If a floor furnace is sealed to prevent water entry, what is the minimum clearance from grade?

For a floor furnace that is sealed to prevent water entry, the minimum clearance from grade is 2 inches. This requirement is designed to ensure that the furnace is adequately protected from potential water damage while still allowing for effective airflow and operation. The 2-inch clearance helps to account for the natural settling of soil and debris that can accumulate over time, ensuring that the furnace remains functional and safe.

Maintaining this clearance is crucial for several reasons. It prevents water from entering the combustion area, which could lead to operational failures or hazards, including rusting or degraded components. Additionally, this clearance provides a safety buffer, helping to prevent blockages from dirt or debris that may otherwise obstruct the furnace's operation.

The specified distance is part of regulatory standards to ensure that heating appliances operate safely and effectively, supporting longevity and reliability in various environmental conditions.