

Replacement Remarks

Q674F1022

umpers. F1097 142 Obsolete F1105 145 Obsolete

. Southwest special; W2-X2 jumper. Q674F1022 . Lennox heat pump; EM HEAT LED; used

Y594G1252

with T874G1154.

F1113 1 50 Obs olete

. Lennox heat pump; part no. 24F6201; V-VR

Y59461252

umper; EM HEAT LED; changeover in cooling; used

with T874G1014, G1022.

F1121 153 Obsolete

. Westinghouse heat pump; EM HEAT LED;

Y594G1252

used with T874G1048.

F1139 148 Obsolete. Tappan heat pump; EM HEAT LED; auto fan

Y594G1252

in emergency heat mode; used with T874G1147.

F1162 151 Obsolete

. Crispaire heat pump; EM HEAT LED; used

Y594G1393

with T874G.

F1170 153 Obsolete. Heatwave (Southwest Mfg.) heat pump; EM

Y594G1252

HT LED; used with T874G1105. F1188 153 Obsolete. Luxaire heat pump. F1196 178 Obsolete. Williamson; EM HEAT and SERVICE LEDs;

Y594G1252

Q674F1220

used with T874N1008; used in Y594N1007. F1204 154 Obsolete

. Special for Crispaire; EM HEAT and COMP

Y594G1393

FAULT LEDs; used with T874G1089; used in

Y594G1153. F1212 155 Includes AUX HEAT and EM HEAT LEDs; used with

T874G1246, G1451, G1592, G1915; used in

Q674F1212 or

Y594G1252

Y594G1252. F1220 178 Used with T874N1016; used in Y594N. Q674F1220 F1238 155 Obsolete. Rheem part no. 41-20797-14; AUX HEAT

Y594G1252 and EM HEAT LEDs; used with T874G1097, G1212, G1220, G1238.

F1246 156 Obsolete. Westinghouse heat pump; EM HEAT and

AUX HEAT LEDs; auto fan in emer

ency heat mode;

Y594G1252

changeover in cooling mode.

F1253 157 Obsolete. Wesco/Addison heat pump; used with

Y594G1252 T874G1261, G1279, G1287.

F1261 179 Includes two LEDs; used with T874N1024; used in

Y594G1419 Y594N.

F1279 158 Obsolete

. Westinghouse heat pump; two LEDs; used

Y594G1252 with T874G.

F1295 147 Obsolete. Keeprite/Westinghouse heat pump;

Y594G1252 SERVICE, AUX HEAT and EM HEAT LEDs; used with T874G1188.

F1311 155 York heat pump; AUX HEAT and EM HEAT LEDs; used

Y594G1252 with T874G1410.

F1329 142 Obsolete. Heil Quaker part no. HQ712005HW; one

Q674F1022

LED and field selectable inserts.

F1337 166 Obsolete

. WeatherKing heat pump; two LEDs and field

Q674F1022 Wiring differences (old=new): selectable inserts; used with T874D1009; used in Y594D1222.

Both the thermostat and subbase must be replaced.

Wiring differences (old=new): V=R, Y=W2, F=G, X2=X, R=O, M=Y; L-E

uired.

Wiring differences (old=new):

umper

R=O, M=Y, F=G, Y=WC, V=VR=R; must use sin transformer.

Wiring differences (old=new): C=X.

Wiring differences (old=new): A=L.

Wiring differences (old=new): Y1=O, C=X, W1=Y, X=L.

Wiring differences (old=new): L=X2, Y=Y1.

Wiring differences (old=new): L1=L.

Wiring differences (old=new): S=L; replacement does not include A or T terminals.

R=RC-RH; replacement has no LEDs.

60-2485—878

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

gray

(

)

(

)

Table 9. Q674 Subbase Cross Reference.

Model

Number

Fig.

No. Description

F1345 194 Obsolete. Addison heat pump; EM HEAT and CHECK

LEDs; used with T874G; used in Y594G.

F1360 167 Obsolete

. Rheem part no. 41-20797-17; AUX HEAT

and EM HEAT LEDs; used with T874G1493.

F1378 195 Obsolete. Includes EM HEAT and AUX HEAT LEDs;

used with T874G1501.

F1394 139 Obsolete

HEAT LEDs; S

. Nepco heat pump; HEAT PUMP and AUX

stem: AUX HEAT-HEAT PUMP-2

STAGE HEAT-OFF-COOL; used with T874D1595.

F1402 169 Obsolete

. Coleman heat pump; two LEDs; used with

T874G1576; used in Y594G1377. F1410 170 Used with T874G1246, G1915; used in Y594G1393. F1428 199 Obsolete. Used with T874G1600; used in Y594G1401.

F1436 167 Includes AUX HEAT and EM HEAT LEDs; changeover

in heatin

mode; used with T874G1626; used in

Y594G1526. F1444 227 Includes AUX HEAT, EM HEAT and CHECK LEDs;

used with T874G1642; used in Y594G1419. F1451 204 Obsolete. York part no. 2TB047700524A; one LED and

field selectable inserts. F1477 227 TRADELINE;

color; used with T874G1741,

G1824; used in Y594G1476, G1534. F1485 211 Trol-A-Temp by Honeywell; changeover is provided by

Trol-A-Temp zone panel; used with T874G1758; used

in Y594G1492. F1501 223 Obsolete

. Carrier two-speed compressor heat pump;

used with T874S1001. F1519 231 Obsolete

. Nordyne; used with T874G1832, G1840;

used in Y594G1542, G1559.

F1535 229 Obsolete. Lennox heat pump; gray color; used with

T874G1857; used in Y594G1583. F1543 204 Obsolete

F1550 243 Obsolete

. TRADELINE Q674F1022 Wiring differences (old=new):

. Amana part no. 10573901; includes two

LEDs; used with T874G1899; used in Y594G1591. F1568 155 Obsolete

onl

. Gray color; includes two LEDs; used with

T874G1931.

F1584 169 TRADELINE; includes two LEDs; used with

T874G1972; used in Y594G1633. Direct replacement

for Coleman/Evcon Y594G1377

Q674D1402

; Coleman part no. 3600-373.

T874G1576/

F1592 238 Heat Controller; Fan: AUTO-ON; System: AUX HEAT-

HEAT PUMP- 2 STAGE HEAT-OFF-COOL; includes

two LEDs; used with T874C1844; used in Y594C1413. F1600 169 Obsolete

. Amana part no. 10573903; includes two

LEDs; used with T874G1980; used in Y594G1641. F1634 139 Standard OEM; S

stem: AUX HEAT-HEAT PUMP2 STG HEAT-OFF-COOL; includes two LEDs; used with T874D2155.

Both the thermostat and subbase must be replaced.

Q674 Trade

Replacement Remarks

Y594G1252

Wiring differences (old=new): Y1=O, C=X, W1=Y, X=L.

Y594G1526

Y594G1252

Wiring differences (old=new): L1=L; changeover in cooling

onl

T874D1165/

Q674B1018

Replacement has HEAT-OFF-

COOL s

stem switching and

no LEDs.

Y594G1633

Y594G1393 Y594G1419

Wiring differences (old=new):

umper W1-Y1.

None

Y594G1419

Q674F1012 Wiring differences (old=new):

X2=X; X1=B.

Y594G1476

None See Trol-A-Temp.

T8611M2025

Includes night setback.

programmable

Y594G1252

Y594G1161

Replacement has auto

eover in cooling mode

chan

onl

Wiring differences (old=new): E=X2, C=B, L=F.

X2=X, X1=B.

Y594G1633

Y594G1476 Y1-W1

Y594G1633

umper required.

Y594R1425 E-W2 jumper required; system

switch: EM.HT.-HEAT-OFFCOOL.

Y594G1633 Wiring differences (old=new);

W3=W2.

Y594G1716

79 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 9. Q674 Subbase Cross Reference.

Model

Number

F1667 155 WaterFurnace logo; part no. TA21H03; System: OFF-

Fig.

No. Description

Q674 Trade

Replacement Remarks

Y594G1716 AUTO-HEAT-EM HT; includes two LEDs; used with T874G2046.

F1675 248 Obsolete

includes four LEDs.

Q674G

G1005 184 Obsolete G1013 186 Obsolete

. WaterFurnace logo; part no. TA21H03;

stem: OFF-AUTO; Fan: None

. Used in Y594F1063. Q674G1070 . Climate Control; used with T874D1298. See OEM for

See OEM for replacement.

replacement.

G1021 91 Obsolete

. Includes O and B terminals; used with

Q674G1070 T874A-F,Q or T874D1082; used in Y594D1032.

G1047 92 Obsolete G1054 188 Obsolete

T874D1298.

G1062 232 Obsolete

. Used with T874C1018, C1125. T8611 . Singer part no. 0200-5963; used with

See OEM for replacement.

. Singer; used with T874D1298. See OEM for

replacement. G1070 91 TRADELINE Q674G1070 G1088 92 Obsolete

. LSI-Mammoth part no. 71120201; used with

T874C.

