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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8216
Fig. 235. Schematic and hookup of T874G and Q674F. Used in heat pump applications.
Fig. 236. Schematic and hookup of T874A-D with Q674C. Used in standard applications.
H2
FALL
L1
(HOT)
L2
1
R
W2
X
L
G
O
E
Y
RTD1 OTD1
EHR1
ODT2
EHR2
RTD2
RTD3
RTD1
SYSTEM
MONITOR
FAN
RELAY
RD
COOL
CHANGEOVER VALVE
EM. HT.
RELAY
LACO
COMPRESSOR
CONTACTOR
CHP
2
3
4
5
8
9
10
H1
FALL
H1 ANTICIPATOR
H2
ANTICIPATOR
CHANGEOVER
RISE
C1
RISE
C1
ANTICIPATOR
OFF
COOL
AUTO
HEAT
EM. HT.
SYSTEM
SWITCH
AUTO
ON
FAN
SWITCH
AUX. HT.
LED (GRN)
EM. HT.
LED (RED)
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
1
M7064
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
Y1
RC
1
1
1
M7570
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
B
Y2
W2
RH
A
H1 ANTICIPATOR
H2 ANTICIPATOR
C1
RISE
H1
FALL
FALL
H2
C2
RISE
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
O
1
6
9
10
11
4
8
AUTO
ON
FAN
SWITCH
SYSTEM
SWITCH
OFF
HEAT DAMPER
HEAT RELAY 1
COMPRESSOR
RELAY 1
HEAT RELAY 2
COMPRESSOR
RELAY 2
AUTO
SERVICE
LED (RED)
W1
G
COOL DAMPER
FAN RELAY
CONTROL MODULE