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24VAC TRANSFORMER
Use the transformer provided with the furnace or air han
dler for low‐voltage control power (24VAC - 40 VA mini
mum).
WARNING
Electric Shock Hazard. Can cause injury
or death. Unit must be grounded in
accordance with national and local
codes.
Line voltage is present at all components
when unit is not in operation on units with
single‐pole contactors. Disconnect all
remote electric power supplies before
opening access panel. Unit may have
multiple power supplies.
IMPORTANT !
If unit is equipped with a crankcase heater, it should
be energized 24 hours before unit start-up to pre
vent compressor damage as a result of slugging.
1.
Size Circuit and Install Disconnect
: Refer to unit
nameplate for minimum circuit ampacity, and maximum
fuse or circuit breaker size (HACR per NEC). Install pow
er wiring and properly sized disconnect switch.
NOTE
— Units are approved for use only with cop
per conductors. Ground unit at disconnect switch or
connect to an earth ground.
2.
Install Thermostat
: Install room thermostat (ordered
separately) on an inside wall in the center of the condi
tioned area and 5 feet (1.5m) from the floor. The ther
mostat should not be installed on an outside wall or
where it can be affected by sunlight or drafts.
NOTE
— 24VAC, Class II circuit connections are
made in the control box.
CAUTION
ELECTROSTATIC
DISCHARGE
(ESD)
Precautions and
Procedures
Electrostatic discharge can affect
electronic components. Take care
during unit installation and service to
protect the unit's electronic controls.
Precautions will help to avoid control
exposure to electrostatic discharge by
putting the unit, the control and the
technician at the same electrostatic
potential. Touch hand and all tools on an
unpainted unit surface before
performing any service procedure to
neutralize electrostatic charge.
NOTE
— For proper voltages, select control wires gauge per table below.
WIRE RUN LENGTH
AWG# INSULATION TYPE
LESS THAN 100' (30 METERS)
18 TEMPERATURE RATING
MORE THAN 100' (30 METERS) 16 35ºC MINIMUM.
NOTE
— Wire tie provides low voltage wire strain relief and maintains
separation of field-installed low and high voltage circuits
.
NOTE
— Do not bundle any excess 24VAC control wires inside control box
.
A. ROUTE CONTROL WIRES — NON-COMMUNICATING
Install low voltage control wiring from outdoor to indoor unit and from
thermostat to indoor unit. All low voltage wiring must enter unit through
provided field-installed busing installed in electrical inlet.
Run 24VAC control wires through hole with grommet.
Make 24VAC control wire connections to heat pump control (A175).
CONTROL
(A175)
HOLE
A
B
B. ROUTE CONTROL WIRES — COMMUNICATING
Maximum length of wiring (18 gauge) for all connections on the RSBus is 1500 feet (457 meters). Wires should be color-coded, with a temperature rating
of 95
º
F (35
º
C) minimum, and solid-core (Class II Rated Wiring). All low voltage wiring must enter unit through provided field-installed busing installed
in electrical inlet.
Communicating systems using the iComfort
t
-enabled thermostat require four thermostat wires between the thermostat and the furnace/air handler
control and four wires between the outdoor unit and the furnace/air handler control. When a thermostat cable with more than four wires is used, the extra
wires must be properly connected to avoid electrical noise (see illustration below).
Use a wire nut to bundle the four unused wires at each end of the cable. Each bundle should also include an additional wire that should be connected
on each end to the C terminal as shown in figure 7.
iComfort
t
-enabled
thermostat
iComfort
t
-enabled
Outdoor Unit
Single Wire To
C Terminal
Unused Wires
Single Wire To
C Terminal
iComfort
t
-enabled
Indoor Unit
Unused Wires
FIGURE 6
