How far must linings be interrupted from electric-resistance and fuel-burning heaters in a duct system?

The required interruption distance for linings from electric-resistance and fuel-burning heaters in duct systems is significant for safety and operational efficiency. The correct answer indicates that the linings must be interrupted by 6 inches from both types of heaters.

This distance is established to prevent overheating, fire hazards, and to ensure safe airflow. Electric-resistant heaters can generate significant heat, and linings too close could potentially ignite or degrade, leading to system failure. Similarly, fuel-burning heaters produce combustion gases and heat that, when combined with linings, could create a dangerous situation if the materials are not installed at a safe distance.

Maintaining this 6-inch separation ensures that linings are adequately protected from the heat produced by the heaters while also allowing for proper airflow within the duct system. It adheres to the safety standards outlined in the mechanical code, promoting both reliability and safety in HVAC installations.