An economical venting solution for condensing and noncondensing appliances, the Concentric Venting System (CVS) features a UL1738 approved super-ferritic stainless steel inner wall. The proprietary twist-lock connection eliminates use of clamps or mechanical fasteners and saves installation time. Only one penetration is needed through the roof or the wall for both exhaust and combustion air. Multiple pipe lengths and telescoping pipe extensions eliminate field cutting of pipe. CVS is the only concentric vent system to incorporate o-rings on the inner wall and outer casing to prevent exhaust or combustion air leakage. Custom adapters are available to transition from co-linear to coaxial venting systems. The built-in condensate management system prevents standing condensation. The Concentric Venting System is a fully sealed, gas tight system to deliver superior performance with the heating unit.
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.
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.
3″ inner and 5″ outer.
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.
Advantages of Concentric
A concentric (or direct-vent, or two-pipe) system maintains indoor air quality by reducing drafts with one penetration, and allows for better humidity level control inside a dwelling. Concentric venting brings to the heating appliance outdoor air as combustion air through an air-tight, sealed system that is safe.
- CVS Concentric Vent System (PDF, 1.2MB )
- Gas Fireplace Venting Solution (PDF, 1.97MB )