What is the minimum requirement for a spark arrester's area compared to the net free area of the flue it serves?

The minimum requirement for a spark arrester's area in relation to the net free area of the flue it serves is established to ensure that sufficient airflow is maintained while effectively preventing sparks from escaping. This ensures both safety—by minimizing the risk of fires caused by embers—and functionality, allowing for adequate venting of combustion gases.

When the spark arrester's area is three times greater than the net free area of the flue, it creates a balance that allows smoke and exhaust to be expelled efficiently while capturing any potential sparks. A ratio of three to one is optimal, as it supports proper draft and maintains the chimney's overall performance, enabling efficient operation without obstruction. This design helps prevent overheating and ensures that the chimney system is safe and effective in preventing fire hazards.