Honeywell Q674F User Manual

T874G,R Multistage Heat Pump Thermostats

and Q674F,J,L Subbases

INSTALLATION INSTRUCTIONS

APPLICATION

The T874G,R Thermostats with Q674F,J,L Subbases provide 24 to 30 Vac control of a two-stage heating/one-

Table 1. Thermostat/Subbase Specifications.

Thermostat/Subbase System Fan Changeover

T874G/Q674F OFF-EM.HT.-HEAT-AUTO-COOL AUTO-ON Auto and Manual T874G/Q674J EM.HT.-AUTO-OFF AUTO-ON Auto T874R/Q674L EM.HT.-HEAT-OFF-COOL AUTO-ON Manual

stage cooling heat pump system. See Table 1 for thermostat/subbase specifications.

Switching

OPERATION

On a two-heat thermostat, the two stages of heat sequentially as the temperature drops. mercury switch initiating a call for heat or cool.

There are about 2°F (1°C) between stages so that the second stage makes only when the first stage cannot handle the load. This is the

LEDs (light emitting diodes) are included on your subbase. Refer to the list below for specific meaning.

The CHECK LED lights when something needs to be checked or done to maintain efficient operation of the system. See your heating system instructions for the specific meaning.

The SYSTEM LED lights when the system is calling for heating or cooling.

The AUX. HT. LED lights when the auxiliary heat (second stage) is operating. Auxiliary heat operates when the heat pump alone cannot handle the load.

The EM. HT. LED lights when the system switch is placed in the EM. HT. position. Emergency heat is operating; in most systems, the compressor has failed and the heat pump is not operating.

LEDs are not field replaceable or addable.

interstage differential

Make

make

refers to the

RECYCLING NOTICE

This control contains mercury in a sealed tube. Do not place the 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 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.

not

place your old

INSTALLATION

When Installing this Product…

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

2. Check the ratings given in the instructions and on the product to make sure the product is suitable for your application.

3. Installer must be a trained, experienced service technician.

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

X-XX UL

69-0268-11

T874G,R MULTISTAGE HEAT PUMP THERMOSTATS AND Q674F,J,L SUBBASES

쐃 If you must mount the subbase on a vertical outlet

CAUTION

1. Disconnect power supply to prevent electrical shock or equipment damage.

2. Run wires as close as possible to the subbase. To prevent interference with the thermostat linkage, keep wire length to a minimum. Push excess wire back into the hole and plug the hole to prevent drafts from affecting the thermostat operation.

3. Do not overtighten the thermostat captive mounting screws because damage to the subbase threads can result.

4. Do not short across coil terminals on relay; this can burn out the heat anticipator.

Location

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

Do not install the thermostat where it can be affected by: — drafts, or dead spots behind doors and in corners. — hot or cold air from ducts. — radiant heat from sun or appliances. — concealed pipes and chimneys. — unheated (uncooled) areas such as an outside wall

behind the thermostat.

box, order part no. 193121A Adapter Assembly. See Fig. 1. The assembly includes an adapter ring, two screws, and a cover plate to cover marks on the wall. Install the ring and cover plate on the vertical outlet box.

For a wall installation, hold the subbase in position and mark holes for the anchors. See Fig. 2. Obtain wall anchors locally. Take care that the wires do not fall back into the wall opening. Set aside the subbase. Drill four 3/16 in. (5 mm) holes and gently tap anchors into the holes until flush with the wall.

WIRES THROUGH WALL OPENING

WALL ANCHORS (2)

WALL

MOUNTING HOLES

Mounting the Subbase

The thermostat subbase can be mounted on a vertical outlet box, horizontal outlet box, or directly on the wall.

VERTICAL OUTLET

BOX

ADAPTER RING

MOUNTING SCREWS (2)

SUBBASE

HORIZONTAL OUTLET

BOX

NOT INCLUDED WITH UNIT.

ACCESSORY PARTS AVAILABLE (193121A).

SUBBASE

COVER PLATE

MOUNTING SCREWS (2)

Fig. 1. Installation of subbase on outlet box.

M925

M926

SUBBASE

MOUNTING SCREWS (2)

Fig. 2. Installation of subbase on wall.

쐇 Pull wires through the cover plate (if used) and

subbase cable opening. See Fig. 12.

쐋 Secure the cover plate (if used) and subbase with

the screws provided. Do not fully tighten the subbase screws.

쐏 Level the subbase using a spirit level, as shown in

Fig. 11, and firmly tighten the subbase mounting screws. The subbase mounting holes provide for minor out-of-level adjustments.

IMPORTANT

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

Wiring the Subbase

All wiring must comply with local electrical codes and ordinances. Follow the equipment manufacturer wiring instructions when available. To wire the subbase, proceed as follows:

쐃 Connect system wires to the subbase. See Fig. 3

through 11. A letter code is located near each terminal for identification. The terminal barrier permits straight or conventional wraparound wiring connection (Fig. 13).

쐇 Firmly tighten each terminal screw. 쐋 Fit wires as close as possible to the subbase. Push

excess wire back into the hole.

쐏 Plug the hole with nonflammable insulation to

prevent drafts from affecting the thermostat.

69-0268—11

T874G,R MULTISTAGE HEAT PUMP THERMOSTATS AND Q674F,J,L SUBBASES

THERMOSTAT SUBBASE SYSTEM COMPONENTS

FALL

RISE

H1 ANTICIPATOR

H2 ANTICIPATOR

FALL

C1 ANTICIPATOR

RISE

FAN SWITCH

AUTO

SYSTEM SWITCH

OFF

EM. HT.

HEAT

AUTO

COOL

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND

OVERLOAD PROTECTION AS REQUIRED.

TERMINAL LABELED C/X ON SOME MODELS.

W3 TERMINAL ON SOME MODELS ONLY.

COOL CHANGEOVER VALVE

EM. HT. LED (RED)

AUX. HT. LED (GREEN)

B RELAY

AUX HT. RELAY

EM. HT. RELAY

AUX. HT. RELAY

FAN RELAY

COMPRESSOR CONTACTOR

M5986A

L1 (HOT)

Fig. 3. Internal schematic and typical hookup for T874G/Q674F in heat pump system. Includes AUX. HT. and EM.

HT. LEDs.

69-0268—11

T874G,R MULTISTAGE HEAT PUMP THERMOSTATS AND Q674F,J,L SUBBASES

THERMOSTAT

ANTICIPATOR

FALL

H2 ANTICIPATOR

RISE

C1 ANTICIPATOR

RISE

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

REMOVE JUMPER FOR INDEPENDENT CONTROL OF W1 AND E TERMINALS.

Fig. 4. Internal schematic and typical hookup for T874G/Q674J in heat pump system. Includes AUX. HT., CHECK

SUBBASE

FAN SWITCH

AUTO

SYSTEM SWITCH

EM. HT.

AUTO

OFF

and SYSTEM LEDs.

AUX. HT. LED (YELLOW)

SYSTEM LED (GREEN)

CHECK LED (RED)

FAN RELAY

COMPRESSOR CONTACTOR

SYSTEM COMPONENTS

COOL CHANGEOVER VALVE

HPS

L1 (HOT)

SEQ 2

SEQ 1

EM. HT. RELAY

M1629

69-0268—11

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