What’s That Sound? Your Furnace is Telling You Something.

At some point, your furnace is likely to start speaking up. It’s a mechanical system, after all. But what do the noises mean? Read on to learn about common furnace sounds and which ones might require a professional inspection.


An irritating noise like the sound of metal rubbing on metal or nails on chalkboard could indicate a problem with your furnace’s blower wheel. This is a potentially major issue that could damage your system.

If you hear this sound, contact a technician immediately. A technician will determine if the issue is a quick fix, like a loose blower wheel, or if the wheel or motor mount needs to be completely replaced. Either way, you will want to solve the problem as soon as possible.

Wheezing and whooshing

An unsettling wheezing sound coming from your furnace could be the result of a dirty air filter. It’s very important to check and replace your air filters regularly based on the manufacturer’s recommendations. Your system will work more efficiently, saving you money while improving comfort and indoor air quality.


When you hear a thwap, it could mean something is stuck in the blades of the blower or inside the housing of the furnace. Imagine the sound of a playing card attached to the spokes of a bicycle wheel.

Contact a technician to look at your furnace because there is a good chance the motor is being strained, which could result in a larger problem down the road.

Popping or banging

Popping sounds are very common and often indicate that air ducts are expanding and contracting, which is relatively harmless. But if the noise is loud or sounds more like a bang, you may be dealing with a dirty furnace burner and you’ll need to contact a professional. Having your system cleaned and inspected annually can help you avoid this issue, and many others, altogether.

Do you hear any of these sounds coming from your furnace? Contact a FOCUS ON ENERGY® Trade Ally contractor and they can assist you in decoding what a noise could mean for your furnace.

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