Skip to Content

Return Air Vents: HVAC 101

Air intake vent

What are return air vents, really? The first thing you should know is that they’re an integral part of any air conditioning or heating system.

This includes an entire variety of HVAC systems, window units, portable AC units and more.

Making a comparison

Although it may not seem as important when you compare the return air vents to the other parts of the AC or heating system, you will soon learn their importance.

Grasping the purpose:

I suggest breaking the term down into its basic definition. By doing this, you can easily grasp the purpose of return air vents.

Let’s go over some of the basics.

Defining Return Air Vents

The most basic definition of the term “return air vents” is just as it sounds, which is vents that return air.

What air, you ask? The air inside your home that is needs to either be heated more or cooled down through your HVAC system so you can live more comfortably.

Are they different from supply vents?

Before we go any further, it is important to note that supply vents are not the same thing as return air vents. Therefore, make sure not to confuse both of these terms.

Return air vents are all about recycling. 

The main purpose of a return air vent is to suck the air in your home back into the HVAC components. This is pretty much recycling the air in your home.

Once it is heated, or “conditioned”, the air goes back in your home’s living space via duct work that ends at the supply vents.

For example, in the winter you kick on your furnace. Air is drawn through the return vent(s) and heated by your furnace heat exchanger.

When the air is warm enough, it travels to fill up your furnace plenum, then through the ductwork that feeds the areas of your house that need warm air.

An intricate process:

This is why you don’t feel any air coming out of the return air vent. However, the process is much more intricate.

Example of small return vent

How can you spot a return air vent? The return air vent can come in many sizes.

The size of the vent will depend on your HVAC system and its air ducts. Although the size can vary, the usual shapes of the vents will usually be square or rectangular.

Finding the Return Air Vent

Moreover, if you don’ feel any air coming out while the AC unit is on, this is another sign you’ve found the return air vent.

Another way you can spot these types of vents is their size.

When you compare return air vents with the supply vents, you will find the return air vents much larger in comparison.

You can also find these vents in the lowest part of the wall.

Why are Return Air Vents Important?

The function of a return air vent is to keep your home pressurized. Many things can affect the environment if the return air vents are not working.

A combination of things:

This can include a difference in temperatures, airflow hinderance and an inefficient AC system. When you combine all of this, it can cost you money in the end, which is why return air vents are important.

Changes in air pressure

As your HVAC system blows air into your home, it changes the air pressure inside the house. All this air needs to go somewhere, and this is when the return air vents come into play.

The difference in sizes

These vents are much larger than supply vents because their job is to return all the excess air back into the HVAC system.

This is done through a system of air ducts that run throughout your home and into the HVAC unit.

More means better

You can get the most out of your return air vents by having one or two placed in every room of the house. However, you can make it work with just one vent.

If this is the case, you can do what I do, which is leaving the doors open of each room to let the air circulate.

Install more:

It would be a good idea to install more return air vents whenever you have an opportunity.

By doing this, you will keep your home pressurized constantly and be able to maximize your AC unit’s overall performance.

Do More to Optimize Your Return Air Vents

If you’re wondering how to optimize your return air vents, you will find a few things that you can do.

One of the first things you can do is clear the area of any obstructions in the way of the vents.

Ultimate comfort

This can maximize the airflow for ultimate comfort. It’s also ideal to avoid closing any supply vents because it could increase the air pressure inside the ducts. You can also clean the air vents on a regular basis as well.      

Cleaning the Return Air Vents

The great thing about return air vents is that they’re not mechanical in design. Therefore, you won’t run the risk of breaking anything.

The grates themselves can be made of metal or a hard plastic, so you don’t even have to use any special cleaners.

Just need a couple of things

You’ll just need a damp cloth and water. Make sure that you dry the grate with a dry towel once you are finished.


Simply by pulling on the grate, it should come off the vent. Take a damp cloth and wipe the grate all around to clean it successfully.

Working like new:

If you’re changing the filter as well, you can take the cloth and wipe the inside of the ventilation. Doing this once every two months can keep your return air vents working like new.

Speaking of filters, some return air vents will have the air filter directly behind the grill. This is actually a more convenient way to service, inspect and replace the filter. 

Air filter behind air return vent


Q: What is a return air vent?

A: The return air vent is an integral part of your HVAC or AC system that keeps your home pressurized. It is where air is brought back (recycled) through your home’s heating and cooling system.

Q: How do the return air vents work?

A: The return air vents work by absorbing the warm air along with the moisture and cooling it through the HVAC system. Or, by taking in cooler air to be heated.

Q: Why can’t I feel air coming out of the return air vents?

A: In part, you can’t feel air coming out of these vents because their job is to suck the air into the ventilation. 

If you place a piece of paper on the vent while your heater or A/C is running, it should stick on top of the vent grill.

Q: Are supply vents the same as return air vents?

A: No, supply vents work by blowing the cool air out and into the house while the return air vents take the hot air into the duct system, vice versa when you’re heating your house.

The Final Overview

Keeping things simple has always worked for me. Therefore, in order to understand how return air vents work, I suggest breaking down the term itself.

Basic form

In its most basic form, these types of vents return the air back into the HVAC or air conditioning unit.

Not mechanical but still important

It’s also noteworthy that this is not a mechanical device that needs repair or hard maintenance.

However, the vents still play an important part of any AC unit. Remembering all this will help you appreciate the return air vents a bit more.

Sharing is Caring!