DuraVent CVS Wall Thimble: a framed wall passage for gas appliance venting
The DuraVent CVS Wall Thimble is a framed sleeve that carries a gas appliance’s vent through an outside wall. It fits between standard wall studs and gives the pipe a finished opening on each side. This thimble is for gas appliances only, and the appliance maker must approve CVS for that model. CVS is DuraVent’s concentric vent: the exhaust runs up a 3 inch inner pipe while combustion air comes in through the 5 inch outer pipe around it.
The space needed around the pipe depends on the appliance. CVS used as a double wall gas vent inside an enclosure is listed for zero clearance to wood framing. Pellet venting needs 1 inch from anything that can burn. For direct vent gas stoves and fireplaces, the appliance maker sets that gap. Leave any required gap empty, not filled with insulation. The outside gas vent cap must sit at least 12 inches above the ground, deck, or porch and above expected snow. The appliance maker may require more space. Need the sleeve with an insulation ring? See the DuraVent CVS Wall Thimble with Reduced Air Infiltration. The DuraVent CVS Wall Thimble ships free from My Cozy Outdoors with No Sales Tax (except WY) and the full manufacturer warranty.
Details
SKU: 35CVS-WT
Applications
Concentric Venting System (CVS) (direct vent or two-pipe system) for use with condensing natural gas or propane Categories II, III and IV appliances or Canada’s Type BH Gas Vent Systems, (having a maximum rated operating temperature of 500°F). For use with Stoves and inserts of Type L gas, pellet, oil, corn and biofuel (Rated to a continuous use flue temperature up to 570°F). CVS can be used on a wide range of appliances, including: gas boilers, warm air furnaces, water heaters, unit heaters, tankless water heaters, pellet stoves, direct vent gas or propane stoves, heaters, and fireplaces.
Materials and Construction
Unitized concentric construction. Inner: Laser-welded UL approved 444 super-ferritic stainless steel .012″ Outer: Laser-welded, paintable, zincalume .018″ Silicone O-ring seals on inner liner and outer wall. Precision twist-lock connection on outer wall.
Clearances
CVS is listed to 0” clearance as a double-wall vent system for Category II, III, and IV appliances, for flue temperature of up to 400°F for horizontal enclosures, and up to 480°F for vertical enclosures. CVS must maintain 1” clearance to combustibles when used with pellet fuel. When CVS is used as a concentric/direct vent system on gas, the clearance to combustibles is specified by the appliance manufacturer.
Diameters
3″ inner and 5″ outer.
Listings
CVS vent pipe is listed to UL 1738 (MH25700) as a double-wall vent system for Category II, III and IV appliances. It is pressure rated to 10 WC for the inner pipe. This product is also intended to be used as a direct vent system for Listed to UL 1738 (DGSH.MH25700) and ULC S636 (DGSH7.MH25700). Pressure rated to 10” W.C. Listed to UL 641 (DFTX.MH8381), ULC S609 (DFTX7.MH8381), and ULC/ORD 441 (DFVAC.MH21150). Listed in combination with gas appliances, has been tested and listed as a decorative gas appliance system or as a direct vent heater system. Check with your appliance manufacturer for approval.