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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8166
Fig. 156. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
Fig. 157. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
COMPRESSOR
FAILURE
H1
FALL
H2
FALL
L1
(HOT)
L2
1
CO
RISE
H1
ANTICIPATOR
1
2
4
6
9
8
C1
RISE
OFF
EM. HT.
SYSTEM
SWITCH
FAN
SWITCH
10
C1 ANTICIPATOR
H2 ANTICIPATOR
HEAT
AUTO
COOL
ON
ON
EM. HT. LED
(RED)
L1
E
AUX. HT.
RELAY
CONTACT
EM. HT.
RELAY
R
G
O
COOL
CHANGEOVER VALVE
FAN RELAY
OUTDOOR
THERMOSTAT
EM. HT. LED
(GREEN)
X
AUX. HT. RELAY
COMPRESSOR CONTACTOR
W2
Y
M5720
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
SYSTEM COMPONENTSSUBBASETHERMOSTAT
L2
1
COMPRESSOR
CONTACTOR
H2 ANTICIPATOR
M2860
AUTO
ON
FAN SWITCH
W1
C1
E
W2
H1 ANTICIPATOR
C1 ANTICIPATOR
CO
RISE
C1
FALL
H2
FALL
H1
R
X
Y1
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
AUTO
G
TIME DELAY
RELAY 2
FAN RELAY
COOL CHANGEOVER
VALVE
LOCKOUT
RELAY
HI PRESSURE
SWITCH
EM. HT.
LED (RED)
CHECK LED
(GREEN)
TIME DELAY
RELAY 1
DEFROST
RELAY
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
L1
(HOT)
RISE
2
3
4
6
8
9
10
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS