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MOUNTING
HOLES (2)
SPIRIT LEVEL
MOUNTING
HOLES (2)
Fig. 3. Level the subbase.
THERMOSTAT
1
H1
ANTICIPATOR
H1
2
FALL
2
3
4
5
C1
ANTICIPATOR
RISE
C1
1
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2
SINGLE SETPOINT LEVER AND BIMETAL.
Fig. 4. Internal schematic and typical hookup of T874A Thermostat with
THERMOSTAT
WIRING
CABLE OPENING
TERMINAL
POST (2) FOR
TO SPRING FINGER
MOUNTING
CONTACTS ON THE
THERMOSTAT
THERMOSTAT
(UP TO 12)
SUBBASE
SYSTEM
SWITCH
HEAT
OFF
COOL
FAN
SWITCH
LO
MED
HIGH
ON
Q674Q Subbase with automatic changeover.
T874A,D,R THERMOSTATS AND Q674B,D,F,Q SUBBASES
Wire Subbase
IMPORTANT
Use 18-gauge, color-coded thermostat wire for
wiring the Q674 Subbase.
Disconnect power supply to prevent electrical shock or
equipment damage. All wiring must comply with local
electrical codes and ordinances. Follow equipment
manufacturer wiring instructions when available.
Connect the system wires to the subbase as
shown in Fig. 4 through 9. A letter code is located
near each terminal for identification. The terminal
barrier allows straight or conventional wraparound
wiring connections. Either method is acceptable.
See Fig. 10.
M927
Run wires as close as possible to the subbase,
keeping wire length to a minimum.
Push excess wire back into the hole.
Plug the hole to prevent drafts.
W1
HEAT RELAY 1
B
R
G1
G2
O RELAY
O
COMPRESSOR CONTACTOR
Y1
3
SYSTEM COMPONENT
B RELAY
1
K1 RELAY
L2
K2 RELAY
3-SPEED FAN SCHEMATIC
L1
(HOT)
L2
L1
K1
K1
K2
K2
K2
HI
LO
MED
M8005
69-0107—2
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