IMPORTANT
The specifications given in this publication do not include normal manufacturing tolerances; therefore, an individual unit might not exactly match the listed specifications. Also, this product is tested and calibrated under closely controlled conditions, and some minor differences in performance can be expected if those conditions are changed.
Models:
T8775A and T8775C TRADELINE® models include a thermostat, wallplate for mounting and wiring, mounting hardware, 4074FAB resistor, installation instructions and an owner’s guide.
Electrical Ratings:
24 Vac nominal: 18 Vac to 30 Vac, 60Hz.
Heating: .02 to 1.5 A run; 3.5A inrush.
Cooling: .02 to 1.5 A run; 6.0 A inrush.
Fan: .02 to 0.5 A run; 2.5A inrush.
Temperature Ratings:
Setting Range:
40°F to 90°F (4.5°C to 32.0°C) in heating.
45°F to 99°F (7.0°C to 37.0°C) in cooling.
Ambient Range:
40°F to 110°F (4.4°C to 43.3°C).
Shipping Temperature Range:
-20°F to 120°F (-28.9°C to 48.9°C).
Humidity Ratings: 5% to 90% RH, non-condensing.
Mounting Hardware:
Sheet metal screws: Two 1-in. (25 mm) 4-24, type AB. Drywall anchors: Two conical anchors, 3/16 in. (5 mm)
diameter by ¾ in. (19 mm) length.
4074 FAB Resistor:
1 Kohm, 3 Watts.
Installation Instructions packed with resistor.
Batteries: Not required.
Finish: Premier White®.
Accessories:
50000066-001 Decorative Cover Plate. Used to cover wall
marks, or to mount T8775 Thermostat to an electrical box. 32007680-001 Cover Ring.
Dimensions: See Fig. 1.
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the TRADELINE® Catalog or price sheets for the complete ordering number.
If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:
Separate Wallplate from Thermostat
Mount Wallplate to Wall
NOTE: Level wallplate for appearance only. The thermostat functions normally even when not mounted level.Mount wallplate to wall (See Fig. 4) as follows:
IMPORTANT
Use 18-gauge wire to wire the T8775A,C Thermostats.
All wiring must comply with local electrical codes and ordinances. Disconnect the power supply to prevent electrical shock or equipment damage.
NOTE: To ensure proper mounting of the thermostat, restrict all wiring to the shaded area. See Fig. 5.
The shape of the terminals permits insertion of straight or wraparound wiring connections; either method is acceptable. See Fig. 6.
Refer to Fig. 7 through 11 for typical wiring diagrams.
Setting Fuel Switch (T8775C only)
The fuel switch is preset at the factory in the F position. See Fig. 12. This is the correct setting for gas or oil systems. If the T8775C is being installed on an electric heat system, or a heat pump, set the switch to the E position. The E position allows the fan to turn on immediately with the heating equipment in a system where the G terminal is connected.
DIP Switch
To adjust the heat cycle rate or the Fahrenheit/Celsius temperature display, locate DIP switch 1, 2 and 3 on the back of the thermostat. See Fig. 13.
Set Heat Cycle Rate
Use DIP switches 1 and 2 to set the heat cycle rate. See Table 1.
Table 1. Heat Cycle Rate.
Heating System | Cycles Per Hour | DIP Switch 1 | DIP Switch 2 |
Steam, Gravity | 1 | On | On |
High Efficiency Warm Air (90%+ efficiency), Hot Water, Heat Pump | 3 | Off | On |
Gas or Oil Warm Air (factory setting) | 6 | Off | Off |
Electric Warm Air | 9 | On | Off |
In Floor Radiant Heat | Check with the manufacturer for recommended cycle rate. |
Fahrenheit/Celsius Indication
Use DIP switch 3 to set the desired temperature indication. See Table 2.
Table 2. Temperature Indication.
Fahrenheit/Celsius Display | DIP Switch 3 |
Fahrenheit (factory setting) | Off |
Celsius | On |
Mount Thermostat to Wallplate (see Fig. 14)
SYSTEM Switch: (See Fig.15)
Heat: The thermostat controls the heating system. Off: Both the heating and cooling systems are off. Cool: The thermostat controls the cooling system.
FAN Switch: (See Fig.15)
Auto: The fan only runs with the heating and cooling system.
On: The fan runs continuously. Use for improved air circulation.
Features and operation of The Digital RoundTM Thermostat (see Fig. 15 and 16):
Backlit Display
Push the backlight button to turn on the backlight (See Fig. 15).
Display Temperature Setpoint
Adjust Temperature Setpoint
Turn the dial clockwise to raise the temperature setpoint. Turn the dial counterclockwise to lower the temperature setpoint (see Fig. 16).
Power Stealing
The T8775 thermostat steals power from R and W or Rc and Y depending on the system switch position. See Table 3.
Table 3. T8775 Power Stealing.
Power Stealing Circuit | ||
System Switch | T8775A | T8775C |
Heat | R and W | R and W |
Off | — | R and W |
Cool | — | Rc and Y |
Table 4. The sequence of Operations.
Fan Switch Settings | System Switch Settings | Call for Action | Energize Terminals | Display Icons |
Auto | Off | None | None | None |
Auto | Heat | Heating | Wa | Flame |
Auto | Cool | Cooling | Y,G | Snowflake |
On | Off | Fan | G | None |
On | Heat | Heating | W,G | Flame |
On | Cool | Cooling | Y,G | Snowflake |
a If fuel switch is set to E, both W and G are energized in a call for heat.
Cooling (T8775C only)
CAUTION
Low-Temperature Hazard.
Operating at too low of an outdoor temperature may cause compressor damage.
Do not operate cooling if the outdoor temperature is below 50°F (10°C). Refer to the manufacturer’s recommendations.
Minimum Off-Timer
The minimum off-timer in the T8775C Thermostat assures that the cooling compressor does not turn on for at least five minutes after it turns off. The snowflake will flash in the display if there is a call for cooling during the 5-minute off-time.
The following activates the 5-minute minimum-off timer:
Heating
Fan
Automation and Control Solutions
Honeywell International Inc. 1985 Douglas Drive North Golden Valley, MN 55422
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Scarborough, Ontario M1V 4Z9
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