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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
217 60-2485—8
Fig. 237. Schematic and hookup of T874C with Q674B. Used in standard applications.
Fig. 238. Schematic and hookup of T874C with Q674F. Used in heat pump applications.
H1
H2
FALL
G
B
R
FAN RELAY
OFF
COOL
SYSTEM
SWITCH
H2 ANTICIPATOR
H1 ANTICIPATOR
C1 ANTICIPATOR
AUTO
ON
FAN SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
M7716
THERMOSTAT
SUBBASE
SYSTEM COMPONENT
S
3
4
6
8
10
FALL
RISE
C1
L1
(HOT)
L2
1
2
1
Y
COMPRESSOR
CONTACTOR
W1
W2
HEAT 1
HEAT 2
HEAT
5
LOW LED
(YELLOW)
HI LED
(GREEN)
H1
FALL
L1
(HOT
)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
FACTORY INSTALLED JUMPER BETWEEN TERMINALS W1 AND Y1.
H1
ANTICIPATOR
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
OFF
COOL
2
4
6
X
O
C
W1
W2
B
R
G
Y1
COOL
CHANGEOVER
VALVE
FAN RELAY
AUX. HT.
RELAY
HEAT PUMP
RELAY
M7719
C1
ANTICIPATOR
B RELAY
THERMOSTAT SUBBASE SYSTEM COMPONENTS
COMPRESSOR
CONTACTOR
AUX. HT.
LED (RED)
H2
RISE
C1
FALL
H2
ANTICIPATOR
1
8
10
2 STAGE HT.
HT. PUMP
AUX. HT.
CHECK
LED (RED)