Which type of air-handling systems should not use gypsum board ducts?

Gypsum board ducts are not suitable for use with evaporative coolers primarily because these systems generate a significant amount of moisture. Evaporative coolers, also known as swamp coolers, rely on the process of water evaporation to cool the air. The introduction of moisture can lead to issues such as mold growth and corrosion within the gypsum board. Gypsum board is porous and can absorb moisture, which may compromise its structural integrity and performance over time.

In contrast, cooling systems, heating systems, and ventilation systems can generally use gypsum board ducts, provided that they are installed properly and do not expose the material to excessive moisture. It’s important to match the duct material with the specific conditions and requirements of the air-handling system to ensure effectiveness, safety, and compliance with code standards.