What type of system would be characterized by the use of positive static pressure to expel gases?

A system characterized by the use of positive static pressure to expel gases is specifically a forced-draft venting system. This type of system utilizes fans or blowers to create the necessary pressure to push combustion gases out of the system and into the atmosphere. The application of positive static pressure ensures that gases are effectively expelled, thereby enhancing the efficiency of the combustion process and ensuring safety by preventing backdrafts.

The forced-draft system is distinct in its reliance on mechanical assistance to achieve the necessary airflow for venting, making it particularly effective for high-efficiency appliances that may not produce sufficient natural draft on their own. This ensures not only adequate venting but also aids in maintaining proper combustion conditions.

In contrast, other types of systems like natural draft rely on temperature differences and buoyancy to expel gases without mechanical intervention, while induced-draft systems create a negative pressure to draw gases out, which is fundamentally different from operating at positive static pressure. Mechanical draft systems can utilize both positive and negative pressures, complicating their direct comparison to the clear definition of forced-draft systems.