Sealing Air Duct Leaks

Ductwork is the collection of tubes that distribute conditioned air throughout your home. Studies show that ductwork leaks waste between 20 and 40 percent of your cooling and heating dollars. Some ways that ductwork loses energy are through conduction of heat through the duct walls, leakage of heated air into and out of ducts, and infiltration, or imbalances in pressure caused by faulty air ducts.

Methods for finding air duct leaks depend on the kind of duct which is leaking. Supply duct leaks blow air out, and return duct leaks draw air in. Once a trained technician determines the kind of duct, he can perform a few quick tests to find out where your air ducts are leaking.

Once your leak is found, the technician should repair the larger holes first. It is important that a quality adhesive is used. It is also important that the repair materials will last as long as the duct itself. Cloth and metal duct tapes are not recommended because they do not have quality adhesives.

Recommended duct sealing materials include UL-181 duct sealing mastic, UL-181 tape, and high quality caulking or foam sealant. Mastic can be purchased in tubs or tubes and requires little preparation. Your trained technician will know how to prepare the mastic.

For large gaps, the technician should use a backing before applying the mastic. Fiberglass mesh tape works well, but be sure he uses a tape that will not lose its seal.

If you suspect you have a leaky air duct call for a complete air conditioning system evaluation by one of our trained technicians.