_ Installation Instructions Single Package Heat Pumps I
6.Air DistributionSystem
For airflow data (blower performance data, blower speed
tap settings, filter sizes, etc.) see the Parts List.
Ductwork
NOTE: The total heat gain/heat loss from the structure as
expressed in total Btu/hr MUST be calculated by manufac-
turer's method or in accordance with "A.S.H.R.A.E. Guide"
or "Manual J - Load Calculations" published by the Air
Conditioning Contractors of America or in Canada
"H.R.A.I. Residential Heating and Cooling Load Calcula-
tion Manual." The total heat gain calculated should be
equal to or less than the cooling capacity output based
on D.O.E. test procedures, steady state efficiency times in-
put.
Ductwork, supply registers, and return air grilles MUST be
designed and sized to handle the unit's cooling air vol-
ume requirements. If the unit is connected to an existing
system, the ductwork MUST be checked to make sure it is
adequate. Extra runs or larger duct sizes may have to be
installed.
Maximum recommended velocity in trunk ducts is 1000
feet per minute (5.08m/s). Velocity in branches should not
exceed 800 feet per minute (4.06m/s). Refer to the Parts
List for unit air volume requirements and system sizing rec-
ommendations.
Ductwork Connections
The use of flexible, non-combustible connectors be-
tween main trunk ducts and supply and return air plenums
is recommended to minimize vibration transmission.
NOTE: Connect supply and return air plenums to unit in a
manner that will allowthe top of the unit to be removed with-
out removing plenums. Plenums MUST be individually
sealed to unit casing. Ducts MUST be terminated inside
structure.
Filters
All return air MUST pass through a filter before entering the
unit. An electronic air cleaner, optional filter racks or other
accessible filter arrangements MUST be installed in the re-
turn air ductwork. Minimum recommended filter areas are
listed in the Parts List and are based on a velocity of 300
ft/min (1.2m/s) for disposable filters and 500 ft/min
(2.54m/s) for washable high velocity filters.
CAUTION
Do NOT operate the unit without all filters in place.
NOTE: Ductwork sizing affects temperature rise and cool-
ing temperature differential. Be sure to properly size duct-
work to the capacity and airflow characteristics of your unit.
Failure to do so can affect limit controls, compressors, mo-
tors, and other components and will lead to premature fail-
ure of components. This will also adversely affect day to
day unit performance.
Refer to unit rating plate for proper Electric Heat Accessory
sizing and see the Temperature Rise Check section in the
Electric Heat Accessory Installation Instructions.
Ductwork Insulation
It is recommended that ductwork installed outdoors have a
minimum of 2" (51mm) of fiberglass insulation and be cov-
ered by a weatherproof vapor barrier that is protected
against damage. Caulking and flashings, or other means
adequate to provide a permanent weather seal, must be
used.
It is recommended that ductwork installed in attics or other
areas exposed to outdoor temperatures have a minimum
of 2" (51mm) fiberglass insulation and have an indoor type
vapor barrier.
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