AAON HA-50 - Manual (Page 5)

5
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! CAUTION
Before leaving installation, a complete
operating cycle should be observed
to verify that all components
are functioning properly.
ELECTRIC HEATING (Optional)
The electric heat is available as an option.
Heating is accomplished by passing electrical current
through a specified amount of resistance heaters which
will produce the required heat. The indoor blower motor
will energize at the same time as the heaters.
When heat is called for, the cooling section in inoperable
except for the indoor blower motor.
The system is designed to heat or cool 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 heater coil will overheat, and may cut the
heater off entirely by action of the safety high tempera-
ture limit device.
BLOWER INFORMATION
DUE TO JOB SPECIFICATION REVISIONS, IT MAY
BE NECESSARY TO ADJUST OR CHANGE THE
SHEAVE OR PULLEY TO OBTAIN THE DESIRED
AIRFLOW AT THE TIME OF INSTALLATION.
START-UP TECHNICIAN MUST CHECK BLOWER
MOTOR AMPERAGE TO ENSURE THAT THE AM-
PERAGE LISTED ON THE MOTOR NAMEPLATE IS
NOT EXCEEDED.
Clean blower wheels are necessary to reduce electrical
use, maintain capacity and reduce stress on the unit.
FILTER INSTALLATION / REPLACEMENT
Filter rails and filters are shipped inside the unit for
field installation. Install filter rails and slide filters
into place before operation of the unit.
To replace filters, slide each filter out of filter rack and
inspect. Replace old filters with the size indicated on
each filter. Be sure arrow points towards the blower.
Filters should be checked every 30 days and replaced
or cleaned as necessary.
Do not permit the unit to be operated unless filters are
in place. Operation of the unit without filters will
result in a clogged evaporator coil.
IT IS IMPORTANT TO KEEP COILS,
BLOWER AND FILTERS CLEAN !
OWNER'S INFORMATION
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.
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.
CONDENSATE PIPING
The unit requires a drain trap to be connected to the
drain pan 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.
Drain pans in any air conditioning equipment, even
when they have a built-in slope to the drain, will have
moisture present and will require periodic cleaning to
prevent any build up of algae of bacteria.
Cleaning of the drain pans will also prevent any
possible plugging of the drain lines and an over-
flow of the pan itself. All cleaning of the drain pans
and inside of the equipment should be done by
qualified personnel.