19
Marvair Wall Mount Heat Pump I&O Manual
11/2021 New
2.4 Porting and Duct Work
WARNING
FIRE HAZARD
Improper adjustment, alteration, service, maintenance or installation could cause serious
injury, death and/or property damage.
Installation or repairs made by unqualified persons could result in hazards to you and
others. Installation MUST conform with local codes or, in the absence of local codes, with
codes of all governmental authorities have jurisdiction.
The information contained in this manual is intended for use by a qualified service
agency that is experienced in such work, is familiar with all precautions and safety
procedures required in such work, and is equipped with the proper tools and test
instruments.
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 openings on the heat pump unit.
WARNING
Cut the supply opening in the exterior wall for the supply and return.
IMPORTANT: All units 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.
The duct must be constructed of galvanized steel with a minimum thickness of .019".
Minimum Airflow Requirements
WARNING
The duct system must be engineered to assure sufficient air flow through the Heat Pump, even
under adverse conditions such as dirty filters, etc. Proper engineering will insure longevity and
maximum performance from the Heat Pump unit.
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. Ductwork
must be constructed of galvanized steel with a minimum thickness of .019". Ductwork must be firmly
attached, secured and sealed to prevent air leakage. Do not use duct liner on inside of supply duct within
four 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 (UL-181) to a minimum of 197
o
F.
