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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8100
Fig. 51. Schematic and hookup of T874D with Q674B. Used in standard applications.
Fig. 52. Schematic and hookup of T874C with Q674B. Used in standard applications.
C2
RISE
L1
(HOT)
L2
1
L1
(HOT)
L2
1
3
3
C1
RISE
H2
FALL
H1
FALL
M5944
H1 ANTICIPATOR
H2 ANTICIPATOR
C1 ANTICIPATOR
C2 ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER.
B, O TERMINALS ON SOME MODELS.
1
2
3
1
3
4
6
8
9
10
11
Y2
Y1
O
RH
B
W2
RC
G
W1
2
SYSTEM
SWITCH
HEAT
OFF
COOL
ON
AUTO
FAN
SWITCH
HEAT RELAY 1
FAN RELAY
HEAT RELAY 2
HEAT CHANGEOVER VALVE
COOL CHANGEOVER VALVE
COMPRESSOR CONTACTOR 1
COMPRESSOR CONTACTOR 2
THERMOSTAT SUBBASE
SYSTEM COMPONENTS
H1
FALL
H2
FALL
C1
RISE
L1
(HOT)
L2
1
2
3
1
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
OPTIONAL FIELD WIRE JUMPER. W3 AND F TO BE JUMPERED EXCEPT FOR TWO STAGE GAS APPLICATION.
FIELD WIRE JUMPER TO ALLOW SINGLE SYSTEM TRANSFORMER.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1 ANTICIPATOR
H2 ANTICIPATOR
C1 ANTICIPATOR
SYSTEM
SWITCH
HEAT
OFF
COOL
10
9
8
6
5
4
1
FAN SWITCH
AUTO
ON
HEAT RELAY 1
FAN RELAY
HEAT RELAY 2
W1
G
RC
W3
W2
F
RH
B
O
Y1
COMPRESSOR
CONTACTOR
M5999