Duct System And Filters - Lennox Merit CBA25UHE Installation Instructions Manual

Air handler units
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INSTALL CONDENSATE DRAIN
The air handler is provided with 3/4" NPT condensate
drain connections.
IMPORTANT
Confirm primary and secondary drains are open.
1 - CBA25UHE units are equipped with a drain pan,
which includes green (main drain) and red (secondary
drain) plugs. Unscrew the plugs to remove them
before inserting condensate drain fittings.
ALL CBA25UHE MODELS
UNSCREW PLUGS
AND CONNECT
PROPERLY SIZED
FIELD-PROVIDED
FITTINGS AND
DRAIN LINES.
RED SECONDARY
DRAIN PAN
FIGURE 8. Drain Line Connections
2 - Install properly sized, field-provided connection
fittings and connect primary drain line to the main
drain pan connection.
NOTE - When installing drain line connection fittings to
the drain pan, hand tighten the fitting and use a thread
sealant. Over-tightening the fittings can split connections
on the drain pan.
3 - If the secondary drain line is to be used, remove the
plug or the knockout and route the drain line so that
water draining from the outlet will be easily noticed
by the homeowner. Refer to local codes for drain
trap requirements on the secondary drain line.
4 - Check again to ensure drain ports and drain pan
are free of all debris.
5 - Plug and check any unused drain pan openings for
tightness. Torque plugs to 30 in. lb. to prevent water
leaks or seepage from the drain pan.
6 - Install a 2" trap in the main (primary) drain lines as
close to the unit as practical (see figure 6). Make
sure the top of the trap is below the connection to
the drain pan to allow complete drainage of the pan.
NOTE - Horizontal runs must have an anti-siphon air vent
(standpipe) installed ahead of the horizontal run. See fig-
ure 6. An extremely long horizontal run may require an
oversized drain line to eliminate air traps.
NOTE - Do not operate air handler without a trap in the
main (primary) drain. The condensate drain is on the
negative pressure side of the blower; therefore, air being
pulled through the condensate line will not allow positive
drainage without a proper trap.
7 - Route the drain line to the outside or to an
appropriate drain. Drain lines must be installed so
they do not block service access to the front of the
air handler. A 24" clearance is required for filter, coil,
or blower removal and service access.
GREEN MAIN
DRAIN PLUG
DRAIN PLUG
NOTE - Check local codes before connecting the drain
line to an existing drainage system. Insulate the drain
lines where sweating could cause water damage.
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 be
draining completely. Drain line fittings must not be
leaking. Water must be draining 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 con-
ditioned 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 ex-
tend 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 expan-
sion 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
CBA25UHE
-024, -030
-036, -042
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. Before using any
filter with this system, check the specifications provided
by the filter manufacturer against the data given in the
appropriate Lennox Product Specifications bulletin.
Additional information is provided in Service and
Application Note ACC002 (August 2000)..
Page 9
Filter Size – In.
15" x 20" x 1"
18" x 20" x 1"
IMPORTANT

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Merit seriesCba25uheCba25uh

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