TM 9-4120-395-14&P
Figure 4-7. Fresh Air Damper
(7)
Install the two retained screws (1) into the holes at the bottom of the fresh air damper so that it is
secured to the bottom front door assembly (3).
(8)
Secure the bottom front door assembly with 1/4 turn fastener. Retain the two remaining screws for
future use.
4-8.
DUCTING.
Duct liner in supply duct may ignite if placed closer than 4 feet (1.22 meters) from
the air conditioner.
a.
Duct work is optional depending upon application. If used, duct work should be designed and installed in
accordance with the National Board of Fire Underwriters, Pamphlets 90A and 90B and insulated with a
minimum 1 inch vapor-barrier insulation. See Figure 4-8 for examples of duct work.
b.
A flex boot should be used to prevent transmission of vibration and noise to the duct system. The fabric
must be Underwriters Laboratory rated to a minimum of 197 degrees Fahrenheit (92 degrees Centigrade).
4-9
