ICC Commercial Mechanical Practice Exam

In residential garages, what type of air can be taken from the exterior for appliances installed at floor level?

1. Makeup air

2. Dilution air

3. Return air

4. Combustion air

The correct answer is: Combustion air

Combustion air is the correct choice because appliances that operate using combustion, such as gas furnaces or water heaters, require a specific type of air to support the combustion process. When appliances are installed at floor level in residential garages, they draw combustion air directly from the exterior to ensure there is enough oxygen for efficient and safe operation. This is crucial for preventing the buildup of harmful gases and ensuring the appliance operates within safe parameters. Makeup air refers to the air that replaces air that has been exhausted from a space, which is not specifically designated for combustion needs. Dilution air is used in systems that mix exhaust gases with fresh air to reduce pollutants, but does not provide the necessary oxygen for combustion. Return air is typically air that is circulated back to the heating or cooling system from the occupied space and is not suitable for use in providing combustion air. Therefore, combustion air is the appropriate term for the air needed from the exterior in this context.