DuraVent FasNSeal Single Wall Increaser Wye: joins a smaller boiler outlet to a larger shared vent
The DuraVent FasNSeal Single Wall Increaser Wye is a stainless steel vent fitting with a smaller side branch that joins the main run at a 45 degree angle. It connects a smaller boiler outlet to a larger shared vent in one fitting. Boilers can share that vent only when the appliance maker allows it. The branch can be up to 6 inches smaller than the main run. FasNSeal is DuraVent’s stainless steel vent for high efficiency gas boilers, furnaces, and water heaters, built to carry pressurized exhaust and its acidic condensate outside. Condensate is the liquid that collects as the exhaust cools.
Choose the branch and main run size combination on this page, from 6 by 8 inch to 12 by 14 inch. Each part has a gasket and a built in locking band at its wider end to seal and hold the connection. This wye has a locking band on its branch, too. Each joint takes up 2 inches of pipe length, which matters when planning the run. Need the double wall version? See the DuraVent FasNSeal W2 Double Wall Increaser Wye. The DuraVent FasNSeal Single Wall Increaser Wye ships free from My Cozy Outdoors with No Sales Tax (except WY) and the full manufacturer warranty.












Commercial projects may require custom parts and unique system designs. Duravent offers complete project assistance:








































