Why Is My Furnace Making Strange Noises?

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woman listening for strange furnace noises in denver home

As you use your furnace more often, especially during the winter months, it could put a strain on your system and raise your odds of experiencing issues. You may start noticing strange sounds, which is a telltale sign that something is going wrong with your system and you may need furnace repair in Denver.

No matter what time of year it is, you can stay on top of furnace problems early by listening for some common noises that could indicate there’s an issue with your furnace.

Continue reading to learn more about those noises, or reach out to the Denver HVAC experts at Bell Plumbing, Heating, Cooling & Electrical if you notice any of these noises or need to schedule heating service in the Denver Metro area!


The furnace uses a part called the air handler to circulate air throughout the house. The part is essentially a large motor with a fan attached to it. A lot of friction is generated by the motor during operation, so to help cope with it the system is equipped with a number of oiled bearings. These bearings lessen the friction greatly, but they do wear out over time.

As the bearings wear down, the friction on the air handler increases and produces a loud grinding sound. If you hear this sound, you should have the bearings in your furnace replaced as soon as possible. Otherwise, the air handler motor may overheat and burn out.


The burner assembly is the part of the furnace that ignites natural gas in order to generate heat. Over time, carbon particles collect on the burner assembly jets. Eventually, the burner assembly will become so clogged that it starts to ignite later than it should. When the assembly finally ignites, it burns through all of the excess gas at once and generates a loud booming sound. Getting your burner assembly cleaned should take care of the problem for you. Make sure you schedule it quickly, though, before the assembly gets too clogged to ignite at all.

Rattling or Banging

Rattling or banging noises coming from your furnace could be a sign of loose or broken components within your furnace. Over time, the vibrations and operational stresses can cause screws, fasteners, or e components like the blower wheel or motor mount to dislodge and damage your furnace. Contact us for regular furnace maintenance in Denver to stay ahead of the issue and identify problems before they get out of hand.

Squealing or Screeching

If you hear a high-pitched squealing or screeching noise from your furnace, you may have a problem with the blower motor or the connecting belt between the motor and the fan. Worn-out or misaligned belts are a common problem with squealing and screeching noises and needs immediate attention from a furnace specialist or HVAC pro. You may need the belt adjusted or the blower motor tweaked and lubricated to mitigate these sounds and the efficiency of your furnace.


While occasional clicking sounds when your furnace starts up or shuts down is pretty normal, ongoing clicking may point to issues with your ignition system or a malfunctioning flame sensor. These components are a vital part of your furnace’s ignition process and the team at Bell, Plumbing, Heating, Cooling & Electrical and address these odd furnace nosies to prevent disruptions in the heating cycle.


It’s normal to hear popping sounds in your furnace and is often caused by the natural expansion and contraction of ductwork as it heats up and cools down. But when the sound is excessive, you’re probably dealing with dirty burners or delayed ignition. Regular cleaning and furnace maintenance, especially in your combustion components, can get on top of the problem and ensure a quieter operation.


Whistling noises could point to issues your air filter or issues within the ductwork. Regularly checking and replacing your furnace’s air filter helps prevent airflow restrictions. The team at Bell can also inspect your ducts for obstructions or damages that contribute to a quieter and more efficient furnace operation.


A rumbling noise could be indicate of a burner assembly problem or complications related to combustion. These issues can be dangerous and requires immediate attention from a HVAC technician. Call us today to check over everything, including your burner assembly to keep your home warm and safe.

Call for Furnace Help in Denver, CO Today

Bell Plumbing, Heating Cooling & Electrical offers heating repair services throughout Denver, CO. If your furnace is making strange noises, or you need any other kind of furnace repair, call our team right away!

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