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Instructions for when and how to use The Duct Plug

The Duct Plug Squeezing the plug to be installed


The Duct Plug is a reusable tool for sealing supply & return boots for Duct Pressurization Testing. It’s designed to be used in the rough-in stage of building construction before drywall is installed, or in the final stages of construction in ceiling & wall vents (best if used before register grills are screwed into place) or on non-secured floor vents at any stage after the HVAC system has been installed and sealed.


A visual inspection should be performed of the supply or return boot before installing and using The Duct Plug. This inspection should ensure that all seams in the HVAC boot have been properly sealed with Mastic or approved material for air sealing. If boot has drywall, flooring or any other material installed around the boot then joints between the boot and surrounding material should be properly sealed with caulk, mastic, foam or approved method for sealing joints and gaps. If any unsealed gaps or joints are observed in or around the boot, then it is recommended to not use The Duct Plug and instead use approved taping methods on those boots. Confirming these areas are properly sealed will insure accurate air leakage test results.


To use The Duct Plug, remove any installed register grills, compress the foam plug by squeezing it with your hand and insert plug into the collar of the metal boot and release. The foam plug will expand and seal itself into place creating an airtight seal. It is recommended to only install the foam plug in the metal boot collar and not the flex duct. The metal boot collar does not need to be a perfect circle, the foam plug will seal in oval and oblong collars effectively.