What is the minimum distance vertically above an adjoining grade for an outdoor combustion air intake opening?

The correct minimum distance vertically above an adjoining grade for an outdoor combustion air intake opening is essential to ensure proper air flow and prevent potential hazards. It is set at 12 inches to help keep the intake free from obstructions, such as snow, debris, or water, which could inhibit air supply or cause contamination.

This height also helps to minimize the chances of pollutants or exhaust from nearby structures entering the combustion air intake, which is critical for the safe and efficient operation of combustion appliances. The requirement serves to maintain the integrity of the combustion process, ensuring that the equipment operates safely and efficiently under various environmental conditions.

Keeping the intake opening at 12 inches above grade acts as a preventive measure against potential issues that could arise from lower placements, thus ensuring a reliable air supply for combustion.