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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8140
Fig. 119. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
Fig. 120. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
H1
FALL
C1
L1
(HOT)
L2
1
H2
FALL
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
H1 ANTICIPATOR
C1
ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
RESET
HEATER
H2 ANTICIPATOR
FAN SWITCH
AUTO
ON
C815A
OUTDOOR
THERMISTOR
AUX. HT. RELAY
FAN RELAY
SERVICE
EM. HT. RELAY
COMPRESSOR
CONTACTOR
HEAT CHANGEOVER
RELAY
12
6
5
4
3
2
1
T
W2
G
X
SERVICE LED
(YELLOW)
EM. HT.
LED (RED)
Z
K
Y
W1
R
11
1
THERMOSTAT SUBBASE
SYSTEM COMPONENTS
M5955
H2
FALL
H1
FALL
C1
L1
(HOT)
L2
1
FAN SWITCH
AUTO
ON
FAN RELAY
AUX. HT. RELAY
"H" RELAY
EM. HT. RELAY
CHANGEOVER VALVE (COOL)
COMPRESSOR
CONTACTOR
C815A1039
THERMISTOR
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
EM. HT.
LED (RED)
G
R
W
H
B
X
T
O
Y
12
11
6
5
4
3
2
H1/C1
ANTICIPATOR
H2
ANTICIPATOR
RESET HEATER
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
M3173B
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
1