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THERMOSTAT
FALL
H1 ANTICIPATOR
H1
H2
H2 ANTICIPATOR
FALL
H3 ANTICIPATOR
H3
FALL
RESET
RISE
C1
C1 ANTICIPATOR
C2 ANTICIPATOR
RISE
C2
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2
CONNECT CHANGEOVER RELAY TO 'O' TERMINAL FOR CHANGEOVER IN COOLING OR TO 'B' TERMINAL FOR CHANGEOVER IN HEATING.
Fig. 8. T874W/Q674L for three-stage heat and two-stage cool with outdoor reset and compressor monitor.
T874H,Q,W MULTISTAGE THERMOSTATS AND Q674B,C,G,L SUBBASES
SUBBASE
1
2
3
FAN SWITCH
AUTO
4
ON
5
6
8
SYSTEM
SWITCH
EM.HEAT
9
HEAT
OFF
10
COOL
11
12
T
C815A OD THERMISTOR
W3
U
AUXILIARY
HEAT LED
(GREEN)
G
EMERGENCY
HEAT LED
R
(RED)
E
L
CHECK LED
(RED)
X
B
2
O
Y1
Y2
5
SYSTEM COMPONENTS
1
AUX. HEAT RELAY
FAN RELAY
EM. HEAT RELAY
COMPRESSOR
MONITOR
CHANGEOVER
RELAY (HEAT)
CHANGEOVER
RELAY (COOL)
COMPRESSOR
CONTACTOR 1
COMPRESSOR
CONTACTOR 2
L1
(HOT)
L2
M156A
69-0087—6
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