What is the difference between a return air grille and a supply air register?

A return air grille and a supply air register are both components of HVAC (Heating, Ventilation, and Air Conditioning) systems, but they serve different functions and are located in different parts of the system.

A return air grille is a vent or opening in a wall, ceiling, or floor through which air is drawn back into the HVAC system for recirculation.

It is typically located on the wall or ceiling in a room and is connected to the return ductwork that carries air back to the HVAC unit.

The primary function of a return air grille is to collect air from the room and return it to the HVAC system to be cooled, heated, or filtered before being redistributed as supply air.

Return air grilles may have a simple louvered design or may include filters to capture dust, debris, and allergens from the returning air.

A supply air register is a vent or opening in a wall, ceiling, or floor through which conditioned air is delivered into a room from the HVAC system.

It is typically located on the wall, ceiling, or floor and is connected to the supply ductwork that carries conditioned air from the HVAC unit to the room.

The primary function of a supply air register is to distribute conditioned air (either cooled or heated) from the HVAC system into the room to maintain the desired temperature and airflow.

Supply air registers may have adjustable louvers or dampers to control the direction and volume of airflow into the room, allowing for personalized comfort preferences.

In summary, the main difference between a return air grille and a supply air register lies in their respective functions and locations within the HVAC system. The return air grille collects air from the room to be recirculated through the HVAC system, while the supply air register delivers conditioned air from the HVAC system into the room for heating, cooling, and ventilation purposes.