G1096 90 Obsolete

. Climate Control part no. 02005958; used

with T874D1439, D1447.

G1104 94 Obsolete

. McQuay part no. 0200-5963; two LEDs;

used with T874D1116.

G1120 202,

Obsolete LEDs; no fan switching; used with T874D1694, G1926.

226

G1138 91 Obsolete

. McQuay part no. 60684701; two SERVICE

. Trane part no. BAS-0433; used with T874A-F. Q674G1070

G1153 184 Obsolete. Carrier part no. HH93AZ212; used in

See OEM for

replacement.

See OEM for

replacement.

See OEM for

replacement.

See OEM for

replacement.

Q674G1070

Y594D1396. G1161 184 Gra G1179 202 Obsolete. McQuay logo; part no. 073319601; includes

color. Q674G1070 Replacement is beige color.

Q674G1161 Replacement has no LEDs.

two LEDs.

Q674J

J1001 180 Obsolete

J1019 159 Obsolete

stem: EM.HT.-AUTO-OFF; Fan: AUTO-ON

. Singer heat pump part no. 02005964; EM

HEAT LED; changeover heat mode.

. Westinghouse heat pump; EM HT LED;

See OEM for replacement.

Y594G1252

System: EM.HT.-ON-OFF; used with T874G1048. J1027 160 Obsolete

auto fan in emer

. York part no. 025-22291; EM HEAT LED;

ency heat mode; changeover in cool

Y594G1567

mode; used with T874G1170, G1196, G1428, G1345,

G1444; used in Y594G1013, G1138, G1229. J1035 161 Carrier heat pump; part no. HH93AZ173; System:

Y594G1674 SUPL.HT.-ON-OFF; SUPL HEAT LED; used with T874G1055

J1043 162 TRADELINE heat pump model; designed for use on

Trane heat pumps; AUX HT and EM HT LEDs; auto fan in emer

HH07AT171).

Q674J1043 or

Y594G1161

ency heat; changeover in cooling mode; used

with T874G1204 and C815A1008; used in Y594G1161.

J1050 183 Obsolete

. Westinghouse heat pump; EM HEAT and

Y594G1674 AUX HEAT LEDs; used with T874G1071.

Both the thermostat and subbase must be replaced.

Wiring differences (old=new): W=W2.

Designed for use on Trane

heat pumps.

60-2485—880

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

gray

(

)

Table 9. Q674 Subbase Cross Reference.

Model

Number

Fig.

No. Description

J1068 144 Obsolete. Carrier heat pump; part no. HH93AZ183;

used with T874J1002 (HH07AT175) or T874J1028

HH07AT165).

J1076 180 Obsolete. McQuay part no. 02005964; two LEDs; used

with T874A,D.

J1084 171 Obsolete

. BDP heat pump; part no. 34427DP126,

P272-1879; EM HEAT LED; used with T874J1010.

J1118 196 Obs olete

SUPL HEAT LED; S with T874G1055

J1126 160 Obsolete

. Carrier heat pump; part no. HH93AZ188;

stem: SUPL.HT.-ON-OFF; used

HH07AT171).

. Luxaire no. 026-00068-000; EM HEAT LED;

used with T874G1568; used in Y594G1351.

J1142 174 Obsolete. American Standard part no. WY28X0250;

AUX HEAT and EM HEAT LEDs; used with T874G1675; used in Y594G1443.

J1159 206 Obsolete. Carrier heat pump; part no. HH93AZ196;

used with T874J1002

HH07AT175) or T874J1028

HH07AT165).

J1167 175 Obsolete. Carrier heat pump; MANUAL, AUTO, HEAT

PUMP and DEFROST LEDs; S

stem: SUPL HEAT-

ON-OFF; used with T874G1717; used in Y507J1201.

J1175 216 Obsolete

. Snyder General part nos. 1505756, 1506756; CHECK, AUX HEAT and SYSTEM LEDs; used with T874G1774, G1782; used in Y594G1500, G1518.

J1191 161 Obsolete. Carrier heat pump; gray color; used with

T874G1790.

J1209 160 TRADELINE; desi

part no. 2TH11702424 6TH11702424

ned to replace Y594G1013 (Yor k

, Y594G1229 (York part no.

and York part no. 2TH11704124; used

with T874G1865; used in Y594G1567.

J1217 171 Obsolete. Nordyne part no. 9132250; used with

T874J1036, J1044.

J1225 160 Obsolete

. TRADELINE; gray color; designed to replace Y594G1013 (York part no. 2TH11702424), Y594G1229

York part no. 6TH11702424) and York part no. 2TH11704124; used with T874G1873; used in Y594G1575.

J1241 144 Obsolete

. Carrier Canada part no. HH93AZ183-W;

color; System: SUPL HT-ON-OFF; includes one

LED.

J1258 161 Obsolete

. Carrier Canada part no. HH93AZ173-W;

color; System: SUPL HT-ON-OFF; includes one

LED.

J1266 160 York Canada;

color; includes EM HT LED; used in

Y594G1625.

J1274 161 TRADELINE; System: SUPL HT-ON-OFF; includes

one LED; used with T874G2004; used in Y594G1674.

J1282 244 Obsolete

. TRADELINE; System: SUPL HT-ON-OFF; includes SUPL HT LED; used with T874J1069; used in Y594J1019.

Both the thermostat and subbase must be replaced.

Q674 Trade

Replacement Remarks

Y594J1019

Q674F1022 Replacement has no LEDs.

Y594J1019 Wiring differences (old=new):

W1=W2, F=L.

Y594G1674 Wirin

differences (old=new):

C=X;Y1=W1;

umper required;

no auto fan in emer

ency

heat.

Y594G1567

Y594G1161

Y594J1019

Y594G1252

Wiring differences (old=new): C=X, D=L; replacement has AUX HEAT and EM HEAT LEDs.

Y594G1252

Wiring differences (old=new): E=W2, W1=W3, X=E, C=X.

Y594G1252

Wiring differences (old=new): C=X; replacement has °F scaleplate.

Y594G1567

Y594J1019 Wiring differences (old=new):

F=L.

Y594G1567

Replacement is beige.

See OEM for replacement.

Y594G1674

Y594G1567

Replacement is beige color.

Y594G1674

Recontrol

T8511G1021

81 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 9. Q674 Subbase Cross Reference.

Model

Number

Q674K

Fig.

No. Description

System: OFF-HEAT-AUTO-COOL; Fan: None

Q674 Trade

Replacement Remarks

K1000 93 Obsolete. Carrier part no. HH93AZ172; RC-RH jumper. Q674E1049 Fan switch is not operational. K1018 95 Obsolete. Oneida Heater part no. 3040284-02;

stem: OFF-WOOD-WOOD/OIL-OIL; used with

Q674K1026

T874F1106.

K1026 95 S

stem: OFF-WOOD-WOOD/ OIL-OIL; used with

Q674K1026

T874F1155. K1034 93 Obsolete K1042 93 Obsolete

includes removable

. Snyder General part no. 4ELN-7920. Q674E1049 Fan switch is not operational. . Carrier part no. HH93AZ172-W; gray color;

Q674E1049 Fan switch is not operational.

umper between RC and RH

terminals.

Q674L

L1017 101 Obsolete

stem: EM.HT.-HEAT-OFF-COOL; Fan: ON-AUTO

. York heat pump; EM HEAT LED; cooling

mode chan

eover; compressor lockout; auto fan in

Y594R1243

Wiring differences (old=new): W=W2, X=L, B=X.

EM.HT; used with T874R1046. L1025 102 Obsolete

HEAT LED; V-VR

J1038. L1033 115 Obsolete

. Lennox heat pump; part no. 24F6101; EM.

umper; used with T874R1020,

. Rheem heat pump; EM HEAT LED; used

Y594R1243

Wiring differences (old=new): M=Y, F=G, V-VR=VR, Y=W2, R=O.

with T874R1152. L1041 103 Obsolete. Carrier heat pump; part no. HH93AZ175;

SUPL HEAT LED; used with T874G1055

Y594G1419 Wirin

C=X, jumper Y1=W1.

differences (old=new):

HH07AT171), G1071 (HH93AZ175), G1113.

L1066 122 Obsolete

. Fedders heat pump; used with T874R1269;

used in Y594R1037. L1074 124 Obsolete

SUPL HT LED; used with T874J1002

T874J1028

. Carrier heat pump; part no. HH93AZ186;

HH07AT175) or

HH07AT165).

L1082 104 Obsolete. Crispaire heat pump; W2-H jumper; EM

HEAT LED; used with T874R10 6 1, R1111. L1090 105 Obsolete. Fedders heat pump; EM HEAT LED;

eover in heat mode; used with T874C1398,

chan

Y594R1615

Y594J1001

Y594R1243

Y594R1425

Wiring differences (old=new): K=E, C=X, W1=B, Z=L.

Replacement has auto fan in

ency heat mode.

emer

Wiring differences (old=new): K=E, C=X.

