69-0268—11
3
T874G,R MULTISTAGE HEAT PUMP THERMOSTATS AND Q674F,J,L SUBBASES
H1
FALL
RISE
CO
L1
(HOT)
L2
1
3
C1
RISE 1
2
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
TERMINAL LABELED C/X ON SOME MODELS.
W3 TERMINAL ON SOME MODELS ONLY.
C1 ANTICIPATOR
H1 ANTICIPATOR FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
AUTO
HEAT
OFF
COOL
1
2
4
6
8
9
10
O
W2
X
E
L
B
W3
R
G
Y
AUX. HT. RELAY
FAN RELAY
EM. HT. RELAY
B RELAY
M5986A
THERMOSTAT SUBBASE SYSTEM COMPONENTS
11
12
COMPRESSOR
CONTACTOR
EM. HT.
EM. HT.
LED (RED)
AUX. HT.
LED (GREEN)
COOL CHANGEOVER
VALVE
H2
FALL
H2
ANTICIPATOR
AUX HT. RELAY
Fig. 3. Internal schematic and typical hookup for T874G/Q674F in heat pump system. Includes AUX. HT. and EM.HT. LEDs.