What best describes Return Air in an HVAC system?

• A. Air removed from a space to be recirculated or exhausted.
• B. Outdoor air introduced to the space.
• C. Air used for combustion in equipment.
• D. Humidity control air only.

Answer: (A)

Return air is the air that comes from the occupied space back to the air handling system to be conditioned again. It originates in the room being served and is circulated back through the equipment, often mixed with outdoor air at the air handler before being supplied again. The key distinction is that outdoor air is fresh air introduced for ventilation, combustion air is used for burners, and humidity-control air isn’t a standard term describing return air. In some layouts, a portion of return air may be exhausted to the outdoors to maintain balance, but the essential concept is air from the space being returned to the system for recirculation.