C1406, C1414. L1108 106 Obsolete

. Westinghouse; EM HEAT LED.

L1116 107 Obsolete. Carrier part no. HH93AZ171; SUPL HEAT

LED; used with T874D1264

HH07AT173).

L1132 108 Heil Quaker part no. HQ711598; used with T874R1137,

Y594R1243

See OEM for replacement.

Y594R1292

R1673, R1731, R1749, R1814; used in Y594R1110,

R1466, R1524, R1532, R1607. L1140 109 Obsolete. Includes EM HEAT and AUX HEAT LEDs;

used with T874R1053; used in Y594G1136. L1157 115 Obsolete

. Rheem part no. 41-20796-14; EM HEAT and

Y594R1763

Q674L1207

Designed for use on Trane heat pumps.

AUX HEAT LEDs; used with T874R.

121 Obsolete. Used with T874C. 123 Obsolete. Used with T874R.

L1165 110 Obsolete. Lennox no. 24F5901; factory installed V-VR

umper; EM HEAT and SERVICE LEDs; stage 2 heat is

isolated; used with T874C1448, R1178 and

Y594C1322 Y594R1243 Y594R1763

Wiring differences (old=new): V-VR=R, M=Y, F=G, X=B, Y=W, A=T, R=O, E=X2.

C815A1013. L1173 112 Obsolete

. Westinghouse; AUX HEAT and EM HEAT

Y594R1243

LEDs.

Both the thermostat and subbase must be replaced.

60-2485—882

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

)

Table 9. Q674 Subbase Cross Reference.

Model

Number

Fig.

No. Description

L1181 113 Used with T874R1129; used in Y594R.

L1199 114 Obsolete

. Lennox no. 24F6001; used with T874D1207

and C815A1013.

L1207 115 Used with T874R1152, R1590, R1640, R1921; used in

Y594R1243, R1706.

L1215 116 Obsolete. Crispaire heat pu m p; used with T874R1111;

used in Y594R1128.

L1223 117 Obsolete

L1231 182 Obsolete L1249 115 Obsolete

. Westinghouse special. See OEM for

. Used with T874R1186 and W89. None . Used with T874R1194 and W89.

L1256 118 Obsolete. Westinghouse special; used with

T874W1007.

L1264 119 Obsolete

. Intertherm heat pump; EM HEAT and SERV LEDs; used with T874R1202, R1608, R1699; used in Y594R1185, R1409, R1482.

L1272 120 Obsolete

. York part no. 025-22290; used with T874R1046, R1145; used in Y594R1011, R1102; used with T874R1228, R1251 R1327 and C815A1039; used in Y594R1144, R1151, R1193.

L1280 233 Obsolete. Lennox no. 52C7601; used with T874W1023

and W89.

L1298 182 Obsolete. Singer heat pump; used with T874R1160

and W89.

L1314 115 Obsolete

. Westinghouse heat pump; used with T874R1244 and W89.

L1322 127 Obsolete. EM HEAT and AUX HEAT LEDs; used with

T874C1455.

L1330 120 Obsolete. York heat pump; used with T874R.

L1348 115 Obsolete

. Williamson heat pump; used with T874R1236.

L1355 111,

Obsolete used with T874C1448, R1178 and C815A1015.

190

L1363 129 Obsolete

. Lennox part no. 31F3201; V-VR jumper;

. York heat pump; EM HEAT LED; used with T874G1402.

L1371 124 Obsolete

. BDP heat pump; part no. 34427DP125, P272-1878; EM HEAT LED; used with T874J1010.

L1389 114 Obsolete

. Lennox part no. 41F6501; V-VR jumper; used with T874D1207.

Both the thermostat and subbase must be replaced.

Q674 Trade

Replacement Remarks

Y594R1243

Wiring differences (old=new): X1=X.

T8611M2025

programmable

Wiring differences (old=new): V-VR=R, Y=W3, X=C, R=O, M=Y, M2=Y2-W2, F=G;

umper Y2-W2; no outdoor

reset needed; use only one

stem transformer.

Q674L1207 or

Y594R1243 Y594R1243

Replacement has auto fan in

ency heat mode. Wiring

emer differences (old=new): A=L; set anticipator to 1.2.

replacement.

Y594R1243

T8611M2025

Includes night setback.

programmable

Wiring differences (old=new):

Y594R1672

Y594R1763

W2=W, X=B, Z=no connection, K=X, W1=H.

Y594R1672

Y594W1014

See OEM for replacement.

Q674L1207 or

Y594R1243 Y594R1243

Y594R1664

Wiring differences (old=new): L=X, X=B.

Q674L1207

Y594R1763

Wiring differences (old=new): V-VR=R, M=Y, F=G, X=B, Y=W, A=T, R=O, E=X2.

Y594R1425

Wiring differences (old=new): W=W2, X=E, B=X; jumper YW1.

Y594J1001 Wiring differences (old=new):

W1=W2, F=L.

T8611M2025

programmable

Wiring differences (old=new): V-VR=R, Y=W3, X=C, R=O, M=Y, M2=Y2-W2, F=G;

umper Y2-W2; no outdoor

reset needed; use onl

stem transformer.

one

83 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

Table 9. Q674 Subbase Cross Reference.

Model

Number

Fig.

No. Description

L1397 103 Obsolete. Carrier part no. HH93AZ185A; SUPL HEAT

LED.

L1405 106 Obsolete

. BDP heat pump; part no. HH641501; used

with T874R1335; used in Y594R1201.

L1413 133 Obsolete. Fedders heat pump; used with T874R1343;

used in Y594R1219.

L1421 125 Obsolete

. Coleman heat pump; used with T874R1368;

used in Y594R1235.

L1439 131 Obsolete. Carrier part no. HH93AZ187; SUPL HEAT

LED; S T874R1384

L1447 128 Obsolete

stem: SUPL HT-HEAT- COOL; used with

HH07AQ170).

. Williamson heat pump; three LEDs; used

with T874R1392; used in Y594R1250.

L1454 131 Obsolete

LED; used with T874R1384

L1462 113 Obsolete

. Carrier part no. HH93AZ197; SUPL HEAT

HH07AQ170).

. LSI heat pump; part no. 104710002; used

with T874R1400.

L1496 136 Obsolete

. Trane heat pump; used with T874R1426;

used in Y594R1284.

L1504 134 Rheem part no. 41-20796-24; used with T874R1442,

R1434, R1459; used in Y594R1631, R1649, R1854.

L1512 108 Includes two LEDs; used with T874R1467; used in

Y594R1292.

L1520 123 Includes EM HEAT and AUX HEAT LEDs; used with

T874R1475; used in Y594R1300.

L1538 130 Obsolete. Snyder General heat pump; used with

T874R1483, R1517, R1566 and C815A1005; used in Y594R1318, R1342, R1375.

132 Obsolete

. Used with T874R1574, R1582; used in

Y594R1383, R1391.

L1546 140 Obsolete

. Rheem part no. 41-20797-21; three LEDs;

used with T874W1031 and C815A1005; used in Y594W1022.

L1553 137 Obsolete

. Includes three LEDs; used with T874R1491;

used in Y594R1326.

L1561 121 Obsolete. Used with T874C1638; used in Y594C1322.

123 Obsolete

L1579 135 Obsolete

. Used with T874R.

. Carrier heat pump; part no. HH93AZ198;

SUPL HEAT LED; used with T874R1384

HH07AQ170). L1587 168 Used with T874R1616; used in Y594R1425. L1595 200,

Obsolete. Miller heat pump; used with T874R1624 or

201

T874R1202; used in Y594R1433. L1603 134 Obsolete. Used with T874R1632. L1611 136 Obsolete. American Standard heat pump; part no.

WY28X235; used with T874R1657; used in

Y594R1441.

Both the thermostat and subbase must be replaced.

Q674 Trade

Replacement Remarks

Y594G1393

Wiring differences (old=new): C=X.

Y594R1243

Y594R1425

Wiring differences (old=new): K=E, C=X, Z=L; remove

umper.

W1-Y

Y594R1797

Q674L1207 or

Y594G1393

Y594R1425

Wiring differences (old=new):

C=X.

Wiring differences (old=new): A=L.

Y594R1393

Wiring differences (old=new): C=X.

Y594R1243

Wiring differences (old=new): X1=X.

Y594R1763

Y594R1300

Y594R1292

Y594R1300

Y594R1763

Wiring differences (old=new): C=B, W1=W, E=X2, X=F.

Y594R1243

Wiring differences (old=new): C=X, X=L, W=W2.

T8611M2025

Includes night setback.

programmable

Y594R1615

Y594C1322

Use Y594C1322 when T874C is used.

Y594R1243

Use Y594R1243 when T874R is used.

Y594R1243

Wiring differences (old=new): C=X.

Y594R1425

Y594R1243

Y594R1763 Y594R1243 Y594R1763

60-2485—884

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

gray

(

)

gray

Table 9. Q674 Subbase Cross Reference.

