507787-01
Issue 2007
Page 9 of 22
Duct System and Filters
Duct System
The air handler is provided with flanges for the connection
of the supply plenum.
Supply and return duct system must be adequately sized
to meet the system’s air requirements and static pressure
capabilities. The duct system should be insulated with
a minimum of 1” thick insulation with a vapor barrier in
conditioned areas or 2” minimum in unconditioned areas.
Supply plenum should be the same size as the flanged
opening provided around the blower outlet and should
extend at least 3 ft. from the air handler before turning or
branching off plenum into duct runs. The plenum forms
an extension of the blower housing and minimizes air
expansion losses from the blower.
Filters
A filter is provided. Table 3 lists the filter size for each unit.
Model
Filter Size – in.
-018, -024, -030
15" x 20" x 1"
-036, -042, -048, -060
18" x 20" x 1"
Table 3. Unit Air Filter Size Chart
If a high efficiency filter is being installed as part of this
system to ensure better indoor air quality, the filter must
be properly sized. High efficiency filters have a higher
static pressure drop than standard efficiency glass/foam
filters. If the pressure drop is too great, system capacity
and performance may be reduced. The pressure drop
may also cause the limit to trip more frequently during
the winter and the indoor coil to freeze in the summer,
resulting in an increase in the number of service
calls. Before using any filter with this system, check
the specifications provided by the filter manufacturer
against the data given in the appropriate Product
Specifications. Additional information is provided in
Service and Application Note ACC002 (August 2000).
IMPORTANT
Installing Duct System
Connect supply air duct to the flange on top of the air
handler. If an isolation connector is used, it must be
nonflammable.
Field-Fabricated Return Air Duct Flange for
Horizontal Applications
A return air duct system is recommended, but not factory-
provided. If the unit is installed in a confined space or
closet, run a full-size return connection to a location outside
the closet.
BOTTOM OF
CABINET
DUCT
ADAPTER
1−1/2
(38)
”A”
BRAKE DOWN 90 DEGREES
1/4 (6) DIA.
2−HOLES
"A"
1−1/2(38)
3/4
(19)
3/4
(19)
1−1/2
(38)
3/4
(19)
1/2
(13)
3/4
(19)
DUCT
FLANGE
CABINET
DOOR FLANGE
UNIT SIZE
Cabinet and Duct Flange
-018, -024,
-030
-036, -042,
-048, -060
18-3/8"
21-1/2"
Figure 9. Cabinet and Duct Flange
Brazing Refrigerant Lines
Refrigerant lines must be connected by a qualified
technician in accordance with established procedures.
Refrigerant lines must be clean, dry, refrigerant-grade
copper lines. Air handler coils should be installed
only with specified line sizes for approved system
combinations.
Handle the refrigerant lines gently during the installation
process. Sharp bends or kinks in the lines will cause a
restriction.
Do not remove the caps from the lines or system
connection points until connections are ready to be
completed.
IMPORTANT
