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ABOVE
FINISHED
SPACE?
OVERFLOW DRAIN LINE
ALWAYS RUN AN OVERFLOW DRAIN LINE. IF NOT POSSIBLE TO
ROUTE OVERFLOW DRAIN LINE, INSTALL LOW VOLTAGE
OVERFLOW SWITCH KIT. WIRE KIT TO SHUT DOWN
COMPRESSOR PER INSTRUCTIONS.
NO
YES
LENNOX #
X3169
CLEAN OUT
VENT
PRESS IN
(DO NOT GLUE)
VENT MUST EXTEND
ABOVE HEIGHT OF
COIL DRAIN PAN BY
TWO INCHES (51MM)
1" X 3/4" X 3/4"
REDUCING
TEE WITH
PLUG
LENNOX* P−TRAP
49P66, J−TRAP #
91P90 OR ANY
PVC SCH 40 P− OR
J−TRAP 3/4"
OVERFLOW
DRAIN
OPTIONAL
SAFETY
PAN
AIR HANDLER DRAIN PAN
WHEN A COIL IS LOCATED ABOVE A FINISHED SPACE, A 3/4" (19.1MM) SECONDARY DRAIN
LINE MUST BE:
S
CONNECTED TO SECONDARY DRAIN PAN
OR
S
CONNECTED TO THE OVERFLOW DRAIN OUTLET OF THE AIR HANDLER DRAIN PAN.
TRAPS MUST BE DEEP ENOUGH TO OFFSET MAXIMUM STATIC DIFFERENCES
GENERALLY, TWO INCHES (51MM).
DRAIN LINE SHOULD
SLOPE A MINIMUM OF
ONE INCH PER 10
FEET (25MM PER 3
METERS)
NOTE
WHEN A AIR HANDLER IS LOCATED ABOVE A FINISHED SPACE THE SECONDARY
DRAIN PAN MUST HAVE A LARGER FOOTPRINT THAN THE AIR HANDLER.
MAIN
DRAIN
TO APPROVED
DRAIN
FOR NEGATIVE PRESSURE COILS (BLOWER
AFTER COIL) TRAPS ARE REQUIRED ON ALL
DRAIN LINES CONNECTED TO COIL.
COMPACT OVERFLOW SWITCH WITH 3/4" FEMALE SLIP INLET
AND MALE ADAPTER, TWO PART DESIGN FOR USE WHERE
OBSTRUCTIONS PREVENT DIRECT THREADING
SECONDARY
DRAIN PAN
2"
(51MM)
TRAP DEPTH
*LENNOX P−TRAP 49P66 REQUIRES A LARGER INSTALLATION SPACE THAN THE J−TRAP 91P90.
Figure 13. Typical Main and Overflow Drain Installations
Inspecting and Replacing Filters
IMPORTANT
Filter access door must be in place during unit operation.
Excessive warm air entering the unit from unconditioned
space may result in water blow−off problems.
Filters may be duct−mounted or installed in the cabinet. A
filter is installed at the factory. Note that filter access door
fits over access panel. Air will leak if the access panel is
placed over the filter door.
Filters should be inspected monthly and must be cleaned
or replaced when dirty to assure proper furnace operation.
To replace filter:
1. Loosen the thumbscrews holding the filter panel in
place.
2. Slide the filter out of the guides on either side of
cabinet.
3. Insert new filter.
4. Replace panel.
See table 4 for replacement filter sizes.
Table 4. Filter Dimensions
Unit Model No.
Filter Size Inches (mm)
−018/024
15 X 20 x 1(381 x 508 x 25)
−024/030
20 x 20 x 1(508 x 508 x 25)
−036
20 x 20 x 1(508 x 508 x 25)
−048 and −060
20 x 24 x 1(508 x 610 x 25)
−068
20 x 25 x 1(508 x 635 x 25)
Sealing the Unit
WARNING
There must be an airtight seal between the bottom of the
air handler and the return air plenum. Use fiberglass
sealing strips, caulking, or equivalent sealing method
between the plenum and the air handler cabinet to
ensure a tight seal. Return air must not be drawn from a
room where this air handler or any gas−fueled appliance
(i.e., water heater), or carbon monoxide−producing
device (i.e., wood fireplace) is installed.
