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Covenant Heating and Cooling Blog

Noises You Should Never Hear Your Furnace Making

woman-covering-her-earsWhen it comes to your comfort, it’s hard to ignore some signs that your HVAC system is struggling. For instance, if it’s in the middle of winter and your vents are blowing out cool or lukewarm air, you’ll likely give our pros a call right away for repairs. For other problems though, such as funny noises, you may be tempted to wait on calling in a pro, or you may decide to ignore the sounds altogether, shrugging it off as a normal part of furnace operation.

Please don’t do this. We want you to protect yourself and your family, and one way to do so is to alert a trained HVAC pro when your furnace system is making unusual noises—noises that may indicate a hazard. Keep reading to learn some of the noises you should never hear from your furnace—and give us a call if you do!

Banging or Booming

Typically, a bang or a boom that you might hear coming from a furnace is the sign of a dirty burner. This may seem like a benign problem, but it can actually be pretty dangerous. This noise is caused by a delay in ignition due to that dirt and grime buildup. The gas builds up, and when it ignites, a mini “explosion” happens inside the system.

Cleaning the burners yourself is not something we recommend. There is too much room for error, and you don’t want to spend more money in the long run. It’s always safest to call in a pro, particularly when it comes to a gas-powered heater.


Rattling doesn’t seem like it would be that threatening of a noise, right? Well, if you hear a rattling sound coming from your furnace, don’t just assume it’s a loose panel or screw. While this might be the case, only a trained professional can tell for sure. You might be dealing with a cracked heat exchanger, which can be a very dangerous issue to have.

Cracked heat exchangers are not something very visible to the naked eye, and are more common in aging furnaces than they are newer systems, but the result is carbon monoxide leaking into your home. This can make you ill, and in more severe cases has resulted in fatalities.


A loud screeching sound is most likely an indication that the blower motor in your furnace isn’t working as it should. A malfunctioning blower motor means that the heat produced by your furnace won’t be able to circulate warm air around your home effectively.

This may just mean that the blower motor needs lubrication. But, it could instead suggest that the fan has stopped altogether. To adequately diagnose the situation, it’s important that a local HVAC professional does a proper inspection. Once the problem has been properly diagnosed, a professional can advise you on the next steps.


If you hear what sounds like metal-on-metal, this can be a sign of a serious problem with the furnace system’s blower wheel. If this is, in fact, the case, you need to turn off your furnace and contact a trained professional right away, in order to prevent further damage to the wheel. More damage to the wheel means more damage to your wallet.

For quality service on your HVAC in Gallatin, TN, contact Covenant Heating and Cooling, where we are “Dedicated to the Promise of Serving You.”

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