How to Identify Return and Supply Vents Easily

Don’t sweat this easy test 

Woman setting temperature
Photo: aquaArts studio / E+ / Getty Images
Woman setting temperature
Photo: aquaArts studio / E+ / Getty Images
Sean Jackson
Written by Sean Jackson
Contributing Writer
Updated Oct 31, 2023
SKILL LEVEL
Easy
COMPLETION TIME
10 minutes
COST
$50–$100
Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.
Geo Icon
What you'll need:
TOOLS
  • Return and supply vents
  • A step stool or ladder (optional)
SUPPLIES
  • Paper or tissue
  • Cloth
  • Warm, soapy water

Your supply and return air vents balance the air temperature and humidity in your home. That’s why finding and testing them to make sure they’re working properly is something you should do every year. This guide will help you find your home’s return and supply air vents, determine what function each of them serves, and fix common problems that arise with them.

Read more

What Are Return and Supply Air Vents?

There are two types of air vents in your home: return and supply air vents. Your supply air vent is more noticeable, as it’s the one blowing the cooler air into your home. Meanwhile, return air vents can be a bit trickier to find. They gather warmer air, pulling it into the ductwork. From here, your HVAC reconditions the air, removing the warmer molecules from it. Upon doing so, it dispenses the reconditioned air through your ductwork and back out into your living space through the supply air vents. 

Prepping to Identify Supply and Return Ducts

This task is pretty simple, and it doesn’t require many materials on your part. Gather a flimsy sheet of paper or tissue. Also, have a microfiber cloth soaked in warm, soapy water to clean dusty or dirty air vents. You can also use a handheld vacuum or a brush attachment to remove particles from the air vents. Doing this ahead of time allows for cleaner air to filter into and out of your home while improving airflow. Also, you’ll want a ladder or step stool ready to inspect hard-to-reach air vents. 

  1. Turn on the HVAC System

    Person adjusting a thermostat
    Photo: Jackyenjoyphotography / Moment / Getty Images

    You’ll want to turn on the HVAC system that way you have air blowing through your vents. This ensures you’ll be able to properly identify the types of vents you have. 

  2. Find an Air Vent

    You can find air vents along the baseboards, on your walls, or on the ceiling. You might need a step stool or ladder to access vents on the ceiling or wall. Just make sure the ladder or step stool is level on the floor before climbing it. Even better, have a friend or family member spot you as you test your vents.

  3. Test the Air Vent

    Aluminum air vent
    Photo: Penpak Ngamsathain / Moment / Getty Images

    Once you find the air vent, take the piece of paper or tissue and place it six inches in front of the air vent. If the vent tries to blow the paper into the room, you’ve found your supply vent. Meanwhile, if the vent appears to try to suck your piece of paper in, you’ve found a return air vent. 

    Why Isn’t Air Blowing Into or Out of My Air Vents?

    When you encounter an air vent that doesn’t try to pull in air or blow it out, there could be a problem with your HVAC system. Here are some of the most common issues homeowners have:

    Dirty Ductwork

    Dirty ductwork can impede airflow through particle buildup. Once every three to five years, have your air ducts cleaned. The average air duct cleaning costs around $40, but the size of your home, condition of your ductwork, and types of ductwork all play a role in the total price. 

    Unbalanced Ductwork

    At least once a year, you should do a DIY duct leakage test. Do this by finding the duct joints, where two come together then run your hand around checking for air leaks. You can also notice an imbalance if parts of your home are warmer than others, signifying there might be improper airflow in your home. 

    Have your local duct installer take a look at the system if it’s imbalanced. If your ducts are older than 15 years, then you might have to replace them. At that time, your technician can help you determine the most efficient ductwork for your home and help you discover creative ways to hide ductwork. 

    Blocked Vents

    You might have the compulsion to close vents in rooms you’re not using to avoid heating or cooling them unnecessarily. However, closing vents in unused rooms creates a temperature and humidity imbalance in the air, putting more work on your home’s HVAC system. In turn, you can experience stuffy rooms, higher energy bills, and your air conditioner kicking on more. Therefore, when you go to see what kind of vents you have in each room, make sure they all stay open too. 

DIY vs. Hiring a Pro

You can hire an HVAC pro to locate these vents for you during an inspection or tune-up. A service call ranges in price from $100 to $250, and this doesn’t take into account any problems they find when inspecting. 

Meanwhile, for under $100 (less if you don’t need to buy a ladder), you can do the project yourself. Best of all, it will only take a few minutes to test each one. And it’s a good way to ensure each vent is clean while doing so. 

Frequently Asked Questions

Some of the signs of HVAC issues include rising energy bills, rooms not cooling or heating properly, loud noises when in operation, and signs of condensation. To illustrate, if you’re wondering how to stop condensation on air vents, you’ll need to have your HVAC inspected. 

Your chimney comes with dampers, which are similar to air vents. Dampers are metal plates that allow hot air and smoke to flow from the fireplace up your chimney and out of your home. When you close the damper, it prevents cool air from getting into your home. This is why you’ll want to check to make sure your damper is open before starting your fireplace and you want to ensure it’s closed after the fire goes out. You can open and close them via an external knob, pull chain, or lever. 

Need professional help with your project?
Get quotes from top-rated pros.
Learn more about our contributor
Sean Jackson
Written by Sean Jackson
Contributing Writer
Sean Jackson is a freelance copywriter from Delaware, Ohio, covering real estate, home improvement, insurance, personal finance, and solar energy for CNET, Bankrate, ZDNet, and Marketwatch.
The homeowners guide to heating and air conditioning services
From average costs to expert advice, get all the answers you need to get your job done.
See all articles
HVAC unit outside of home
Heather Ayer
•
Apr 16, 2025
Apr 16, 2025
The cost to add R-410A refrigerant and recharge your home’s air conditioner depends on many factors, such as your location and the cause of the leak.
Family playing together on the lounge floor
Heather Ayer
•
Apr 14, 2025
Apr 14, 2025
The EPA banned R-22 refrigerant, but if you still have a system that runs on it, here’s the latest on R-22 refrigerant prices for the remaining reserve.
A woman turning on AC unit
Taylor Freitas
•
Apr 16, 2025
Apr 16, 2025
The cost of a new AC unit depends on the size and type. Our guide breaks down AC replacement cost factors so you can decide which option matches your budget.
Portable dehumidifier sitting in the hallway of a house
Melissa Graham
•
Apr 3, 2025
Apr 3, 2025
If your home feels like a rainforest, it’s time to determine why your house is so humid and how to get rid of the excess moisture.
A ceiling fan in a white bedroom.
Mitchell Grant
•
Apr 10, 2025
Apr 10, 2025
If you’re wondering why your ceiling fan is slow, check out this article. Some of the more common reasons aren’t as simple as you might think.
An attic turned into a minimalistic bedroom
Stephanie Mickelson
•
Apr 6, 2025
Apr 6, 2025
If you’re wondering why your attic is so hot, take a closer look at the ventilation, insulation, and your roof to find the best solution for cooling it down.