Why Is My Furnace So Loud? 12 Key Reasons
Updated on Oct 31, 2024
9 Minute Read

Why Is My Furnace So Loud? 12 Key Reasons Behind Furnace Noises

Find out the reasons and possible ways of fixing the issue

Why is my furnace so loud when running? This is quite a common question that homeowners ask when cold weather takes its turn. The furnace is what should keep you warm during fall and winter (especially winter!), but except for this, it should also not be heard.

What if you hear strange or scary noises coming from your heating appliance?

This article will help you find out what could be their cause.

We will tell you what may lead to odd noises your furnace may produce. Also, you will learn a few useful recommendations that will allow you to maintain your heating appliance and keep it quiet.

Why Is My Furnace So Loud 12 Key Reasons Behind Furnace Noises

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Why Is My Furnace So Loud All Of a Sudden?

Before we move on to explaining why your furnace may produce strange sounds, we want to note that it’s normal and fine if this heating appliance is slightly and quietly humming while it’s working.

However, if that noise starts disturbing you and becomes way too loud, it means that your furnace should be checked and maybe fixed!

Also, there are certain noises your furnace may produce that should be never ignored! They may be the signals of a bigger problem that can be dangerous not only to your furnace but also to your home.

If you hear any of the noises listed below coming from your furnace, contact a reliable heating and cooling company immediately and ask them for solutions regarding your furnace issue:

  1. High pitched screeching or whistling
  2. Rattling
  3. Banging or booming
  4. Scraping sound

But except from these sounds, there are also factors that should be paid attention to. They often indicate the presence of a problem in your appliance.

Why Is My Furnace So Loud All Of a Sudden

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12 Key Points about Furnance Noices in Brief:

  1. Dirty/Clogged Filters: Filters clog, which makes the furnace work way harder than it needs to be, thus making excessive noise.
  2. Loose Ductwork: Eventually, ducts become loose and over time will cause sounds of vibration or hanging sounds while air moves through it.
  3. Faulty Blower Motor: A dying blower motor or fan blades that are not aligned may create a sound of squealing, humming, or even thumping.
  4. Poorly timed ignition or a problem with the pilot light itself can cause small explosions that create loud banging noises.
  5. Damaged bearings in the motor and the assembly of the blower will, over time, generate grinding or screeching noises.
  6. An imbalance in air pressure, due to improper design of the ducts or blockages of vents, will cause whistling noises.
  7. A crack in the heat exchanger may also create rattling or clicking sounds and is considered a serious safety hazard.
  8. Improper Installation: If a furnace has not been installed properly, it will tend to lean one way or the other and vibrate in those places, therefore making loud noises.
  9. Loose Parts: Screws and panels, among other parts, might become loose and rattle or make shaking noises.
  10. Dirt in Burner: A dirty burner consequently causes an imbalance in the ignition of flames and makes popping sounds while trying to light.
  11. Belts Problems: In the case of the blower motor system, it is possible that there is a high-pitched squeal emanating when either of its belts is worn out or broken.
  12. Malfunctioning Thermostat: Faulty thermostat problems can lead to irregular cycling of the furnace, hence affecting the noise evenness.

And you can find all malfuntion points below in more details.

12 Key Points about Furnance Noices

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Dirty Furnace Filter Can Be a Culprit

If your furnace produces screeching or whistling, the simplest explanation for these sounds is that the appliance’s air filter is clogged with dust, hair, and dirt. That screeching sound you hear is most likely the air trying to get through.

Fortunately, this noise issue is easy to take care of by yourself. If you use disposable filters, replace the existing filter with a new one. If the filter you have right now is a permanent one, you will have to clean it.

In case you don’t have a spare filter that can be reinstalled instead of the old one, it’s better to remove the old filter and let your furnace run without a filter at all for a day or two.

With no filter at all, it’s anyway better than with the clogged one, which will continue restricting proper airflow until your furnace’s fan motor or heat exchanger becomes seriously damaged.

Check Your Blower Motor

Another reason for the screeching sounds that your furnace is making is its blower motor. A blower motor is the power source for the blower. It forces warm air through your ductwork to keep your entire home warm.

