What is excluded from the definition of an air duct?

The definition of an air duct typically pertains to components that are specifically designed to convey air as part of heating, ventilation, and air conditioning (HVAC) systems. Compressed air systems involve the use of compressed gases and do not serve the primary purpose of air movement required for comfort or process applications associated with traditional air ducts.

As such, compressed air systems are distinct from the standard air ducts used in HVAC applications, which facilitate the distribution of conditioned air throughout a building. This distinction is crucial because it helps to clarify the intended function and operational characteristics of an air duct, differentiating it from systems that do not fit the traditional criteria.

In contrast, exhaust systems, ventilation systems, and heating systems are all integral parts of the air distribution network in buildings and typically rely on air ducts for proper functionality, making them included in the definition rather than excluded.