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When a vent is less than 10 feet high, the vent should be at least as large as the flue collar outlet.b) Vents for draft hoods or flue collars 12 inches in diameter or less should NOT be reduced more than one pipe size.
Used for installing OV 4 pipe as Type BW. Note: Requires special factory supplied parts to install 4 pipe as Type BW. The OV series offers oval gas vent pipe and fittings and can be used for Type B, Type B 2x4, Type BW and Type B 2x6 depending on the pipe size. It features a snap together die formed ends, and is UL 441 listed. Note: Special factory supplied parts are required to use 4 OV as Type BW vent.