Return Air Grille: An Integral Part of Your HVAC System A return air grille, or return vent grille, is a crucial component of your HVAC (Heating, Ventilation, and Air Conditioning) system. It plays a critical role in drawing air from the conditioned space (such as rooms and hallways) back into the system to be filtered, recirculated, and reconditioned (i.e. heated or cooled). By understanding the various types and maintenance of return air grilles, you can greatly enhance the efficiency and air quality of your system.