How far above the earth must ducts be installed in accordance with the regulations?

Ducts must be installed at least 4 inches above the earth to prevent moisture intrusion and potential damage. This height ensures that the ducts are protected from environmental factors such as flooding, snow accumulation, or soil movement, which can compromise the integrity of the ductwork. Maintaining this distance helps to extend the service life of the ducts and ensures they operate efficiently without obstruction or contamination from the ground.

This requirement aligns with best practices in mechanical installations, emphasizing the necessity of proper elevation to safeguard the system's performance. Adhering to these installation guidelines not only promotes durability but also ensures compliance with safety regulations designed to protect both the equipment and the surrounding area.