Requirements for Central Air Conditioner Return Vents

About Central Air Conditioning

• Most air-conditioning systems consist of an evaporator, condenser and compressor that are all located in a cabinet, which is usually placed on a concrete slab next to the foundation or on a rooftop. Vents for both supply and return of air run from inside the home through the exterior wall or roof to connect with the main unit. Packaged air-conditioning units may also contain electric heating coils or a natural gas furnace so that the unit functions for heating as well as cooling.

Central Air Conditioning Vents

• The proper size, location and type of vents will run the system effectively and efficiently. A sufficient number of supply vents should be installed to provide proper airflow for the size of the room. Dampers on supply vents should be in the fully opened position and unobstructed by furniture. Older homes may require vents that allow for the greater airflow when retrofitting to install an air-conditioning system, according to home improvement writer John D. Wagner of the This Old House website.

Air Conditioning Return Vents

• Return air ducts should be installed very near the ceiling on interior walls in order to “vacuum” the hot air that rises to the upper part of the room. The cooler room that enters the room by way of the supply vent cools the room and then is removed as it warms and rises to the ceiling. This return vent system is an important feature on the second floor of homes. Often, when there is a significant difference in the coolness between the first and second floors of a home, it is because of inadequate return venting on the second floor. Undersized vents can also lead to problems removing warmed air back to the condenser. Always follow manufacturer’s recommendations on the size and location of return vents for your unit.

Improper Air Flow

• Closing off air vents in unused rooms can disrupt the pressure balance that is designed into your home air-conditioning system. Closing off vents can increase the pressure in the remaining ducts, which can lead to duct leakage at other points in the system, according to the SRP website.