Model

Number

L1637 207 Obsolete. Carrier heat pump; part no. HH93AZ195;

Fig.

No. Description

Q674 Trade

Replacement Remarks

Y594J1001

used with T874J1002 (HH07AT175) or T874J1010

HH07AT165).

L1678 209 Trol-A-Temp by Honeywell; gray color; used with

None See Trol-A-Temp.

T874R1707; used in Y594R1490.

L1686 209 Trol-A-Temp b

Honeywell; used with T874R1715;

None See Trol-A-Temp.

used in Y594R1508.

L1702 132 Obsolete

. Snyder General heat pump; part no.

Y594R1672 654958B07; used with T874R1723 and C815A1005; used in Y594R1516.

L1710 230 Used with T874R1822; used in Y594R1615. L1728 228 Obsolete. Lennox; gray color; used with T874R1855;

Y594R1615

Y594R1763 used in Y594R1714.

L1736 120 Desi

ned to replace Y594R1011 (York part no.

2TH11702224

; used with T874R1871; used in

Y594R1664

Y594R1664. Designed to replace Y594R1151 (York part no.

Y594R1672 2TH11702324), Y594R1193 (York part no. 6TH11702224

and York part no. 2TH11704024; used

with T874R1889 and C815A1054; used in Y594R1672.

L1751 230 Gray color; used with T874R1897, used in

Y594R1680 Y594R1680.

L1769 124 Obsolete. Nordyne part no. 9132260; used with T874J. See OEM for

replacement.

L1777 120 Obsolete

. Gray color; designed to replace Y594R1151

Y594R1672

York part no. 2TH11702324), Y594R1193 (York part no. 6TH11702224) and York part no. 2TH11704024; used with T874R1905 and C815A1059; used in Y594R1698.

Designed to replace Y594R1011 (York part no. 2TH11702224

; used with T874R1913; used in

Y594R1664

Y594R1706.

L1785 103 Obsolete

. Carrier part no. HH93AZ175-W; Canada;

Y594G1476

color; System: Supl Ht-Heat-Off-Cool; includes

one LED.

L1793 124 Obsolete

. Carrier Canada part no. HH93AZ186-W;

Y594J1019

color; Fan: Auto-On; System: Supl Ht-Heat-Off-

Cool; includes one LED.

L1801 197 American Standard (Trane) part no. THT1225; includes

Y594R1763

two LEDs; used with T874R1939; used in Y594R1748.

L1819 168 Obsolete. Inter-City Products part no. HQ1149407HW;

Y594R1425 includes three LEDs; used with T874R1947; used in Y594R1755.

L1827 197 TRADELINE; includes two LEDs; used with

Y594R1763 T874R1954; used in Y594R1763; direct replacement for Trane/American Standard Y594R1748

T874R1939/Q674L1801) Trane part no. ASYSTAT

631A, Y594R1136

L1835 140 Obsolete. Inter-City Products; includes three LEDs;

used in Y594W1030.

L1843 115 Obsolete

. Consolidated Industries part no. 9036100;

T874R1053/Q674L1140).

T8611M2025

programmable

Y594R1680

color; includes two LEDs; used with T874R1962;

used in Y594R1771.

Both the thermostat and subbase must be replaced.

Wiring differences (old=new): C=B, W1=W, X=X2.

Wiring differences (old=new): Y1=Y, L=F, W1=W, E=X2, C=B.

Replacement is beige.

Wiring differences (old=new): C=X; Y1-W1 jumper required.

Includes night setback.

Includes CHECK LED.

85 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

Table 9. Q674 Subbase Cross Reference.

Model

Number

L1850 120 York Canada; gray color; includes one LED; used with

Fig.

No. Description

Q674 Trade

Replacement Remarks

Y594R1672

T874R1970; used in Y594R1789.

L1868 125 TRADELINE; includes two LEDs; used with

Y594R1797 T874R1988; used in Y594R1797; direct replacement for Evcon/Coleman Y594R1235 Q674L1421

Coleman part no. 3600-368.

L1876 245 Obsolete. Amana part no. 10573902; includes two

T874R1368/

Y594R1797 Wiring differences (old=new):

LEDs; used with T874R2002; used in Y594R1805.

L1884 245 Obsolete

. Amana part no. 10573904; includes two

Y594R1797 Wiring differences (old=new):

LEDs; used with T874R2010; used in Y594R1813.

L1892 103 Obsolete

. TRADELINE; System: SUPL HT-HEAT-

Y594G1674 Replacement has auto OFF-COOL; includes one LED; used with T874G2004; used in Y594G1666; direct replacement for Carrier Y507J1011

T874G1055/Q674L1041) Carrier part no.

HH07AT171/HH93AZ175.

L1900 241 Obsolete

. TRADELINE; System: SUPL HT-HEAT-

Y594J1019 Replacement has auto OFF-COOL; includes SUPL HT LED; used with T874J1069; used in Y594J1001; direct replacement for Carrier T874J1028/Q674J1068 HH07AT165/HH93AZ183

Carrier part no.

, Carrier T874J1002/ Q674J1068 (Carrier part no. HH07AT175/ HH93AZ183

L1918 125 Obsolete. York logo; part no. 2TH11703424A; includes

Y594R1797

two LEDs; used with T874R2028 in Y594R1821.

L1934 123 Obsolete. Addison logo; part no. 843-277; includes

T8611M2025

three LEDs; used with T874W1106 in Y594W1055.

Q674N

N1015 60 Obsolete

N1023 61 Obsolete

Q674P

P1005 126 Obsolete. Carrier heat pump; part no. HH93AZ169;

Q674Q

Q1004 59 Obsolete

stem: OFF-HEAT-COOL-EVAP; Fan: AUTO-ON

. Goettl heat pump; changeover in heat mode;

evaporative cooler circuit; used with T874C1182.

. Sigler heat pump; evaporative cooler circuit;

used with T874C1349.

stem: SUPL HT-HEAT-COOL; Fan: AUTO-ON

used with T874G1071

stem: HEAT-OFF-COOL; Fan: LOW-MED-HI-ON

HH07AT171).

. McQuay special; used with T874A1267. See OEM for

See OEM for replacement.

Y594G1419

replacement.

Q1012 64 Used with T874A1291. None

Q674R

R1003 69 Obsolete

stem: OFF-COOL; Fan: LO-HI-CONT

. Carrier part no. HH93AZ190; international

mbols on fan and switches; used with T874V1008

See OEM for replacement.

HH07AT177).

Q674S

S1000 70 Obsolete. Fiberglas; Canada; SERVICE LED; used

Q674W

stem: HEAT-COOL; Fan: None

with T874C1653; used in Y594C1348.

stem: OFF-ON; Fan: LO-MED-HI

See OEM for replacement.

W1006 240 Obsolete. Snyder General part no. 044271801. See OEM for

replacement.

Both the thermostat and subbase must be replaced.

C/X=X.

C/X=X, W3=W2.

eover.

chan

changeover.

Wiring differences (old=new):

umper Y1-W1;

C=X; replacement has OFF-EM HTHEAT-AUTO-COOL s switchin

stem

60-2485—886

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 10. Y594 Cross Reference.

Model

Number

Fig.

No. Description

Trade Model

Replacement

Y594A

A1001 46 Obsolete. Amana part no. D68535-11; contains

T874A1077, Q674B1075.

A1019 82 Obsolete

. Amana part no. P68535-12; contains

T874A1077, Q674E1056.

A1035 44 Obsolete

. Trane part no. 268-0187-1; contains

T874A1085, Q674B1018.

A1043 46 Obsolete

. Trane part no. 268-0201-5; contains

T874A1085, Q674B1075.

A1050 55, 66 Obsolete

. Trane part no. 268-0201-3; contains

T874A1085, Q674D1008.

A1068 82 Obsolete

. Sears part no. 42-9144; contains

T874A1119, Q674E1007.

T874A1036/

Q674B1075

T874A1036/

Q674E1049

T874A1036/

Q674B1018

T874A1036/

Q674B1075

T874A1036/ Q674D1040

T874A1036/

Q674E1049 A1126 64 Contains T874A1291, Q674Q1012. None A1159 91 Obsolete

. Contains T874A1440, Q674G1005. T874A1150/

Q674G1070

A1167 184 California Economizer; Premier White® color;

contains T874A1580 and Q674G1161.

A1175 55 Obsolete

. York logo; part no. 2TH04703224;

contains T874A1622, Q674D1180.

A1191 46 Obsolete

. Amana logo: part no. P6853524R;

contains T874A1002, Q674B1075.

T874A1036/ Q674G1070

T874A1010/ Q674D1040

T874A1036/

Q674B1075

Y594B

B1026 44 Trane part no. BAYSTAT012; contains T874B1035,

Q674B1018.

B1034 46 Obsolete

. Trane part no. 163-552-1; contains

T874B1035, Q674B1075.

B1042 88 Obsolete

. Goodman part no. CHTS36-60; contains

T874B1100, Q674E1338.

