T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
165 60-24858
Fig. 155. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
H2
FALL
L1
(HOT)
L2 1
R
W3
W2
X
L
G
O
E
Y
RTD1 OTD1
EHR1
ODT2
EHR2
RTD2
RTD3
RTD1
SYSTEM
MONITOR
FAN
RELAY
RD
COOL
CHANGEOVER VALVE
EM. HT.
RELAY
LACO
COMPRESSOR
CONTACTOR CHP
2
3
4
5
6
8
9
10
H1 FALL
H1 ANTICIPATOR
H2
ANTICIPATOR
CHANGEOVER
RISE
C1
RISE
C1
ANTICIPATOR
OFF
COOL
AUTO
HEAT
EM. HT.
SYSTEM
SWITCH
AUTO
ON
FAN
SWITCH
AUX. HT.
LED (GRN)
EM. HT.
LED (RED)
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
W3 TERMINAL ON SELECT MODELS.
1
2
2
M1589
THERMOSTAT SUBBASE SYSTEM COMPONENTS