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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
179 60-2485—8
Fig. 173. Schematic and hookup of T874H with Q674C. Used in heat pump applications.
Fig. 174. Schematic and hookup of T874G with Q674J. Used in heat pump applications.
H1
FALL
CO
RISE
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1 ANTICIPATOR
C1 ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
AUTO
COOL
CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
M1400
FAULT
LED
(RED)
CHECK
FILTER
LED (YELLOW)
FAN RELAY
12
11
10
9
8
4
3
2
G
R
O
2
C
3
Y
RISE
C1
H1
FALL
H2
FALL
C1
RISE
C2
RISE
L1
(HOT)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
REMOVABLE JUMPER.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
HA
CA
ODA
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
EM. HT.
AUTO
EM.. HT. RELAY
AUX. HT. RELAY
M1403
1
2
3
4
5
6
8
9
10
X2
G
T
R
F
W
U
B
O
Y
COMPRESSOR
CONTACTOR
COOL CHANGEOVER
VALVE
"F" RELAY
C815A
OUTDOOR
THERMISTOR
FAN RELAY
EM. HT.
LED (RED)
AUX. HT.
LED (GREEN)