What is the function of a return air duct?

The function of a return air duct is primarily to channel air back to the HVAC system for reconditioning. This process helps maintain air circulation within the system, ensuring that the environment remains comfortable and that the air can be properly conditioned—either heated or cooled—before it is redistributed as supply air. By returning air from the living space, the system can effectively regulate temperature and humidity levels, enhancing overall efficiency and comfort.

This return pathway is essential for the air handing process, allowing stale or warm air to be continuously cycled through the system, where it can then be filtered, conditioned, and redistributed. An effective return air duct design is crucial for balancing air pressure throughout the HVAC system, which can affect the overall functionality and comfort levels within a building.