T8775A,C THE DIGITAL ROUND
™
69-1677EF—03
2
Wiring
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.
Refer to Fig. 2 through 6 for typical wiring
hookups.
Fig. 2. Typical hookup of T8775A in a heat-only
system.
Fig. 3. Typical hookup of T8775C in heat-only system
with fan.
Fig. 4. Typical hookup of T8775C in heat-cool
system with single transformer.
Fig. 5. Typical hookup of T8775C in heat-cool
system with two transformers.
Fig. 6. Typical hookup of T8775C in single-stage heat
pump system.
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
W
R
HEATING
RELAY OR
VALVE COIL
M19513
1
1
M19514
HEATING
RELAY OR
VALVE COIL
FAN
RELAY
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
2 FACTORY INSTALLED JUMPER.
1
2
W
R
Rc
B
O
Y
G
1
HEATING
RELAY OR
VALVE COIL
COMPRESSOR
CONTACTOR
FAN
RELAY
M19515
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
2 FACTORY INSTALLED JUMPER.
2
W
R
Rc
B
O
Y
G
1
2
1
HEATING
RELAY OR
VALVE COIL
COMPRESSOR
CONTACTOR
FAN
RELAY
M19517
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
REMOVE FACTORY INSTALLED JUMPER BETWEEN R AND RC.
2
W
R
Rc
B
Y
G
1
4
COMPRESSOR
CONTACTOR
HEAT
CHANGEOVER
VALVE
COOL
CHANGEOVER
VALVE
FAN
RELAY
M19516
1 POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
2 FACTORY
INSTALLED
JUMPER.
3 USE A JUMPER WIRE (NOT SUPPLIED) TO CONNECT W TO Y.
4 USE EITHER O OR B FOR HEAT PUMP CHANGEOVER.
3
2
W
R
Rc
B
O
Y
G
