Your home’s HVAC system is responsible for keeping a comfortable climate in your home. This is done by sucking in air from the inside of your home, filtering and cooling/heating it, and then blowing it back into your home.
But where does your HVAC system suck in air from your home? And how does the air intake location affect the climate in your home?
In this article, I’ll go over return air vents and their location. I’ll also discuss whether you should block a return air vent and the difference between an air vent register and grille.
Location of air return vents
Most older homes (pre-1990) have one big air return vent located centrally somewhere in the home. Usually it’s located in a hallway, but could be somewhere else such as in the living room.
Newer homes usually have several small air return vents located around the home—such as the bedrooms, bathrooms, kitchen, etc.
Generally, the specific location of return air vents is due to cost rather than energy efficiency.
For instance, a home might have its return air vents in the ceiling because the ductwork runs in the attic of the home. So putting the return vent in the ceiling makes the most sense since it will have a direct path to the return duct in the attic.
How to identify an air return vent
So you’ve found an air vent, but how do you confirm whether its a return vent or a supply vent?
One way is to hold a piece of toilet paper up to the vent. If the paper gets sucked toward the vent, then its a return vent.
Another way to tell is by inspection. Return vents usually have grilles on them. This is different than supply vents—they usually have registers on them.
I’ll explain the differences between registers and grilles below.
Air vent registers versus grilles
When it comes to air vent registers and air vent grilles, you might have heard these two terms used interchangeably. While they are similar, they are actually two different things:
- An air vent register is used on the supply vent. The register has slotted louvers inside of it that are used to direct airflow inside of a room. In most registers, the direction of the vanes are adjusted by a lever or slider.
- An air vent grille is used on the return vent. The grille has slotted vanes that are non-adjustable in a fixed position. Its purpose is mostly for keeping objects out of the air intake.
Another type of air vent device is the air vent diffuser. Diffusers are similar to air vent registers, but they are non-adjustable.
While registers allow you to direct airflow in a certain direction, diffusers disperse air in all directions.
Should you block a return air vent?
You should never block a return air vent. Blocking a return air vent will cause issues with air temperature, pressure, and circulation.
Even if a return vent isn’t completely blocked, you still need to keep it clear.
Keep all objects such as furniture, curtains, and appliances at least 1 foot away from return air vents.
Blocking a return vent can cause damage to your HVAC system by causing air leaks. Air leaks occur when there is a high pressure difference between the inside and outside of your ductwork.
If the return air vents are blocked, then the blockage will cause excess negative pressure inside your ducts. The excess negative pressure has the potential to cause your ductwork to implode on itself.
Besides your ductwork, your HVAC unit itself is at risk from the lack of airflow.
An air conditioner that doesn’t have enough return airflow can be damaged by the pressure imbalances in the system. In a worst-case scenario, wet compression can take place and cause your compressor’s head bolts to strip.
A furnace that doesn’t have enough airflow can suffer a range of issues, such as tripping out on high limit or a cracked heat exchanger.
Should you close off a return air vent?
Some people think that it’s appropriate to close one or more of their return vents depending on the season, such as in summer or winter.
The truth is that you should never close a return vent—even when the seasons change.
Too much return air is never a bad thing. So there’s no reason to choke or dampen a return vent.
Do you need a return air vent filter?
Most homes have either one of these types of setups:
- Air filter installed in the return duct at the HVAC unit, OR
- Air filter installed in the return vent in the home
In most cases, either one of these filter setups are sufficient to keep your home’s air clean and your HVAC unit effective.
But what if you install an air filter in both the return duct AND in the return vent? In most cases, that’s not necessary. However, if you have tons of debris, dust, or pet hair in your home, installing both filters can help your primary filter last longer.
I talk more about this in-depth in the article below.
Good day and thank you for the article. I have a question regarding changing the pressure in my return vent system. We have a 60 year old, 1 1/2 floor home with a poorly installed furnace in the basement. (I believe) our biggest problem is circulation of air. We have no return vent on the upper floor and half the vents on the main have very little flow. I suspect this is because our furnace in directly under two of them and those two are doing all the work. How can I change the pressure in my vents to increase suction at the far end of house (35′)? My return vents are “boxed in rafter” style, not pipe. Thank you greatly for any help, our small town professionals are terrible 🙁
Cheers
Jeremy
Hi Jeremy,
That sounds like a complicated issue. I recommend finding a company that specializes in air balancing to look at your system.
Hope this helps,
-Trey
My returns are in the 2nd floor ceiling. Seem fine but in winter I can feel cold air seeping in if I walk or stand under it. Means I’m wasting energy heating colder air from the attic that is making its way into the home.. is there a fix for this? Or is it just poorly designed
Thanks!!
Hi Scott,
I’m assuming the central air system connected to your return vent is off during the winter. If you’re feeling cold air seep into your home through the return vent, you could have a leaky duct somewhere in the attic.
