Where in a Room Should I Place the Return Air Vent?

Toward the Interior

• Most supply air vents, which blow warmed or cooled air into a home, are at a room's perimeter because windows, doors and even exterior walls can leak outdoor air inside. By heating or cooling the room's perimeter, the room's interior feels comfortable as well. That is why placing a return air vent in the room's interior, away from exterior walls, windows and doors, is best. Air that has lost most of its warmth or coolness travels through the return air vent and duct work to be reheated or re-cooled by a furnace or central air conditioner.

Away from Combustion Sources

• For proper safety, and according to building code, an air return air vent should be at least 10 feet from a combustion area, such as a furnace or gas-burning stove. After all, you don’t want a byproduct of combustion — carbon monoxide — to mix with the air circulating around your home. In many cases, a ventilation system installer will suggest placing the return air vent in a different room entirely. This is one reason why a return air vent should not be placed in a kitchen.

Clear of Obstacles

• Obstruction of a return air vent prevents temperature comfort. Poor placement can result in furniture, rugs or other items blocking air from entering the return vent. To prevent this situation, many homes have return air vents high on walls or even on ceilings. Other ventilation systems have return air vents both high and low; the high vents are closed in summer, and the low vents are closed in winter. The configuration is logical because hot air rises.

In Positions Compatible with Duct Runs

• Whether return air vents are placed high or low may depend largely on the existing duct work's configuration. While a return air vent obviously should not be placed right next to a supply air vent, it doesn’t necessarily need to be on the opposite side of the room from a supply air vent. The return vent doesn't draw air to it; it is simply an opening for air to return to the furnace or central air conditioner. This factor makes compatibility with existing duct runs essential to return air vent placement.