T874B1019/

Q674B1018

T874B1019/

Q674B1075

T874B1019/

Q674E1049

Y594C

C1009 82 Obsolete

. Amana part no. D68535-9; contains

T874C1059, Q674E1056.

C1017 142 Obsolete. Amana part no. D68535-10; contains

T874C1059, Q674F1022.

C1058 46 Obsolete

. Contains T874C1000, Q674B1075. T874C1018/

T874C1018/

Q674E1049

T874C1018/

Q674F1022

Q674B1075 C1082 82 Obsolete

. Trane part no. 166-162-1; contains

T874C1083, Q674E1007.

C1256 45 Obsolete

. Amana part no. D68535-16; contains

T874C1059, Q674B1059.

C1280 45 Obsolete. Williamson; contains T874C1570,

Q674B1000.

C1314 56 Obsolete

. LSI; contains T874C1471, Q674B1257. T874C1018/

T874C1018/

Q674E1049

T874C1018/

Q674B1034

T874C1018/

Q674B1034

Q674B1018 C1322 121 Obsolete C1330 142 Obsolete

T874C1059, Q674F1022.

Both the thermostat and subbase must be replaced.

. Contains T874C1638, Q674L1561. Y594C1322 . Amana part no. D68535-21; contains

T874C1018/

Q674F1022

Remarks

Replacement is bei

No LEDs on replacement.

Jumper RC-RH

Jumper RC-RH; no RESET LED on replacement.

e color.

87 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Table 10. Y594 Cross Reference.

Model

Number

Fig. No. Description

Trade Model

Replacement

C1348 70 Obsolete. Fiberglas; contains T874C1653,

Q674S1000.

C1355 45 Obsolete. Nordyne “Miller” part no. 9122250;

contains T874C1695, Q674B1000.

C1363 45 Obsolete

. Nordyne “Intertherm” part no. 911100001;

contains T874C1703, Q674B1000.

C1371 184 Obsolete. California Economizer; contains

T874C1802 and Q674G1005.

C1389 237 Obsolete

. TRADELINE; Premier White® color;

contains T874C1810 and Q674B1547.

C1413 238 Heat Controller “

Energy Night” logo; contains

T874C1844 and Q674F1592.

C1421 249 Obsolete

. TRADELINE; contains T874C1877 and

Q674B1554.

C1439 T874C1869 and Q674C1579. None

Y594D

D1016 44 Obsolete

. Trane part no. 268-0201-2; contains

T874D1082, Q674B1018.

D1024 72 Trane part no. BAYSTAT010; contains T874D1082,

Q674C1009.

D1032 91 Obsolete

. Trane part no. BAYSTAT011; contains

T874D1082, Q674G1021.

D1040 46 Amana part no. P68535-19R; contains T874D1082,

Q674B1075.

D1057 55, 66 Obsolete

. Trane part no. BAYSTAT007; contains

T874D1082, Q674D1008.

D1149 46 Obsolete

. Amana part no. P68535-20C; contains

T874D1322, Q674B1075.

D1156 48 Obsolete

. Trane part no. BAYSTAT013; contains

T874D1082, Q674B1133.

D1180 82 York part no. 025-23321-000; contains T874D1504,

Q674E1007.

D1222 166 Obsolete

. WeatherKing; contains T874D1009,

Q674F1337.

D1248 82 Obsolete

. Reznor part no. 93437; contains

T874D1629, Q674E1007.

D1297 82 Obsolete

. ArcoAire part no. 1506753; contains

T874D1769, Q674E1346.

D1305 82 Obsolete

. Comfortmaker part no. 1505753; contains

T874D1785, Q674E1346.

D1321 45 Obsolete

. Goodman part no. CHT 90-120; contains

T874D1843, Q674B1000.

D1339 82 Obsolete

. Nordyne part no. 5471180; contains

T874D1009, Q674E1007.

Both the thermostat and subbase must be replaced.

T874C1000/

Q674B1075

Wiring differences (old=new): Y=Y1;

Remarks

umper RC-RH and Y1W1; replacement has no SERVICE has fan switchin OFF-COOL s

LED; replacement

and HEAT-

stem switching.

T874C1018/

Q674B1034

T874C1018/

Q674B1075

Wiring differences (old=new):

umper RC-RH; Y1-W;

Y=Y1; replacement has no SERVICE LED.

T874C1018/ Q674G1070

Y594C1389

Y594R1425 E-W2 jumper required; system:

EM.HT.-Heat-Off-Cool.

Y594D1347 Replacement has auto

eover; jumper RH-RC.

chan

T874D1165/

Q674B1018

T874D1165/ Q674C1058

T874D1165/ Q674G1070

T874D1165/

Q674B1075

T874D1165/ Q674D1040

T874D1165/

Q674B1075

T874D1165/

Q674B1018

Replacement has no FILTER LED.

T874D1165/

Q674E1049

T874D1165/

Q674F1022

Wiring differences (old=new): R=RH;

umper RC-RH; replacement has no EM.HT. or AUX. HT. LEDs.

T874D1165/

Q674E1049

T874D1165/

Q674E1049

T874D1165/

Q674E1049

T874D1165/

Q674B1034

T874D1165/

Q674E1049

60-2485—888

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 10. Y594 Cross Reference.

Model

Number

Fig.

No. Description

Trade Model

Replacement

D1347 82 TRADELINE® contains T874D1942, Q674E1403. Y594D1347 D1354 82 SUPER TRADELINE® contains T874D2031

Y594D1354

cover), Q674E1049, and TG504A with two keys.

D1370 45 Obsolete

T874D2049 and Q674B1539.

D1388 72 Obsolete

T874D2049 and Q674C1520.

D1396 184 Obsolete

T874D2049 and Q674G1153.

D1404 55, 66 Obsolete

T874D2049 and Q674D1164.

D1412 82 Obsolete

HH07AT209; taupe color; contains T874D2064 and

. Carrier part no. 50QE90022101; contains

. Carrier part no. 50QE90023101; contains

. Carrier part no. 50QE90025101; contains

. Carrier part no. 50QE90024101; contains

. Carrier “Weathermaker” part no.

T874D1165/

Q674B1034

T874D1165/ Q674C1058

T874D1165/ Q674G1070

T874D1165/ Q674D1040

T874D1165/

Q674E1049

Q674E1445.

D1420 82 Obsolete

HH07AT208; taupe color; contains T874D2072 and

. Carrier “Zone Perfect” part no.

T874D1165/

Q674E1049

Q674E1445.

D1438 55, 66 Obsolete

. Contains T874D2098 and Q674D1008. T874D1165/

Q674D1040

D1446 55, 66 Obsolete

. Contains T874D2106 and Q674D1008. T874D1165/

Q674D1040

D1453 208 Obsolete

contains T874D2163 and Q674D1172.

D1461 45 Obsolete

contains T874D2171 and Q674B1562.

. Amana logo; part no. P1217501F;

. Amana logo; part no. P1217701F;

T874D1165/ Q674D1040

T874D1942/

Q674B1034

Y594E

E1015 72 Obsolete

T874E1040, Q674C1009.

. Trane part no. BAYSTAT015; contains

T874B1019/ Q674C1058

Y594F

F1022 44 Obsolete

. Contains T874F1031 and 40003440-001

T874F1015

wallplate with installed diode.

F1048 72 Obsolete

T874F1130, Q674C1009.

F1063 91 Obsolete

T874F1130, Q674G1005.

. Reznor part no. 93436; contains

. Reznor part no. 93435; contains

T874F1015/ Q674C1058

T874F1015/ Q674G1070

Y594G

G1013 160 Obsolete

. York part no. 2TH11702424; contains

Y594G1567

T874G1170, Q674J1027.

G1138 160 Obsolete

. York part no. 025-22286; contains

Y594G1567

T874G1196, Q674J1027.

G1153 154 Obsolete

. Crispaire part no. HP10-51; contains

Y594G1252 Wiring differences (old=new):

T874G1089, Q674F1204. G1161 162 Contains T874G1204, Q674J1043. Y594G1161 G1195 155 Obsolete

. Heil Quaker part no. HQ521387HW;

Y594G1252

contains T874G1246, Q674F1212. G1229 160 Obsolete

. York part no. 6TH11702424; contains

Y594G1567

T874G1428, Q674J1027. G1245 155 Obsolete

. BDP part no. HH641502; contains

Y594G1252

T874G1451, Q674F1212. G1252 155 TRADELINE; contains T874G1246, Q674F1212. Y594G1252

Both the thermostat and subbase must be replaced.

Remarks

Replacement has °F scaleplate.

Replacement is beige color.

Replacement is bei

Replacement has 2 setpoint levers.

Replacement has °F scaleplate and 2 setpoint levers.

A=L.

e color.

89 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

Table 10. Y594 Cross Reference.

Model

Number

Fig. No. Description

G1294 79 Obsolete. LSI; contains T874G1378, Q674C1124. See OEM for

Trade Model

Replacement

H2 is night setback.

Remarks

replacement.

G1328 194 Obsolete

T874G1543, Q674F1345.

