Duct linings must be removed how many inches downstream of a fuel burning duct heater?

Duct linings must be removed 6 inches downstream of a fuel-burning duct heater to ensure safety and efficiency in the heating system. The primary reason for this requirement pertains to the combustion process and the potential for condensation.

When a fuel-burning heater operates, it generates heat and can produce combustion byproducts. If the duct lining material is not removed a sufficient distance from the heater, there is a risk that the heat and moisture could negatively affect the lining, potentially leading to degradation of the material or even contributing to deterioration that could impact airflow and efficiency.

Moreover, the removal of duct lining also helps to prevent any flammable materials close to the heat source, thereby reducing the risk of fire or other hazards associated with high temperatures. By adhering to the 6-inch guideline, systems can maintain optimal performance and ensure safety standards are upheld in accordance with mechanical codes.