26
ComPac 9/04-12
BASIC MODEL MAXIMUM TOTAL STATIC MINIMUM FILTER AREA
20/24
.30
2.25 sq. ft.
30/36
.40
3.00 sq. ft.
42/48/60/72
.50
3.90 sq. ft.
Table 6. Maximum Static Pressure
(For units with 2" Pleated Filters)
IMPORTANT
General Information
Note: The following instructions are for general guidance only. Due to the wide variety of
installation possibilities, specific instructions will not be given. When in doubt, follow standard
and accepted installation practices, or contact Marvair
®
for additional assistance.
Wall Openings
Measure the dimensions of the supply and return ports on the unit.
Cut the openings in the exterior wall for the supply and return. IMPORTANT: All units
with electric heat must have one inch clearance on all four sides of the supply outlet
duct flange on the unit. The one inch clearance must extend on all sides of the supply
duct for the first three feet from the unit.
IMPORTANT: Marvair
®
requires a minimum of one inch from the surface of any supply
ducts to combustible material for the first three feet of the duct.
Ducting
Extensions should be cut flush with the inside wall for applications without duct work.
Applications using duct work should be designed and installed in accordance with all
applicable safety codes and standards. Marvair
®
strongly recommends referring to the
current edition of the National Fire Protection Association Standards 90A and 90B before
designing and installing duct work. The duct system must be engineered to insure sufficient air
flow through the unit to prevent over-heating of the heater element. This includes proper supply
duct sizing, sufficient quantity of supply registers, adequate return and filter area. Ductwork
must be of correct material and must be properly insulated. Duct work must be constructed
of galvanized steel with a minimum thickness of .019 inches. Ductwork must be firmly
attached, secured and sealed to prevent air leakage. Do not use duct liner on inside of supply
duct within 4 feet of the unit.
Galvanized metal duct extensions should be used to simplify connections to duct work and
grilles. Use fabric boots to prevent the transmission of vibration through the duct system. The
fabric must be U.L. rated to a minimum of 197°F.
Minimum Airflow Requirements
The duct system must be engineered to assure sufficient air flow through the unit even under
adverse conditions such as dirty filters, etc. Use Table 6 below and Table 1, CFM at
External Static Pressure (Wet Coil) in section 1.4.
2.4 P
ORTING
AND
D
UCT
W
ORK
(AVP20-72)
