What is the minimum clearance from grade for the lowest portion of a floor furnace?

The minimum clearance from grade for the lowest portion of a floor furnace is 6 inches. This requirement is established to ensure proper airflow and prevent potential issues with water accumulation or debris interfering with the operation of the furnace. By maintaining this clearance, the furnace is positioned high enough to avoid contact with moisture on the ground, which could lead to rust or other damage over time, thus enhancing safety and reliability in its operation.

This standard also helps to ensure that the unit operates efficiently by allowing sufficient airflow, which is critical for combustion and heating processes. Proper clearance can be crucial for preventing operational hazards and maintaining the furnace's longevity.