What is the purpose of the return air duct?

The purpose of the return air duct is primarily to ensure the maximum energy efficiency of the HVAC system. This duct plays a crucial role in the circulation of air within the system. It returns air from the conditioned space back to the heating or cooling unit, allowing for the redistribution of air that has already been treated. By circulating the air effectively, the return air duct minimizes the workload on the HVAC system, which can lead to improved energy efficiency. Systems with good return airflow can maintain consistent temperature and comfort levels while consuming less energy.

While return air ducts may indirectly assist in other functions—such as helping filter out pollutants or maintain overall temperature control—their main objective is linked to optimizing energy efficiency and facilitating proper air circulation throughout the system.