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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8112
Fig. 75. Schematic and hookup of T874A with Q674C. Used in standard applications.
Fig. 76. Schematic and hookup of T874A-D with Q674C. Used in standard applications.
C1
RISE
L1
(HOT)
L2
1
3
H1
FALL
2
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
SYSTEM SWITCH
OFF
AUTO
FAN SWITCH
AUTO
ON
HEAT RELAY
FILTER LED
(YELLOW)
SERVICE
LED (RED)
FAN RELAY
W1
X
A
G
R
O
O
Y
T
T
12
11
10
9
8
4
1
H1
ANTICIPATOR
THERMISTOR
C1
ANTICIPATOR
EXTERNAL
TEMP.
READOUT
COMPRESSOR CONTACTOR
MOMENTARY
CIRCUIT
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
MOMENTARY POSITION. SPRING RETURN TO "ON" UPON SWITCH RELEASE.
FILTER LED ON SELECT MODELS.
1
2
3
M5731
Y1
RC
1
M7025
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
B
Y2
W2
RH
X
H1 ANTICIPATOR
H2 ANTICIPATOR
C1
RISE
H1
FALL
FALL
H2
C2
RISE
C2 ANTICIPATOR
C1 ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
FOR T874C, DELETE C2.
O
A
1
6
9
10
11
4
8
AUTO
ON
FAN
SWITCH
SYSTEM
SWITCH
OFF
HEAT CHANGEOVER
VALVE
HEAT RELAY 1
COMPRESSOR
CONTACTOR 1
HEAT RELAY 2
L1
(HOT)
L2
1
COMPRESSOR
CONTACTOR 2
AUTO
FILTER
LED (YEL)
SERVICE
LED (RED)
W1
G
L1
(HOT)
1
L2
COOL CHANGEOVER
VALVE
FAN RELAY
FILTER LED ON SELECT MODELS.
2
3
3
2