What is a key advantage of a positive (supply) pressure vent system?

A positive (supply) pressure vent system introduces conditioned air into a building, which effectively helps to maintain a higher pressure inside compared to the outside environment. This pressure differential reduces the likelihood of backdrafts, where flue gases from combustion appliances backflow into the building rather than venting outside. By minimizing the risk of backdraft, these systems enhance indoor air quality and safety, especially for appliances that rely on proper ventilation for safe operation.

While options related to energy consumption, maintenance needs, and humidity may have some relevance in specific contexts, they do not directly address the primary benefit associated with the prevention of backdraft on combustion appliances, which is critical for both safety and efficiency in building operations.