AAON M2-036 - Manual (Page 66)

66
Operating Control Systems
Two Stage (TN) - Low / High Fire / High
Speed Inducer Only
Modulating (MD) - Modulating (25 to
100%) / 2 Speed Draft Inducer - Mid-Fire
Start (55%)
Modulating (MH) - Modulating (25 to
100%) / 2 Speed Draft Inducer - High Fire
Start (100%)
Refer to unit wiring diagrams located in unit
door.
Furnace Maintenance
Duct Furnace Inspection
1. The duct furnace should be inspected
annually by a qualified service agency. The
condition of the burners, heat exchanger,
draft inducer, vent system, operating
controls and wiring should be determined.
Check for obvious signs of deterioration,
accumulation of dirt and debris and any heat
or water related damage. Any damaged or
deteriorated parts should be replaced before
the unit is put back into service.
2. Clean burners, heat exchanger, draft
inducer and vent ducts with a soft brush or
vacuum.
3. Check Heat Exchanger for cracks. If any
are present, replace heat exchanger before
putting unit back into service.
4. Check the attachment point of the duct
furnace to the cabinet or ducts to verify that
they are air tight.
5. Check the automatic gas valve to insure
that the gas valve seat is not leaking.
Duct Furnace Operation Check
1. Turn on power to the unit and set
thermostat or heat controller to call for heat,
allowing duct furnace to operate.
Disconnect all electrical power
sources before servicing the unit.
More than one power source may be
provided. Failure to do so may result
in injury or death from electrical
shock or entanglement in moving
parts.
WARNING
If any original wiring needs to be
replaced it must be replaced with
wiring materials suitable for 105ºC.
Label all wires prior to disconnection
when servicing unit. Wiring errors can
cause improper or dangerous
operation. Verify proper operation
after servicing.
CAUTION
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 trained, qualified
installer. A copy of this IOM should
be kept with the unit.
WARNING