Honeywell Y594 User Manual

Y594

(Multistage Thermostat Subbase)

TRADELINE

®

APPLICATION

These Y594G and Y594J combination packs are designed
to meet the specific requirements of Carrier heat pump
equipment. The Y594 packs are designed for 2 stage heat
and 1 stage cool applications. The system switch is SUPL
HT-HEAT-OFF-COOL or SUPL HT-ON-OFF. The fan
switch is AUTO-ON. See Table 1 for model information
and cross reference from Carrier part numbers.

Table 1. Heat Pump Thermostat/Subbase Combinations.

OS No.

Y594G1666 7 T874G2004

Y594G1674 6 T874G2004

Y594J1001 5 T874J1069

Y594J1019 4 T874J1069

Thermostat Ratings

SWITCHING: sealed mercury switch.
SWITCH RATINGS:

First Stage Heating and Cooling: 6.5A inrush, 1.5A

maximum running at 25 Vac.

Second Stage Heating and Cooling: 1.5A maximum

running at 30 Vac.

Changeover Switch: 6.5A inrush, 1.5A running at 25

Vac.

HEAT ANTICIPATOR:

First Stage Heating and Cooling: fixed voltage type,

1.0A.

Second Stage Heating: adjustable, 0.10 to 1.2A; other

models, fixed voltage type, 1.0A.

TEMPERATURE SETTING RANGE: 42°F to 88°F (6°C to

31°C).

Fig.

No. Contains Replaces Honeywell Replaces Carrier

Q674L1892

Q674J1274

Q674L1900

Q674J1282

Y507J1011 T874G1055

Y507J1003 T874G1055

Q674L1041

Q674J1035

— T874J1002

Q674L1074 or
Q674L1637

— T874J1002

Q674J1068 or
Q674J1159

Package

INSTALLATION INSTRUCTIONS

Subbase Ratings

SWITCH RATING: 7.5A inrush, 2.5A running at 30 Vac.
MOUNTING: Designed for mounting on wall or horizontal

outlet box.

Changeover

Mode

99TZ90041106 HH07AT171

99TZ90040106 HH07AT171

— HH07AT175

— HH07AT175

HH93AZ175

HH93AZ173

HH93AZ186 or
HH93AZ195

HH93AZ183 or
HH93AZ196

OPERATION

The two stages of heat are energized sequentially with
changes in temperature. Stage one comes on first; then if
the temperature at the thermostat continues to move away
from the setpoint, the second stage comes on. The
thermostat is set with about 2°F (1°C) between stages. As
the heating equipment runs and the temperature begins to
move back toward the set point, stage 2 goes off first, then
stage one.

Subbases include an LED (light emitting diode) indicator.
This indicator lights to show that the heat pump cannot
operate and the supplemental heat stage is providing all
heating. This condition can occur in two instances; when
the subbase system switch is set at SUPL. HT. and when
the heat pump compressor has malfunctioned.

The LEDs are not field replaceable.

Manual
changeover in
cooling

Auto
changeover in
cooling

Manual
changeover in
cooling

Auto
changeover in
heating

Copyright © 1995 Honeywell Inc. • • All Rights Reserved

X-XX UL

69-0920

Y594 (MULTISTAGE THERMOSTAT SUBBASE) PACKAGE

RECYCLING NOTICE

This control contains mercury in a sealed tube.
Do not place control in the trash at the end of its
useful life.

If this control is replacing a control that contains
mercury in a sealed tube, do not place your old
control in the trash.

Contact your local waste management authority for
instructions regarding recycling and the proper
disposal of this control, or of an old control
containing mercury in a sealed tube.

INSTALLATION

When Installing this Product…

 Read these instructions carefully. Failure to follow

them could damage the product or cause a hazard­ous condition.

 Check the ratings given in the instructions and on

the product to make sure the 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.

CAUTION

 Disconnect power supply to prevent electrical

shock or equipment damage.

 Run wires as close as possible to the sub-

base. To prevent interference with the
thermostat linkage, keep wire length to a
minimum. Push excess wire back into the
hole, and plug hole to prevent drafts from
affecting thermostat operation.

