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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8134
Fig. 113. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
H2
H1
FALL
C1
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1/C1
ANTICIPATOR
FALL
H2 ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
HEAT
EM. HT.
LED (RED)
EM. HT.
COOL
EM. HT. RELAY
EM. HT. RELAY
EM. HT. RELAY
DEFROST RELAY
DEFROST
RELAY
FAN RELAY
M4720
COMPRESSOR
CONTACTOR
HIGH
PRESSURE
SWITCH
COOL CHANGEOVER
VALVE
LOW AMBIENT
CUTOFF
O
Y
G
E
X1
X2
L
CHECK LED
(GREEN)
OPTIONAL COMP.
FAILURE DEVICE
B
W2
W3
R
HEAT
CONTRACTOR 3
HEAT
CONTRACTOR 2
OUTDOOR
THERMOSTAT
HEAT
CONTRACTOR 1
HIGH LIMIT
SWITCH
REVERSING
VALVE
1
2
3
4
5
6
7