What is an HVAC Return Air Vent System?
Understanding how your HVAC system works can help you avoid mistakes that can cause problems. Learn about your HVAC return air vent system and why it’s so important.
By Anne Fonda
You probably don’t think much about the return air vents in your home, unless you’re wondering if you should paint them when you paint the room. (You can, and it makes the air return vents blend in rather than stand out if you paint them the same color as the wall or ceiling.)
But enough about painting. Let’s move on.
The difference between supply and return air vents
Before we get into the details of the return air system, we should discuss the difference between supply and return air vents.
Supply vents
Supply vents, also known as heat registers, are the vents that deliver cool or warm air from your furnace, heat pump, or air conditioner. You can feel the air blowing out. These vents are commonly located on the floor or at the baseboard level, but may also be located in the ceiling.
Air return vents
Air return vents, also known as return air grilles or cold air return vents, return the conditioned air via the return air ducts to the furnace, air handler, or packaged system. This starts the heating and cooling cycle over again. These vents do not have air blowing out. You may be able to feel a slight suction if you place your hand on the vent.
You may have one large central return vent in the ceiling or in a wall towards the center of your home. A central return vent may have a return air vent filter. Or you may have a dedicated return vent system where you have a smaller air return vent in each room and hallway. These vents are usually located higher up on a wall and do not have filters. Bathrooms will not have these vents, to keep moisture out of the ductwork.
The system of return air vents you have will depend on the size of your home, if it has multiple stories, when it was built, and other factors. Both systems work the same way.
Understanding your HVAC return air system
Return air vents and the return air ducts balance the airflow and air pressure in your forced air HVAC system. When warm or cool air blows out the supply vents, it needs somewhere to go. Eventually, the return air system pulls the air in, sending it back to be heated or cooled again. It’s essentially one big repeating cycle.
If you have a large central return air vent with an air filter, the return air system will filter out dust and allergens there. With dedicated return air vents, the air will be filtered at the air handler or furnace, or a whole-house air cleaner if you have one.
Airflow and CFM
The airflow to and from your HVAC system is measured in cubic feet per minute (CFM). Proper airflow helps your HVAC system run efficiently and helps ensure healthy air circulation and maintain even temperatures throughout your home. In a ductwork and vent system with no clogs, big leaks, or other issues, CFM in = CFM out.
A properly functioning return air system can also help improve your indoor air quality by filtering out allergens and pollutants.
Maintaining and optimizing HVAC return airflow
Should you use air return vent covers? No. Covering a return air vent disturbs proper air pressure and airflow. You can buy a decorative return air grille to make it look nicer, but you should never block it, either with a solid magnetic cover or block it with furniture or drapes.
This is one reason return air vents don’t have a damper where you can open or close the vent as supply vents/registers do. You need unrestricted return airflow to maintain the proper air pressure.
If you have a large return air vent with a filter, change the filter regularly. You can also use a vacuum cleaner brush attachment to vacuum any dust off of the return air grille. For dedicated return air grilles, you can dust them with a duster on an extension pole, like you would use to dust a ceiling fan.
Schedule regular professional HVAC maintenance in the spring before the cooling season starts and again in the fall before the heating season starts. This will help you get the best performance out of your HVAC system.
Connect with your local Trane Comfort Specialist
Work with your local Trane dealer to troubleshoot issues with your HVAC system, as well as provide expert HVAC repairs and installation.
Anne Fonda
Content Writer, Trane Technologies
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Kimberly Sexton, Senior Systems Engineer
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