 Do not overtighten thermostat captive

mounting screws because damage to
subbase threads can result.

 Do not short across coil terminals on relay.

This may burn out the heat anticipator.

 Never install more than one wire per terminal

unless factory-supplied jumper with spade
terminal is used.

IMPORTANT

Thermostats are calibrated at the factory by using
subbases mounted at true level. Inaccurate sub­base leveling will cause thermostat control
deviation.

Location

Install the thermostat about 5 ft (1.5m) above the floor in
an area with good air circulation at average room
temperatures.

Do not mount the thermostat where it may be affected by:
— drafts, or dead spots (no air movement) behind doors,

in corners, and above or below shelves.

— hot or cold air from ducts.
— radiant heat from the sun, lights, or appliances.
— concealed pipes and chimneys.
— unheated or uncooled areas such as an outside wall

behind the thermostat.

Mounting and Wiring the Subbase

Disconnect power supply to prevent electrical shock or
equipment damage. All wiring must comply with local
electrical codes and ordinances. Follow equipment
manufacturer wiring instructions when available.

Mount the subbase on a wall or horizontal outlet box. To
mount it on a vertical outlet box, order Honeywell part no.
196393A Cover Plate Assembly, which includes an
adapter ring with two screws for vertical outlet box
mounting and a cover plate to cover marks on the wall.

To install subbase, proceed as follows:

 Prepare a hole for the thermostat wires at the

chosen location. Run wires to location.

 Pull about 6 in. (152 mm) of wire through the hole.

IMPORTANT

Use 18 gauge, color-coded thermostat cable for
proper wiring.

 If mounting the subbase on a vertical outlet box,

install adapter ring with the two screws provided in
the assembly. See Fig. 1.

 Pull wire through cover plate, if used, and subbase

wire opening. Secure the cover plate and subbase
with the two screws provided, but do not tighten
down.

 Level the subbase using a spirit level. See Fig. 2.

Tighten subbase mounting screws. The subbase
mounting slots provide for minor out-of-level
adjustments.

IMPORTANT

An incorrectly leveled subbase will cause the
temperature control to deviate from setpoint

 Connect the system wires to the subbase. See

Fig. 4-7. A letter is stamped near each terminal for
identification. The terminal barrier permits straight or
conventional wraparound wiring connections. See
Fig. 3. Either method is acceptable. Run wires as
close as possible to the subbase, keeping wire
length to a minimum. Push excess wire back into
hole. Plug hole to prevent drafts.

Mounting the Thermostat

 Remove the thermostat cover by pulling the bottom

edge of the cover away from the base until it snaps
free of the retaining posts.

NOTE: The cover is hinged at the top and must be

removed by pulling out at the bottom.

 Carefully remove and discard the polystyrene

packing insert that protects the mercury switches
during shipment.

 Turn the thermostat over and locate the spring

fingers that engage the subbase contacts. Make
sure the spring fingers are NOT bent flat, preventing
proper electrical contact with the subbase.

 Set adjustable heat anticipator indicators, if

provided, as described in Setting the Heat
Anticipator(s) section.

69-0920

2

Y594 (MULTISTAGE THERMOSTAT SUBBASE) PACKAGE

VERTICAL
OUTLET
BOX

1
HORIZONTAL
OUTLET
BOX

SUBBASE

SUBBASE
MOUNTING SCREWS (2)

CAPTIVE
MOUNTING SCREWS (2)

1 NOT INCLUDED WITH UNIT.

2 ACCESSORY PARTS AVAILABLE (193121A).

Fig. 1. Installation of subbases and thermostat on

SPIRIT LEVEL

TOP
MOUNTING
HOLES (2)

outlet box.

1

6

0

5

T

A

E

H

WIRING
TERMINAL

MOUNTING
SCREWS (2)

ADAPTER
RING

0

8

0

7

0

2

THERMOSTAT

L

O

THERMOSTAT

O

C

0

8

0

COVER

7

0

0 6

5

50 60 70 80

THERMOSTAT
CABLE OPENING

COVER
PLATE

 Note the tabs along the top inside edge of the

thermostat base. The tabs fit into the subbase

2

notches. Mount the thermostat on the subbase and
tighten the captive mounting screws. See Fig. 1. Do
not overtighten captive mounting screws. This can
damage the threads in the subbase.

