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AllTech Services, Inc. Blog

Sounds You Don’t Want Your Heater to Make


I think we could all agree that it would be fantastic if someday there was an HVAC system available that could self-diagnose when it has problems and let us know by a simple text message what it is and how to fix it. While we can’t promise that won’t ever happen, for now, it’s not a reality, and it’s up to professionals like us and observant homeowners like you to catch problems.

So, how do you know if your furnace or other heating system has problems? Well, one of the key indicators is that it’s making strange noises. There are some sounds you’re always going to hear coming from your heating system. The whoosh of air coming through the vents, for example, and maybe even a slight, gentle rattle of the ductwork as temperatures fluctuate.

What you should be alert to, however, is any noise outside of the usual sounds you hear. We’re going to cover below what some of those sounds are, and what they might mean for your system. Read on!


Have you detected a clanking sound? Maybe you hear something that resembles metal-on-metal? The problem with this is that you probably are hearing metal-on-metal, and that’s not okay. You’re probably hearing evidence of a problem with the heater’s blower wheel.

This isn’t a problem you want to neglect. If you hear this, you’ll want to turn off your heater and contact our trained and experienced professionals right away to prevent further damage to your heater’s components and damage to your budget!


Are you hearing a screeching coming from your furnace? This can be quite an alarming sound, but initially, it’s not a huge problem. What you’re probably hearing is worn motor bearings creating friction. The good news is, for our technicians, this is a relatively simple fix. We just need to relubricate those worn motor bearings, or even replace some of the bearings.

What happens when you don’t address this problem, however, is that friction increases, and it can cause the blower motor to burn out entirely. Then your system could break down prematurely. Fortunately, this is one of many issues we check on during maintenance, so if you’re staying on top of your annual (or biannual if you have a heat pump system) maintenance appointments, your heater should be in good shape!


As we mentioned above, a gentle rattling might be nothing more than your air ducts fluctuating with the temperature changes. However, you should definitely take note if the rattling intensifies, or seems like it’s coming from elsewhere in your system other than your ductwork.

There’s a rare but real possibility that this rattling could be coming from a broken or cracked heat exchanger—and a cracked heat exchanger is definitely bad news.


Do you hear a “boom” when your gas furnace starts up? This is common in ill-maintained systems. The reason for this is because it’s caused by the burners getting coated with dirt and grime. The burners’ heat collects beneath this dirt and grime and eventually “bursts” through when the burners ignite. This might not sound like a huge problem, however it rattles the whole system, which could lead to a number of different issues.

Contact AllTech Services, Inc. for expert Vienna furnace service!

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