8
Air Filter Requirements
An air filter is not supplied with this package unit as shipped
from the factory. The installer must provide a high velocity
filter that is appropriately sized to the return air duct opening
or internal filter rack. The filters must comply with ANSI/UL
900 or CAN/ULC-S111.
WARNING:
Never operate the unit without a filter in place.
Dust and lint could accumulate on internal parts,
resulting in loss of efficiency, equipment damage
and possible fire.
NOTE TO INSTALLER: After installing or replacing the filtration
system for this unit, add the following statement on or adjacent
to the filter service panel: “Replace filter(s) installed in your
system only with the same dimensional size filters that
are being replaced.”
• A suitable air filter must be installed upstream of the
evaporator coil of the return air system. Refer to
Table 1
for recommended external filter sizes.
• All return air must pass through the filters before entering
the evaporator coil. It is important that all filters be kept
clean and replaced frequently to ensure proper operation
of unit. Dirty or clogged filters will reduce the efficiency of
the unit and result in unit shutdowns.
• Air filter pressure drop must not exceed 0.08 inches WC.
Table 1. Recommended External Air Filter Sizes
EXTERNAL FILTER SIZES
NOMINAL COOLING
(TONNAGE)
FILTER SIZE
(IN. X IN.)
APPROXIMATE AIR FLOW
RANGE (CFM)
APPROXIMATE FILTER
AREA (SQ. IN.)*
2.0 20 x 25 600-900 450
2.5 20 x 30 750-1200 550
3.0 25 x 25 1100-1300 625
3.5 24 x 30 1200-1600 750
4.0 18 x 24 (2 required) 1400-1800 850
5.0 20 x 25 (2 required) 1700-2200 1000
INTERNAL FILTER SIZES
CABINET
HEIGHT
OUTDOOR
FAN DIAMETER
FILTER SIZE
(IN. X IN.)
APPROXIMATE AIR FLOW
RANGE (CFM)
APPROXIMATE FILTER
AREA (SQ. IN.)*
30”
20 (2) 14”x25”
700 - 1300
700
24” (1) 12”x20” and (1) 16”x25” 640
34”
20 (2) 16”x25”
900 - 1400
800
24” (1) 12”x20” and (2) 10”x25” 740
38”
20” (2) 18”x25”
1100 - 1600
900
24” (1) 12”x20” and (2) 12”x25” 840
42”
20” (2) 20”x25”
1300 - 1800
1000
24” (1) 12”x20” and (2) 14”x25” 940
* Based on velocity of 300 ft/min for disposable filters.
Unconditioned Spaces
All duct work passing through unconditioned space must
be properly insulated to minimize duct losses and prevent
condensation. Use insulation with an outer vapor barrier. Refer
to local codes for insulation material requirements.
Acoustical Duct Work
Certain installations may require the use of acoustical lining
inside the supply duct work.
• Acoustical insulation must be in accordance with the current
revision of the Sheet Metal and Air Conditioning Contractors
National Association (SMACNA) application standard for
duct liners.
• Duct lining must be UL classified batts or blankets with a
fire hazard classification of FHC-25/50 or less.
• Fiber duct work may be used in place of internal duct liners if
the fiber duct work is in accordance with the current revision
of the SMACNA construction standard on fibrous glass
ducts. Fibrous duct work and internal acoustical lining must
be NFPA Class 1 air ducts when tested per UL Standard
181 for Class 1 ducts.
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