Chimney Safety Institute of America (CSIA) Certification Practice Test

What material should combustion air ducts be made of?

1. Aluminum

2. Plastic

3. Galvanized steel

4. Fiberglass

The correct answer is: Galvanized steel

Combustion air ducts must be made of galvanized steel primarily because this material provides the necessary durability and resistance to high temperatures that are typical in environments where combustion takes place. Galvanized steel is designed to withstand the corrosive effects that might arise from combustion gases and other environmental factors, ensuring that the ductwork remains structurally sound and functional over time. Other materials listed, while they have their own applications, do not meet the specific requirements for safety and performance in combustion air systems. For instance, aluminum may not be strong enough to bear the heat and pressure, and plastic could melt or deform under high temperatures, making it unsuitable for such environments. Fiberglass, although it has excellent insulation properties, may not provide adequate durability or structural integrity for combustion air ducts. Therefore, galvanized steel remains the preferred choice to ensure both safety and efficiency in combustion air systems.