Furnace Noise Problems

A furnace is a helpful piece of equipment that keeps your home warm throughout the cold winter months. However, furnaces are prone to making lots of excessive noise. Should you be concerned by your furnace making excessive noise, or is this part of the regular operation of the furnace? 

Furnaces make various loud noises while in use. Some of the noises created by the furnace are normal during operation. However, other noises can indicate issues within the system. Most notably, a loud rumbling noise after a complete cycle in your furnace may indicate a dangerous fuel issue. 

Keep reading to learn details about all the different causes of furnace noise. I’ll explain what different furnace noises actually mean and what you can do to fix them. By the end of this piece, you’ll better know how to care for your furnace.

What Are the Causes of Furnace Noise Problems?

A furnace ensures you remain warm for the winter. However, they’re prone to noise problems, even when they work correctly. So, what are the most common causes of a noisy furnace?

Here are the most common causes of furnace noise problems: 

  • Gas problems
  • Damaged motor/belt
  • Poor airflow
  • Loose components
  • Damaged blower fan
  • Normal operation

See below for more information about the most common causes of a noisy furnace: 

Gas Problems

When a furnace has issues with the gas system, it can result in a loud banging noise. This happens as small gas explosions occur within the furnace. 

If you’ve noticed that your furnace is making an occasional loud banging noise, don’t attempt to repair it yourself. Gas furnaces may explode when repaired improperly, so it’s best to hire a trained technician for the job.

Read: Why Lennox Furnace Not Igniting?

Damaged Motor/Belt

Furnaces will make a shrieking noise when the motor or fan belt has been damaged. This noise is similar to the shriek that an old car in poor condition would make. 

When the motor or fan belt has been damaged, the furnace needs urgent repair to prevent further damages from occurring. Don’t turn on your furnace in the meantime, as this can cause irreparable damage.

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Read: Furnace Blower Motor Makes Noise When Starting – Troubleshooting Guide

Poor Airflow

Furnaces make a whistling noise when they have restricted airflow. The whistling noise is caused by air being forced through a small hole in a blocked pipe. Poor airflow can harm your furnace’s effectiveness and cause damage to other components. Hire an expert to inspect your furnace if it makes a whistling noise.

Read: How Often To Change Furnace Filter?

Loose Components

If a screw, washer, nut, or other component comes loose within a furnace, it’ll be tossed around when the machine operates. This will cause a rattling sound as the metal piece bangs against other complements in the furnace. If a piece is loose inside a furnace, it may harm other components within the system. 

Damaged Blower Fan

Another common source of noise in a furnace is a damaged or broken blower fan. A damaged blower fan will cause your furnace to make a loud rumbling noise. Damaged blower fans are a severe issue that a qualified plumber or technician must repair. It’s important to note that quiet rumbling noises aren’t any cause of concern. 

Read: Best Furnace Flame Sensors

Normal Operation

When your furnace is working, it’ll make some noise. This sound should be hardly noticeable unless you’re right next to the furnace. Furnaces make a quiet rumbling noise as they burn through fuel to heat your home. If your furnace is making noises other than a quiet rumble, it’s likely one of the problems mentioned earlier.

When Should You Worry About Furnace Noise?

Now that you’re aware of the common causes of noise in furnaces, it’s time to figure out what noises should be a cause of concern. Especially because some amount of noise is expected from your furnace. So when should you worry about the noises coming from the furnace in your home? 

You should worry about your furnace when it makes any noise other than a quiet hum. Furnaces make a quiet rumbling noise when in regular operation. If your furnace is making any loud banging, scratching, whistling, or screeching noises, it’s likely due to a major issue in the system. 

Modern furnaces are designed to run extremely quietly. Many modern furnaces are installed in people’s kitchens, and you wouldn’t know it was there until you opened the press and saw the unit. 

However, older furnaces aren’t particularly quiet, and you can definitely tell when it’s on.

If your furnace is making noticeable noises that it’s never made before, it’s likely due to damages, blockages, or other issues happening within the system. The only noise your furnace should make is a quiet hum when it’s running a cycle. 

Furnaces are heating components that usually burn gas or flammable liquids to operate. Therefore, a furnace that’s not operating effectively could catch fire, explode, or leak harmful gasses into your home. Therefore, you should have your furnace repaired as soon as you hear any sort of unusual or loud noise coming from it.

Read: How To Clean Gas Furnace?

How Do You Fix a Noisy Furnace?

Furnaces are an integral aspect of your home. You use it all the time during the cold winter months. So when your furnace is making noise, you’ll likely be eager to resolve the issue before it develops into a serious problem that could leave your house freezing cold. So how do you fix a noisy furnace before it becomes a severe issue? 

You should hire a certified professional to fix a noisy furnace. Furnaces contain complex systems and explosive fuel sources. Therefore making a mistake during a DIY repair could result in an explosion that causes severe injury or death. As a result, it’s a job best left to professionals. 

If your furnace is old and making noise due to regular operation, you can try insulating the pipes around the system. This can dampen the noise your furnace produces. At the same time, you can swap out the filters in your furnace to improve airflow and stop loud whistling noises. 

Furnaces make different noises due to various issues occurring within the unit. However, a furnace may be making one noise but has multiple issues in the system. As a result, determining what’s wrong with the furnace will require some level of expertise. 

If your furnace is making any rattling, banging, or other concerning noise, it’s not an issue you should solve yourself. Not only is it dangerous to repair a furnace without the necessary knowledge, but you’ll also likely cause further harm to the complex HVAC system, which will entail an expensive repair down the road.

How To Prevent a Noisy Furnace in the Future?

Now that you know what to do when your furnace becomes noisy, why your furnace is making noise, and when you should worry about furnace noise, it’s time to figure out what you can do to prevent noise problems in the future. 

So, how can you prevent your furnace from becoming noisy? 

To prevent a noisy furnace in the future, hire a qualified person to service the furnace every year. Qualified professionals will clear airways and lubricate moving parts to reduce noise permanently. Since noises typically indicate problems with your furnace, it’s best to call a professional.

Final Thoughts 

Furnace noise problems usually happen when something is wrong in your furnace. Furnaces make a quiet hum sound when they’re in good condition and operational. If a furnace is making any other sound, it’s likely due to a severe issue in the system that needs repair. 
Furnaces make several different sounds when they’re damaged. Your furnace may whistle, bang, bump, grind, or rattle, depending on the root of the issue. Whenever your furnace is making excessive noise, you should hire a professional to fix the damages, as repairing a furnace can be extremely dangerous.