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.