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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8150
Fig. 132. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
Fig. 133. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
H2
FALL
H1
FALL
C1
L1
(HOT)
L2
1
1
2
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/C1
ANTICIPATOR
H2
ANTICIPATOR
RESET
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
OFF
HEAT
EM. HT.
COOL
COMPRESSOR
CONTACTOR
FAN RELAY
M1858
2
3
4
5
6
11
12
Y
T
C
X
E
R
G
O
COOL CHANGEOVER
VALVE
3R
SEQ 1
SEQ 2
EM. HT. RELAY
4R
4R
5R
HPS
4R
4R
C815A
OUTDOOR
THERMISTOR
SYSTEM
LED
(GREEN)
EM. HT.
LED
(RED)
W1
AUX. HT.
LED
(YELLOW)
H2
FALL
H1
FALL
C1
L1
(HOT)
L2
1
G
R
K
W2
L
C
Z
W1
2
3
4
6
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
1
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
FAN
SWITCH
AUTO
ON
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
M2018
H1/C1
ANTICIPATOR
H2 ANTICIPATOR
Y
FAN
RELAY
EM. HT.
RELAY
AUX. HT.
RELAY
CO
W1 RELAY
COMPRESSOR
CONTACTOR
1
5
EM. HT.
LED (YEL)
RESET
LED (RED)
COMPRESSOR
FAILURE