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

The minimum distance vertically above an adjoining grade for an outdoor combustion air intake opening is established at 12 inches. This requirement is intended to ensure that the combustion air intake is positioned adequately to prevent potential contaminants and moisture from entering the air supply system. By maintaining this height, it helps to reduce the risk of debris, snow, or water blocking the intake, which could negatively affect combustion efficiency and safety.

This standard is particularly important in regions with varied weather conditions, as it helps ensure that the air supply remains clear and unobstructed. It also works to enhance the overall performance and reliability of combustion appliances. Thus, positioning the intake at least 12 inches above grade is essential for optimal operation and safety.