Your return air vents capture warm air, pushing it through the ducts to remove warmer molecules and keep things cool. Having your return air vents off the ground will help them capture warmer air. In older homes, you might have one return air vent per floor.
Air return vents are large intake ducts, covered by a metal grill. There will be at least one on each floor of your home, maybe more, and they will typically be located low on the wall or on the floor. These air return vents pull air from your living spaces back into the ductwork of your HVAC system.
Return air vents are usually found in the lower wall of a room or hallway. Ideally, your return air vents and supply vents should be on opposite sides of the space. Otherwise, you may be pulling some of the heated or cooled air back into the system before it has a chance to circulate.
If you have a combined heating and cooling system and need to decide between placing the return vents high or low, consider your climate. If you live in cooler climates, it might be wise to install them towards the floor, whereas if you reside in warmer areas, they should ideally be installed close to the ceiling.
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.
What room should return air ducts not be installed? Return air ducts should generally not be installed in rooms with high humidity or areas prone to moisture accumulation, such as bathrooms or kitchens.
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.
Hot air rises and cool air sinks. Therefore, opening the right return vents in the summer and winter significantly improves the distribution of air by your forced-air system. You'll also enjoy more even heating and cooling throughout your home. In the summer, open your high returns and close the low ones.
Additionally, having a return vent in every room ensures that all areas of your home receive fresh, filtered air to maintain better indoor air quality.
When vents are placed near the ceiling, air is able to more freely circulate throughout the room. Furniture is also less likely to obstruct the flow of air. This allows your home's heating and cooling system to make each space more comfortable while improving your energy efficiency along the way.
While return vents don't always require filters, adding them provides additional filtration, improving indoor air quality and keeping dirt and debris out of your system.
Symptoms include weak airflow and uneven cooling or heating throughout your home, with some rooms feeling much cooler or warmer than others. Homeowners should regularly check vents for consistent airflow. If you notice a significant drop in air pressure or uneven temperatures, it could indicate return air issues.
Ideally, return air ducts would be located both near the floor and the ceiling. Return duct inlets should be located at the farthest distance from the supply duct outlets. Fresh air intakes are especially important in newer construction or in buildings that have been extensively insulated and weatherproofed.
In older homes, it's somewhat common to find return vents on or near the floor. You can have an HVAC technician move these to a higher location if you notice your HVAC constantly kicks on or some rooms feel more humid than others.
The floor location allows the system to pull in the coolest air in the room for heating. If you were living in a more tropical climate, you would want to do the opposite to focus on removing warm air near the ceiling to cool it before recirculating it.
Parts of Your Home Are Hotter or Colder
If there's not enough return air, your living room can be 10℉+ warmer or cooler than, for example, the bedrooms.
In an air conditioning climate the return duct goes near the ceiling to draw off the hot air and cool it down. In a heating climate, the return duct goes near the floor to draw off the cold air and heat it up.
Guess where that air goes, that's being sucked into the Return Air vent. It goes back to the air handler, into a large plenum (box), mixed and joined with the Return Air from the other rooms. Blending the air together helps eliminate the hot/cold rooms and zones in your house.
High returns upstairs (suck the stratified heat off the ceiling) & low return down stairs (suck the cool puddled air off the floor). If supplies are located and designed correctly, they will mix the air so that stratification is not an issue, so return location is mostly irrelevant.
Instead, there should be at least one return vent in every room, with two or three being ideal. If your house has only one return vent, this is not a problem — make sure to keep the doors open in every room so the air can circulate properly. Make sure there are no furniture, draperies, rugs, etc. blocking return vents.
Restrictive vents or grills: A vent that isn't the right size or shape can make a ton of unwanted noise. Some vents aren't made very well and have very narrow openings for air to enter or have vents that fall closed easily, which means that the HVAC system or furnace has to work super hard to get enough return air.
Ceiling vents do a better job cooling and floor vents do a better job heating. If your priority is cooling, put your HVAC in the attic and ducting and heating vents in the ceiling. If you prioritize heating, put the HVAC and vents in (or below) the floor. This principle works for return heating vents as well.
The theory is that in the Summer cooling season, you want to be circulating warmer air back through the HVAC system to be cooled. Since that warmer air is at the top of your room, you will want to make sure the highest air return is open and the lowest is closed.
If they are too small, airflow will be restricted and there will not be enough air circulation to heat or cool the inside of your home. Return air ducts must be sealed and unobstructed — Sealing return air ducts is just as important as sealing supply ducts.