Installation, Operation and Maintenance Manual
Page
23
of
100
3.7.1
Condensate Trap
Probably the most misunderstood portion of a condensate drain system is trap installation. The primary purpose of
a condensate trap is to prevent air from being drawn back into the unit during operation. Traps must be installed in
a manner that will stop the air from passing through, but still allow the condensate to drain from the condensate
pan.
Therefore, a factory supplied trap (field installed on ceiling units and factory installed of floor units) must be installed
into the ceiling unit drain system external of the evaporator section. To eliminate air trapping, an air vent must be
used to allow air to exit. Venting the drain after the first trap is recommended.
Figure 8 - Recommended Condensate Trap Dimensions shows the recommended dimensions for fabricating a
proper trap, when required to be field fabricated:
Figure 8 - Recommended Condensate Trap Dimensions
Notes:
1.
This trap is capable of handling static pressures equal to 4” H2O which is the maximum static available for
ceiling units. If the unit fans are standard, there is no need to consider different dimensions but if higher
total static pressure is expected, more vertical drop is required.
2.
Some applications have no convenient means of allowing a gravity drain. In this case, a condensate pump
can be used. These come either factory mounted with the side mounting kit option or shipped loose.
Factory mounted condensate pumps do not require a separate power source.
3.
Condensate pumps that ship loose or are field provided, typically require a dedicated 110-volt power
source. Field pipe connections must be made to the pump discharge connection. A check valve (field
supplied?) must be installed to prevent short cycling. Pumps must be located below the condensate drain
pan level.
