38
Marvair MAA/MGA Wall Mount AC Installation & Operation Manual
05/2023 Rev.21
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 for the
first 3 feet (1 meter). 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 (122cm) 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 (92°C).
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.
BASIC MODEL
MAXIMUM STATIC
MAA1018A/1020A/1024A
.50
MAA1030A/1036A
.50
MAA1042A/1048A/1060A/2060A/2072A
.50
MGA1072A
.50
Table 9. Maximum Static Pressure
(For units with 2" Pleated Filters)
3.5 Fresh Air Hood (non-economozer air conditioners only)
The fresh air hood is located on the inside, behind the slots on the bottom front panel. To access the
hood, remove the screws that hold the front panel. The air flow can be adjusted from no (0%) fresh air
to approximately 15% of rated air flow of fresh air, in 5% increments. The hood is shipped from the
factory in the closed position (no fresh air). To provide fresh air, remove the two screws on either side
of the hood and reposition as desired.
Figure 4. Fresh Air Hood Damper, Models MAA1024A-MAA1072A