G1344 194 Obsolete

contains T874G1469, Q674F1345.

G1351 160 Obsolete

. Addison part no. 8403-197; contains

. Heat Controller part no. 7601-110B;

. Luxaire part no. 026-00068-000; contains

Y594G1252 Wiring differences (old=new):

Y1=O, X=L, C=X.

Y594G1252 Wiring differences (old=new):

Y1=O, X=L, C=X; W1=Y.

Y594G1567

T874G1568, Q674J1126. G1369 155 Obsolete G1377 169 Obsolete

. Contains T874G1246, Q674F1212. Y594G1252 . Coleman part no. 3600-373; contains

Y594G1633

T874G1576, Q674F1402. G1385 155 Obsolete

. ArcoAire; contains T874G1592,

Y594G1252

Q674F1212. G1393 170 Obsolete

. Contains T874R1393, Q674L1454. Y594G1393 G1419 227 TRADELINE; contains T874G1642, Q674F1444. Y594G1419 G1427 177 Obsolete. Mammoth part no. 73034101; contains

T874G1659, Q674C1330.

G1443 174 Obsolete

. American Standard (Trane) part no.

See OEM for replacement.

Y594G1161

H2 is night setback.

ASYSTAT650; contains T874G1675, Q674J1142.

G1476 227 TRADELINE; same as Y594G1419 except Premier

Y594G1476

White® color; contains T874G1741, Q674F1477.

G1492 211 Trol-A-Temp; contains T874G1758, Q674F1485. None See Trol-A-Temp for

replacement.

G1500 216 Obsolete

T874G1774, Q674J1175.

G1518 216 Obsolete

T874G1782, Q674J1175.

. Comfortmaker part no. 1505756; contains

. ArcoAire part no. 1506756; contains

See OEM for replacement.

See OEM for

replacement. G1526 167 TRADELINE; contains T874G1626, Q674F1436. None G1534 227 TRADELINE; °C; white; Australia; contains

None

T874G1824, Q674F1477.

G1542 231 Obsolete

. Intertherm part no. 9129290; contains

Y594G1252 Cooling changeover only.

T874G1832, Q674F1519.

G1559 231 Obsolete

. Miller part no. 9129310; contains

Y594G1252 Cooling changeover only.

T874G1840, Q674F1519. G1567 160 TRADELINE; contains T874G1865, Q674J1209. Y594G1567 G1575 160 Obsolete

. TRADELINE; same as Y594G1567

Y594G1567 Replacement is beige. except Premier White® color; contains T874G1873, Q674J1225; direct replacement for York 2TH11702424 Q674J1027 contains T874G1428/Q674J1027

G1583 229 Obsolete. Lennox Canada part no. 97E78; contains

T874G1857, Q674F1535.

G1591 243 Obsolete

Y594G1013 contains T874G1170/

and 6TH11702424 (Y594G1229

. Amana part no. 10636701; contains

Y594G1161 Wiring differences (old=new):

E=X2, C=B, L=F.

Y594G1633 T874G1899 and Q674F1550.

G1609 155 Obsolete

. Econar; contains T874G1915 and

Y594G1252 Q674F1212.

Both the thermostat and subbase must be replaced.

60-2485—890

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

)

(

)

Table 10. Y594 Cross Reference.

Model

Number

Fig.

No. Description

G1617 73 Obsolete. Carrier part no. 50QE90020101; contains

T874G1949 and Q674C1504.

G1625 160 York Canada part no. 2TH11702524; contains

T874G1964 and Q674J1266.

G1633 169 TRADELINE; contains T874G1972 and

Q674F1584; direct replacement for Y594G1377

T874G1576/Q674F1402) Evcon/Coleman part no.

3600-373.

G1641 169 Obsolete. Amana part no. 10636703; contains

T874G1980 and Q674F1600.

G1658 155 Obsolete

. Tempstar “Inter-City Products” part no.

1149910; contains T874G1998 and Q674F1212.

G1666 103 Obsolete

. TRADELINE; manual changeover; contains T874G2004 and Q674L1892; direct replacement for Y507J1011 Q674L1041

Carrier part no. 99TZ90041106

T874G1055/

HH07AT171/HH93AZ1750).

G1674 161 TRADELINE; automatic changeover; contains

T874G2004 and Q674J1274; direct replacement Y507J1003 no. 99TZ90040106

T874G1055/Q674J1035) Carrier part

HH07AT171/HH93AZ173).

G1716 155 WaterFurnace logo; part no. TA21H03; contains

T874G2046 and Q674F1667.

Y594H

H1004 79 Obsolete

. LSI part no. 73033901; contains T874H1039 and Q674C1124.

H1012 164 Contains T874H1062 and Q674C1249; replaces

T874H1005/Q674C1041.

H1020 177 Obsolete

. Mammoth part no. 71117101; contains T874H1096 and Q674C1330.

H1038 74 Obsolete

. Carrier part no. 50QE90019101; contains T874H1161 and Q674C1496.

H1046 172 Obsolete

. Carrier part no. 50QE90026101; contains T874H1153 and Q674B1406.

H1053 173 Obsolete

. Carrier part no. 50QE90027101; contains T874H1153 and Q674C1322.

Y594J

J1001 241 Obsolete

. TRADELINE; manual changeover; contains T874J1069 and Q674L1900; direct replacement for T874J1002 or T874A1028 used with Q674L1074 or Q674L1637

HH07AT175 or HH07AT165 used with HH93AZ186 or HH93AZ195

Both the thermostat and subbase must be replaced.

Trade Model

Replacement

Y594H1012

Wiring differences (old=new):

Remarks

Y1=O, Y2=Y, L=R, R=none;

umper required; no night

R-L setback.

T8600D2028

programmable

Y594G1567

Wiring differences (old=new): Y1=O, Y2=Y, L=R; W-Y jumper

uired; night setback.

Replacement has °F scaleplate.

Y594G1633

Y594G1633 Wiring differences (old=new):

W3=W2.

Y594G1252

Y594G1674 Replacement has auto

eover.

chan

Y594G1674

Y594G1716

T8600D2028 H2 is night setback.

Y594H1012

Y594H1012 Wiring differences (old=new):

R1=R, R2=L; use

umper

provided.

Y594H1012

Wiring differences (old=new): X1=O, Y2=Y; L-R

umper

required.

T874A1130/

Q674B1075

Wiring differences (old=new):

Y=Y1; W1-Y1 jumper required; replacement has no LEDs.

Y594H1012

Wiring differences (old=new): Z=X.

Recontrol

T8511G1021

91 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

Table 10. Y594 Cross Reference.

Model

Number

Fig. No. Description

J1019 244 Obsolete. TRADELINE; automatic changeover;

contains T874J1069 and Q674J1282; direct

Trade Model

Replacement

Recontrol

T8511G1021 replacement for T874J1002 or T874J1028 used with Q674J1068 or Q674J1159

HH07AT175 or HH07AT165 used with HH93AZ183 or HH93AZ196

Y594N

N1007 178 Obsolete. Williamson part no. 75-189; contains

T874N1008 and Q674F1196.

N1015 179 Obsolete

N1023 178 Obsolete

. Contains T874N1040 and Q674F1261.

. Intertherm part no. 9111882; contains

T874N1057 and Q674F1220.

N1031 178 Obsolete

. Nordyne “Miller” part no. 9122240;

contains T874N1065 and Q674F1220.

T874N1016/

Q674F1196

Y594G1419

T874N1016/

Q674F1220

T874N1016/

Q674F1220

Y594P

P1005 97 Obsolete

. Carrier part no. 50QE90021101; contains

T8600D2028 Wiring differences (old=new):

T874P1055 and Q674C1512.

Y594R

R1011 120 Obsolete

. York part no. 2TH11702224; contains

Y594R1664

T874R1046 and Q674L1272.

R1029 47 Obsolete

. Bryant; contains T874R1004 and

Y594R1243 Wiring differences (old=new):

Q674B1042.

R1037 122 Obsolete

. Fedders part no. 88-58-00540-001;

Y594R1615 Wiring differences (old=new):

contains T874R1269 and Q674L1066.

R1102 120 Obsolete

. York part no. 025-22285-000; contains

Y594R1664

T874R1145 and Q674L1272.

R1110 108 O bsol ete

. Heil Quaker part no. HQ712004HW;

Y594R1292

contains T874R1137 and Q674L1132.

R1128 116 Obsolete

. Crispaire part no. HP9-51; contains

Y594R1243 Wiring differences (old=new):

T874R1111 and Q674L1215.

R1136 109 Obsolete R1151 120 Obsolete. York part no. 2TH11702324; contains

. Contains T874R1053 and Q674L1140. Y594R1763

Y594R1672

T874R1251, Q674L1272 and C815A1039.

R1185 201 Obsolete

. Intertherm part no. 9111871; contains

Y594R1672 Wiring differences (old=new):

T874R1202 and Q674L1264.

R1193 120 Obsolete

. York part no. 6TH11702224; contains

Y594R1664

T874R1327 and Q674L1272.