Hope this helps,
-Trey
Hello,
How do I quiet a very noisy return vent? Thanks.
KS
Hi Kimberly,
Return vents make noise due to the velocity of the air passing through the vent. The “quick and dirty” fix would be to bend the fins on the return vent to allow more air to pass through the vent unrestricted. I’ve seen this trick work a few times, but not always.
Another way to fix a noisy return vent is to swap out the vent grille for one with less restriction. Try finding a grille with more open space for air to pass through.
Hope this helps,
-Trey
Hi Trey,
I replaced my old HVAC in my attic with a high efficiency system. At that time, I had one return air vent (20″ x 25″ x 1″ filter) in the hallway of my 1 story, 2078 sq. ft. house. The installer recommended that I install another return air vent. The second return vent was installed in a tiny 9′ x 7′ room. I notice that the filter that room stays clean for months while the one in the hallway must be replaced monthly. My kitchen, dining room and family room are in an open open area (approx. 800 sq. ft.). I think the second return vent should have been installed in that larger central area to improve the air quality and circulation efficiency. Am I wrong about this?
Thanking you in advance :-)!
SG
Hi Sandra,
Does the tiny room see much traffic? If the tiny room doesn’t get much use that could explain why the filter stays clean.
As for the placement of the second return vent, there might be a good reason why the installer put it in that location. I would contact the installer to clarify what their logic was to put it in the tiny room.
Hope this helps,
-Trey
Hello Trey,
I have one return vent placed high and located in the main living area of a 832 sq ft home with a partial basement + Crawlspace. Gas furnace is a downflow to basement. My issue is that when the furnace runs it’s pulling cold air out of any nook and cranny it can find in this old house, and I’m working on those. I weatherstripped the bedroom and bath doors to stop some of this and now those rooms are warmer, but can always feel a chill in the main area. Do I need another return vent? Cool air gets pulled up from the basement and past an old back door as well. I finally figured out what’s going on and it’s driving me nuts quite frankly. Is it bad to have sealed those rooms, pressure-wise? Return vent is 14×20. Thanks in advance!
Hi Dawn,
Yeah you might need more return air. I would get an HVAC company to measure system’s airflows.
Hope this helps,
-Trey
Hi Trey,
Great information in this article. I have had havc guys to my house to fix my issue. All of them give me a different answer and want a lot of $ to replace what seems to be working. All of my research says you have the most logical answer for my issue. I have about a 2,000 sq ft on my first floor. Furnace is in the attic with flexible ducts. I am told there are no leaks in the ducts. 9 or 10 registers, good size, 1 large 20″ x 30″ grill return in an open hallway in the middle of the downstairs, with the filter changed often enough and I am now using a #5 filter instead of #10. Air flow is great to the farthest register from the furnace. As I feel the air going in other rooms closer to the furnace the flow drops off and even drops off more as the heater is run for a longer amount of time. It takes way to long to heat up my downstairs. Is my issue needing to add another return and how do I make sure it is put in the correct place to have the most efficiency? I don’t trust the havc guys.
~Lynn
Hi Lynn,
I would call an air balancing specialist to give a second opinion.
Hope this helps,
-Trey
The only return air vent in my upstairs is near the ceiling. It was installed there to pull the hot air from the ceiling in the summer when the AC is running. I have been covering it during the winter to keep from pulling out any warm air. My problem is that my upstairs is cold and I can feel the coolness halfway up the stairs when going up. Am I wrong in covering the vent in the winter time? My HVAC equipment is all in the basement.
Hi Judith,
Don’t cover the return vent at any time. If you cover the return vent, it will cause huge problems in your system, regardless if its heating or cooling.
This article is so helpful. Thank you.
I have a big machine (the furnace?) next to an outside wall. It is designed to handle ducts in 6 areas but only 4 were ever installed. Long story. This was over 10 years ago.
Is there any financial value in replacing the machine for a smaller one?
I am still trying to understand why I have to have a/c on in three rooms and I have no idea which is the one room that was chosen as the one which must always be on when I use the system. Would appreciate some help.
Hi Heather,
It’s hard to tell without seeing your system, but most systems are designed to cool the entire home – so I’m guessing that’s why you need to have the AC cooling all your rooms.
Restricting the airflow to one or more rooms is bad for your unit and will cause problems in the long run.
If you want to replace your machine, I recommend getting a local HVAC contractor to take a look at your system and make recommendations.
-Trey
Hi!
My air return vents – 2 on the top floor (hallway, and ceiling in a bedroom), 1 on the main floor, 1 in the basement – omit a foul odor, sort of like rotting garbage. The odor is intermittent – smells for a day, goes away for a few days, comes back stronger for a few days. It also seems to be worse when we run plumbing and hot water (dishwasher and washing machine). For context, we recently took possession of the house, and this odor started about 2 months after that. We had our air ducts cleaned, and that helped for a few weeks, but the odor has come back. Any ideas on what could be causing the issue?
