When your air ducts are leaking, you’re losing cold air from your air conditioner or hot air from your furnace. When the air can leave the ducts early, that means a space further along the ducts isn’t getting the conditioned air it needs to be comfortable. It may also mean that your system is much less efficient, causing your appliances to work longer than they would otherwise need to in order to get your home to the right temperature. Correcting this issue can be a significant improvement to your system. But how do you spot an air leak? Air is invisible to the eye. Here’s how you can tell if your air ducts are leaking.

Conduct a Visual Inspection

If there are sections of your vents that you can see without ripping out the walls, then just taking a look at them can help you find out if the ducts are leaking. When you’re looking, what are you looking for?

  • Tearing: Tears in the ducts are often the result of damage or force. If one spot has tearing, there are likely to be issues in other spots as well.
  • Disconnections: Sometimes the seals between different sections of ducts come loose. These need to be professionally corrected to seal up properly.
  • Gaps: Any other gaps or holes should be of concern too.
  • Duct tape: As a stopgap, some homeowners put duct tape on the ducts to fix gaps. Despite the name, duct tape is not a good solution for these issues. So, if you see duct tape, you should probably get whatever is beneath it fixed.

Keep in mind that your visual inspection is necessarily incomplete. Even if you go into the attic to look at air ducts, there will be plenty in your ceiling or walls that you don’t have access to.

Feel for Air

While you’re performing your visual inspection, make sure that the fan on your HVAC system is set to have the fan on. That way, when you’re walking around, you can put your hand near the vent and feel for air. Often, that will help you find errors or pinpoint issues. Run your hand over the joints especially, which are the most common spots for the ducts to leak.

Use Incense or (Safe) Smoke

When you can’t feel the air, you can sometimes still see it. We suggest you walk around with a lit incense stick or a safe flame. The movement of either can help you spot leaks. Just hold the source of smoke or flame up to where you think the leak is and wait to see movement. Again, you will need to make sure that your fan is set to “on,” or there will be no air flowing through the ducts to create the leaks.

Get Professional Testing

The only way to get a full assessment of your ducts, their quality, and whether they are leaking is to have HVAC professionals in to test them. Using advanced equipment, technicians can actually tell where your ducts have an issue, even if it is currently blocked by drywall.