T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
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Fig. 112. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
OFF
COOL
COMPRESSOR
FAILURE
FAN
SWITCH
ON
SYSTEM
SWITCH
1POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M8383
AUX. HT. RELAY
4
EM. HT. LED
(RED)
AUX. HT. LED
(GREEN)
EM. HT.
HEAT
COOL CHANGEOVER
VALVE
FAN RELAY
EM. HT. RELAY
AUTO
Y
C1
H1
FALL
H1/C1
ANTICIPATOR
H2
ANTICIPATOR
H2 FALL
COMPRESSOR
CONTACTOR
6
O
5
R
W2
L1
(HOT)
L2
1
G
2
3
E
X
L1
THERMOSTAT SUBBASE SYSTEM COMPONENTS