Where must class I ducts, duct coverings, and linings be interrupted to provide specified clearances?

Class I ducts, duct coverings, and linings are designed to transport air in HVAC systems while ensuring safety through proper installation and clearances. The North Carolina Mechanical Code specifies that these ducts must be interrupted at every heater to maintain the required clearances.

Heaters can generate significant heat, which necessitates additional separation to avoid potential fire hazards and ensure the safe operation of the HVAC system. By interrupting the duct at each heater, the installation ensures that there is enough space for heat dissipation and minimizes the risk of heat-related damage to the duct materials and surrounding structures.

In contrast, junctions, fans, and vents do not typically require the same level of interruption for clearances. Junctions, while they connect different duct sections, do not necessarily generate heat that would necessitate interruption for clearance. Fans and vents, while important components, also do not pose the same risks related to clearance requirements as heaters do. Therefore, the requirement to interrupt ducts at heaters is crucial for maintaining safety standards and operational efficiency in HVAC systems.