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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
117 60-2485—8
Fig. 85. Schematic and hookup of T874A-D with Q674E. Used in standard applications.
Fig. 86. Schematic and hookup of T874G with Q674E. Used in heat pump applications.
H1
FALL
4
H1
ANTICIPATOR
W2
HEAT RELAY 2
L1
(HOT)
L2
1
COMPRESSOR
CONTACTOR 1
M5983
POWER SUPPLY. PROVIDE DISCONECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
1
SYSTEM COMPONENTSSUBBASETHERMOSTAT
FAN RELAY
H2
RISE
C1
RISE
C2
OFF
SYSTEM
SWITCH
FAN
SWITCH
HEAT
AUTO
COOL
ON
AUTO
R
Y1
W1
Y2
FALL
6
8
10
9
11
1
H2 ANTICIPATOR
C1
ANTICIPATOR
C2 ANTICIPATOR
HEAT RELAY 1
G
COMPRESSOR
CONTACTOR 2
H1
FALL
H2
FALL
CO
RISE
C1
RISE
L1
(HOT)
L2
1
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1 ANTICIPATOR
H2 ANTICIPATOR
C1 ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
HEAT
AUTO
COOL
AUX. HT. RELAY
DEFROST RELAY
CONTACT
COOL
CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
DEFROST
RELAY
M4667
1
2
3
5
6
8
9
10
VR
Y
V
F
M
R
HIGH
PRESSURE
SWITCH
DEFROST RELAY
CONTACT
FAN RELAY
DEFROST
SWITCH
D. F. O.