AAON RL-240 - Manual (Page 24)

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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 emergency or complete
shutdown of the unit.
During the cooling season, if the airflow 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.
Compressor life will be 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 airflow.
If this amount of air is reduced the gas heat
exchanger or electric heating coil may
overheat, and may turn 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
blower 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.
Wiring Diagrams
Unit specific wiring diagrams in both ladder
and point-to-point form are laminated and
affixed inside the controls compartment
door.
Condensate Drain Pan
Unit requires drain traps to be connected to
the condensate drain pan of the unit. Units
include drain pan connections on both the
front and back sides of the unit. Condensate
drain pipes or p-traps for each connection
are factory supplied and shipped loose in the
controls compartment for field installation.
However, unit may require a deeper p-trap
depending on the type of unit and pressure at
the coil. See Installation section of this
manual for more information.
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