R1201 106 Obsolete. BDP part no. HH641501; contains

Y594R1243

T874R1335 and Q674L1405.

R1219 133 Obsolete

. Fedders part no. 88-58-00560-001;

Y594R1425 Wiring differences (old=new):

contains T874R1343 and Q674L1413.

R1235 125 Obsolete. Coleman part no. 3600-368; contains

Y594R1797

T874R1368 and Q674L1421.

R1243 115 TRADELINE; contains T874R1152 and Q674L1207. Y594R1243 R1250 128 Obsolete

. Williamson part no. 75-191; contains

Y594R1425 Wiring differences (old=new):

T874R1392 and Q674L1447.

R1284 136 Obsolete

. Trane part no. BAYSTAT339; contains

Y594R1763

T874R1426 and Q674L1496.

Both the thermostat and subbase must be replaced.

Wiring differences (old=new):

Remarks

L=X2, Y=Y1.

Y=Y1, W=O; Y1-W1 jumper

uired.

W1=W2.

K=E, C=X, W1=B, Z=L.

A=L.

W2=W, X=B, Z=no connection, K=X, W1=H.

K=E, C=X, Z=L; remove

installed jumper.

factor

A=L.

60-2485—892

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

Table 10. Y594 Cross Reference.

Model

Number

Fig.

No. Description

R1292 108 Contains T874R1467 and Q674L1512; replaces

Y594R1110

T874R1137/Q674L1132).

Trade Model

Replacement

Y594R1292

Remarks

R1300 123 Contains T874R1475 and Q674L1520. Y594R1300 R1318 130 Obsolete

T874R1483, Q674L1538 and C815A1005.

R1326 137 Obsolete

. Comfortmaker part no. 1505721; contains

. SUPER TRADELINE; contains

Y594R1763 Wiring differences (old=new):

W1=W, E=X2, X=F, C=B.

Y594R1615

T874R1491 and Q674L1553.

R1334 47 Obsolete

Q674B1042.

R1342 130 Obsolete

T874R1517, Q674L1538 and C815A1005.

R1359 113 Obsolete

T874R1525 and Q674L1181.

R1375 130 Obsolete

C815A1005.

R1383 132 Obsolete

T874R1574 and Q674L1538.

R1391 132 Obsolete

T874R1582 and Q674L1538.

R1409 119 Obsolete

T874R1608 and Q674L1264.

. Slant Fin; contains T874R1509 and

. ArcoAire part no. 1506721; contains

. ArcoAire part no. A02074; contains

. Contains T874R1566, Q674L1538 and

. Comfortmaker part no. 1505739; contains

. ArcoAire part no. 1506739; contains

. Intertherm part no. 6244630; contains

Y594R1243 Wiring differences (old=new):

W1=W2.

Y594R1763 Wiring differences (old=new):

W1=W, E=X2, X=F, C=B.

Y594R1243 Wiring differences (old=new):

X1=X.

Y594R1763 Wiring differences (old=new):

W1=W, E=X2, X=F, C=B.

Y594R1243 Wiring differences (old=new):

W=W2, C=X, X=L.

Y594R1243 Wiring differences (old=new):

W=W2, C=X, X=L.

Y594R1763 Wiring differences (old=new):

W2=W, X=B, Z=F, K=X2, W1=O.

R1417 113 Obsolete

. Comfortmaker part no. 1505-735;

contains T874R1301 and Q674L1181.

R1425 168 SUPER TRADELINE; contains T874R1616 and

Y594R1243 Wiring differences (old=new):

X1=X.

Y594R1425

Q674L1587.

R1433 200 Obsolete

T874R1624 and Q674L1595.

. Miller part no. 9115900; contains

Y594R1243 Wiring differences (old=new):

W2=W, X=B, Z=F, K=X2, W1=O.

R1441 136 Obsolete

. American Standard (Trane) part no.

Y594R1763 ASYSTAT651; contains T874R1657 and Q674L1611.

R1466 108 Heil Quaker part no. 1060321; model no.

Y594R1292 HAXB004TW01; contains T874R1673 and Q674L1132.

R1482 119 Obsolete

contains T874R1699 and Q674L1264.

. Nordyne “Miller” part no. 9122230;

Y594R1763 Wiring differences (old=new):

W2=W, X=B, Z=F, K=X2, W1=O.

R1490 209 Trol-A-Temp; contains T874R1707 and Q674L1678. None See Trol-A-Temp for

replacement.

R1508 209 Trol-A-Temp; contains T874R1715 and Q674L1686. None See Trol-A-Temp for

replacement.

R1516 132 Obsolete

contains T874R1723, Q674L1702 and C815A1005.

R1524 108 Obsolete

. Snyder General part no. 654958B07;

. Inter-City Products part no.

Y594R1763 Wiring differences (old=new):

W1=W, C=B, X=X2.

Y594R1292 HQ1147925HW; contains T874R1731 and Q674L1132.

R1532 108 Heil Quaker part no. 1060322; model no.

Y594R1292 TAXB004TW01; contains T874R1749 and Q674L1132.

R1607 108 Obsolete

. Keeprite THPC; contains T874R1814 and

Y594R1292 Q674L1132.

Both the thermostat and subbase must be replaced.

93 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

(

)

(

)

(

)

Table 10. Y594 Cross Reference.

Model

Number

Fig. No. Description

R1615 230 TRADELINE; contains T874R1822 and

Q674L1710; replaces Y594R1326 Q674L1553

T874R1491/

R1623 134 Obsolete. Rheem Universal Parts part no. 41-

20796-46; contains T874R1558 and Q674L1504.

R1631 134 Rheem part no. 41-20796-29; contains T874R1442

and Q674L1504.

R1649 134 Ruud part no. 41-20796-33; contains T874R1434

and Q674L1504.

R1656 134 Obsolete

. WeatherKing part no. 41-20796-64;

contains T874R1830 and Q674L1504.

R1664 120 TRADELINE; contains T874R1871 and

Q674L1736; direct replacement for York 2TH11702224 Q674L1272

Y594R1011 contains T874R1046/

R1672 120 TRADELINE; contains T874R1889, Q674L1736

and C815A1054; direct replacement for York 2TH11702324

Y594R1151 contains T874R1251/

Q674L1272/C815A1039) and 6TH11702224

Y594R1193 contains T874R1327/Q674L1272).

R1680 230 TRADELINE; same as Y594R1615 except Premier

White® color; contains T874R1897 and Q674L1751; direct replacement for Y594R1326

T874R1491/Q674L1553).

R1698 120 Obsolete

. TRADELINE; Premier White® color;

contains T874R1905, Q674L1777 and C815A1054.

R1706 120 Obsolete

. TRADELINE; same as Y594R1664 except Premier White® color; contains T874R1913 and Q674L1777; direct replacement for Y594R1011

T874R1046/Q674L1272) York part no.

2TH11702224.

R1714 228 Obsolete. Lennox part no. 97E79; Canada; Premier

White® color; contains T874R1855 and Q674L1728.

R1722 115 Obsolete

. Econar; contains T874R1921 and Q674L1207.

R1748 197 American Standard (Trane) part no. ASYSTAT651A;

contains T874R1939 and Q674L1801.

R1755 168 Obsolete. Inter-City Products part no.

HQ1149376HW; contains T874R1947 and Q674L1819.

R1763 197 TRADELINE: contains T874R1954 and

Q674L1827; direct replacement for Y594R1136

T874R1053/Q674L1140), Y594R1748

T874R1939/Q674L1801) Trane part no. ASYSTAT651A, Y594R1441 (T874R1657/ Q674L1611

Trane part no. ASYSTAT651.

R1771 115 Obsolete. Consolidated Industries part no.

9036100; contains T874R1962 and Q674L1843.

R1789 120 York Canada part no. 2TH11701524; contains

T874R1970 and Q674L1850.

Both the thermostat and subbase must be replaced.

Trade Model

Replacement

Remarks

Y594R1615

Y594R1300

Y594R1664

Y594R1672

Y594R1680

Y594R1672 Replacement is beige.

Y594R1664 Replacement is bei

Y594R1763 Wiring differences (old=new):

Y1=Y, L=F, W1=W, E=W2, C=B.

Y594R1243

Y594R1763

Y594R1425

Y594R1763

Y594R1680

Y594R1672

Includes CHECK LED.

Replacement has °F scaleplate.

60-2485—894

(

)

Table 10. Y594 Cross Reference.

Model

Number

Fig.

No. Description

R1797 125 TRADELINE; contains T874R1988 and

Q674L1868; direct replacement for Y594R1235

T874R1368/Q674L1421) Evcon/Coleman part no.

3600-368).

R1805 245 Obsolete. Amana part no. 10636702; contains

T874R2002 and Q674L1876.

R1813 245 Obsolete

. Amana part no. 10636704; contains

T874R2010 and Q674L1884.

R1821 125 Obsolete

. York logo; part no. 2TH11703424A;

contains T874R2028 and Q674L1918.

