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Wire control signals to the unit’s low voltage
thermostat connections on the control board,
located in the controls compartment. Consult
unit wiring diagram for more detailed
instructions on control signal wiring
connections. If any factory installed wiring
must be replaced, use a minimum 105°C type
AWM insulated conductors.
Thermostat Control Wiring
If a thermostat is used for unit control, locate
thermostat on an inside wall 4-5 feet above
the floor where it will not be subjected to
drafts, sun exposure, or heat from electrical
fixtures or appliances. Control wiring must
deliver adequate voltage to components to
assure proper operation. Control voltage
returning from controller circuit must be a
minimum of 21 VAC. To assure proper
wiring use the following chart to determine
the allowable wiring distances.
Table 5 - Control Wiring
Wire Size
(Stranded) - Copper
Conductors Only
Total Wire Distance
Allowable
20 AWG
200 ft
18 AWG
350 ft
16 AWG
500 ft
14 AWG
750 ft
12 AWG
1250 ft
Total Wire Distance Allowable =
(Quantity of Control Wires) x
(Control Wire Distance)
Take the total wire distance allowable and
divide by the number of wires to be
connected. This indicates the distance
allowable for that size wire. The wiring to the
unit must not exceed the total wire distance
allowable. If the voltage at the connectors is
less than 21 VAC, isolation relays must be
installed. If under external control 21 VAC
must be field verified. All external devices
must be powered via a separate external
power supply.
Example:
A total of 5 wires must be pulled 75ft to a
control the unit. What size wire must be
used?
According to Table 5, 18 AWG allows for
70ft (350 ft. /5 wires) and 16 AWG allows for
100ft (500 ft. /5 wires). Thus, 16 AWG must
be used.
Rotation must be checked on all
MOTORS AND COMPRESSORS of
three phase units. Supply fan motors
must all be checked by a qualified
service technician at startup and any
wiring alteration must only be made at
the unit power connection.
Scroll compressors are directional
and can be damaged if rotated in the
wrong direction. Compressor rotation
must be checked for proper operation,
without using external refrigerant
pressure gauges. Often, a
compressor running in reverse
rotation will be much louder than a
normal compressor, and will not
develop much of a temperature
differential between the suction and
discharge lines.
Disconnect all electrical power
sources before servicing the unit.
More than one power source may be
provided. Failure to do so may result
in injury or death from electrical shock
or entanglement in moving parts/
CAUTION
CAUTION
WARNING