How to Seal HVAC Ducts
Air leakage causes your air conditioning system to work harder to provide properly conditioned air to the rooms of your home. Sealing the metal HVAC ducts will improve the efficiency of your HVAC unit and lower your monthly utility bills. There are a number of sealants available, but water-based sealants are easier to apply to the ductwork, produce less fumes, and clean up easier than their solvent-based counterparts. Using a water-based duct sealer housed in a bucket will result in less wasted product and provide you more control during the sealer application. Does this Spark an idea?
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Things You'll Need
- Clean rags
- A bucket of water-based duct sealer
- Two-inch paintbrush
- Small bucket of water
- Flashlight
- Duct tape
- Permanent marker
Instructions
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1
Turn off the air conditioning unit. Wipe the down the longitudinal seams and connections of the ductwork with a clean rag.
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2
Load the lower third of the paint brush bristles with duct sealer.
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3
Apply a thick coat of duct sealer around the first duct connection. Reload the paint brush as necessary to keep the coating of duct sealer heavy.
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4
Seal along the longitudinal seam of the duct. Make a full-brush-width path of duct sealer on both sides of the seam.
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5
Apply duct sealer around each screw as you work your way along the duct line.
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6
Run a full two-inch path of duct sealer around taps that come off the duct.
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7
Place the paint brush into the bucket of water when every seam, connection, and screw is sealed. Allow the duct sealer to cure.
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8
Remove the paint brush from the water. Dry the brush slightly.
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9
Inspect the connections, seams, and screws that you sealed earlier by shining the flashlight along the edges. Apply additional sealer to any area through which you see light spots or voids. Place the paintbrush back in the water after you complete the inspection. Allow the sealer to dry for 24 hours.
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10
Wrap duct tape around the flex duct, where the flex duct meets the tap.
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11
Turn on the air conditioning unit. Run your hand along all connections, seams, and screws to feel for air leakage. Using a permanent marker, mark areas where you feel air leaking.
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12
Shut down the air conditioner unit. Apply duct sealer to any areas that you marked with the permanent marker in step 11.
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