R1839 134 Rudd lo

o; part no. 41-20796-48; contains

T874R2036 and Q674L1504.

R1854 123 Obsolete

. Rheem logo; part no. 41-20796-47;

contains T874R1996 and Q674L1504.

Y594W

W1014 54 Contains T874W1015, Q674B1216 and

C815A1005.

W1022 140 Obsolete

. Rheem part no. 41-20797-19; contains

T874W1031, Q674L1546 and C815A1005.

W1030 68 Obsolete

. Inter-City Products part no. 1072350; contains T874W1072, Q674L1835 and C815A1005 Outdoor Thermistor.

W1055 247 Obsolete

. Addison logo; part no. 843-277; contains T874W1106, Q674L1934 and C815A1005.

Y594Y

Y1004 210 Obsolete

. Mammoth part no. 71117301; contains T874Y1005 and Q674E1353.

Y1012 248 Obsolete

. WaterFurnace logo; part no. TA21H03; contains T874Y1013 and Q674F1675.

Both the thermostat and subbase must be replaced.

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

Trade Model

Replacement

Y594R1797

Remarks

Y594R1797 Wiring differences (old=new):

C/X=X.

Y594R1797 Wiring differences (old=new):

C/X=X, W3=W2.

Y594R1797

See OEM for replacement.

Y594R1300

Y594W1014

T8611M2025.

T8611M2025

Includes night setback.

programmable

T8611M2025

See OEM for replacement.

95 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

WIRING DIAGRAMS

FALL

H1 ANTICIPATOR

FALL

RISE

THERMOSTAT

H2 ANTICIPATOR

C1 ANTICIPATOR

C2 ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

JUMPER RH, RC FOR SINGLE TRANSFORMER.

SUBBASE SYSTEM COMPONENTS

HEAT RELAY 1

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

HEAT RELAY 2

HEAT CHANGEOVER VALVE

COOL CHANGEOVER

VALVE

FAN RELAY

COMPRESSOR CONTACTOR 2

COMPRESSOR CONTACTOR 1

M2903

L1 (HOT)

Fig. 44. Schematic and hookup of T874A,B,C,D,E,F with Q674B. Used in standard applications.

NOTE:

Model Heating Cooling No. Bulbs Bulbs

T874A H1 C1 T874B H1 C1,C2 T874C H1,H2 C1 T874D H1,H2 C1,C2 T874E C1,C2 T874D H1,H2

SUBBASE SYSTEM COMPONENTS

HEAT RELAY 1

HEAT RELAY 2

HEAT CHANGEOVER VALVE

COOL CHANGEOVER VALVE

FAN RELAY

COMPRESSOR CONTACTOR 2

COMPRESSOR CONTACTOR 1

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

OPTIONAL LED ON SOME MODELS.

M933C

L1 (HOT)

FALL

H1 ANTICIPATOR

FALL

RISE

THERMOSTAT

H2 ANTICIPATOR

C1 ANTICIPATOR

C2 ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

JUMPER RH, RC FOR SINGLE TRANSFORMER.

Fig. 45. Schematic and hookup of T874C,D with Q674B. Used in standard applications.

60-2485—896

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

FALL

H1 ANTICIPATOR

FALL

RISE

THERMOSTAT

H2 ANTICIPATOR

C1 ANTICIPATOR

C2 ANTICIPATOR

SUBBASE

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

SYSTEM COMPONENTS

HEAT RELAY 1

HEAT RELAY 2

HEAT CHANGEOVER VALVE

COOL CHANGEOVER VALVE

FAN RELAY

COMPRESSOR CONTACTOR 2

COMPRESSOR CONTACTOR 1

Fig. 46. Schematic and hookup of T874A,B,D with Q674B. Used in standard applications.

M2904

L1 (HOT)

SUBBASE SYSTEM COMPONENTS

COOL CHANGEOVER

AUTO

HEAT

OFF

COOL

VALVE

FAN RELAY

AUX. HT. RELAY

COMPRESSOR CONTACTOR

L1 (HOT)

M2906

FALL

THERMOSTAT

H1/C1

FALL

ANTICIPATOR

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

SYSTEM SWITCH

Fig. 47. Schematic and hookup of T874R with Q674B. Used in heat pump applications.

97 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT

FALL

H1 ANTICIPATOR

FALL

RISE

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

CLOGGED FILTER, SERVICE SWITCH.

H2 ANTICIPATOR

C1 ANTICIPATOR

C2 ANTICIPATOR

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

SUBBASE

FILTER LED (RED)

SYSTEM COMPONENTS

HEAT RELAY 1

FAN RELAY

EXTERNAL FAN SWITCH

HEAT RELAY 2

HEAT CHANGEOVER VALVE

COOL CHANGEOVER VALVE

COMPRESSOR CONTACTOR 1

COMPRESSOR CONTACTOR 2

L1 (HOT)

M2905

(HOT)

Fig. 48. Schematic and hookup of T874D with Q674B. Used in standard applications.

60-2485—898

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT SUBBASE

H1 ANTICIPATOR

FALL

H2 ANTICIPATOR

FALL

C1 ANTICIPATOR

RISE

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

HEAT LED (RED)

LO SPEED LED (GREEN)

HI SPEED LED (GREEN

COOL LED (YELLOW)

SYSTEM COMPONENTS

HEAT RELAY 1

BLOWER RELAY

HEAT RELAY 2

COMPRESSOR CONTACTOR

HSII CONTROL PANEL

L1 (HOT)

M5945

Fig. 49. Schematic and hookup of T874C with Q674B. Used in standard applications.

THERMOSTAT

H1 ANTICIPATOR

FALL

RISE

H2 ANTICIPATOR

C1 ANTICIPATOR

RISE

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

SUBBASE SYSTEM COMPONENTS

COOL CHANGEOVER VALVE

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

AUX. HT. RELAY

COMPRESSOR CONTRACTOR

FAN RELAY

L1 (HOT)

M8000

Fig. 50. Schematic and hookup of T874G with Q674B. Used in heat pump applications.

99 60-2485—8

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES

THERMOSTAT SUBBASE

FALL

H1 ANTICIPATOR

FALL

H2 ANTICIPATOR

RISE

C1 ANTICIPATOR

RISE

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER.

B, O TERMINALS ON SOME MODELS.

C2 ANTICIPATOR

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

SYSTEM COMPONENTS

HEAT RELAY 1

FAN RELAY

L1 (HOT)

HEAT CHANGEOVER VALVE

L1 (HOT)

COOL CHANGEOVER VALVE

COMPRESSOR CONTACTOR 1

COMPRESSOR CONTACTOR 2

HEAT RELAY 2

M5944

Fig. 51. Schematic and hookup of T874D with Q674B. Used in standard applications.

THERMOSTAT

H1 ANTICIPATOR

FALL

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

OPTIONAL FIELD WIRE JUMPER. W3 AND F TO BE JUMPERED EXCEPT FOR TWO STAGE GAS APPLICATION.

FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER.

RISE

H2 ANTICIPATOR

C1 ANTICIPATOR

SUBBASE

FAN SWITCH

AUTO

SYSTEM SWITCH

HEAT

OFF

COOL

SYSTEM COMPONENTS

HEAT RELAY 1

HEAT RELAY 2

COMPRESSOR CONTACTOR

FAN RELAY

L1 (HOT)

M5999

Fig. 52. Schematic and hookup of T874C with Q674B. Used in standard applications.

60-2485—8100

Bryant T874, Q674 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

APPLICATION

FEATURES

SPECIFICATIONS

Super Tradeline®/Tradeline® Models

INSTALLATION

When Installing this Product…

Mount Subbase

Location

Wire Subbase

Outdoor Disconnect

Install and Adjust Stop Brackets

Mount Thermostat

SETTINGS

Set the Heat Anticipator

Temperature Setting

Subbase Setting

Setting the Adjustable Differential

HEATING

Verify the Adjustment

Cooling

CHECKOUT

Outdoor Reset Thermistor (Where Applicable)

Thermometer

CALIBRATION

Thermostat

UNDERSTANDING CIRCUITS

Tracing Method:

OPERATION

Heat Anticipation/Cool Anticipation

Interstage Differential

Droop

Outdoor Reset

Service and Replacement of C815A Outdoor Thermistor

Restricted Setpoint (DoD)

Applications

Features

LED Indicators

Heat Pump Application

Commercial Rooftop Application

Space Temperature Sensing Low Voltage Controls

Two-Stage Thermostat

Cycling Rate

Voltage Anticipation

Outdoor Reset—How it Works

Outdoor Reset

Changeover

Low Temperature Lockouts

Heat Pumps with Dual Compressors

Two speed Heat Pump

Defrost Control

Defrosting

Auxiliary Heat

Two-Stage Thermostat

Stage or Time Modulated Control

Three-Stage Thermostat

Emergency Heat

Switching to Emergency Heat

Crankcase Heat

Compressor Fault Relay

CROSS REFERENCE

WIRING DIAGRAMS