Honeywell T874 - Page 204

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8 204
Fig. 218. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
L1
(HOT
)
L2
1
X
L
W2
EM. HT.
LED (RED)
AUX. HT.
LED (GRN)
AUX. HT.
RELAY
FAN RELAY
"B" RELAY
G
COOL CHANGEOVER
VALVE
EM. HT. RELAY
COMPRESSOR
CONTACTOR
O
Y
E
B
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H1/C1
ANTICIPATOR
C1
H1
FALL
H2
W3
AUX. HT.
RELAY
H2
ANTICIPATOR
1
2
3
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
TERMINAL LABELED C/X ON SOME MODELS.
W3 TERMINAL AVAILABLE ON SOME MODELS ONLY.
M3683A
AUTO
ON
FAN
SWITCH
FALL
R
2
3
4
6
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS