TL;DR
B-vent is double-wall metal venting, an aluminum inner pipe inside a galvanized outer shell with an insulating air gap, listed for natural-draft gas appliances such as standard water heaters, older furnaces, and gas fireplaces. The air gap keeps flue gases warm enough to rise by buoyancy while reducing clearance to combustibles to 1 inch for most listed pipe.
What it means
B-vent is double-wall metal venting, an aluminum inner pipe inside a galvanized outer shell with an insulating air gap, listed for natural-draft gas appliances such as standard water heaters, older furnaces, and gas fireplaces. The air gap keeps flue gases warm enough to rise by buoyancy while reducing clearance to combustibles to 1 inch for most listed pipe. It must terminate vertically above the roof with a listed cap and cannot serve high-efficiency condensing appliances, whose cool acidic exhaust requires plastic venting, nor solid fuels. Installation follows NFPA 54 and the manufacturer's listing, with sizing from the fuel gas code vent tables.
Where it sits in the glossary
B-vent is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
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