Duct System And Filters; Brazing Refrigerant Lines; Test Condensate Drain; Field-Fabricated Return Air Duct Flange For Horizontal Applications - Lennox Merit CBX25UHV Installation Instructions Manual

TEST CONDENSATE DRAIN

Test the drain pan and drain line after installation:
1 - Pour several quarts of water into drain pan. Use
enough water to fill both the drain trap and the line.
2 - Check the installed drain pan. Drain pan must drain
completely. Drain line fittings must not leak. Water
must drain from the end of the primary drain line.
3 - Correct any leaks found.

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 1 lists the filter size for each unit.
Table 1. Unit Air Filter Size Chart
Model
-018 12" x 20" x 1
-024 and -030 15" x 20" x 1
-036 18" x 20" x 1
-042, -048 and -060 18" x 24" x 1
IMPORTANT
If a high­efficiency filter is being installed as part of this
system to ensure better indoor air quality, the filter must
be properly sized. High­efficiency filters have a higher
static pressure drop than standard­efficiency 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, result­
ing in an increase in the number of service calls.
Before using any filter with this system, check the spe­
cifications provided by the filter manufacturer against the
data given in the appropriate Lennox Product Specifica­
tions bulletin. Additional information is provided in Ser­
vice and Application Note ACC­00­2 (August 2000).
Actual Minimum
Filter Size
Filter Size
11.50" x 19.50" x .75"
14.50" x 19.50" x .75"
17.50" x 19.50" x .75"
17.50" x 23.50" x .75"
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.
Cabinet and Duct Flange
CABINET
DOOR FLANGE
1−1/2
(38)
DUCT
FLANGE
3/4
(19)
1−1/2(38)
1/2
(13)
−024 & −030 18−3/8 (467)
−036 to −060 21−3/4 (552)
Figure 17. 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 combina­
tions.
Handle the refrigerant lines gently during the installation
process. Sharp bends or kinks in the lines will cause a
restriction.
Page 10
3/4
(19)
3/4
(19)
"A"
BRAKE DOWN 90 DEGREES
1/4 (6) DIA.
2−HOLES
"A"
UNIT SIZE
−018 14−7/8 (378)
IMPORTANT
BOTTOM OF
CABINET
DUCT
ADAPTER
3/4
(19)
1−1/2
(38)