Air Handler Drain Pans and Indoor Air Quality

  May 11, 2011

Keep air handler drain pans dry. Many older drain pan designs were not pitched toward the outlet, so complete drainage isn't assured. Water left standing in the pan is an excellent breeding site for microbial growth. Since the drain pan is located in the supply air stream, these contaminants are readily distributed throughout the building.

The best remedy for a flat drain pan is to replace it with one that is pitched. If that's not possible, add an insert inside the existing drain pan to provide the required pitch. In either case, make sure the new pan or insert is well sealed and doesn't leak inside the air handler. As a further precaution, apply an antimicrobial coating to reduce the potential for microbial growth.

While you're considering drain pans, take a look at the interior insulation in the air handling and rooftop units. Be sure to prevent the insulation from coming in contact with condensate water.

The internal insulation for an air handling or rooftop unit is often installed so that it comes in contact with the condensate pan. In the event that internal insulation becomes contaminated with water, the insulation should be replaced and measures should be taken to prevent future contamination.


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