Honeywell T874 - Page 175

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
175 60-2485—8
Fig. 168. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
H1
FALL
C
L1
(HO
T)
L2
1
EM. HT.
LED (RED)
AUX. HT.
LED (GRN)
W3
O
L
G
R
W2
E
X
X2
B
W1
Y
AUX. HT. RELAY
EM. HT. RELAY
HEAT
CHANGEOVER
VALVE
W1 RELAY
COMPRESSOR
RELAY
W3 RELAY
COOL CHANGEOVER
VALVE
COMPRESSOR
MONITOR
FAN RELAY
H2
FALL
H1
ANTICIPATOR
C ANTICIPATOR
H2
ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
REMOVE JUMPER WHEN W1 RELAY IS USED.
FACTORY-INSTALLED JUMPER.
1
M5067
FAN
SWITCH
AUTO
ON
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
3
2
2
3
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
1
2
3
4
5
6
11