DuraVent FasNSeal Tapered Reducer: a gradual step down to a smaller vent
The DuraVent FasNSeal Tapered Reducer is a cone shaped stainless steel fitting that connects a larger appliance outlet to a smaller vent. Its tapered sides narrow the exhaust passage gradually rather than making an abrupt change. The sizes on this page each step down one size. 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. Choose a 4 to 3 inch or 5 to 4 inch reducer to match the connection. Reductions in this single wall system cannot exceed 2 inches.
The surrounding pipe needs the right slope and support. Horizontal sections must rise away from the appliance at least 1/4 inch per foot, letting condensed liquid flow back toward the drain. The pipe cannot carry its own weight. Horizontal sections need hangers every 6 feet. Wall brackets support vertical sections every 12 feet, after an offset, and where a turn upward is followed by more than 10 feet of pipe. Need double wall construction? See the DuraVent FasNSeal W2 Tapered Reducer double wall fitting. The DuraVent FasNSeal Tapered Reducer 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:








































