Lennox MWMA009S4-*L, Service Manual

Page: 79 / 168

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MAIN DRAIN
(Sloped at 1/4” per foot AWAY from unit and should
be supported as needed to prevent sagging.)
INDIVIDUAL DRAIN OUTLET FROM EACH INDOOR UNIT
Indoor
Unit
Indoor
Unit
Indoor
Unit
Figure 52. Condensate Drain Multiple Indoor Units Suspended from Ceiling Using a Single Properly Sloped
Gravity Drain
14.3. Indoor Unit Lift Pump
14.3.1. Condensate Piping Requirements - MMDA and M22A/M33A/M33B
14.3.1.1 MMDA
CAUTION
Make sure that drain piping is properly routed and insulated in order to prevent both leaks and condensation.
IMPORTANT
Drain should have a slope of at least ¼ inch per foot and should be approved corrosion-resistant pipe. You must confirm
operation of every drain and pump in the system as part of the commissioning procedure.
1. Use a field-provided hose clamp to secure the drain line stub on the side of the unit chassis to a field-supplied 1” (25
mm) drain line. See figure below.
NOTE: Take care not to over-tighten the hose clamps this may damage the drain line stub.
INSULATION
INDOOR
UNIT
CONDENSATE
LINE STUB
HOSE CLAMP
FLEXIBLE DRAIN
CONNECTOR
PVC DRAIN
PIPE
Figure 53. Condensate Piping Connection
2. Make a water-tight connection between the field-provided condensate drain line and the flexible condensate connector.
Use 1-1/2” OD / 1-1/4” ID PVC pipe for the drain line.
3. See figure for applications including an indoor unit using the internal drain pump.
4. In all cases, drain should be as short as possible and should not have any droops or kinks that would restrict condensate
flow and shall be constructed using an approved pipe. There must be a 2-inch (51 mm) space between the end of
the condensate drain and the final termination point (ground, open drain, etc.) to ensure that the line will drain
freely.