Final Electrical Check Ductwork Connections
1. Make a final wiringcheck to be sure system is correctly
wired. Inspect field installed wiring and the routing to
ensure that rubbing or chafing due to vibration will not
occur.
NOTE: Wiring MUST be installed so it is protected from
possible mechanical damage.
5. DUCTWORK
Ductwork Sizing
The use of flexible, non-combustible connectors between
main trunk ducts and supply and return air plenums is
permitted. If flexible connectors are used, they should be
protected from potential mechanical damage such as
punctures and tears.
NOTE: When connecting the supply and return plenums to
the unit, make sure that the plenums are sealed against the
side casing of the unit and do not interfere with removal of
the top of the unit.
The maximum recommended velocity in trunk ducts is 1000
feet per minute. The maximum recommended velocity in
branch ducts is 800 feet per minute.
Ductwork sizing affects the discharge temperature, airflow
velocity, and efficiency of the system. Be sure to properly
size ductwork to the capacity of the unit and to the airflow
requirements of the conditioned space. Failure to properly
size ductwork can result in inadequate airflow and poor
efficiency. Undersized ductwork may result in tripped limit
controls and premature failure of compressors, motors and
other components.
FILTERS
All return air MUST pass through a filter before entering the
unit. An electronic air cleaner, optional filter racks, or other
accessible filter arrangement must be installed in the return
air ductwork. Minimum recommended filter sizes are listed
in FIGURE 5 and are based on maximum face velocities of
300 ft/min for disposable filters and 500 ft/min for washable
(high velocity) filters. See figure 5 for filter sizes.
Ductwork Insulation
Ductwork installed outdoors must have a minimum 2" thick
fiberglass "wrap" insulation and a weatherproof vapor
barrier installed around it. The insulation and vapor barrier
must be protected against potential damage. Caulking,
flashing, and other means of providing a permanent
weather seal must be used.
REDUCED EQUIPMENT LIFE HAZARD
Failure to follow this caution may result in improper
unit operation.
Do not operate the unit without a filter.
FIGURE 5 Filter Sizes
PHF3 Filter sizes
Disposable Filters
Model
PHF324000K00A1
PHF330000K00A1
PHF336000K00A1
PHF342000K00A1
PHF348000K00A1
Nominal Size
(Qty x w x d)
1 x 20" x 20"
1 x 20" x 24"
2 x 15" x 20"
2 x 18" x 20"
2 x 20" x 20"
Minimum Area
(sq inches)
384
480
576
672
768
Nominal Size
(Qty x w x d)
1 x 12" x 20"
1 x 15" x 20"
1 x 18" x 20"
1 x 20" x 20"
1 x 20" x 24"
Wasable Filters
Minimum Area
(sq inches)
231
288
346
404
461
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