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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8220
Fig. 243. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
Fig. 244. Schematic and hookup of T874J with Q674J. Used in heat pump applications.
H1
FALL
RISE
CO
L1
(HOT)
L2
1
C1
RISE
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
TERMINAL LABELED C/X ON SOME MODELS.
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
R
G
Y
AUX. HEAT RELAY
FAN RELAY
EM. HT. RELAY
B RELAY
M7715
THERMOSTAT SUBBASE SYSTEM COMPONENTS
11
12
COMPRESSOR
CONTACTOR
EM. HT.
EM. HT.
LED (RED)
AUX. HEAT
LED (GREEN)
COOL CHANGEOVER
VALVE
H2
FALL
H2
ANTICIPATOR
RISE
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
ON
OFF
2
3
4
5
6
8
9
10
11
12
R
X
E
L
C
G
W2
Y
P
O
FAN RELAY
HEAT
CHANGEOVER
VALVE NO. 1
HEAT
CHANGEOVER
VALVE NO. 1
HEAT
CHANGEOVER
VALVE NO. 2
HEAT
CHANGEOVER
VALVE NO. 2
HEAT
CHANGEOVER
VALVE NO. 3
M7743
THERMOSTAT SUBBASE SYSTEM COMPONENTS
COOL CHANGEOVER
VALVE
SUPL. HT.
CO
H1
H2
FALL
FALL
CO
C1
RISE
COMPRESSOR
CONTACTOR
P RELAY
X RELAY
O.D.T.
SUPL. HEAT
LED (RED)
H1
ANTICIPATOR
H2
ANTICIPATOR
C1
ANTICIPATOR