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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
203 60-2485—8
Fig. 216. Schematic and hookup of T874G with Q674J. Used in heat pump applications.
Fig. 217. Schematic and hookup of T874N with Q674C. Used in heat pump applications.
H1
FALL
H2
FALL
CO
RISE
C1
RISE
L1
(HOT)
L2
1
2
1
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
REMOVE JUMPER FOR INDEPENDENT CONTROL OF W1 AND E TERMINALS.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1
ANTICIPATOR
H2 ANTICIPATOR
C1
ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
EM. HT.
AUTO
EM. HT.
RELAY
COOL CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
M1629
1
2
4
6
8
9
10
Y
C
X
E
W1
R
G
O
AUX. HT.
LED
(YELLOW)
CHECK
LED
(RED)
SYSTEM
LED
(GREEN)
4R
HPS
4R
5R
4R
4R
SEQ 1
SEQ 2
3R
FAN RELAY
M5900
L1
(HOT)
L2
1
Y
L
X
W2
W3
R
ODT
EHR
HEAT CHANGEOVER VALVE
EHR
COMPRESSOR
CONTACTOR
OPTIONAL
COMPRESSOR FAILURE
CHECK LED
(GREEN)
FAN SWITCH
ON
AUTO
SYSTEM
SWITCH
OFF
AUTO
H2
FALL
H1
FALL
1
4
5
6
H1 ANTICIPATOR
H2
ANTICIPATOR
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT SUBBASE
SYSTEM COMPONENTS
C1
RISE
8
9
C1 ANTICIPATOR
W1
D. P.
G
HEAT
CONTACTOR #2
FAN RELAY
2
10
CO
HEAT
CONTACTOR #3
HEAT CONTACTOR #1