What defines a type B-W gas vent?

A type B-W gas vent is specifically designed for venting gas appliances, particularly wall furnaces. The defining characteristic of a B-W vent is that it operates with specific capacities to ensure safe and efficient venting. The requirement that it shall not have a listed capacity less than that of the vented wall furnace is crucial for preventing backdrafts and ensuring that the vent can handle the combustion byproducts produced by the appliance effectively. This safety measure ensures that the venting system is adequately matched to the appliance's capacity, reducing the risk of malfunction or unsafe conditions.

The other options do not accurately describe the B-W gas vent’s characteristics. While the vent must be capable of handling the maximum output of the appliance, asserting that it must have a greater capacity than the appliance it serves does not reflect the exact standards. Additionally, stating that it can only be used with high heat appliances or is interchangeable with standard ducting misunderstands the specific applications and construction standards needed for safe operation of gas venting systems. The B-W vent is established for particular scenarios and functions that align with specific appliance types rather than general ducting purposes.