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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
60-2485—8128
Fig. 105. Schematic and hookup of T874C with Q674L. Used in heat pump applications.
Fig. 106. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
OFF
COOL
IHRI
RHI
FAN SWITCH
ON
SYSTEM
SWITCH
SYSTEM
MONITOR
SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M8384
EM. HT. RELAY
1
EM. HT. LED
(RED)
W2
2
EM. HT.
HEAT
FAN RELAY
HEAT RELAY 2
HEAT RELAY 1
W1
AUTO
C
Y
H1
FALL
H2 ANTICIPATOR
H1 ANTICIPATOR
C1 ANTICIPATOR
H2
FALL
C1
RISE
COMPRESSOR
CONTRACTOR
8
10
L1
(HOT)
L2
1
G
K
L
R
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
4
6
H2
FALL
H1
FALL
C1
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
H1/C1
ANTICIPATOR
H2 ANTICIPATOR
SYSTEM
SWITCH
FAN SWITCH
AUTO
ON
OFF
HEAT
EM. HT.
COOL
AUX. HT. RELAY
EM. HT. RELAY
COOL CHANGEOVER
VALVE
COMPRESSOR
CONTACTOR
FAN RELAY
M4724
2
3
4
5
6
E
Y
X
W2
R
G
O
EM. HT.
LED
(RED)