What is the minimum aperture size for a combustion air inlet screen?

What is the minimum aperture size for a combustion air inlet screen?

• A. 1 inch
• B. 2 inches
• C. 3 inches
• D. 4 inches

Answer: (A)

Air supply for combustion must be enough to support safe, complete combustion while still protecting the intake from large debris and animals. The aperture size of the combustion air inlet screen determines how freely air can pass. The smallest opening allowed is one inch, because openings smaller than that would overly restrict airflow, risking incomplete combustion or backdrafting, while still providing basic protection. Larger openings would meet the requirement but aren’t the minimum that the code allows. So, the minimum aperture size is one inch.

Air supply for combustion must be enough to support safe, complete combustion while still protecting the intake from large debris and animals. The aperture size of the combustion air inlet screen determines how freely air can pass. The smallest opening allowed is one inch, because openings smaller than that would overly restrict airflow, risking incomplete combustion or backdrafting, while still providing basic protection. Larger openings would meet the requirement but aren’t the minimum that the code allows. So, the minimum aperture size is one inch.