39
Marvair GAA A/C w/Gas Heat I&O Manual
06/2023 Rev.5
4.11 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 90 A and 90 B
before
designing and installing ductwork. The ductsystem
must be engineered to insure sufficient air flow through the unit to prevent over-heating. 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.
Note:
Follow local codes and standards when designing duct runs to deliver the required airflow. Minimize
noise and excessive pressure drops caused by duct aspect ratio changes, bends, dampers and outlet grilles
in duct runs.
4.12 Hanging the Unit on the Wall
1. Remove and discard the 4 x 4 shipping boards attached to the base of the unit.
2. All GAA models have built-in mounting flanges. See Figure 2.
3. Refer to Figure 2. Attach the bottom support bracket to the wall using appropriate 3 / 8” diameter
hardware.
For example, on wooden structures, use 3 / 8 x 2-1 / 2 inch all-thread lag screws. The screws must penetrate
the center of the wall stud. Drill a pilot hole in the stud to prevent it from splitting.
Figure 4. Mounting Unit on a Wall
4. For wiring into the back of unit, locate the lower of the two knock-outs on the wall side of the unit.
Drill a one inch hole in the building wall to match this opening. Allow sufficient clearance to run
3 / 4” conduit through the hole and to the unit.
5. Apply a bead of silicone sealer on the wall side of the mounting brackets. Circle the mounting
