What is the primary purpose of a chimney cap for Type B vents?

A chimney cap for Type B vents serves primarily to prevent rainwater from entering the vent system. This is crucial because water ingress can lead to the deterioration of the vent, cause rust or corrosion, and ultimately compromise its functionality. By keeping rainwater out, a chimney cap also helps to protect the interior of the vent from moisture damage that can interfere with proper venting of combustion gases.

While it’s true that enhancing airflow is important for the function of chimney vents, that is not the primary purpose of the cap. The same applies to eliminating odors or improving aesthetic appeal; these factors are secondary to the essential function of protecting the vent system from environmental elements like rain. In essence, the chimney cap acts as a safeguard, ensuring longevity and effective operation of Type B vents by preventing water intrusion.