 Place the upper edge of the thermostat cover on the

base and swing cover downward until it engages
retaining posts on base. Tighten the locking cover
screws if assembly is provided.

SETTING

Setting the 2nd Stage (Y594G1666 and
Y594G1674 Only) Heat Anticipator

Set the adjustable heat anticipator to match its primary control
current draw. If the primary control nameplate has no rating or
if further adjustment is necessary, use the following procedure
to measure the current draw of each stage:

 Remove thermostat from the subbase. Make sure

the power is on.

 Connect an ac ammeter of appropriate range

between the heating terminals of the subbase:
Stage 2: between W2 and R.

 Move the system switch to HEAT or ON.
 After one minute, read the ammeter and record the

reading.

 Remount the thermostat and use a ballpoint pen to

M6009

set the adjustable heat anticipator(s) to match the
reading(s) measured in step 4. See Fig. 8.

Temperature Setting

Move the heating and cooling levers to the desired
positions. The minimum differential between heating and
cooling setpoints is 3°F (2°C). Some thermostat models
have nonadjustable lever stops, which set the maximum
heating control point at 68°F or 72°F (20°C or 22°C) and
the minimum cooling control point at 78°F (26°C). Do not
attempt to exceed these limits. Some models have only
one lever for heating and cooling.

MOUNTING
HOLES (2)

FOR STRAIGHT
INSERTION–
STRIP 5/16 in. (8 mm)

SUBBASE TERMINAL SCREW

POST (2) FOR
MOUNTING
THERMOSTAT

Fig. 2. Leveling the subbase.

FOR WRAPAROUND–
STRIP 7/16 in. (11 mm)

BARRIER

Fig. 3. Wiring connections.

TO SPRING FINGER
CONTACTS ON THE
THERMOSTAT
(UP TO 12)

M927

M928

Subbase Setting

Available subbase system switch positions vary by
thermostat model. Positions control thermostat operation
as follows:

OFF: Heating and cooling systems are off. If the fan

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

HEAT: Heating system is controlled by the thermostat.

Cooling system is off.

COOL: Cooling system is controlled by the thermostat.

Heating system is off.

ON: Thermostat automatically switches between heat

and cool modes, depending on the indoor tempera­ture.

SUPL. HT.: Supplemental heat is energized. Cooling

system is off. Compressor cannot operate.

Fan switching positions control fan operation as follows:

ON: Fan operates continuously.
AUTO: Fan operates with heat pump and supplemental

heat as controlled by the thermostat.

3

69-0920

Y594 (MULTISTAGE THERMOSTAT SUBBASE) PACKAGE

R

9

OFF
ON
SUPL.

HEAT

32

6

ON

SUPL. HEAT

FIELD WIRING CONNECTION

DENOTES CONNECTION POINT BETWEEN SUBBASE AND THERMOSTAT

THERMOSTAT SUBBASE

FALL

H1

H1 ANTICIPATOR

H2 ANTICIPATOR

H2

RISE

CO

C1

FALL

RISE

CO

2

4

5

6

8

9

C1 ANTICIPATOR

10

11

12

3

CO STAGE

H1

H2

FAN
SWITCH

AUTO

ON

SYSTEM
SWITCH

SUPL. HT.

ON

OFF

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

1

CO

C1

5

ON
FAN

AUTO

10 8

12

SUPL. HEAT

ON

G

Y

11

4

R

Y

G

W2

SUPL. HT.
LED (RED)

L

C

E

X

P

O

O

P

E

L

C

W2

X

SYSTEM COMPONENTS

L1

L2

(HOT)

1

COMPRESSOR CONTACTOR

FAN RELAY

HEAT RELAY 1

OUTDOOR
THERMOSTAT

HEAT RELAY
CONTACT 1

HEAT RELAY
CONTACT 2

"P" RELAY

HEAT RELAY 2

HEAT RELAY 3

COOL CHANGEOVER
VALVE

"X" RELAY

M4563

69-0920

Fig. 4. Y594J1019 Thermostat/Subbase switching and internal connections.

