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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
193 60-2485—8
Fig. 199. Schematic and hookup of T874G with Q674F. Used in heat pump applications.
Fig. 200. Schematic and hookup of T874R with Q674L. Used in heat pump applications.
H1
FALL
O
G
R
E
X
FAN RELAY
W3 RELAY
EM. HT.
OFF
AUTO
SYSTEM
SWITCH
H1 ANTICIPATOR
C1 ANTICIPATOR
AUTO
ON
FAN SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
M2977
B
COMPRESSOR
CONTACTOR
AUX. HT. RELAY
4
5
8
9
10
H2
FALL
RISE
C1
L1
(HOT)
L2
1
H2
ANTICIPATOR
2
CHECK
LED
(RED)
Y
AUX. HT. LED
(GREEN)
COOL
HEAT
W3
W2
EM. HT. RELAY
COMPRESSOR
FAULT
L
HEAT CHANGEOVER
VALVE
COOL CHANGEOVER
RELAY
3
11
12
CO
RISE
EM. HT.
LED (RED)
THERMOSTAT
SUBBASE
SYSTEM COMPONENTS
T
G
R
Z
X
W1
FAN RELAY
EM. HT.
OFF
SYSTEM
SWITCH
AUTO
ON
FAN SWITCH
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
M2978
COMPRESSOR
CONTACTOR
SERVICE
1
3
6
11
L1
(HOT)
L2
1
2
SERVICE
LED
(YELLOW)
Y
EM. HT.
LED (RED)
COOL
HEAT
W2
OUTDOOR
THERMOSTAT
SEQ 2
K
SEQ 1
HEAT CHANGEOVER
VALVE
H2 ANTICIPATOR
RISE
H2
H1
C1
FALL
4
5
C1 ANTICIPATOR
12
H1 ANTICIPATOR
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
OUTDOOR
THERMOSTAT