Main trunk line with flexible duct runs to the. A duct boot is a component of a ventilation system whose function is for convertingductwork to a vent for proper ventilation of a room. Why Are There Water Stains On My Ceiling Around The Ac Vents Advanced Air Duct Insulation Central Air Conditioners Air Conditioner Ducts Pre- drill 18 holes on the vent boot to attach it to the subfloor makes it easier later. . Used as the transition from round pipe to the register opening on forced air duct systems our torpedo boots turn a parallel 90 degree from the pipe to the register. Click to see full answer. After refrigerant lines have been installed they should be evacuated to a pressure of. These airflow volumes are then used to size and lay out the ducts. FREE Shipping by Amazon. Cover boot with insulation. Department of Energy Standard Work Specifications for. Click to see full answer. Apply mastic or metal tape t...