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How to Check Your Air Ducts for Leaks

If you’ve been feeling like your utility bills are suddenly spiking, or that your AC or heat just isn’t working as well as you want it to, or as well as it has in the past, there’s a chance that your air ducts have one, or more, holes and are leaking from them somewhere. Your home’s HVAC—heating, ventilation, and air conditioning—is made up of several different parts both inside and outside your home. It is possible that there is a problem with any part of the HVAC, but it’s much more likely that the problem lies in your air ducts.

Do not panic, it happens. I’ll be summarizing everything you need to know to assess and patch this problem up quick and easy, so keep reading. Of course if you’re looking for the undeniably quick and easy way to find and fix the problems with your air ducts, you could just pick up the phone and call a professional—but let’s not be lazy. Checking your air ducts for leaks is a good thing to do about once a year, regardless of if you are experiencing any issues mentioned above.

Looking for Duct Leaks:

There are a few things to look for to determine whether it could be your air ducts leaking or not. If you do not find any leaks after your inspection, then there’s a larger issue at hand that this article cannot help you with and now would be the time to call that professional. If you are feeling heating and cooling inconsistencies in certain areas of your house—your bedroom is very hot while your living room feels like an igloo—or you’ve noticed a high volume of dust accumulating in certain areas around the house, it is time to check the air duct system. Dust could be coming through the duct from the attic and finding its way out of the leak.

If you’ve noticed these things, or just have a sneaking suspicion that something is going on with your duct system, there are a few steps to take to check your ducts for holes and leaks. You may want to grab a flashlight to make things easier. You may also want to grab some gloves if you are not wanting to get your hands dirty—and wear some old clothes that you don’t care for much anymore. First thing you are going to want to do is turn the AC on full blast—this will make it easier to find any leaks if there are any. Next step is pretty simple: look for any visible tears or holes in the duct. The larger the tear or hole, the easier it is to spot it, but the harder to fix. Make sure you mark any spot that you find that is teared and is leaking with something obviously visible and won’t rub/fall off so you can come back to fix it later.

If you are not seeing any visible tears, then use your hand to feel along the entire duct—especially the joints, which are where two air ducts connect. If you have previously used duct tape to patch up any leaks in the past, now is the time to get rid of it and turn to a more permanent fix—putting aside the irony of the name, duct tape can only get you through so much and is not exactly the best solution when it comes to patching leaky air ducts. If you still aren’t feeling anything with your bare hand and do not want to give up just yet, use a smoke pencil or incense to see the leaks. Anything that gives off some visible smoke will be useful—you can even break out that fog machine that only gets some use around Halloween for some spooky effects. The smoke will be more sensitive to any air inconsistencies than your hand will be. You will see the smoke twirl irregularly and that will indicate that air is being sucked in or pushed out through a hole.

Another easy tool that can be used is a small, thin piece of toilet paper that will easily be moved when hit with some air. If you’ve found some leaks and have been marking them like mentioned above, you’re going to have to seal them up next. In case it has not been made clear enough: do not forget to mark any and every spot you find a leak, otherwise this whole process will be a waste.

Sealing the Leaks:

There are two options for sealing the leaks on your air duct. The first, and more sticky way, is using mastic. Mastic is similar to putty and it will seal the leaks securely and efficiently. The problem with mastic is that it’s pretty messy to handle, so it can be a little bit more of an unsightly project to take on. The second option is foil tape. This type of tape is obviously a step up from duct tape, but essentially works the same way. Foil tape works better for smaller leaks and more for leaks that are along the straighter parts of the duct and less for leaks on the joints, as it is more difficult to get the tape secured on angles. Clean the surface well before applying the tape or mastic, ensuring there is no dust so they attach to the duct as strongly as possible. Mastic will be better to use with bigger leaks and for leaks that are right on the joint of the duct, since it is malleable and will seal the leak more consistently.

In some cases, it may even be better to use the foil tape combined with the mastic—you can never be too prepared! Sometimes the leaks you find will be extensive and not able to be patched up. In this case it may be time to get a new duct system. This is a more expensive option, but it will ultimately outweigh the spike in your utility bill so don’t rule it out if it becomes necessary.

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