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Mounting C815A Thermistor (T874W only)
The T874W is used with the C815A Thermistor mounted in
the outdoor section. Locate it in an area where it can
measure the true outdoor ambient temperature. Avoid
mounting the C815A in an area where it is exposed to high
temperatures or direct sunlight. Refer to heat pump
equipment instructions for proper mounting.
THERMOSTAT
FALL
RISE
C1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
1
AND OVERLOAD PROTECTION AS REQUIRED.
2
SERVICE LED ON SELECT MODELS.
THERMOSTAT
H1 ANTICIPATOR
H1
FALL
RISE
CO
C1 ANTICIPATOR
RISE
C1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
Fig. 5. T874H/Q674C in heating-cooling system with SERVICE LED and FILTER LED.
T874H,Q,W MULTISTAGE THERMOSTATS AND Q674B,C,G,L SUBBASES
2
H1
ANTICIPATOR
3
H1
FAN SWITCH
4
AUTO
ON
SYSTEM
8
SWITCH
9
AUTO
C1
ANTICIPATOR
CO
10
RISE
Fig. 4. T874H/Q674C in heating-cooling system.
2
FAN SWITCH
3
AUTO
ON
4
8
9
SYSTEM
SWITCH
OFF
10
AUTO
FOR STRAIGHT
INSERTION–
STRIP 5/16 in. (8 mm)
SUBBASE
Y1
G
R
Y2
OFF
B
O
2
X
SERVICE LED
(YELLOW)
C
SUBBASE
SERVICE
LED (YELLOW)
FILTER LED (RED)
3
BARRIER
SUBBASE TERMINAL SCREW
Fig. 3. Wiring connections.
SYSTEM COMPONENTS
COOL CHANGEOVER
VALVE
FAN RELAY
COMPRESSOR
CONTACTOR
1
L2
L1
(HOT)
COMPRESSOR
FAULT
SYSTEM COMPONENTS
Y1
COOL CHANGEOVER
VALVE
G
FAN RELAY
R
COMPRESSOR
CONTACTOR
Y2
B
O
X
X1
C
24 VAC
X2
FOR WRAPAROUND–
STRIP 7/16 in. (11 mm)
M928
M3680A
1
L2
L1
(HOT)
M5902
69-0087—6
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