What type of vent must be used when the vent of a wall furnace will be concealed in a partition wall?

When venting a wall furnace that will be concealed within a partition wall, the appropriate vent type to use is a BW vent, commonly referred to as a "B-vent," which is designed specifically for gas venting applications. BW vents are designed to handle the combustion gases produced by appliances and maintain adequate ventilation and safety, especially in concealed installations.

The design of BW vents allows them to safely convey the flue gases from the appliance out of the building, while being insulated to prevent heat transfer to the surrounding structure. This is crucial when the vent is located within a wall, as it ensures that combustible materials do not come into contact with hot surfaces, thus reducing the risk of fire hazards.

In contrast, the other vent types, such as B vent or L vent, may not have the same safety ratings and construction specifics required for concealed installations. Properly identifying the vent type is critical for maintaining compliance with safety regulations and ensuring the efficiency and safety of the heating appliance.