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Furnace Making Fluttering Noise? 4 Common Causes (+ Fixes)

A fluttering noise in the furnace may not be as bothersome as some of the other sounds that come out of this appliance, but it’s still a sign you shouldn’t ignore. When your furnace is making a fluttering noise, there are a few steps you need to take to find the cause and implement the right fix. 

Your furnace is making a fluttering noise because of problems with the heat exchanges or inducer wheel, clogged burners, or a blockage in the flue line. To stop the noise, check and repair the heat exchanger and inducer wheel, clean the burners, and ensure that the flue line isn’t blocked.

This article will explain the four most common causes behind a fluttering noise coming from a furnace. I’ll also go over how to fix each problem and eliminate the fluttering sound. 

Problems With the Heat Exchanger

The heat exchanger has a vital role in an HVAC system. It’s the part of the furnace that keeps harmful gases from entering your home, as it sits just behind the blower assembly. Being on the lookout for problems with the heat exchanger is essential. Even a tiny crack in this part can cause nitrogen dioxide and sulfur dioxide to get into your home. 

That crack can also lead to the heat exchanger making noises as air pushes against it. Some people describe the noise made by a problematic heat exchanger as a fluttering sound. You should also be on the lookout for symptoms like sleepiness and irritation in your nose and ears. These indicate that gases are escaping into your home. 

How To Fix

A visual inspection of the heat exchanger should be enough to tell you whether this is the part giving you problems. Here’s what you need to do: 

  1. Switch the furnace off.
  2. Take the cover off and look inside.
  3. Locate the heat exchanger. It looks like a sheet of metal. You can find it between the blower and combustion chamber. 
  4. Take a close look at the entire structure to see if there are any other problems.
  5. Check the heat exchanges for cracks and bends. 
  6. Make sure the heat exchanger is fitted correctly. When one of the corners gets loose, it can create a fluttering sound.

If the heat exchanger is damaged, it’s time to get a replacement. You can watch how to replace the heat exchanger in the video below:

The Burners Are Clogged With Debris

Even though no flame can be created due to dirty burners, gas will continue to flow into the chamber. The ignitor might continuously create sparks, leading to a sparking noise.

Simultaneously, the continuous gas supply to the burners may cause parts to start fluttering around. Of course, this is what results in the fluttering noise.

Closely listen to where the fluttering sound is coming from. If you find that the sound originates from the furnace unit’s main compartment, it’d be a good idea to check the burners. Many people find that debris and gas residue build up rather quickly on this part of the furnace. The burners eventually become blocked, leading to additional problems. 

How To Fix

The good news about this possible cause behind a furnace making fluttering noise is that you can clean the burners. The process is super easy, and you can do it without calling an HVAC expert. Here’s what you need to do:

  1. Switch off the entire HVAC system.
  2. Find the main furnace compartment. Open up the front panel by unscrewing the screws on all corners. 
  3. Locate the burner on the inside of the furnace. Take it out to check if it’s dirty. 
  4. Get a toothbrush and sandpaper. You should use fine-grit sandpaper and be very gentle to avoid damaging the burner.
  5. Use sandpaper to remove any debris visible on the outermost surface of the burner. 
  6. Use the toothbrush to get to the nooks and crannies. 
  7. Tap the burner lightly with your hand or a tool handle, then use compressed air to blow out any remains. 

If you’re struggling with this procedure, take a look at the video below: 

Blockage in the Flue Line

The flue line carries gas from the furnace’s combustion chamber toward the outside of the building. This is a crucial function that ensures the health and safety of everyone inside. When combustion occurs in the furnace, gases might leak into your home. This can be dangerous for your health, leading to unpleasant gas poisoning symptoms. 

If the flue line has problems, you might hear a fluttering sound. This is caused by the pipes shaking as the gas passes through them. This often happens due to a leak in the pipes. 

There could also be an obstruction inside the flue line. In that case, the gas build-up is causing the fluttering noise in the flue line. 

How To Fix

You need to investigate the flue line to determine where the sound is coming from. When you hear the fluttering noise, walk closer to the flue line. Here’s what you need to do:

  • If the sound originates from the flue line, look for holes or improper fittings between the pipe connections. 
  • If there are no leaks, remove the pipes to check inside. Wear a safety mask as dangerous combustion gases pass through the flue line.

If you see something got stuck inside one of the pipes, remove it with a long, sturdy object.

Problems With the Inducer Wheel

The inducer motor comprises multiple smaller parts. Some people have discovered that problems with the small wheel on the inducer lead to a fluttering sound. 

When the wheel gives off a sound, it often indicates a problem with the inducer motor. While the issue may not cause a malfunctioning of the inducer motor right now, it could lead to more significant future problems. 

How To Fix

To determine if the inducer wheel is the cause of the furnace making a fluttering noise, you need to remove the inducer motor and open it up. 

This is a relatively complex procedure, so be careful — being reckless when dealing with these small parts can easily cause irreparable damage. 

You can find the inducer motor inside the main compartment of the furnace. The wheel shouldn’t be hard to find, but a professional may need to remove it from the motor to inspect it thoroughly. You’ll need a replacement motor if there’s a more serious problem behind the fluttering noise. 

The video below shows you how to replace an inducer motor in a furnace:

Summary

When the heat exchanger in your furnace is faulty, you may hear a fluttering noise when the system starts up. Problems with the burners, the flu line, and the inducer wheel can also cause a similar sound. 

Having a professional check your furnace will ensure the fluttering sound is found without delay. A professional can provide a fix on the spot to give you peace of mind.

Author

  • Vincent Steele

    Vincent is a freelance writer based in Santa Ana, California. When he isn't writing articles for Temperature Master, he can be found biking or hanging out with his cat, Shelly.

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