AAON RN Series User Manual

71
Packaged Direct Expansion (DX) Units
All DX refrigeration systems are factory
assembled, leak tested, charged with
refrigerant, and run tested.
All refrigerant systems include an
evaporator, condenser, liquid line filter
driers, expansion valves and scroll
compressors.
Never cut off the main power supply to the
unit, except for servicing, emergency, or
complete shutdown of the unit. When power
is cut off from the unit crankcase heaters
cannot prevent refrigerant migration into the
compressors. This means the compressor will
cool down and liquid refrigerant may
accumulate in the compressor. The
compressor is designed to pump refrigerant
gas and damage may occur when power is
restored.
If power to the unit must be off for more than
an hour, turn the thermostat system switch to
"OFF", or turn the unit off at the control
panel, and leave the unit off until the main
power switch has been turned on again for at
least 24 hours for units with compressor
crankcase heaters. This will give the
crankcase heater time to clear any liquid
accumulation out of the compressor before it
is started.
Always control the unit from the thermostat,
or control panel, never at the main power
supply, except for servicing, emergency or
complete shutdown of the unit.
During the cooling season, if the air flow is
reduced due to dirty air filters or any other
reason, the cooling coils can get too cold
which will cause excessive liquid to return to
the compressor. As the liquid concentration
builds up, oil is washed out of the
compressor, leaving it starved for lubrication.
The compressor life will be seriously shorted
by reduced lubrication and the pumping of
excessive amounts of liquid oil and
refrigerant.
Note: Low Ambient Operation
Air-cooled DX units without a low ambient
option, such as condenser fan cycling or the
0°F low ambient option, will not operate in
the cooling mode of operation properly when
the outdoor temperature is below 55°F. Low
ambient and/or economizer options are
recommended if cooling operation below
55°F is expected.
COMPRESSOR CYCLING
3 MINUTE MINIMUM OFF TIME
To prevent motor overheating
compressors must cycle off for a
minimum of 3 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 7
starts per hour.
WARNING
CRANKCASE HEATER
OPERATION
Some units are equipped with
compressor crankcase heaters, which
must be energized at least 24 hours
prior to cooling operation, to clear any
liquid refrigerant from the
compressors.
CAUTION

AAON RN Series Specifications

General

Category	Heat Pump
HSPF	Up to 10.0
Refrigerant	R-410A
Compressor Type	Scroll
Efficiency	High
Series	RN
Voltage Options	208-230/460V
Unit Weight	Varies with model
Dimensions	Varies with model