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2.8. MMDB Indoor Unit Gravity Drain
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.
Make a water-tight connection between the field-provided condensate drain extension and the provided flexible drain
piping.
2.
Confirm proper slope (not less than 1/4 inch per foot) and routing of condensate lines to ensure moisture is drained away
from the indoor unit.
3.
Drain should be as short as possible and should not have any droops or kinks that would restrict condensate flow and
shall be approved resistant pipe. There must be a 2-inch 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.
4.
After the system installation is complete, the condensate drain line must be checked for leaks and proper drainage. If a
field-provided condensate pump has been installed, it must be checked to ensure proper operation. This check is part of
the commissioning sequence.
DRAIN LINE
3 ft. (1 m)
SUPPORT
STRAPS
Slope at least 1/4”
per foot
Indoor Unit
Figure 9. Single Indoor Unit Suspended from Ceiling using a Properly Sloped Gravity Drain
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 10. Condensate Drain Multiple Indoor Units Suspended from Ceiling Using a Single Properly Sloped
Gravity Drain
