Metal-Fab's round and oval Type-B vent is listed by Underwriters Laboratories for use with approved category 1 gas furnaces, heaters, and boilers. A category 1 appliance operates with a non-positive vent static pressure. The double wall design of B-vent enables the product to be used in homes and commercial buildings at close clearance to combustible. Metal-Fab's B-vent design incorporates features that make installation quick, easy, and safe. Some of those features are:

• Elimination of sharp edges by hemming the flue and casing.
• Assembly & disassembly, without tools, using positive twist lock.
• 360 degree rotation of small diameter fittings using swivel tees, wyes, and elbows.
• Space savings inside standard stud walls using oval pipe.

UL listed to mate with other specifically identified and listed round gas vent, 3"-6" diameters, allowing you to add a new run of Metal-Fab B-vent to an existing run of common vent. Metal-Fab 3"-6" diameter B-vent pipe is now standard with our new Surelocka® B-Vent Locking System . The patented locking system provides a secure lock with just the push of a tab, and can be easily disassembled by pulling the tab back out. Commercial Vent or "BIG Vent" is available in round sizes of 14" - 30". Big Vent sections (in 16" - 30" diameters) are joined together using Metal-Fab's quick connect locking system.