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Why Is My Furnace Making Noise? Potential Reasons and Fixes

When your furnace is making loud, unexpected noises, it can definitely be a cause for concern. Modern furnaces are made to be as quiet as possible to not disturb your family in your day-to-day life. 

If you've got a furnace making noise, you can use this guide to determine the potential cause and begin troubleshooting solutions. The sooner you act, the sooner you can enjoy a quieter, safer, and warmer home!

Furnace Making Noise: Potential Causes

Nearly all furnaces generate a little bit of noise when they turn on and begin heating the air. So, if you're wondering, "Why do I hear my furnace?" the answer might be, "Because it's working!"

That said, most furnaces only generate a minimal level of noise while operating. If your furnace is loud enough to drown out conversations or be heard from several dozen feet away, there may be a problem.

Furnaces can make some odd sounds, including:

  • Humming
  • Buzzing
  • Knocking
  • Whistling
  • Loud noises

If you notice any of these sounds coming from your furnace, you'll want to determine the cause of the noise and seek immediate furnace repair services.

Furnace Making Humming Noise

A humming furnace is one of the least worrisome issues homeowners will need to deal with. In most cases, this light humming noise is just the furnace blower motor.

It indicates that your furnace is blowing warm air through your home's vents. As such, humming that's soft enough to speak over isn't uncommon or a cause for concern.

However, if that humming grows incredibly loud or turns into a buzzing sound, you might be experiencing a serious problem with your furnace's fans or fan motors.

Furnace Making Buzzing Noise

A loud buzzing noise almost always indicates that your furnace is working hard to generate warm air. This may mean that its blower fans are extremely dirty or that the motor powering the furnace fans is beginning to fail.

Furnace Making Clicking Noise

Is your furnace making clicking noises? If so, the most likely reason is an absence of gas fuel or a failing ignition system. If your furnace is securely connected to a fuel source, it's likely time to replace the internal pilot light.

Furnace Making Knocking Noise

What about a furnace making popping noises? Well, popping noises (also described as knocking noises) can have several potential causes.

When a furnace makes a knocking noise, the issue could be dirty burners, unstable gas flow, or a failing pilot light. Discovering which of these issues is to blame can be challenging, so professional assistance is recommended.

Furnace Making Whistling Noise

When a furnace makes a high-pitched noise, the issue is often one of the two things: A gas leak, or moisture evaporating inside the furnace.

If your furnace's gas valve is leaking, the whistling noise will likely come from the gas valve or hose. Using a carbon monoxide detector is a great way to determine whether gas is making your furnace whistle.

Of course, if gas isn't to blame, your furnace might have gotten a little humid. Furnaces that sit in basements are most prone to developing a little moisture during the warmer spring and summer months.

When a wet furnace begins to heat up, the moisture inside or around it can evaporate quickly, turning into high-pressure steam. When this air escapes the furnace, it can make a whistling noise.

Furnace Making a Loud Noise

When a furnace making loud rumbling noises ruins yet another afternoon or good night's sleep, you might feel like shutting down your furnace for good.

But if your furnace is making loud noises, it's probably a good idea to shut it off. After all, loud noises often indicate gas flow problems (including leaks) or excessive dirt on the furnace burners or pilot light.

People Also Ask

Do you have additional questions about furnace noises and what they mean? If so, be sure to check out these related questions and their answers. You might find the information you're looking for below!

Can a Furnace Explode?

Furnace explosions are rare, but they're not impossible. Notably, furnaces that utilize a gas fuel source are far more prone to explosions than wood-fueled or electric furnaces.

That said, most modern gas furnaces have a built-in safety valve that triggers when a gas leak is detected. Choosing a furnace with this feature is an excellent way to help prevent gas-related furnace explosions.

How Can You Tell if Your Furnace Is Leaking Carbon Monoxide?

One of the best ways to tell if your furnace is leaking carbon monoxide is to install a carbon monoxide detector near your furnace. This small device can detect small changes in air quality and composition.

If too much carbon monoxide enters your basement, garage, or utility room, a carbon monoxide detector will sound a loud alarm or trigger emergency services to visit your home.

How Do You Know if Your Furnace Is Dying?

