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How to Seal Air Ducts For Year Round Savings

One of the most overlooked ways to increase home energy efficiency and save homeowners money and energy year round is to seal air ducts. Your air duct system is responsible for transferring air to your heating and cooling system as well as delivering conditioned air to the rooms in your home.

If you have air leaks or blocked returns/registers, your heart (aka your HVAC unit) will have to work harder than it needs to, reducing its lifespan and increasing its energy use. To take care of the life-blood of your home, check and/or change your air filters every 30 days and go around and inspect your air duct system for proper air flow.

Although sealing air ducts will minimize the amount of dust that spreads in your home, it is recommended that you schedule a professional air duct cleaning every 5 years or so. To find out if your air ducts are in need of a deep cleaning, open up a couple supply and return vents and stick a flash camera in there to take some pictures.

If it looks anything like the before picture, you should seriously consider investing in a good duct cleaning. Other signs that you need your air ducts cleaned is if people are constantly coughing, getting asthma attacks, or getting sick in your home.

before and after cleaning

How to Seal Air Ducts

    • Before you start your project of taping and sealing your ducts, you’ll want to identify the leaks first. Although it is probably a good idea to seal all the joints in your air ducts, you can find out if they are leaking by using a piece of toilet paper or incense stick to detect air leaks. Look at all the points where metal pieces are joined.
    • After finding the air leaks in your duct work, you’ll want to clean the area off first. A simple dusting and wiping will remove dust and debris allowing the caulk and tape to stick better.
    • Duct mastic is the preferred material to seal air ducts and joints. Ironically, duct tape is not a good solution to seal air ducts. It will begin peeling and won’t last very long. If you do choose to use tape, make sure you use mastic, butyl tape, foil tape, or other approved duct sealing tape.
    • You can spread the duct mastic around with a putty knife or paint brush. Make sure to wear old clothing in case it gets on you. If you are helping spread the sealant with your finger, use plastic or cotton gloves. Just be careful screws and other metal pieces that could cut your hand. The mastic should be about as thick as a quarter/nickel.

Although sealing your duct work is a fairly easy DIY project, in order to fully insulate and seal your ducts, you’ll want to consult with a professional air quality expert. Dirty air ducts have a detrimental impact on the performance of your heating system and the quality of your indoor air.

Make sure you are taking the proper steps to seal and insulate your home. For more information on how to seal your air ducts, see this HGTV.com How-To.

By sealing your air ducts, you will not only experience increased energy efficiency and lower energy bills, but also a dramatic improvement in the quality of your indoor air. If you do make major insulation changes, call your trusted HVAC professional to assess the ventilation balance of your system. We will also test your air flow to see if your systems is operating correctly and efficiently.

Read our air-sealing blogs for more information on saving money and energy this fall/winter:

For more information on insulation and where to seal air leaks, consult energy.gov’s Tips for Sealing Air Leaks and Tips: Air Ducts.


If you have any questions about how you can further winterize your home and seal air leaks, give the comfort heroes at Cassel a call.

We would be glad to answer all of your questions. We are experts in saving homeowners money on their energy bills.

Check out some rebates and tax breaks you could be eligible for.

Click here for 10 Maintenance Tasks to complete this fall.

If you want to learn more about how to stay safe and save money with your heating and cooling systems, call us at (217) 866-1596 for more information and expert tips (available 24/7).

We’ll Get Your Castle Comfortable Again!

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