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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
121 60-2485—8
Fig. 93. Schematic and hookup of T874D with Q674K. Used in standard applications.
Fig. 94. Schematic and hookup of T874D with Q674G. Used in standard applications.
H1
FALL
H2
FALL
C1
RISE
C2
RISE
L1
(HOT)
L2
L1
(HOT)
L2
1
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
NO FAN
SWITCH
SYSTEM
SWITCH
11
10
9
8
6
4
1
OFF
HEAT
AUTO
COOL
C2 ANTICIPATOR
C1 ANTICIPATOR
H2
ANTICIPATOR
H1 ANTICIPATOR
HEAT FAN RELAY
HEAT RELAY
COMPRESSOR
CONTACTOR 1
COMPRESSOR
CONTACTOR 2
W1
W2
RH
Y1
RC
Y2
M4664
W2
W1
RC
HEAT CHANGEOVER
VALVE
OFF
AUTO
SYSTEM
SWITCH
1
M7013
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
B
L1
(HOT)
L2
1
Y2
HEAT
RELAY 2
RH
X
A
Y1
COMPRESSOR
CONTACTOR 1
COMPRESSOR
CONTACTOR 2
L1
(HOT)
L2
1
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.
NO FAN
SWITCH
HEAT
RELAY 1
O
T
COOL CHANGEOVER
VALVE
"T" RELAY
1
6
9
10
11
FILTER
LED (YELLOW)
SERVICE
LED (RED)
4
8