Lennox CBX25UH Series Installation And Service Procedure page 14

On units of this type, where the blower "draws" rather than "blows" air through the coil, traps must be installed in the con­
densate drain lines (primary and auxiliary, if used). Traps prevent the blower from drawing air through the drain lines into
the air supply.
CONDENSATE DRAIN
ABOVE
ALWAYS RUN AN OVERFLOW DRAIN LINE. IF NOT POSSIBLE TO
FINISHED
ROUTE OVERFLOW DRAIN LINE, INSTALL LOW VOLTAGE
SPACE?
OVERFLOW
COMPRESSOR PER INSTRUCTIONS.
COMPACT OVERFLOW SWITCH WITH 3/4" FEMALE SLIP INLET
NO
AND MALE ADAPTER, TWO PART DESIGN FOR USE WHERE
OBSTRUCTIONS PREVENT DIRECT THREADING
OVERFLOW
DRAIN
YES
NOTE — WHEN A AIR HANDLER IS LOCATED
ABOVE A FINISHED SPACE THE SECONDARY
DRAIN PAN MUST HAVE A LARGER FOOTPRINT
THAN THE AIR HANDLER.
SECONDARY
DRAIN PAN
TRAPS MUST BE DEEP ENOUGH TO OFFSET MAXIMUM STATIC DIFFERENCES —
GENERALLY, TWO INCHES (51MM).
1
LENNOX P-TRAP 49P66 REQUIRES A LARGER INSTALLATION SPACE THAN THE J-TRAP 91P90.
2
PIPE NIPPLE PROVIDED IN BAG ASSEMBLY - SCH 80, 3/4" I. D. X 5" - 34K7401 (1): CUT THE PIPE
IN HALF AND USE IT TO ROUTE THE MAIN DRAIN.
IMPORTANT
A field-fabricated secondary drain pan, with a drain pipe
to the outside of the building, is required in all installations
over a finished living space or in any area that may be
damaged by overflow from the main drain pan. In some
localities, local codes may require a secondary drain pan
for any horizontal installation.
The air handler is provided with ¾" NPT condensate drain
connections.
SLOPING THE DRAIN
Make sure the unit is sloped (similar to the slope shown in
figure 25) (horizontal or upflow) so that the drain pan will
empty completely without water standing in the pan.
IMPORTANT
OVERFLOW DRAIN LINE
SWITCH KIT. WIRE KIT TO
LENNOX #
X3169
MAIN
AIR HANDLER DRAIN PAN
DRAIN
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.
Figure 24. Typical Main and Overflow Drain
VENT MUST EXTEND
SHUT DOWN
ABOVE HEIGHT OF
COIL DRAIN PAN BY
TWO INCHES (51MM)
CLEAN OUT
PRESS IN
(DO NOT GLUE)
1" X 3/4" X 3/4"
REDUCING
TEE WITH
LENNOX
49P66, J-TRAP #
91P90 OR ANY
PVC SCH 40 P- OR
J-TRAP 3/4"
FOR NEGATIVE PRESSURE COILS (BLOWER
AFTER COIL) TRAPS ARE REQUIRED ON ALL
DRAIN LINES CONNECTED TO COIL.
THIS CORNER SHOULD BE 5/8" (+/- 1/8") HIGHER
THAN DRAIN CORNER
DRAIN CORNER
Figure 25. Sloping the Drain
Page 14
VENT
PLUG
1
P-TRAP
2"
(51MM)
TRAP DEPTH
DRAIN LINE SHOULD
SLOPE A MINIMUM OF
ONE INCH PER 10
FEET (25MM PER 3
METERS)
THIS CORNER SHOULD BE
5/8" (+/- 1/8") HIGHER THAN
DRAIN CORNER
TO APPROVED
DRAIN