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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
147 60-2485—8
Fig. 128. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
Fig. 129. Schematic and hookup of T874G with Q674L. Used in heat pump applications.
FALL
AUTO
ON
H1
HEAT
OFF
COOL
L2
M5653A
POWER SUPPLY. PROVIDE
DISCONNECT MEANS AND
OVERLOAD PROTECTION
AS REQUIRED.
FAN
SWITCH
L1
(HOT)
SYSTEM
SWITCH
SYSTEM
MONITOR
1
1
R
W3
Y
B
L
W2
X
E
FAN RELAY
G
O
LACO
CHP
COMPRESSOR
CONTACTOR
EM. HT. RELAY
COOL CHANGEOVER
VALVE
RD
EM. HT.
LED
(YELLOW)
AUX. HT.
LED
(GREEN)
H2
FALL
EM. HT.
RD
RTD1
EHR1
RTD2
ODT2
EHR2 RTD3
RTD1
H1/C1
ANTICIPATOR
ODT1
A
SERVICE
LED (RED)
C1
H2 ANTICIPATOR
2
3
4
5
6
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1
FALL
L1
(HOT)
L2
1
H2
FALL
CO
RISE
C1
RISE
H1 ANTICIPATOR
H2 ANTICIPATOR
C1
ANTICIPATOR
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
COMPRESSOR
CONTACTOR
M102A
COOL CHANGEOVER VALVE
EM. HT. RELAY
AUX. HT. RELAY
FAN RELAY
G
R
W
X
EM. HT.
LED (RED)
B
O
Y
SYSTEM
SWITCH
EM. HT.
HEAT
OFF
COOL
FAN
SWITCH
AUTO
ON
2
3
4
6
8
9
10
1
THERMOSTAT SUBBASE
SYSTEM COMPONENTS