Why Is My Furnace Making Noises?

This Short Answer Is: The most common explanations for noises coming from a furnace include loose or damaged components, airflow issues, and warm air expansion and contraction of metal ducts due to temperature changes. Homeowners might hear banging or popping sounds, which could indicate a dirty or clogged burner, rattling or vibrating noises caused by loose parts, or whistling and whooshing sounds due to restricted airflow or a dirty air filter. Regular maintenance and inspections by a professional technician can help identify and address these issues, ensuring the furnace operates with minimal noise and without the need for future furnace repair.

Under normal circumstances, your furnace runs tirelessly without complaining to keep your family warm and comfortable. But sometimes, they can become a little more vocal and begin making a loud noise to alert you that something is awry.

Knowing what loud noises to listen for and what to do when you hear them will help you prevent major issues down the line. Be on the alert for these common sounds a furnace makes.

Loud Clicking Noise

If you suddenly hear a loud clicking sound coming from your furnace, it could be a sign that your fan blower motor is broken if its bearings are loose. In gas furnaces, it could also be a warning sound coming from a cracked head.

Other causes include a problem between gas and the igniter or a faulty flame sensor. It could be that there's no gas actually reaching the system due to a bad valve or faulty ignition board. The flame sensor could also be damaged or broken. These problems can pose a health hazard to your family. Call a professional right away to have the cause of the clicking checked out.

Banging Noise or Booms

If you hear a loud bang or boom every time your furnace kicks on, you may be hearing the sound of gas building up before it ignites. We call this delayed ignition. The bang you are hearing is a mini-explosion that occurs when the gas finally ignites. It could be there is too much air mixing with the gas, low gas supply, or a broken pilot light. If left unchecked, this problem is likely to get worse and can lead to large explosions and cause damage to your furnace.

Another reason you hear a banging or popping sound is from the expansion and contraction of your air ducts within your walls. Your duct system feeds warm air throughout your home, which may cause positive pressure within your air ducts resulting in them expanding. Cold air pulled back down to your gas furnace on the return side results in a negative pressure leading to your air ducts contracting. Having a professional HVAC technician examine your ductwork can reduce the popping noise.

Loud Humming Noise or Buzzing

It's important to know a dull hum is to be expected while your furnace starts or is running. However, your furnace is making a buzzing noise is more of an indication you're dealing with an internal electrical problem. There are electrical components inside your heating system which can make humming sounds if something isn't functioning properly. Such as:

  • A faulty transformer

  • Bad inducer motor

  • Failing blower motor capacitor

  • Blower wheel that hasn't been lubricated in recent heating seasons


If you hear a low rumbling that seems to come from inside your furnace whenever it is running, your furnace likely needs cleaning. The rumbling is often the telltale sign that the burner is covered with dirt and grime. This buildup occurs naturally over time and needs to be cleaned periodically. That’s one of the reasons we recommend servicing your furnace before the heating season begins. If you hear rumbling in your furnace, schedule a regular furnace maintenance call to have the burner cleaned.

Squealing or Whistling Sound

This high-pitched squeal sound will send shivers down your spine, but it isn’t quite as severe as it sounds. Squealing or whistling sounds are usually the sound of a slipping or faulty fan belt. Listen closely to determine if the sound only occurs when the fan is running. It will need to be tightened or replaced to restore your furnace to its normal quiet operation.


Rattling noises can be caused by a number of things, from a loose door on the furnace cabinet to broken or loose parts in the interior. It could also mean your heat exchanged is cracked. If you hear rattling that doesn’t go away, call your HVAC dealer to have it serviced.

Don't Ignore A Loud Noise From Your Furnace

All these noises should be taken seriously, even if you have a new furnace and in older furnaces. If a homeowner hears a noise from their furnace that they don't understand, here are the steps to take:

  1. Safety First: Ensure the safety of your home by checking for any unusual odors, such as gas or burning smells. If you suspect a gas leak, immediately turn off the furnace, evacuate your home, and call your gas utility provider or emergency services.

  2. Turn Off the Furnace: If there are no safety concerns, turn off the furnace to prevent further noise or potential damage.

  3. Observe the Noise: Take note of the type of noise (e.g., banging, rattling, whistling) and where it seems to be coming from in the furnace system.

  4. Inspect Visible Components: Carefully inspect visible components like the air filter, ducts, and vents for any obvious obstructions, damage, or loose parts. Clear any blockages you can safely reach.

  5. Check the Thermostat: Ensure that the thermostat settings are correct and that it's functioning as expected. Sometimes, unusual noises can result from thermostat issues.

  6. Restart the Furnace: Turn the furnace back on and listen for the noise. If it persists or worsens, turn it off again and proceed with caution.

  7. Call a Professional: If you cannot identify the source or cause of the noise, or if it continues despite your efforts, it's best to contact a licensed HVAC technician. They have the expertise and tools to diagnose and resolve furnace issues safely.

Remember that strange furnace noises can sometimes indicate underlying problems that, if left unaddressed, may lead to more significant furnace repair issues or reduced efficiency. It's essential to prioritize safety and seek professional help when necessary to ensure your home's comfort and safety.

If you hear sounds you can’t identify, call Buckeye Heating, Cooling & Plumbing and describe the sound over the phone. Our experts can help you pinpoint the cause and come out to correct the problem. Schedule an HVAC technician to visit your Columbus area home today.

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