When introducing combustion air into a confined space, how many openings must be provided?

When introducing combustion air into a confined space, it is essential to provide adequate ventilation to ensure efficient combustion and prevent issues such as backdrafting or incomplete combustion. The correct approach for introducing combustion air involves creating two openings: one positioned near the ceiling and another near the floor.

This method allows for a proper flow of air that takes advantage of the natural tendency of warm air to rise and cool air to settle. The opening near the ceiling allows for the exit of warm, spent air, while the lower opening facilitates the intake of cooler, fresh air necessary for combustion. By having openings at different heights, the system can maintain an appropriate air exchange rate and effectively support the combustion process, ensuring safety and efficiency in the heating system.

Providing just one opening, or two openings at the same height, does not allow for effective air circulation and may lead to insufficient combustion air. Having multiple openings spaced evenly without respect to their height would not optimize the airflow dynamics in the space. Thus, the strategy of positioning one opening near the ceiling and one near the floor is the most effective design to ensure that fresh combustion air is consistently available while allowing for the escape of used air.