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T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
99 60-2485—8
Fig. 49. Schematic and hookup of T874C with Q674B. Used in standard applications.
Fig. 50. Schematic and hookup of T874G with Q674B. Used in heat pump applications.
L1
(HOT)
L2
1
H1
FALL
H2
FALL
C1
RISE
L1
(HOT)
L2
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD
PROTECTION AS REQUIRED.
HEAT RELAY 1
BLOWER RELAY
HEAT RELAY 2
COMPRESSOR
CONTACTOR
HSII
CONTROL
PANEL
LO SPEED
LED (GREEN)
HI SPEED
LED (GREEN
COOL LED
(YELLOW)
HEAT
LED (RED)
FAN SWITCH
AUTO
ON
SYSTEM
SWITCH
HEAT
OFF
COOL
C1 ANTICIPATOR
H2 ANTICIPATOR
H1
ANTICIPATOR
1
4
6
8
9
10
W1
G
R
W2
T
Y1
L
C
H
M5945
THERMOSTAT SUBBASE
SYSTEM COMPONENTS
H1
FALL
H2
FALL
CO
RISE
C1
RISE
L1
(HOT)
L2
1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
THERMOSTAT
SUBBASE SYSTEM COMPONENTS
H1
ANTICIPATOR
H2 ANTICIPATOR
C1 ANTICIPATOR
10
9
8
6
4
2
1
FAN
SWITCH
AUTO
ON
SYSTEM
SWITCH
HEAT
OFF
COOL
R
W2
AUX. HT. RELAY
G
FAN RELAY
Y
COMPRESSOR
CONTRACTOR
O
COOL CHANGEOVER
VALVE
M8000