Honeywell T874 - Page 174

T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8 174
Fig. 167. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
M1592A
(HOT) L1
L2
1
LACO
CHP
Y
B
E
G
L
X
W2
R
ODT 1
RTD 1 EHR 1
RTD 2
ODT 2
EHR 2 RTD 3
RD
COMPRESSOR
FAILURE
FAN RELAY
COMPRESSOR
CONTACTOR
HEAT
CHANGEOVER
VALVE
EM. HT.
RELAY
RTD 1
AUX. HT.
LED (GREEN)
EM. HT.
LED (RED)
FAN SWITCH
ON
AUTO
SYSTEM
SWITCH
EM. HT.
HEAT
AUTO
OFF
COOL
H2
FALL
H1
FALL
2
3
4
5
H1 ANTICIPATOR
H2
ANTICIPATOR
C1
RISE
FALL
7
8
9
10
C1
ANTICIPATOR
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
EHT1
CHANGEOVER