LCEC – Lee County Electric Cooperative

Are your ducts in a row?

Research shows that that duct leaks account for 20 to 60 percent of all air exchange in new and old homes. Conditioned air can easily escape through leaky ducts resulting in unconditioned air being drawn into the home. There are several ways to identify leaky ducts, but most duct leaks are readily identified through close visual inspection of the ductwork and occur within 10 feet of the air handler, the area of the duct system exposed to the highest levels of vibration, pressure, humidity and temperature difference. Depending on the condition of the ducts, you may need to consider either duct repair cleaning.

Duct repairs can be made using metal foil duct tape or mastic adhesive.

Metal foil tape:
• Most duct leaks, regardless of the type of duct, can be repaired using metal foil duct tape.
• Metal foil tape must be burnished or rubbed down with a plastic putty knife or an old credit card. If this step is neglected, the tape will loosen quickly, and the leak will return.
• All tape must be applied to clean, dry surfaces.
• Use caution as the edges of this tape can cut skin.

Mastic adhesive:
• A more permanent method of duct repair.
• A thick latex paste, usually reinforced with chopped fiberglass, that is applied in a thick coat over potential and existing leaks.
• Will not fill large cracks or voids. They must first be taped shut and then reinforced with mastic.
• Once properly sealed with mastic, potential and existing leaks are permanently repaired.

Duct-cleaning can cost as much, if not more, than replacing air ducts. Check out the Energy Efficiency tab on lcec.net for information on cleaning air ducts, types of air ducts and more.