The duct systems must have linings removed for how many inches downstream of a fuel-burning duct heater?

The requirement for duct linings to be removed for a specific distance downstream of a fuel-burning duct heater is based on the need for safety and efficiency. In this context, removing linings for 6 inches downstream is essential to prevent the potential buildup of flammable materials and ensure that the heat generated by the heater has a proper escape route.

By removing the linings, there is also a focus on maintaining airflow efficiency and reducing the risk of overheating that could occur if the linings were left intact. This distance has been specified in the code to create a margin of safety while enabling the heater to function effectively without obstruction.

Compliance with this regulation ensures that there is reduced risk of fire hazards and ensures the long-term operation of the duct heating system is safe. This measure also reflects a recognized standard within the North Carolina Mechanical Code that addresses concerns specific to fuel-burning equipment installations.