But there is one nuance: in order to function properly and quietly, the blower motor requires sufficient lubrication. If it runs for a long time without proper lubrication, your blower motor may not only develop strange sounds but also damage the furnace.

Check Your Blower Motor

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Blower Wheel May Also Be the Source Of Strange Noises

The blower wheel is the component of your furnace that is powered by the blower motor. The blower wheel is needed for moving heated air. This part of your furnace may also sometimes start to make strange and loud noises like a harsh scraping, metal-against-metal sound, etc. as it rotates. This sound means that the blower wheel needs expert adjustment.

Noises Could Be Coming From a Racked Heat Exchanger

If your furnace is producing rattling noises, this could indicate your heat exchanger is about to die soon. When you don’t clean your furnace and forget to change the filter regularly, airflow becomes hard to move freely. Eventually, your furnace will reach the point where the heat exchanger can be cracked by heat buildup!

At this point, you must realize that a cracked heat exchanger is extremely hazardous! It can lead to the leakage of carbon monoxide – a colorless, odorless, but highly lethal gas!

So if you have any suspicion this could be your problem, turn off the furnace and get a qualified HVAC technician to examine it and take care of this issue as soon as possible!

Noises Could Be Coming From a Racked Heat Exchanger

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Dirty Burners May Cause Odd Sounds Too

If you tend to hear a boom or bang sound a few seconds after you switch on your furnace, this is a sign that your burners are dirty. Dirt buildup is what causes that delayed ignition, as well as that explosion sound, which is a definite danger signal!

Fortunately, this problem is easy to take care of by a professional furnace cleaning.

Dirty Burners May Cause Odd Sounds Too

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Check For Any Duct Issues

Your HVAC ducts are made of thin sheets of metal, which means they can carry sounds perfectly well. So if you hear your ducts rattling and banging, the reason could be a change in pressure between the supply and return ducts.

There is another possible reason for this sound: your HVAC ducts may simply need reinforcement. This can happen due to a couple of reasons:

  • The ductwork has become loose from the walls
  • There are weak spots in the ducts themselves

Although none of these issues requires an emergency furnace repair, it is important that your ductwork is inspected and fixed by a professional as soon as possible.

So, now you know why your furnace may sound strange or weird. As you can see from the descriptions above, the key reason is always a kind of malfunctioning be it due to dirt buildup or loose fixtures.

So the sooner you get it repaired the better, especially since some sounds may indicate the presence of serious problems that can be life-threatening!

Check For Any Duct Issues

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Handy Tips For Maintaining Your Furnace

If you have never had any problems with your furnace before, you are a lucky person! however, it doesn’t mean that you need not to be informed about the possible issues that you may come across. Also, it’s good to know what to do to keep your furnace working longer and better.

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For this purpose, we have collected a list of useful tips everyone should know:

  • Check your air filter once in a month and change or clean it at least once every three months
  • Always keep a supply of disposable filters on hand in case you need to replace the existing one
  • Try to figure out where exactly the sound is coming from your furnace before you call a technician. This will help a professional to finish fixing it faster and be more accurate in diagnosis
  • Install a carbon monoxide alarm to monitor levels of this deadly gas
  • Schedule regular professional furnace maintenance to make sure your heating system is safe and works properly
  • Keep the blower wheel clean to ensure your furnace’s best performance
  • Lubricate the furnace blower motor once a year. Simply apply 2-3 drops of motor oil to the oil ports
  • Schedule a regular annual furnace tuneup. It will help you stop problems before they even start

Well, now you know what can make your furnace sound scary or strange, as well as be too loud. We explained what factors may lead to such improper performance and what you should do in order to deal with it efficiently.

Also, you are now aware of a list of maintenance tips that will help you keep your furnace in good working order longer.

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Frequently Asked Questions

⭐Is it possible to fix my furnace myself?

We’d not recommend you do that. Furnaces should be examined and repaired by professionals only.

⭐How much does it cost to fix a furnace?

It depends on what requires fixing and the type of your appliance. E.g. an average repair cost for an electric furnace is between $50 and $300. For oil or propane and gas-powered furnaces, an average ranges from $300 to $1,200 for a furnace service cost.

⭐How long are furnaces supposed to last?

A new furnace should be able to work properly from 15 to 20 years.

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