AAON RN Series, Installation, Operation & Maintanance Manual, Page: 27 / 116

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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.
Note:
Multiple Units with Multiple
Thermostats
When several heating and cooling units are
used to condition a space all unit thermostat
switches must be set in either heating mode,
cooling mode or off. Do not leave part of the
units switched to the opposite mode.
Cooling only units should be switched off at
the thermostat during the heating season.
Gas or Electric Heating
The unit is designed to heat a given amount
of air while operating. If this amount of air
is greatly reduced, approximately 1/3 during
the heating season, the gas heat exchanger or
electric heating coil may overheat, and may
cut the burner or heater off entirely by action
of the safety high temperature limit devices
which are factory mounted at the heat
exchanger and supply fan areas.
Airflow should be adjusted after installation
to obtain an air temperature rise within the
range specified on the unit rating plate at the
required external static pressure.
Should overheating occur with a gas heat
exchanger, or the gas supply fail to shut off,
shut off the manual gas valve to the furnace
before shutting off the electrical supply.
Prolonged overheating of the heat exchanger
will shorten its life.
If unit has not been selected as a 100%
outside air unit (makeup air unit) the return
air duct must be sealed to the unit and the
return air temperature must be maintained
between 55
°
F and 80
°
F.
Table 1 - Electric and Gas Heating Capacities
Polyolester (POE) and Polyvinylether
(PVE) oils are two types of lubricants
used in hydrofluorocarbon (HFC)
refrigeration systems. Refer to the
compressor label for the proper
compressor lubricant type.
CAUTION