
Your heating and cooling system relies on your HVAC ductwork to reach top efficiency. Holes in your ducts can let warm and cool air escape, compromising your whole system's efficiency.
Worse yet, holes draw air contaminants, such as dust, mold spores, insulation fibers and chemical fumes into your home's air, compromising your family's indoor air quality. Repairing damage to your ducts is a simple project that benefits your bank account and your health.
First, the whole circumference of your ductwork should be washed with soapy water, rinsed thoroughly and allowed to dry completely. You can then seal the duct hole with Underwriters Laboratory (UL) 181 foil-backed tape. This tape is safe to use under high-heat conditions. Any tape that's not approved for use on ductwork pose a smoke and fire hazard. Pull out a 6-inch strip of tape, stick the edge just above one side of the hole and wrap the tape around the duct. When you come back to your starting point, slightly overlap the tape and make another pass around the duct. Continue this until the entire hole is covered.
After cleaning the duct, measure the hole's height and width before adding one inch to both measurements. With a marker, mark off these measurements on a section of 26-gauge sheet metal and cut out the section with sheet metal shears. Lay the sheet metal patch over the hole. If you're patching a sheet metal duct, use a power screwdriver to drive a #10 self-tapping sheet metal screw into each corner of the patch. For a fiberboard duct, secure the patch with a strip of foil tape along each side. Finally, run a bead of silicone caulk around the edges of the patch to prevent air leaks.
To further improve the efficiency of your HVAC ductwork, ensure the joints are secure and sealed with mastic or foil-backed tape and that ducts in unconditioned areas are insulated.