Red Seal Sheet Metal Worker Practice Exam

Which type of insulation is generally recommended for duct systems in unconditioned spaces?

1. Polystyrene insulation

2. Fiberglass insulation

3. Foam board insulation

4. Cellulose insulation

The correct answer is: Fiberglass insulation

Fiberglass insulation is generally recommended for duct systems in unconditioned spaces due to its excellent thermal resistance properties and flexibility. This type of insulation effectively helps prevent heat loss or gain as air moves through the ductwork, maintaining the efficiency of the HVAC system. Fiberglass is lightweight, non-combustible, and resistant to moisture, which makes it suitable for various environments, including basements and attics where ducts are often located. Its installation method also allows for easy wrapping or lining of ductwork, effectively minimizing air leakage and optimizing energy efficiency. Other insulation options, while valuable in their own right, may not be as effective specifically for duct systems in unconditioned spaces. For example, polystyrene insulation tends to be rigid and is often used in applications requiring structural support rather than for flexible ductwork. Foam board insulation can also provide good thermal performance, but it is usually more suited to continuous insulation applications and might not wrap around ductwork as efficiently as fiberglass. Cellulose insulation, although it has good thermal properties, is typically used for insulating walls and ceilings where its settling characteristics and moisture absorption can be better managed, making it less ideal for duct systems.