How many feet vertically must a Type B-W gas vent terminate above the bottom of a wall furnace?

A Type B-W gas vent must terminate at least 12 feet above the bottom of a wall furnace to ensure proper venting and safety. This height is crucial for several reasons.

First, vent termination affects the draft needed to safely exhaust flue gases. If the vent pipe does not rise sufficiently above the combustion appliance, it may fail to create adequate draft, potentially leading to backdrafts where flue gases enter the home rather than being expelled outdoors.

Second, the 12-foot height also helps prevent the accumulation of combustibles and ensures that any discharged fumes are safely dispersed above other structures or obstructions in the vicinity. This reduces the risk of fumes re-entering the building or affecting nearby windows and doors.

It’s also important to note that local codes and standards often specify these venting heights based on safety considerations, and installing the type of venting system correctly fosters compliance with those regulations. Overall, the requirement to terminate a Type B-W gas vent 12 feet above the bottom of a wall furnace enhances both the efficiency of the heating system and the safety of the residential environment.