6
3” min
Figure 7. Concrete Pad Installations
Roof
Curb
Figure 6. Roof Curb Installations
CIRCULATING AIR SUPPLY
WARNING:
Do not allow combustion products to enter the
return air ductwork or the circulating air supply.
Failure to prevent the circulation of combustion
products into the occupied space can create
potentially hazardous conditions including
carbon monoxide poisoning that could result
in personal injury or death.
All return ductwork must be secured to the
unit with sheet metal screws. All joints must be
taped and adequately sealed. When return air
is provided through the bottom of the unit, the
joint between the unit and the return air plenum
must be air tight.
The roof curb or framing must provide sound
physical support of the unit with no gaps,
cracks, or sagging between the unit and the
curb or frame.
Return air and circulating air ductwork must
not be connected to any other heat producing
device such as a fireplace insert, stove, etc. This
may result in fire, explosion, property damage,
personal injury, or death from carbon monoxide
poisoning.
• This unit is designed only for use with a supply and
return duct. Any exterior ducts, joints, or openings in
the building roof or walls must be weatherized with
conventional flashing and sealing compounds.
• Air ducts should be installed in accordance with all
applicable local codes and the standards of the National
Fire Protection Association “Standard for Installation
of Air Conditioning Systems” (NFPA 90A).
• Design the ductwork according to methods described
by the Air Conditioning Contractors of America (ACCA)
Manual Q.
• It is recommended that the outlet duct be equipped
with a removable access panel. This opening should
be accessible when the unit is installed in service and
shall be of a size such that the smoke or reflected light
may be observed inside the casing to indicate the
presence of leaks in the heat exchanger. The cover for
the opening shall be attached in such a manner as to
prevent leaks.
• If outside air is used as return air for ventilation or to
improve indoor air quality, the system must be designed
so that the return air to the unit is not less than 50° F
(10° C) during heating operation. If a combination of
indoor and outdoor air is used, the ducts and damper
system must be designed so that the return air supply
to the unit is equal to the return air supply under normal,
indoor return air applications.
must be square and level to ensure proper condensate
drainage. Unit clearances must be in accordance with
those shown in Figure 1 (page 4).
Unconditioned Spaces
All ductwork passing through unconditioned spaces
must be properly insulated to minimize duct losses and
prevent condensation. Use insulation with an outer vapor
barrier. Refer to local codes for any insulation material
requirements.
