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The Duct (Tape) Stops Here

duct sealing without tapeIf you’re the kind of homeowner that feels pretty handy with a screwdriver and a caulking gun, you’ve probably already tackled a lot of home performance projects designed to reduce home energy consumption and lower your monthly utility bill. But now that the programmable thermostat has been set, and you’ve switched out all your light bulbs to energy-efficient LEDs, what about taking care of those duct leaks? Recent research reports have found that duct leaks are typically the single biggest contributor to home energy waste. Effectively sealing these leaks save the average homeowner somewhere between $200 and $800 a year on their annual utility costs. But before you block out the weekend for a duct sealing project, you’ll want to keep one thing in mind…while there are products on the market that can help you reduce duct leakage, duct tape is NOT one of them. Crazy hu? I’ve seen people do all kinds of crazy things with duct tape – from repairing a leaky canoe to crafting a heavy-duty wallet, but the one thing experts say you can’t effectively do with duct tape is seal duct leaks. Here’s an excerpt from an article written by Paul Preuss several years ago. Preuss was writing for Lawrence Berkeley National Laboratory, a federal government research facility quite interested in energy saving solutions. “…. Unfortunately, one of the things you can’t do with duct tape is seal ducts. At least, not for long, according to Max Sherman and iain Walker of the Department of Energy’s Lawrence Berkeley National Laboratory. For three months they tested a variety of sealing materials – many kinds of duct tape, clear plastic tape, foiled-backed tape, mastic and injected aerosol sealant – under conditions similar to those encountered in real heating, ventilating, and air conditioning (HVAC) systems. “We tried as many different kinds of duct sealants as we could get our hands on. Of all the things we tested, only duct tape failed. It failed reliably and often quite catastrophically,” says Sherman, who heads the Energy Performance of Buildings Group in Berkeley Lab’s Environmental Energy Technologies Division (EETD). Walker notes that “tape manufacturers sell all kinds of colors and grades – ‘contractor’ grade, ‘professional’ grade, even ‘nuclear’ grade, whatever that means. But performance doesn’t seem related to grade.” As you might suspect, the one duct sealing method that these researchers found performed well above anything else was aerosol-based duct sealing. According to the Preuss article… “The aerosol sealant system…was tested many times longer than the others. The sticky vinyl polymer is designed to be pumped through the ducts to automatically seek out leaks, span them, and dry; in a program undertaken for the Environmental Protection Agency, Sherman and Walker sealed leaks with aerosol, then cycled the ducts from ambient air pressure and temperature to hot air at twice typical duct-system pressures, every 20 minutes for two years. There was no significant change in duct tightness. While aerosol-based duct sealing (AKA aerosealing) isn’t something a homeowner can do on his/her own – it requires a licensed aeroseal expert – it does have one major advantage over do-it-yourself duct sealing of any kind. And that is, since it works from the inside to find and seal leaks, it seals ALL the leaks – even those hidden behind walls, under insulation or in other parts of the ductwork that are difficult to access. So while you may want to cover over some of the visible and easily accessible duct leaks with professional mastic or aluminum tape, it’s aerosol duct sealing if you want to shore up the remaining 90% of duct leaks that are hidden away. And leave the duct tape for that broken refrigerator shelf.  

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