Return Air Vents – Here’s What You Need to Know

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.
Air vent register versus grille

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.

About Your HVAC Training Shop Author

Hi, my name is Trey Lewis and I’m the founder and chief editor at HVAC Training Shop. My goal for this website is to help homeowners troubleshoot and maintain their home’s HVAC systems. Whether it’s changing an air filter, troubleshooting a blower motor, or just buying a new humidifier, I want to make sure that you’re covered.

6 thoughts on “Return Air Vents – Here’s What You Need to Know”

  1. 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

    Reply
  2. 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!!

    Reply
    • 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

      Reply
    • 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

      Reply

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