Manual 2100-715B
Page
5 of 25
(ACCA) is an excellent guide to proper sizing. All duct
work or portions thereof not in the conditioned space
should be properly insulated in order to both conserve
energy and prevent condensation or moisture damage.
Refer to Maximum External Static Pressure (ESP) of
Operation – Electric Heat Only table on page 25.
Design the duct work according to methods given by
the Air Conditioning Contractors of America (ACCA).
When duct runs through unheated spaces, it should
be insulated with a minimum of 1" of insulation. Use
insulation with a vapor barrier on the outside of the
insulation. Flexible joints should be used to connect the
duct work to the equipment in order to keep the noise
transmission to a minimum.
Ducts through the walls must be insulated and all joints
taped or sealed to prevent air or moisture entering the
wall cavity.
Some installations may not require any return air duct.
It is recommended that on this type of installation, a
filter grille be located in the wall. Filters must be of
sufficient size to allow a maximum velocity of 400 fpm.
NOTE:
If no return air duct is used, applicable
installation codes may limit this cabinet to
installation only in a single story structure.
Filters
A 1" throwaway filter is standard with each unit. The
filter slides into position making it easy to service. This
filter can be serviced from the outside by removing the
service door. A 2" pleated filters is also available as
an optional accessory. The internal filter brackets are
adjustable to accommodate the 2" filter by bending
down the metal tabs holding the 1" filter. There are two
tabs on each side of the filter.
Fresh Air Intake
All units are built with fresh air inlet slots punched in
the service panel.
If the unit is equipped with a fresh air damper assembly,
the assembly is shipped already attached to the unit.
The damper blade is locked in the closed position.
To allow the damper to operate, the maximum and
minimum blade position stops must be installed (see
Figure 1).
There is an adjustable slide on the side of the fresh air
intake that can be adjusted to limit how far the damper
opens so that the amount of fresh air that enters the
structure is regulated.
All capacity, efficiency and cost of operation
information is based upon the fresh air blank-off plate
in place.
The blank-off plate is available upon request from the
factory and is installed in place of the fresh air damper
shipped with each unit.
MIS-938
FIGURE 1
Fresh Air Damper
