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MERIT
®
CBX25UHV SERIES
IMPORTANT
On units of this type, the blower “draws” rather than “blows” air through the coil. A trap must be installed in the primary
(main) condensate drain line. The trap prevents the blower from drawing air through the drain lines into the air supply.
ABOVE
FINISHED
SPACE?
SECONDARY (OVERFLOW) DRAIN LINE
ALWAYS RUN A SECONDARY (OVERFLOW) DRAIN LINE. IF NOT
POSSIBLE, 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
1
P-TRAP
49P66, J-TRAP #
91P90 OR ANY
PVC SCH 40 P- OR
J-TRAP 3/4”
AIR HANDLER DRAIN PAN
WHEN A COIL IS LOCATED ABOVE A FINISHED
SPACE, A 3/4” (19.1MM) SECONDARY DRAIN LINE
MUST BE:
●
CONNECTED TO SECONDARY DRAIN PAN
OR
●
CONNECTED TO THE SECONDARY
(OVERFLOW) DRAIN OUTLET OF THE AIR
HANDLER DRAIN PAN.
TRAP 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 AN 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), A TRAP IS REQUIRED ON THE
MAIN DRAIN LINE CONNECTED TO COIL.
SEE LOCAL CODES FOR TRAP REQUIRE
MENTS ON SECONDARY DRAINS.
USE TWO-PART 3/4” FEMALE SLIP INLET AND MALE ADAPTER
WHEN OBSTRUCTIONS PREVENT DIRECT THREADING OF
OVERFLOW SWITCH.
SECONDARY
DRAIN PAN
2”
(51MM)
TRAP DEPTH
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.
Figure 16. Typical Main and Overflow Drain
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 16). 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 figure 16. 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.
NOTE
- Check local codes before connecting the drain
line to an existing drainage system.
Insulate the drain lines where sweating could cause water
damage.
