DuraVent FasNSeal Wall Thimble Sleeve Extension: adds reach through a thicker wall
The DuraVent FasNSeal Wall Thimble Sleeve Extension is an extra sleeve for the part that carries your vent through a wall. It adds 6 inches of reach to a wall thimble or wall pass through when the wall is too thick for that part alone. Choose a 3 to 16 inch size to match your thimble. 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.
A wall vent must end at least 12 inches above ground and the snow line, and 7 feet above a public walkway or driveway. Keep it 6 feet from any appliance air intake and 3 feet from a gas meter or other building opening. Doors and windows need 4 feet below or beside, or 1 foot above. The appliance maker may require more space. The pipe also needs support: hangers every 6 feet horizontally, and wall brackets after a turn into a vertical run of 10 feet or more, every 12 feet vertically, and after any change in alignment. Each floor or ceiling crossing needs a firestop, a barrier against fire spreading through the opening. Need the thimble this extends? See the DuraVent FasNSeal Insulated Wall Thimble with Adjustable Vent Length. The DuraVent FasNSeal Wall Thimble Sleeve Extension 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:








































