How do I seal up leaky vent holes in my Aluminum ducts?

You can seal any holes in your ducts or loose connections, or leaky corner joints with either aluminum foil tape, mastic sealant tape or duct mastic sealant using a paint brush, putty knife or caulking gun (along with fiber glass dry wall tape for even better seal). You may also need to use sheet metal screws to connect ducts together or sheet metal nails to attach to joists.

For big holes you can use spray foam like Handi Foam Insulation , Great Stuff Gaps & Cracks, Weatherstripping Caulk or Caulk.

Keep in mind, aluminum foil tape (or HVAC tape / metal duct tape), is not like traditional, cloth-backed, rubber duct tape.

Depending on your duct work needs, these sealants will be long-lasting and provide the needed sealing strength in order to prevent unnecessary leakages over the long-term, thus saving you money on your heating and cooling bills.