My Air Conditioner Ducts Are Leaking Water

If you find water spots on your ceiling or water on the floor of your basement, look to see if the water is coming from air conditioning ducts.
If your ducts are uninsulated and you notice moisture on the surface of the ducts, the problem is condensation. This is not an internal problem with the system. The cause is the cool air flowing through the ducts drops the surface temperature of the sheet metal below the dewpoint of the surrounding air. Once this happens, water condensates out of the air, builds up on the ducts and eventually drips off. Fixing this problem is as simple as installing a insulating layer of duct wrap around all the ducts in question.

Step 1

Measure the distance around the outside of the duct (perimeter). Write this measurement down.

Step 2

Measure the thickness of the duct insulation you will be using. Multiply this thickness by four (to account for a layer on each side of the duct). Add this measurement to the perimeter measurement above.

Step 3

Cut a piece of duct insulation at the measurement you calculated in Step 2. Wrap it around the duct; pull it tight.

Step 4

Tape the entire length of the seam with foil tape. Press the tape down firmly to ensure it does not pull off. This will secure the duct insulation to the duct.

Step 5

Cut the next piece of insulation and install in the same manner. Tape the seam where the two pieces of insulation meet with foil tape. This ensures a seamless length of insulation. Continue until all the ducts are insulated.

Things You Will Need

  • Tape measure
  • Duct insulation
  • Utility knife
  • Foil tape