The earliest HVAC systems featured a large, single return vent placed somewhere in the middle of the home, but this is not the most effective system. Instead, there should be at least one return vent in every room, with two or three being ideal.
One per room is ideal, but placing two or three in central locations can provide enough air circulation to maximize the energy efficiency of your HVAC and optimize indoor air quality, so your family stays healthy. If your home has multiple stories, you should have at least one return air vent per floor.
However, most HVAC contractors use a rule of thumb to determine the number of air vents needed. For example, for a standard residential HVAC unit, you'll generally need one supply vent and one return vent for every 100 to 150 square feet of living space.
Today, it is recommended to have one or multiple air vents in each room of your home or business to optimize air flow and reduce the cost of energy spent on cooling your home or office. So, what are air vents and how do they help your HVAC system run better?
Can You Have Too Much Return Air? Too much return air coming through your system isn't much of an issue because the fans and ductwork working to get that air back into the system only pull with so much force to make the HVAC system work correctly.
If there's not enough return air, your living room can be 10℉+ warmer or cooler than, for example, the bedrooms. Not enough return air in summer can cause rooms close to the central unit to be cooler and those farther from it to be warmer. In winter, rooms farther from the furnace can be too cool.
A lack of return air can cause your HVAC system to overheat, leading to frequent shutdowns or overheating warnings. This overworking can also result in the air conditioner blowing warm air, especially in high temperatures.
Return registers can be large and centrally located in your home, or they can be in every room. HVAC professionals recommend that each room have a cold air return vent to help with flow and temperature control. These vents are typically found on an interior wall.
If the return duct is too small or there are an inadequate number of return grilles, your HVAC system won't be able to return enough air to recirculate into the system. Again, it's like if you were breathing in through a straw while jogging.
The Secret to Comfort is Balanced Airflow
The current Supply Air vent pressurizes the room, until (in many instances) the pressure inside the room slows the airflow coming from the Supply Air vent! When we install the Return Air vent, the pressure is alleviated. The Return Air vent balances the Supply Air vent.
Maintenance Needs
Return vent filters, if used, also need regular replacement to avoid airflow issues. By properly maintaining both types of filters, you can get great airflow, reduce strain on your HVAC system, and rest easy knowing you have cleaner air.
1. Openings shall not be located less than 10 feet (3048 mm) measured in any direction from an open combustion chamber or draft hood of another appliance located in the same room or space. 2. Return air shall not be taken from a hazardous or insanitary location or a refrigeration room as defined in this code.
Yes, some systems are designed to work this way, but most modern duct systems will just usually have one or two returns accounting for the entire system.
Up High: having an air return higher up on a wall will be better at sucking in hot air that rises. Making it more efficient at transferring this hot air back into your system to repeat the cooling cycle. Down Low: if you have your air return lower on your wall it will function better as a cold air return.
How much value does HVAC add to the house? Well, there's no exact and direct answer to that question but most real estate specialists agree that you should expect a 35-50% return on investment (ROI). Furthermore, a new HVAC system in a home can get buyers more interested in buying the house and hence close the sale.
Having a number of return vents (preferably one in every room, but also 2 or three is far better than just one) creates regular air pressure. If you have one return vent, your house is great. Maintain the doors to every room open so air can properly flow.
Just as oversized ducting can wreak havoc on your heating and cooling systems, so can undersized ductwork. When the ducting is too small for the specific HVAC system that you have, air flowing through it will start to back up. The air pressure within the ductwork will become higher.
Higher utility bills. Less comfort. That big central air return could be causing all sorts of problems! Though rare, negative pressure in an upstairs hallway can be so severe that the central return starts pulling CO from gas appliances.
Does Every Room Need Air Return Grilles? While it is a myth that air return grilles are required in each and every room in the house, it is definitely necessary to have more than one of these grilles installed at strategic places in the house. The most important place to have these would be the bedroom.
Most homes across the U.S. have forced air systems and in newer homes there will be cold air return vents placed at both the ceiling and the floor of many rooms. Having two air return vents allows you to seasonally control which air is returning to the HVAC system. In older homes, this may not be an option.
Due in large part to the short cycling issues mentioned above, components on an oversized heating and/or air conditioning systems are more likely to fail sooner than those on a properly sized system. As a result, you may end up having to replace your HVAC system sooner than expected.
High Return Air Temp: If the return air temperature is greater than 90°F (adjustable). Low Return Air Temp: If the return air temperature is less than 45°F (adjustable).
As a general rule, the average house having a 2.5-ton or 3-ton air conditioner installed would typically need 10-12 supply registers, a 3-ton air conditioner would need 12-14 supply register openings. These register openings assume a 6″ round pipe attached as normal bigger pipes would allow for fewer supply registers.