When a furnace begins to enter the last stages of its product lifecycle, it tends to show a few warning signs. Some of the most common symptoms of a dying furnace include:

  • Excessively high heating bills
  • Poor heat production
  • Loud noises and bangs coming from the furnace

So, if you've noticed that your heating bills are far higher than they usually are, you may want to invest in a furnace inspection. You may be overdue for a replacement furnace!

Poor heat production and consistent loud noises are other red flags that may signal a failing furnace. Fortunately, repairing or replacing your furnace can help you enjoy lower utility bills and a quieter, warmer home.

How Do I Stop My Furnace From Banging?

If you hear loud banging coming from your furnace, the issue may be dirty burners, a low fuel supply, or a faulty ignition system. The best way to put an end to a loud furnace is to check these common culprits.

If the burners are dirty, you can invest in a professional furnace cleaning service with One Hour Heating & Air Conditioning to get them back into tip-top shape. If you're using a gas-powered furnace, you'll want to check your gas lines for leaks.

Naturally, if the pilot light or ignition system is to blame, you'll want to hire a professional team of technicians to help you replace those faulty components.

What Does a Bad Furnace Sound Like?

Bad furnaces tend to generate a handful of sounds. Sometimes, a failing furnace may begin to make loud banging sounds. Often, these noises are deafening, distracting household members from their everyday tasks.

Still, a faulty furnace can also hum, buzz, or whistle. If you hear loud knocking coming from your furnace, you might also be dealing with a failing furnace.

Why Is My Heating System Knocking?

A loud knocking noise coming from your furnace might indicate old, dirty burners or a faulty gas valve. Loud knock-like bangs are often a standard indicator of repetitive gas ignition.

When furnace burners are covered in rust or grime, they don't efficiently heat the air or the gas around them. As such, they may produce bursts of heat that raise the pressure inside the furnace, resulting in a knocking noise.

A faulty gas valve can also contribute to this issue. If the gas entering a furnace is constantly flowing at different pressures, it will heat unevenly, potentially resulting in a knocking sound inside the furnace.

How Do You Fix a Noisy Furnace?

The best way to fix a noisy furnace is to discover the root issue causing it to make the noise! For example, if you hear loud banging coming from your furnace, the culprit may be dirty burners or a faulty ignition system.

But if your furnace is generating loud whistles, the issue is more likely leaking gas or fast-evaporating moisture. Remember, while furnaces make some noise while operating, they should never be extremely loud.

In any case, if you are not familiar or comfortable with diagnosing furnace issues, don’t hesitate to request an appointment with your local One Hour Heating & Air Conditioning professionals.

Is a Loud Furnace Dangerous?

When you turn on the heat inside your home, your furnace may make a little noise while it's turning on and heating up. But it's not normal to hear loud banging or high-pitched whistling noises coming from your furnace.

If you hear these types of noises, you'll want to turn your heating off and immediately shut off any gas that may be feeding into your furnace. You'll then want to contact a local heating professional to inspect the source of the loud noise.

A furnace making noise when off is another warning sign to consider. When a furnace makes noise but won't turn on, the issue is typically related to a gas leak or pilot light failure, both of which can be dangerous.

How Do I Reduce the Noise From My Furnace?

Learning how to quiet furnace noise often starts with regular furnace maintenance and repair services. Loud noises are often signs of physical obstructions or gas leaks, both of which require immediate attention.

That said, some furnaces generate a decent amount of noise after several months of sitting dormant. If you've installed a new furnace this year, you might wonder, "Why is my new furnace so loud?"

The answer could be that it's gathered a little dust and debris between when you first installed it and when it was turned on for the first time. This initial noise is nothing to worry about.

But if your furnace is whistling or rumbling loudly when turned on, it's time to call a professional.

What if I need my furnace replaced?

If you are getting to the point where your furnace won’t cut it anymore, have no fear! We can help! The professionals at One Hour Heating & Air Conditioning can work with you to determine what you need and what will fit your budget. It’s a big decision, and we’re here to help you make the right one!

Keep Your Furnace in Great Shape

A furnace making noise is more than a nuisance. It can also be a red flag warning you of impending danger. For that reason, it's crucial to seek immediate heating services when your furnace starts getting loud.

Still, you might be able to help your local technicians expedite the diagnostic and repair process by identifying the source of the sound. Hopefully, this troubleshooting guide has helped narrow down the potential culprits.

Our furnace experts won’t leave you in the cold!

If you're dealing with furnace noise, don’t hesitate to call (800) 893-3523 or request an appointment today.