Furnace Noises? What’s Normal & What’s Not

Furnace Noises? What’s Normal & What’s Not

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Everything mechanical makes some noise when it operates. When it comes to furnace noises, it should be fairly unnoticeable. When sudden furnace noises pop up, that’s when you need to take action. Local HVAC contractor Estes Services explains what sounds are normal from your furnace and when it’s time to call a certified technician for help.

Normal Furnace Noises

When a furnace starts up to run a heating cycle, most homeowners notice some noise. This noise is typically not something to worry about. The main reason you notice it is because it wasn’t on a moment ago! 

Sometimes there is a little bit of a pop or click as the furnace fires up, then the heating system settles into a dull hum as it runs. Think of it like the click you hear when you turn on the burner on a gas stove. 

Older furnaces tend to be a bit louder than newer ones, as newer models are often designed with special features and additional insulation to limit the sound you hear as it runs. The normal noise a furnace makes during a heating cycle should not be disruptive inside your home. 

In addition, if you have a variable-speed system, you’re less likely to notice the minor adjustments it makes, compared to the “all or nothing” of a single-speed system. Think of it like “switching gears” versus the car is running or it isn’t. 

Beware These Furnace Noises

Sudden and unusual furnace noises when the equipment starts, runs, or shuts down are cause for concern. These are the main sounds you need to beware of:

  • Grinding or scraping
  • Rumbling
  • Squealing
  • Thumping
  • Loud pops or bangs
  • Loud humming
  • Repeated clicking

Grinding & Scraping

Grinding and scraping furnace noises usually point to dry bearings within the furnace blower motor. These bearings need regular lubrication to maintain proper function. If you have a preventive maintenance plan with Estes Services, your technician handles this during an Atlanta furnace maintenance tune up.


If your furnace completes a cycle but produces a loud rumble through the house, this is a cause for concern. It could be fuel is continuing to burn in the combustion chamber even though the burners are shut down. 

Problems with burners, pilot light, or flame sensors are possible. One of the reasons HVAC contractor intervention is necessary is because this situation increases the risk of carbon monoxide poisoning. 


Squealing sounds are caused by an issue with the furnace’s blower motor. A loose belt is a common cause, but the issue may be more complex within your blower motor.


Thumps and bumping noises, like an unbalanced washing machine, often indicate an unbalanced blower wheel or motor. This is a serious issue that requires immediate HVAC repair. The blower wheel and motor are major furnace parts and you don’t want them bouncing around.

Loud Pops & Bangs

Homeowners often notice a popping sound when the furnace begins a cycle. This is due to warm air that hits the cold metal of the ducts, which causes expansion and produces that noise. When the popping noise is louder, your gas furnace’s burners may be dirty. 

This problem causes gas accumulation and the potential to cause a crack in your heat exchanger. This is very serious and requires immediate furnace repair.

Loud Humming

A low hum is normal while the furnace runs, but if the noise is loud during a cycle or comes on when it wasn’t present before, there could be an issue with the fan or capacitor.

Repeated Clicking

A gas furnace makes a clicking noise when a heat cycle starts and stops, which is normal. If clicking occurs repeatedly throughout the heating cycle, it’s usually a compressor or control panel issue.

What to Do If You Hear Odd Furnace Noises

If you hear strange furnace noises, it’s best to stop your heating system and call Estes Services for furnace repair. We quickly dispatch a NATE-certified technician to diagnose the source of your furnace noises and perform Atlanta furnace repair service to eliminate the malfunction and the sound.

Book a Tune Up

A regular furnace tune up prevents many of these furnace sounds, such as grinding from dry bearings, squealing from a loose belt, and popping from dirty burners. Schedule an annual tune up for your furnace with Estes Services each year! 

Take advantage of an Estes Services preventive maintenance plan for the best value. Choose an HVAC plan, or customize it to include other home systems like plumbing and electrical. 

Repair or Replace Furnace?

Some furnace noises are signs of major heating system malfunctions or indicate your furnace is dying. Estes Services performs a thorough inspection of your furnace’s condition to provide you a clear picture of the problem and the solutions available. 

Repairs can get expensive, and furnaces at or beyond their estimated service life typically experience repeated problems – furnace replacement is sometimes the best solution.

Estes Services is happy to provide a free quote for new furnace installation. We help you choose energy-efficient, high-performing heating systems to deliver steady comfort with minimal noise and disruption inside. 

Get Rid of Strange Sounds from Furnace with Estes Services

If you notice strange furnace sounds, call Estes Services to get to the bottom of the problem at hand. Whether you need a tune up, heating repair, or new heating system, Estes helps you find the right solution to end the noises and improve comfort in your Atlanta area home.