Hi Elena,
The first thing that pops into my head is a dead critter. Are you sure it’s coming from the return vents?
Thanks for replying. The smell is definitely the strongest near the air return vent in the upstairs hallway and the one on the main floor.
Trey, thanks for taking our questions. I have a wide vent (30″ or so)in my living/den area but it does not feed into a return air duct that I can tell. It stradles a wall stud. Each bedroom has a return air. also there is no return air duct in the upstairs bedroom. Should this vent feed into a duct for return?
Thanks
Ron
Hi Ron,
I would get a local professional to get their eyes on the system and check if the positions of those vents are okay.
-Trey
Hi! I just bought a house and when I removed the filter for the return to replace it, I noticed that there is no metal duct work, the opening is just the space between the studs and drywall? Is that OK, shouldn’t it be actual metal duct? Thanks….
Hi Matthew,
Yeah, that type of return is a cavity return and it’s used in some homes. If there is a filter rack at your air handler it might be wise to use a filter there instead. Dust can sometimes find its way to your unit from the cavity since it’s not the cleanest space and is prone to air leakage.
-Trey
My home is approximately 1500 square feet, built around 1978. . I have one return ac duct in an open area that I would like to close in to make into a separate room. Does the return duct need to be open to the entire house or can it be inside an enclosed room?
Hi Kathy,
The return vent can not be inside an enclosed room. If the return vent is inside an enclosed space it will fight to get airflow and cause issues with your system. If you want to make the area where the return vent is into an enclosed room, you will need to have the return vent relocated to an open area.
Hope this helps,
-Trey
This is a great article and the question/answers are super helpful. I did not see anything about particular types of return air vent covers (grilles?). I want to use the routered wood or MDF versions that you can paint in your wall colour, but our HVAC company doesn’t think the air flow is good enough. The manufacturers of these grilles don’t specify the airflow percentage. Are they really lesser than? I really don’t want metal grilles, but I don’t want to restrict air flow either.
Hi Wendy,
Yeah, I’ve been getting lots of questions regarding grilles recently so I’m working on adding a section that covers them.
I agree with your HVAC company – most of the wood and MDF grilles I’ve seen look like they restrict more airflow than the metal grilles due to the size of the slots. I don’t have any statistics to back that up, though.
Have you thought about painting a metal grille instead? I recommend checking out some fixed bar grilles since they provide good airflow and look okay in my opinion.
Hope this helps,
-Trey
I appreciate it. I’ll look into an alternative.
Thank you!
Hi Trey, we recently replaced a closet door where the AC intake is in our son’s condo (950 sf). The previous bifold door had slots where the new doors are sliders-to allow us better access to additional space next to the AC. They are not heavy slider doors. Bad idea? Thanks for your help!
Hi Marina,
You need to ensure that there is a path for airflow to the return vent. I’m not sure exactly what your new door looks like, but you might need to leave the slider open to allow for return airflow.
Hope this helps,
-Trey
Hi Trey,
After I finished my basement, the suction from the return in bedrooms on the 2nd floor away from the master bedrooms has become very poor. This problem becomes very noticeable in the summer months when these bedrooms fail to cool. Perhaps is it not so much of an issue in the winter since hot air naturally rises from the first floor. Note that the master bedroom is fine. I called a heating-cooling tech to inspect and he could not diagnose without opening up the ceiling in the basement, so we did not go that route. I also tried a cleaning service to clean the ducts but they could not find any block either, but not sure how thoroughly they checked as they were there to clean the duct. Any suggestions on how to diagnose/remedy the problem?
Hi George,
It sounds like your basement was added to your HVAC system. Assuming that your HVAC system is large enough to accomodate the new zone, you will need to get your airflows rebalanced.
Hope this helps,
-Trey
I have a main room with two return vents, one in the floor that does not seem to blow any air and one near the floor on the wall that does blow air. Is it necessary to have two? There is no place to put furniture. Can the one on the floor be covered?
Hi Dorothy,
I don’t recommend covering any vents unless you have an HVAC professional take a closer look at your system determine that its ok.
-Trey
I live in a condo built in the late1980s. There are two cold air returns in the condo. They are both next to the furnace closet. One is baseboard level and one is above at ceiling level. Should i do the seasonal close of one or the other as our tempature is not consistent
Hi Marilyn,
Are you sure that those are both returns? Either way, its probably not necessary to close one of them.
-Trey
Hi Trey: I live in a split level and the lower level is unfinished, but the air conditioning/heater unit has a return air duct installed that is blocked off but there is a note on it that says future bathroom of which I just built. That duct is very close to the bathroom wall and I’m not sure how to connect from that duct to the vent grill. Can I use flex hose to connect between the deck and the grill? Thank you.
Hi Dave,
Flex duct isn’t usually recommended for returns since dust tends to build up between the spirals inside the duct. If you use flex duct, put a filter at the return air intake in the bathroom. A better solution would be to get a rigid sheet metal duct installed.
Hope this helps,
-Trey