What is the primary purpose of B vent?

The primary purpose of B vent, also known as Type B vent, is to vent gas-burning appliances. This type of venting system is specifically designed to carry the combustion gases produced by appliances that burn fuel, such as natural gas or propane. B vent systems are constructed with a double-wall design; the inner wall is designed to handle the hot gases being expelled while the outer wall provides insulation, reducing heat loss as the gases travel through the vent.

The effectiveness of B vent in safely expelling combustion products is crucial in preventing the risk of carbon monoxide build-up in living spaces. It also helps ensure that the gases reach the outdoors safely while minimizing the risk of condensation inside the vent system, which can lead to deterioration.

In contrast, electric appliances do not produce combustion gases, so they do not require a venting system like B vent. The other options regarding structural support and insulation pertain to different HVAC components and systems rather than the specific purpose of B vent. Thus, B vent's primary function centers around the safe venting of gas-burning appliances.