How to Replace AC Vent Insulation

Prepare for insulating the AC vents by donning the appropriate protective gear, including gloves, safety glasses and a dust mask. You should also wear long sleeves and pants to protect from irritation caused by the insulation.

Access the area where the AC vent ducts are, using a ladder if needed so you can reach them easily.

Cut off all the old insulation from around the vent duct by finding the foil tape and slicing through it using a utility knife. Once you slit the tape, pull the insulation off the duct. Use caution as you slit the tape so as not to damage the underlying air vent.

Measure the diameter of the vent duct by wrapping a tape measure around it. Note the measurement and cut strips of fiberglass batt insulation to the same length using scissors or a utility knife.

Wrap a strip of the insulation around the vent duct with the two free edges meeting at the bottom.

Wrap a piece of foil based-tape around the insulation at 12-inch intervals to hold it to the duct. Apply another strip along the bottom edge of the insulation to seal the seam where the two edges meet.

Move down to the next section of the vent and wrap another piece of insulation around it, overlapping the first piece by at least 1 to 2 inches so there are no gaps.

Wrap more foil tape around the second piece of insulation, spacing each piece at 12-inch intervals as well. Seal the bottom seam with additional tape.

Continue wrapping the AC vent duct with batt insulation strips until you reach the other end and no portion of it remains exposed.