Go with the airflow
Most modern HVAC systems have at least one return vent per room.
A good rule of thumb is to have one return vent for every 100 to 150 square feet.
It costs $200 to $500 to add a return air vent.
Entering your home should feel like returning to an oasis. But, when the airflow is less than ideal, it can feel like walking into a stagnant, stuffy swamp. If you encounter stale air and inconsistent temperatures at home, inadequate return vents may be to blame. Your home needs a proper balance between the return and supply vents to keep the air fresh.
You may wonder: “How many return vents do I need?” Ideally, you’ll have at least one return vent in each room, but there are a few factors to consider.
HVAC systems help air circulate through a home, moving fresh air in, and pulling stale air out. To do this, they require supply and return air vents.
Supply air vents push warm or cool air into rooms of a home. You should feel air blowing if you place your hand in front of a running supply vent. They have adjustable slates to help control airflow in the space, and they’re smaller than a return vent.
On the flip side, return air vents suck the cool or warm air back into the HVAC system and on to the air to the handler, which filters and recirculates it. You’ll often find return vents on the interior wall of a room, away from the supply vent. They can be on the floor or ceiling, depending on whether the system handles both heating and cooling. Return air vents are often larger than supply air vents, and if you place a tissue in front of a running return vent, it should be sucked toward the vent.
If the air in your home feels stale, or you’re experiencing inconsistent temperatures across a home, you may be wondering if you need more return vents.
While you can add vents to existing ductwork, you’ll first want to test if you can get more airflow from your vents.
Try these steps before installing more return vents:
Keep vents clear. Check existing vents to make sure nothing is blocking them, including bulky furniture or rugs. Move these items to ensure better airflow.
Close vents. Partially close supply air vents in unused rooms to redirect airflow to heavily used spaces.
Replace filter. Make sure to regularly replace your filter to keep an HVAC system running effectively.
Test for leaky ducts. Cracks and holes in ductwork can impact airflow. But, minor leaks can be patched to improve a system’s efficiency.
If your home feels stale or uncomfortable after troubleshooting, it could be time to add more return air vents to your system. Here’s what factors influence how many vents you likely need.
In modern HVAC systems, having at least one return vent in each room is recommended. If a larger room already has a return air vent and still feels uncomfortable, consider strategically adding one or two more to the space. A good rule of thumb is one vent for 100 to 150 square feet of living space.
The type of HVAC you have and its age can impact how many vents you need. In a higher velocity HVAC system, you’ll want to have more vents, although smaller in size, to keep the system running efficiently.
In a cool air system, return vents should be lower to the ground to capture the cooler air that falls. Return vents can be installed on the floor, as well. If the return air vents are sucking heated air from a home, they should ideally be installed on the walls or ceiling to capture rising hot air.
If the system both heats and cools air in a home, placement should be balanced to capture hot and cold air. That could mean a mix of placements or different placements in a single room.
"Quality ductwork will increase the efficiency of your HVAC, sometimes even by 20-30%. This is so because there is reduced air leakage due to better insulation and more optimized airflow. Because this makes your HVAC work more efficiently, it really doesn't have to work too hard to keep the desired temperature; thus, its energy consumption is lowered directly."
— Yashar Mosaferi, President of Klondike AC, Casper, WY
It costs between $200 and $500 to add a return air vent in your home. Factors that influence price include vent size, duct material, and labor. If you’re an experienced DIYer with knowledge of HVAC, you may be able to save some cash and install a vent on your own. However, most homeowners should seek out an experienced local ductwork contractor to handle the project and ensure everything is installed perfectly.
The best location for return air vents depends on whether the system heats or cools. If it does both, you’ll want to place return vents both high on a wall and lower to the ground to collect sinking cold air and rising heat. If the system simply heats a home, you should install return air vents high on the walls or even on the ceiling for the best airflow.
There is no one correct number for return air vents in a home—it depends on several factors. However, modern HVAC has at least one supply vent and one return vent per room or one for every 100 to 150 square feet of living space. If you’re updating your existing HVAC, you should consider adding more return vents for better airflow and efficiency.