4

Y594 (MULTISTAGE THERMOSTAT SUBBASE) PACKAGE

R

C0

C1

9

COOL
OFF
HEAT

SUPL.
HEAT

HEAT

3

6

HEAT

SUPL. HEAT

FIELD WIRING CONNECTION

DENOTES CONNECTION POINT BETWEEN SUBBASE AND THERMOSTAT

THERMOSTAT SUBBASE

FALL

H1

2

3
H1
ANTICIPATOR

4

H2

C1 ANTICIPATOR

RISE

CO

ANTICIPATOR

5

6

8

9

10

11

12

FALL

H2

RISE

CO

C1

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

1

C0 STAGE

H1

H2

FAN
SWITCH

AUTO

SYSTEM
SWITCH

SUPL. HT.

HEAT

OFF

COOL

2

5

ON

10

COOL

SUPL. HEAT

FAN

8

12

11

HEAT

ON

AUTO

4

SUPL. HT.
LED (RED)

G

Y

O

P

E

L

C

W2

X

SYSTEM COMPONENTS

L1

L2

(HOT)

1

R

Y

G

2

W2

L

C

E

X

P

O

COMPRESSOR CONTACTOR

FAN RELAY

OUTDOOR
THERMOSTAT

HEAT RELAY
CONTACT 1

HEAT RELAY
CONTACT 2 HEAT RELAY 3

"P" RELAY

HEAT RELAY 1

HEAT RELAY 2

"X" RELAY

COOL
CHANGEOVER VALVE

M4564

Fig. 5. Y594J1001 Thermostat/Subbase switching and internal connections.

5

69-0920

Y594 (MULTISTAGE THERMOSTAT SUBBASE) PACKAGE

RISE

FALL

R

OFF
ON

SUPL. HEAT

4

ON

SUPL. HEAT

FIELD WIRING CONNECTION

DENOTES CONNECTION POINT BETWEEN SUBBASE AND THERMOSTAT

H1 ANTICIPATOR

H1

FALL

H2

H2 ANTICIPATOR

CO

RISE

C1 ANTICIPATOR

C1

1

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

ON
FAN

2

AUTO

ON

SUPL. HEAT

6

8

L

SUPL. HT.
LED (RED)

9

1

COOL CHANGEOVER VALVE

O

G

R

W

E

L

C

Y

C1

CO

10

H1

H2

SUPL. HEAT

1

FAN
SWITCH

AUTO

SYSTEM
SWITCH

SUPL. HT.

ON

OFF

ON

2

N.O. SWITCH – INSTALLER ADDED, TO LIGHT EM. HT. LED
WHEN COMPRESSOR OPERATION IS NOT NORMAL.

2

4

6

8

9

10

G

Y

O

E

W2

C

SYSTEM COMPONENTSSUBBASETHERMOSTAT

1

L1
(HOT)

L2

FAN RELAY

OUTDOOR

2

2

THERMOSTAT

EM. HT. RELAY
CONTACT 1

EM. HT. RELAY
CONTACT 2

EM. HT. RELAY 1

EM. HT. RELAY 2

EM.HT.
RELAY 3

COMPRESSOR
CONTACTOR 1

M4565

69-0920

Fig. 6. Y594G1674 Thermostat/Subbase switching and internal connections.

6

Y594 (MULTISTAGE THERMOSTAT SUBBASE) PACKAGE

FALL

RISE

R

COOL
OFF
HEAT

SUPL. HEAT

4

HEAT

SUPL. HEAT

FIELD WIRING CONNECTION

DENOTES CONNECTION POINT BETWEEN SUBBASE AND THERMOSTAT

H1 ANTICIPATOR

H1

FALL

H2

H2 ANTICIPATOR

CO

C1 ANTICIPATOR

RISE

C1

1

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

10

1

2

4

6

8

9

10

CO

H1

H2

SUPL. HEAT

C1

SUPL. HT.

