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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8146
Fig. 126. Schematic and hookup of T874G with Q674P. Used in heat pump applications.
Fig. 127. Schematic and hookup of T874C with Q674L. Used in heat pump applications.
H2
H1
FALL
CO
RISE
C1
RISE
L1
(HOT)
L2
1
1
2
2
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
N.O. SWITCH INSTALLER ADDED, TO LIGHT EM. HT. LED WHEN COMPRESSOR OPERATION IS NOT NORMAL.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1 ANTICIPATOR
H2 ANTICIPATOR
C1 ANTICIPATOR
SYSTEM
SWITCH
FAN
SWITCH
AUTO
ON
SUPL. HT.
HEAT
COOL
FAN RELAY
COOL CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR 1
HEAT RELAY 2
HEAT RELAY 1
M4722
1
2
4
6
8
9
10
Y
C
L
E
W2
R
G
O
HEAT RELAY
CONTACT 2
HEAT RELAY
CONTACT 1
HEAT RELAY 3
OUTDOOR
THERMOSTAT
FALL
SUPL. HT.
LED (RED)
FALL
AUTO
ON
H1
HEAT
OFF
COOL
L2
M5652A
POWER SUPPLY. PROVIDE
DISCONNECT MEANS AND
OVERLOAD PROTECTION
AS REQUIRED.
FAN SWITCH
L1
(HOT)
SYSTEM SWITCH
COMPRESSOR
FAILURE
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 (RED)
AUX.HT.
LED (GREEN)
RISE
C1
H2
FALL
C1 ANTICIPATOR
EM. HT.
ODT1
RTD1
EHR1
RTD2
ODT2
EHR2 RTD3
RTD1
H2 ANTICIPATOR
H1 ANTICIPATOR
2
3
4
5
6
8
10
THERMOSTAT SUBBASE
SYSTEM COMPONENTS