DuraVent CVS Adjustable Roof Flashing: a tilting cone for shingle roofs
The DuraVent CVS Adjustable Roof Flashing is a weather barrier where a CVS vent passes through a shingle roof. Its cone tilts to match roof pitches from flat to 12 in 12. The base tucks under the shingles above the pipe and is fastened and sealed to the roof. A storm collar is also required. 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. It serves pellet stoves and inserts, plus gas appliances whose makers approve CVS for them.
When planning the pipe below this flashing, allow at least 1/4 inch of rise per foot on horizontal sections heading away from the appliance. That slope lets condensation return to the appliance and keeps heat from collecting in the pipe. The elbows have a slight tilt for the same purpose. Use fixed pipe lengths and sliding telescoping sections to make up the distance, subtracting 1 1/4 inches at each joint. Need a larger base? See the DuraVent CVS DSA Roof Flashing in soft aluminum. The DuraVent CVS Adjustable Roof Flashing ships free from My Cozy Outdoors with No Sales Tax (except WY) and the full manufacturer warranty.
Details
SKU: 35CVS-F
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.