AAON HB-005 - Manual (Page 7)

7
3. User’s Information
DX (Direct Expansion) Package Units and DX
Units with Remote Condenser
Never cut off the main power supply to the unit, except
for complete shutdown.
Always control the system from the thermostat, or
control panel, and never at the main power supply
(except in an emergency, or complete shutdown of the
system).
During the cooling season, if the airflow is reduced due
to dirty air filters, or other reasons, the cooling coils will
get too cold and result in excessive liquid return to the
compressor. As the liquid concentration accumulates,
oil is washed out of the compressor leaving it starved
for lubrication.
The compressors must be on a minimum of four
minutes, and off for a minimum of five minutes. The
cycle rate must not exceed eight starts per hour.
THE COMPRESSOR LIFE WILL BE SERIOUSLY
SHORTENED BY RESULTING REDUCED
LUBRICATION, AND THE PUMPING OF EXCESS
AMOUNTS OF LIQUID OIL AND REFRIGERANT.
Hydronic Cooling and Heating
Non-compressorized units may contain chilled water
and/or hot water coils. Units are provided with internal
header connections for field piping. Vent and drain
connections can be accessed within the unit.
Piping is to be run via the 4” x 7” piping chase located
in the cabinet floor inside the coil compartment,
accessible through the coil compartment access door
on the front of the unit. Piping to coil header
connections must be supported independently of the
coil to prevent undue stress from weakening
connections over time. Allow adequate flexibility for
thermal expansion of the piping.
Use proper glycol solutions or brines to help prevent
coil freezing. Consult the designer or project engineer
if you have concerns about lower than normal entering
air temperatures (typically air temperatures below
40
°F) that could cause coils to freeze.
Gas or Electric Heating
The system is designed to heat a given amount of air
each minute of operation. If the amount of air heated
is greatly reduced (approximately 1/3 capacity), the
heat exchanger (or heater coil if electric) temperature
will increase above acceptable levels, and will result in
shut down by a high temperature safety switch
incorporated into either the heat exchanger, or the
heater area.
Failure to observe the following instructions may
result in premature failure of your system, and
possible voiding of the warranty.
WARNING
GAS HEAT UNITS – If heat shuts off due to safety
switch, or gas supply shut off failure, then always
close manual gas valve to unit prior to any
electrical service. Prolonged overheating of the
heat exchanger will shorten its life.
WARNING
Improper installation, adjustment, alteration,
service, or maintenance can cause property
damage, personal injury, 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.
WARNING
Figure 7a, Piping Chase Location
Piping Chase
4” x 7”
Return Supply
Front
Back
Utility Entry
4” x 2 1/2”
Shipping
Bracket