What is the minimum vertical distance from the ground level for a combustion air intake located outside a building?

The minimum vertical distance from the ground level for a combustion air intake located outside a building is established to ensure proper air intake for combustion processes while also minimizing the risk of contamination or obstruction from snow, debris, or other environmental factors. The requirement of 12 inches is based on safety and performance standards that help to ensure that the combustion air is drawn from a clean and unobstructed source.

Typically, positioning the intake a minimum of 12 inches above ground level helps to avoid potential hazards such as flooding or the accumulation of debris that could block the airflow. Additionally, it provides adequate clearance from any external elements that might compromise the quality of the air entering the system. In many guidelines and codes, including those relevant to gas practices, this standard is referenced to promote the safe and effective operation of gas appliances.