How to Seal Air Ducts
You can lose hundreds of dollars a year in utility bills because your air ducts are not sealed properly. But leaky ducts don't just cost you money it can also cost you and your families health. Leaky ducts can allow dust, mold, humidity and other toxins like radon gas, pesticides and carbon monoxide to enter your home from basements, attics and crawl spaces. Read on to learn how to save money and protect your families health by following these steps to seal the air ducts in your home.
- Difficulty:
- Moderate
Instructions
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1
Determine if you have leaky ducts. If you have high summer and winter utility bills, fluctuating temperatures between rooms, ducts that run through your garage, crawlspace or attic or if you see kinked ducts you probably have ducts that are leaking.
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2
Hire a professional to check your duct system if you are not sure you have leaky duct work and ducts are especially difficult to access. Professionals can run a test using forced air through ducts to determine if your ducts leak.
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3
Look at duct work that is insulated to see if there are streaks of dirt around the seal. This is a sign you have a leak under the insulation at a duct joint.
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4
Check for air leaks around joints where duct work meets heating or cooling units, around the plenum and areas where ducts split. You will see open spaces, and cracks in old tape or mastic and dust or lint collected around areas that are leaky.
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5
Support flex duct work with metal hanging straps at five foot intervals. This should be a regular installation step but many times installers do not support every five feet. This causes duct work to sag, detach and leak.
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6
Use duct sealing mastic to seal ducts and joints. Mastic is a thick paste sold in tubes.
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7
Apply mastic around joints, collars and corners of the entire air or heating system including unit and plenum areas.
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8
Squeeze a thick line around the inside of the bigger duct opening and slip the next section inside when sealing actual duct work.
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9
Check and seal each of the following areas:
• Disconnected sections or connections
• Connections between air unit and plenum
• All seams including the major unit, plenum, and duct work
• Returns and boots
• Joints between duct branches
• Seams that run lengthwise down duct work
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1
Tips & Warnings
Professionals recommend not sealing air ducts with duct tape. Sounds crazy but duct tape apparently does not seal properly and comes loose over time.
Consult a professional if you are unsure about connecting or disconnecting air or heating units to seal duct work and other areas.
