Leaky ductwork is one of the biggest hidden energy wasters in homes with forced-air HVAC systems. The Department of Energy estimates that a typical home loses 20 to 30 percent of conditioned air through duct leaks, cracks, and poor connections. In New York City, where energy costs are high and many buildings have aging duct systems, sealing these leaks can significantly reduce your utility bills and improve comfort in every room. Duct leaks also pull in unconditioned air from attics, basements, and wall cavities, introducing dust, allergens, and potentially harmful contaminants into your living space. Checking for leaks is a straightforward process that any homeowner can do.
Set your system to fan on mode so the blower runs continuously without heating or cooling. This pressurizes the ductwork and makes leaks easier to detect without dealing with hot or cold air.
Examine all accessible ductwork in basements, attics, utility rooms, and crawl spaces. Look for obvious gaps at joints, disconnected sections, or crushed flexible ducts. These large leaks are the easiest to find and fix.
Run your hand along duct joints and seams while the blower is running. You will feel escaping air at leak points. Pay special attention to connections at the air handler, branch takeoffs, and where ducts pass through walls or floors.
Hold a lit incense stick near duct joints and seams. Watch the smoke trail. If it blows away from the duct or gets sucked toward it on the return side, there is a leak at that point. Mark each leak location with tape for sealing.
Apply duct mastic sealant with a brush or putty knife over all identified leak points. For larger gaps, use fiberglass mesh tape with mastic over it. Use UL-listed metal foil tape for temporary fixes. Never use standard cloth duct tape as it dries out and fails within a year.
If your ducts are mostly inaccessible behind walls or ceilings, or if you suspect major leaks causing significant energy loss, hire a professional for a duct leakage test using calibrated equipment. They can measure total leakage and seal ducts from the inside using aerosol sealant technology.
Call (646) 439-4057Despite the name, standard cloth duct tape is a poor choice for ductwork. It dries out and falls off within months. Use duct mastic sealant or UL-listed metal foil tape for lasting repairs.
Sealing duct leaks typically saves 10 to 30 percent on heating and cooling costs. In a NYC home spending 3000 dollars annually on HVAC energy, that translates to 300 to 900 dollars in savings per year.
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