ON
FAN

AUTO

8

9

HEAT

2

SUPL. HEAT

FAN
SWITCH

AUTO

ON

SYSTEM
SWITCH

HEAT

OFF

COOL

2

N.O. SWITCH – INSTALLER ADDED, TO LIGHT EM. HT. LED
WHEN COMPRESSOR OPERATION IS NOT NORMAL.

L

SUPL. HT.
LED (RED)

1

6

G

Y

O

E

W2

C

SYSTEM COMPONENTSSUBBASETHERMOSTAT

COOL CHANGEOVER VALVE

O

G

R

OUTDOOR

W

2

E

2

L

C

Y

THERMOSTAT

HEAT RELAY
CONTACT 1

HEAT RELAY
CONTACT 2

COMPRESSOR
FAULT

L1
(HOT)

L2

FAN RELAY

HEAT RELAY 1

HEAT RELAY 2

HEAT RELAY 3

COMPRESSOR
CONTACTOR 1

1

M4566

Fig. 7. Y594G1666 Thermostat/Subbase switching and internal connections.

7

69-0920

Y594 (MULTISTAGE THERMOSTAT SUBBASE) PACKAGE

LED Indication

Set system switch on subbase at SUPL. HT. The SUPL.
HT. LED should light. Simulate compressor failure and
energize the system. The FAULT LED should light.

0

.1

.12

.15

.2

.3

.4

1.2

.8

STAGE TWO
ANTICIPATOR
HEATING CONTROL

.6

MOVE INDICATOR TO
MATCH CURRENT RATING
OF PRIMARY CONTROL

M4550

Fig. 8. Adjustable heat anticipator shown.

To switch positions, use thumb and index finger to slide
lever to desired position. Switch lever must stop in detent
directly over the desired function indicator mark for proper
system operation.

CHECKOUT

Heating

Set the system switch on the subbase at HEAT or ON and
the fan switch at AUTO. Move the heating lever on the
thermostat about 10°F (6°C) above room temperature.
Heating (both stages if two-stage thermostat) should start
if there is no time delay or outdoor temperature limiting
system, and the fan should come on. Move the heating
lever about 10°F (6°C) below room temperature. Heating
and fan should shut off.

Cooling

CAUTION

Do not operate cooling if outdoor temperature is
below 50°F (10°C). Refer to manufacturer recom­mendations.

Set the system switch on the subbase to COOL or ON and
the fan switch to AUTO. Move the cooling lever on the
thermostat about 10°F (6°C) below room temperature.
Cooling and fan should start. Move the cooling lever about
10°F (6°C) above room temperature. Cooling and fan
should stop.

CALIBRATION

Thermostat

These thermostats are accurately calibrated at the factory.

They do not

Thermometer

The thermometer in your thermostat has been accurately
calibrated at the factory. The thermometer should only
adjustment if it has been dropped or shifted due to
mishandling.

If the setpoint lever and the thermometer reading do not
agree, use the following procedure:

have provision for field calibration

 Remove the thermostat cover by 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 readings. Be careful
not the touch the thermometer or breathe on it.

 If the readings are the same, replace cover and put

the system into operation.

 If the readings are different, insert a small screw-

driver in the thermometer slot and turn it until the
thermometers have the same reading. See Fig. 9.

 Replace thermostat cover and put the system into

operation.

.

Fan

Set the fan switch to ON. Move the system switch to
different positions; the fan should run continuously. Move
the fan switch to AUTO. Move the system switch to
different positions. Fan operation is controlled with the
heating or cooling system.

Home and Building Control

Honeywell International, Inc.
1985 Douglas Drive North
Golden Valley, MN 55422

69-0920

J.H. 5-95 www.honeywell.com/yourhome

Home and Building Control

Honeywell Limited-Honeywell Limitée
35 Dynamic Drive
Scarborough, Ontario
M1V 4Z9

M5070

Fig. 9. Thermometer calibration.

8