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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8218
Fig. 239. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
Fig. 240. Schematic and hookup of T874A with Q674W. Used in standard applications.
L1
(HOT)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
HEAT
OFF
COOL
2
3
5
11
R
O
X2
T
G
B
W
Y
M7744
THERMOSTAT SUBBASE SYSTEM COMPONENTS
EM. HT.
H1
H2
FALL
FALL
C1
H1
ANTICIPATOR
RESET
U
F
FAN RELAY
AUX. HT.
RELAY
OUTDOOR
THERMOSTAT
COOL
CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
OUTDOOR
SENSOR
COMPRESSOR
MONITOR
1
4
6
AUX. HT.
LED (GREEN)
EM. HT.
LED (RED)
FIELD REMOVABLE JUMPER.
L1
(HOT)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS
AND OVERLOAD PROTECTION AS REQUIRED.
FAN CONTINUOUS IN ON POSITION.
SYSTEM
OFF
ON
FAN
MED
MED
HI
HI
8
10
R
G2
G1
W1
B
Y1
M7745
THERMOSTAT SUBBASE SYSTEM COMPONENTS
LO
LO
H1
FALL
C1
RISE
C1
ANTICIPATOR
H1
ANTICIPATOR
HEAT
RELAY
K1 RELAY
K2 RELAY
COMPRESSOR
CONTACTOR
1
4
9
B RELAY
L2
L1
K1 K1
K2 K2 K2
3 SPEED FAN SCHEMATIC