Air conditioning (main) : Heating & Cooling articles : Sealing Air Ducts
Sealing Air Ducts
Your ducted heating or cooling system can't work efficiently with leaky ducts. Follow our quick how-to guide to find and seal any leaks in your ducts.
Locate the leaks
Air conditioning ducts are usually made of galvanised steel, and have a lot of seams and joints. Any point where two pieces of metal join is a prime candidate for an air leak.
Turn your heating and cooling system's fan on and carefully inspect each join for leaks.
You will generally be able to feel an air leak with your hand. Holding a stick of incense close to the duct and watching the smoke is a good way to locate minor leaks.
Mark any leaks with tape so you can find them again to seal them.
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Turn off the air
Once you've found all the leaks, turn off your heating and cooling system. If you try and seal the ducts while your system is running, air will bubble through the sealant before it has a chance to dry.
Seal the joins
Use a specialised duct sealing mastic to caulk any seams and joints where you have leaks. You'll get the best results by using a caulk gun. A putty knife is also useful for getting the sealant into the joint to ensure adequate coverage.
Some sealants give off harmful fumes, so follow the directions on the tube carefully and make sure you have adequate ventilation when sealing ducts.
If you've got the time and resources, it's a good idea to seal all of the joins to protect against leaks later.
Foil those leaks - with foil!
Use foil tape to seal areas you can't get a caulk gun into. This has a specialised adhesive that bonds firmly to metal. Despite the name, duct tape isn't suitable for sealing ducts, as it will quickly disintegrate.
Turn the air back on
Make sure you wait for the period specified on the sealant tube before turning your system back on.
Get your leaky ducts sealed properly by a qualified heating and cooling specialist.
Click here for quotes from service providers
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