How many square inches must indoor combustion air openings be at minimum?

The minimum requirement for indoor combustion air openings is critical for ensuring that appliances operate efficiently and safely. The correct value of 100 square inches is determined by guidelines and standards that specify how much combustion air is required for gas-fired appliances to function optimally. This amount of air prevents negative pressure situations, which can lead to backdrafting of combustion products and carbon monoxide buildup, thereby enhancing safety.

In general, the square inches of combustion air openings should be calculated based on the total BTU rating of the appliances in the space, with additional considerations for other factors such as the location of the openings and the configuration of the space.

This requirement helps to ensure that adequate ventilation is provided for combustion processes, promoting efficient fuel use and minimizing hazardous emissions. Thus, the specified 100 square inches serves as a foundational guideline for proper airflow in residential or commercial settings.