My cousin Amy recently got married. Now she and her husband are building a new home, some custom job. Anyway, Amy is pretty much a perfectionist and wants everything done just so. And that means by the crème de la crème of experts. So when it was time, she went to the ductwork hotshots. What she found out was amazing.
It seems that the primary reason ducts leak, thus wasting as much as 30% to 40% of energy, is due to poor construction. Most ductwork is simply sheet metal fastened to more sheet metal with screws, which means it has the same amount of integrity as the downspouts on your house. Which isn’t saying much. Don’t misunderstand, sheet metal is a great conveyance system for moving air, but there are a lot of joints, fittings, and seams that are prone to leaking like the proverbial sieve. And if that’s not bad enough, sometimes the HVAC systems in residential or commercial properties are not properly balanced. This results in either too much or too little air pressure within the ductwork, and just like an underinflated or overinflated tire on a car, it doesn’t work well. And there’s always the risk of a blowout.
The second most prominent cause of leaky ductwork is inferior installation. In other words, the guy who installed the ductwork was an amateur. Joints, fittings and seams have to mesh correctly from the word go. If they don’t, they will suffer more and more loosening as time passes.
To my surprise, Amy informed me that one of the biggest culprits of leaks resulted from duct tape. It seems that just because it’s called ‘duct tape,’ it is not made to be used on ducts. That fat, gray roll of duct tape that you have in your garage is not very heat resistant. And once it dries up, it falls off, usually after four to six months.
Again to my surprise, there really is a duct tape made specifically for sealing ductwork. It’s called “foil tape,” and carries a UL-181 approval rating. So if you walk into ACE Hardware and buy some duct tape, be sure it has the proper rating on it. That being said, most expert installers use what is called mastic, which is a type of adhesive that seals the joints.
Proper sealing of residential ductwork can save the homeowner about $100 per year in heating costs, and an equal amount during the summer months in air conditioning, if central AC is utilized. Any homeowner who thinks they might have a leaky system can have their system tested by an HVAC professional.