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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
119 60-2485—8
Fig. 89. Schematic and hookup of T874D with Q674E. Used in standard applications.
Fig. 90. Schematic and hookup of T874D with Q674G. Used in standard applications.
Y1
W1
RC
1
M7023
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
B
Y2
G
W2
RH
X
H1 ANTICIPATOR
H2 ANTICIPATOR
C1
RISE
H1
FALL
FALL
H2
C2
RISE
C2 ANTICIPATOR
C1 ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
O
A
1
6
9
10
11
4
8
AUTO
ON
FAN
SWITCH
SYSTEM
SWITCH
HEAT
OFF
COOL
HEAT CHANGEOVER
VALVE
HEAT
RELAY 1
COMPRESSOR
CONTACTOR 1
FAN RELAY
HEAT RELAY 2
L1
(HOT)
L2
1
L1
(HOT)
L2
1
COOL CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR 2
AUTO
FILTER
LED (YEL)
SERVICE
LED (RED)
W1
A2
A1
OFF
AUTO
SYSTEM
SWITCH
1
M7022
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
X2
L1
(HOT)
L2
1
B
X1
W2
T
RC
H1 ANTICIPATOR
H2 ANTICIPATOR
C1
RISE
H1
FALL
FALL
H2
C2
RISE
C2 ANTICIPATOR
C1 ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
NO FAN
SWITCH
RH
O
1
6
9
10
11
4
7
Y2
Y1
HEAT RELAY 1
HEAT RELAY 2
T RELAY
HEAT
CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR 2
COMPRESSOR
CONTACTOR 1
L1
(HOT)
L2
1
5
8
12
FILTER LED (YEL)
SERVICE
LED (RED)
FILTER
LED (YEL)
SERVICE
LED (RED)
COOL
CHANGEOVER
VALVE