Furnace Noises and What They Mean

April 2, 2024

If you have been hearing a strange sound coming from your furnace, it can certainly be disconcerting. Thankfully, not all furnace sounds are equal. While some sounds may indicate the need for a major repair, there are others that will only require a minimum level of professional maintenance work to address. There is even the possibility that the sound your furnace is making is completely normal since most mechanical devices do make some type of noise as part of their standard operational use. Whatever sound your furnace may be making, getting it looked at by a professional is the smart thing to do.

Some Common Furnace Sounds


If you hear a scraping sound coming from your furnace, it is usually attributable to an issue with your blower wheel. This scraping sound will most often have a metal-against-metal quality to it. One possible reason that you are hearing that sound from your blower wheel is that it may simply require a replacement. It may also have gotten loose, and the sound could be from it pounding up against the blower casing. If unresolved, this could wind up putting major wear and tear on your system.

Squealing or Screeching

The culprit for a squealing or screeching noise is also typically the blower motor. A blower motor has bearings that can dry over time, so this problem can often merely require a professional to apply lubricant. Another possible reason for this type of sound could be a broken belt, which will require a replacement of the part.

Whistling Sounds

Yet another issue that can often be due to the blower motor is if you hear a whistling sound. This can happen when your blower develops an airflow problem. Low airflow will strain its drawing of air, which will result in a whistling sound. This issue can be resolved with a professional first changing your air filter, if necessary, and ensuring the vents are all open. If this fails to stop the problem, a technician may look for a more involved solution.

Banging and Popping

If you are hearing banging and popping noises coming from your furnace, rest assured, it does not always mean that there is a problem. Furnaces can make these sounds during normal operation as ducts contract and expand. If you notice that the sounds are particularly loud and frequent, it could be that there is an issue with your ductwork or a burner is dirty, causing ignition to delay. Loud banging and popping noises require a professional to have a look at your furnace as soon as possible, as they may result in a cracked heat exchanger.


When you hear a rattling sound coming from your furnace, it is most likely that there is a loose door or panel. A technician will first check for this and tighten any loose screws to resolve the issue. If this turns out to not be the problem, they will also look to see if there are any other loose parts that may need tightening. In the most severe cases, the rattling sound could be due to a cracked heat exchanger, which will need addressing immediately as it could wind up leaking carbon monoxide into your residence.


It is possible to hear a slight woosh, roar, or rumble when your furnace completes a cycle. This is a normal occurrence, and there is no need for alarm. A rumbling sound is only indicative of a major problem if it is excessively loud at the end of a cycle. The loud rumbling sound is often due to an issue with the burner, leading to fuel still burning in the chamber after the burners shut down. This could potentially be a serious issue, and if encountered, you should turn off your furnace immediately and seek the help of a professional.


If you initially hear a clicking sound when you fire up your furnace, this is not something of concern. You should, however, take note if you continue to hear the clicking sound throughout the furnace cycle. This repeated clicking sound could be attributable to an issue with your ignition system. If this sound is occurring, it could be due to an array of potential reasons. Turn off your furnace, and contact a professional right away.

Contact Our Team Today

If you are hearing these or any other furnace noises and are in South Charleston, WV or the surrounding area, our team at Mullen Plumbing, Heating and Cooling would love to help. We are a family-owned business whose roots stretch way back to 1950, and we are ready to put all of our years of experience to work for you. Not only can we handle your furnace noise issues, but we are also a full-service plumbing, heating, and cooling team. That means that we can address anything from AC installation to drainage problems. Give Mullen Plumbing, Heating and Cooling a call today so that we can make sure your furnace noise concerns become a thing of the past.

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