Every summer, thousands of air conditioning drain pans in the southern U.S. overflow due to a preventable clog at the condensate pan drain line. If the air handler is located in an attic, most homeowners will realize that they have an issue once it is too late and water starts dripping through the ceiling. If caught quickly, this can be remedied quite nicely. If the condensate pan has been overflowing for several days, however, wet insulation and mold growth on sheetrock and framing can be the result. An insurance claim and professional clean-up could be needed at this point.
The best approach is to check your drain pans twice a year – once near the beginning of summer cooling season and again in August or September when your systems are working overtime to help keep your home comfortable. Whether you do this yourself or hire an HVAC contractor to check for you, here are a few things to look for:
• the condensate drain pan is located directly underneath the air handler. It may have some dampness in summer as moisture is condensing out of the air and dropping into the pan to be exited outdoors
• a pan full of water is not good and an indication that the condensate drain line is clogged
• the line is most commonly clogged with sludge or pieces of insulation, although the clog can occur at an elbow joint or at the termination point outdoors. We sometimes find the line has become buried in landscaping mulch or dirt that prevents a proper flow
To maintain a free-flowing drain line, remove any standing water or sludge from the pan using a wet/dry vac. Compressed air may be used to blow out the line, or you may use a hose to carefully blow out the line. Most clogs will occur at an elbow joint where the line exits the foundation, so you may need to pull the joint apart and let the clog out. Pouring some hot water down the line a couple of times each year will also help keep the line clean.
We like to see the drain line termination point several inches above the ground and away from the foundation so the condensate flows away from the house.
One last thought – drain pans with standing water can harbor some harmful bacteria, including Legionella. If the pan has water in it, we advise wearing respiratory protection. The danger is in breathing the water droplets, not from skin contact.