by Trey Muffet on July 19, 2010
Simple proactive measures can prevent hours of head-scratching and time wasted trouble-shooting problems that could have been avoided in the first place. But unfortunately, we can’t always predict the scenarios might diminish the performance of installed equipment—or even render it useless, as happened to us on a retrofit job we completed last summer. In this case, we learned the hard way that putting stainless steel mesh covers on intakes is a pretty good idea.
The job in question involved installation of a 95% sealed combustion furnace as part of a performance package. After installation, the furnace was tested for combustion safety and commissioned. A few months later, when outdoor temperatures began to drop, the client turned up the heat. Nothing. The inducer motor was running, but the blower wasn’t kicking on and the furnace wasn’t firing. After much deliberation, we found that the inducer motor wasn’t creating enough pressure, so we replaced the bad inducer motor. After that the furnace worked fine.
Why would a perfectly good inducer motor that worked flawlessly upon installation fail in a matter of months, even though the furnace had been sitting idle the whole time? The answer became clear when further inspection revealed a sparrow’s nest in the intake, which was blocking the flow of air to the motor. And that’s not the only time we’ve seen evidence that intake and exhaust vents can be attractive hiding places for curious critters. A similar situation lead us to find a stash of acorns in an intake (the elusive squirrel was never found).
Now our standard practice is to install mesh covers on all external vents—a quick and affordable fix that can save us and our clients a lot of headaches in the future.
by Trey Muffet on July 12, 2010
Here’s something to bear in mind the next time you reach for your duct blaster: At Recurve, we’ve found that using a duct blaster to diagnose leaks isn’t always time well spent. And we all know that in the Home Performance business, time is money.
The problem is that you can spend hours in cramped spaces sealing ducts only to find that there’s little real improvement in leakage levels, and using a duct blaster to locate leaks is a slow process. The alternative? Using a pressure pan in conjunction with a blower door can help you quickly zero in on leaky duct runs that need the most attention, so you can achieve good results in much less time.
Assuming you’re already running a blower door on most of your projects (or have one easily accessible), a pressure pan can take the place of a duct blaster for determining the highest priority areas to seal. With the house prioritized to 50 Pa by the blower door, record the pressure drop with the pressure pan when it covers the register. A large pressure drop (3-6 Pa) indicates that significant leakage is occurring close to that location. A small pressure drop will indicate there is no leakage in that duct run, or that the leakage is far away.
Don’t get us wrong—duct blasters are essential equipment in situations where you need to perform a rigorous leak test. But this quick pressure pan test can save an hour or more compared to taping off the registers and running a duct blaster test, and anything you can do to achieve the desired results in less time will benefit both you and your clients. The bottom line: Knowing where to focus your energy to save your clients’ energy can give you a real competitive advantage.