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TRADELINE
Thermostats/Q674A-E,G Subbases
The T874A-F Thermostats provide 24 to 30 Vac control
for heating and/or cooling systems as listed in Table 1.
TABLE 1—THERMOSTAT HEATING AND/OR
COOLING STAGES.
T874
A
Heating Stages
1
Cooling Stages
1
The Q674A-E,G Subbases provide wiring terminals,
system and fan switching, and mounting bases for T874
Thermostats as listed in Table 2.
TABLE 2—SUBBASE SWITCHING POSITIONS.
Q674
Model
System
A
Heat-Auto-Cool
B
Heat-Off-Cool
C
Off-Auto
D
None
E
Off-Heat-Auto-Cool
G
Off-Auto
On a 2-heat thermostat, the two stages of heat make
sequentially as the temperature drops. Make refers to the
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 interstage differential.
M3375
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 mer-
cury 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 Instructions for the Trained Service Technician.
Application
B
C
D
E
1
2
2
—
2
1
2
2
Switch Positions
Fan
Auto-On
Auto-On
Auto-On
None
Auto-On
None
Operation
Recycling Notice
J.H. • Rev. 5-94 •
T874A-F Multistage
WHEN INSTALLING THIS PRODUCT...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous condi-
tion.
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
F
application.
3. Installer must be a trained, experienced service tech-
2
nician.
—
4. After installation is complete, check out product
operation as provided in these instructions.
CAUTION
1. Disconnect power supply to prevent electrical
shock or equipment damage.
2. To prevent interference with the thermostat
linkage, keep wire length to a minimum and
run wires close as possible to the subbase.
3. Do not overtighten thermostat captive mount-
ing screws because damage to subbase threads
can result.
4. Do not short across coil terminals on heating
relay or gas control. This can burn out the
thermostat heat anticipator.
IMPORTANT: Thermostats are calibrated at the factory
by using subbases mounted at true level. Inaccurate
subbase leveling will cause thermostat control de-
viation.
LOCATION
Locate the subbase about 5 ft [1.5m] above the floor in
an area with good air circulation at average temperature.
Do not mount the subbase where the thermostat may be
affected by:
— drafts or dead spots behind doors and in corners.
— hot or cold air from ducts.
— radiant heat from sun, appliances or fireplace.
— concealed pipes and chimneys.
— unheated (uncooled) areas such as an outside wall
behind the thermostat.
MOUNTING THE SUBBASE
The thermostat subbase can be mounted on a vertical
outlet box, horizontal outlet box or directly on the wall.
1. If you must mount the subbase on a vertical outlet
box, order Honeywell 193121A Adapter Assembly (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.
• ©Honeywell Inc. 1994 • Form Number 60-1165—6
1
M3375
Installation
60-1165—6
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Related Manuals for Honeywell Tradeline T874A-F
Summary of Contents for Honeywell Tradeline T874A-F
- Page 1 1. If you must mount the subbase on a vertical outlet instructions regarding recycling and the proper disposal of box, order Honeywell 193121A Adapter Assembly (Fig. 1). this control, or of an old control containing mercury in a The assembly includes an adapter ring, two screws and a sealed tube.
- Page 2 3. Secure the cover plate (if used) and subbase with the screws provided. Do not fully tighten the subbase screws. Fig. 1—Installation of subbase on outlet box. 4. Level the subbase using a spirit level, as shown in Fig. 3, and firmly tighten subbase mounting screws. The subbase mounting holes provide for minor out-of-level adjustments.
- Page 3 TABLE 3—JUMPER APPLICATIONS. Fig. 6—Jumper adjacent terminals for special If your subbase has: Application Use Fig. system hookup. Strip wire 3/4 in. [19 mm]. RC, RH terminals single transformer system adjacent terminals special system operation or LED nonadjacent indication terminals 3.
- Page 4 Fig. 8—T874A-D/Q674A in standard heating/cooling system. Fig. 9—T874C,D/Q674B in standard heating/cooling system with separate transformers for heating and cooling. SUBBASE SYSTEM COMPONENTS THERMOSTAT (HOT) HEAT RELAY 1 SWITCH HEAT RELAY 2 FALL AUTO H1 ANTICIPATOR HEAT CHANGEOVER VALVE FALL H2 ANTICIPATOR SYSTEM SWITCH COOL CHANGEOVER...
- Page 5 Fig. 10—T874D/Q674B in standard heating/cooling system with single transformer for heating and cooling. Exact replacement for York model no. 2TB04700324. Fig. 11—T874D,E,F/Q674C in standard heating/cooling system. 60-1165—6...
- Page 6 Fig. 12—T874A,D,F/Q674D in standard heating/cooling system. Fig. 13—T874D/Q674E in standard heating/cooling system. 60-1165—6...
- Page 7 Fig. 14—T874A-F/Q674G in standard heating/cooling system. Fig. 15—T874C/Q674B in standard application. 60-1165—6...
- Page 8 Fig. 16—Typical Q674 terminal designations. The thermostat and subbase used determines the number of system components controlled. TEMPERATURE LEVER STOPS INSTALL AND ADJUST LOCKING LEVER Some thermostats have factory-installed temperature SCREWS lever locking screws (Fig. 17) and/or stop brackets The two screws with insulated heads should be used (Fig.
-
Page 9: Mounting The Thermostat
9. Firmly tighten the mounting screw. MOUNTING THE THERMOSTAT 10. If the HEAT and COOL levers are to be locked in 1. Remove the thermostat cover by pulling the bottom place at a specific temperature, use the two insulated head edge of the cover upward until it snaps free of the cover clip. - Page 10 2. Move the system switch to AUTO or HEAT (if SUBBASE SETTING used). The subbase switching positions control the system 3. After one minute, read the ammeter and record the operation as described below (Fig. 23). reading: SYSTEM SWITCH (some subbases do not have all of Stage 1: __________ amperes.
- Page 11 NOTE: Hand heat will offset the thermometer reading. Calibration After making each adjustment, wait ten minutes for the thermometer to stabilize before comparing. THERMOSTAT T874 Thermostats are accurately calibrated at the factory. They do not have provision for field calibration. Fig.
- Page 12 Automation and Control Solutions Honeywell International Inc. Honeywell Limited—Honeywell Limitée 1985 Douglas Drive North 35 Dynamic Drive Golden Valley, MN 55422 Scarborough, Ontario M1V 4Z9 www.honeywell.com/yourhome 60-1165—6...