AAON RK-60 - Manual (Page 4)

4
OWNER'S INFORMATION
WARNING
Failure to observe the following instructions will result
in premature failure of your system, and possible void-
ing of the warranty.
DIRECT EXPANSION (DX) COOLING UNITS
Never cut off the main power supply to the unit, except
for complete shutdown. When power is cut off from the
unit, any compressors using crankcase heaters cannot
prevent refrigerant migration. This means the compres-
sor will cool down, and liquid refrigerant will accumu-
late in the compressor. Since the compressor is designed
to pump refrigerant gas, damage may occur when power
is restored.
If power must be cut off for more than an hour, turn the
thermostat system switch to "OFF", and leave it off until
the main power switch has been turned on again for at
least twenty four hours for units with compressor crank-
case heaters. This will give the crankcase heater time to
clear any liquid accumulation out of the compressor
before it is required to run.
Always control the system from the thermostat, or con-
trol panel, never at the main power supply (except for
emergency or for complete shutdown of the system).
During the cooling season, if the air flow is reduced due
to dirty air filters or any other reason, the cooling coils
will get too cold and 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
SHORTENED BY THIS REDUCED LUBRICATION,
AND THE PUMPING OF EXCESSIVE AMOUNTS OF
LIQUID OIL AND REFRIGERANT.
GAS OR ELECTRIC HEATING
The system is designed to cool or heat a given amount of
air each minute it operates. If this amount of air is
greatly reduced (approximately 1/3 during the heating
season), the heat exchanger / heater coil will overheat,
and may cut the burner / heater off entirely by action of
the safety high temperature limit device which is incor-
porated in the exchanger or heating area.
GAS HEAT UNITS - Should overheating occur, 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.
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal in-
jury or loss of life. Installation and service must be
performed by a qualified installer, service agency or if
gas fired units, the gas supplier. Refer to installation
instructions provided with the unit and this manual.
CAUTION: While the following incorrect operations
may not cause damage to the system, they will impair
the performance, and may cause the built-in safety
devices to cut the system off completely.
1. LOW AMBIENT OPERATION
The cooling section of a direct expansion (DX)
unit will not operate properly when the outdoor
temperature is below 55
°
degrees. Outside air
intake options are recommended if operation
below 55
°
degrees is expected.
2. MULTIPLE UNIT OPERATION
When several units are used in conditioning the
space, and part or all of them are combination
heating-cooling units, all systems thermostat
switches must be set at either heating or cooling
(or set at "off"). Do not leave part of the systems
switched to the opposite mode. All cooling only
units should be switched to "off" at the thermo-
stat during the heating season.
WIRING DIAGRAMS
A complete set of unit specific wiring diagrams in both
ladder and point-to-point form are laminated in plastic
and located inside the control compartment door.
CONDENSATE PIPING
The unit requires a drain trap to be connected to the
drainpan at the unit. If codes require a condensate drain
line, the line should be the same pipe size as the drain
nipple and should pitch downward toward drain.
The condensate drain pipe ("P" trap) is factory supplied
and is shipped loose in the control access compartment
for field installation. An air break should be used with
long runs of condensate lines.
▲
! WARNING
Scroll compressors will be damaged by
operation with the wrong rotation.
THE LOW PRESSURE SWITCH HAS BEEN
DISCONNECTED AFTER TESTING
AT THE FACTORY.
The wiring must be reconnected and proper
rotation determined at the time of start-up by
a qualified service technician using suction
and discharge pressures gauges.
Any alteration should only be made at
the unit power connection.