Why does my furnace make a loud banging sound?

Author: Prof. Adelia Osinski  |  Last update: Monday, December 22, 2025

Loud Bangs If the noise is a banging sound, it's important to note where it comes from. It's normal for loud banging sounds to originate from ducts as the furnace starts up – it's just the sound of the metal ductwork expanding and popping. This is sometimes called oil canning.

How to fix banging noise from furnace?

Clean Any Dirty Burners

If you hear a banging noise when your furnace turns on, this sound is typically caused by dirty burners inside the unit. Carbon and soot, as well as dirt and other debris, can build up on the furnace's burners and restrict the ignition of gas inside the unit.

When should I worry about my furnace noise?

Loud Bangs, Rumbles, Knocks, or Booms

Loud noises like this are a sign of a build of gas in a furnace. The noise you hear can mean your heat exchanger is at risk of cracking. Even worse, it's a sign that something dangerous could happen if you continue to use your heater.

Why is my HVAC making a loud banging sound?

Loose or Unsecured Parts: Over time, components within your air conditioner can become loose due to regular wear and tear. When these parts move around, they can create banging noises as the unit turns off and on. Duct Expansion and Contraction: Your ductwork can expand and contract with temperature changes.

What does a bad bearing sound like on a furnace?

Grinding and scraping furnace noises usually point to dry bearings within the furnace blower motor. These bearings need regular lubrication to maintain proper function. If you have a preventive maintenance plan with Estes Services, your technician handles this during an Atlanta furnace maintenance tune up.

🆕Furnace Makes A Banging Noise Why Is My Furnace Making Noises 2021

Why is my furnace suddenly making a loud sound?

If your furnace is making a loud booming or banging noise, the problem may be caused by a small gas explosion that happens when there's a delay in ignition. Gas can build up in your combustion chamber when the gas burners in your furnace do not ignite on time.

What are the first signs of bearing failure?

A sure sign that your bearing has failed is vibration. If the raceway surface of the bearing becomes damaged by abrasion, the rolling elements (the balls or rollers) will bounce around on the raceway surface during operation, causing high levels of vibration.

How to stop furnace duct from banging?

Clean or Replace the Filter

The pressure will decrease once the heating cycle stops and the metal panels will 'bang' and 'pop' as they contract. To reduce the noise, clean or replace the filter as needed, and check it every month during the heating season.

Why is my heating making a banging noise?

Since your heating system works in a closed loop, water travels from the boiler to the line of radiators and back. End-of-the-line radiators are being warmed by water that's already released a lot of its heat. The banging noise occurs when new hot water is released into a radiator that contains standing cold water.

What is the clunking sound in my HVAC system?

If your furnace is making a clicking noise, this is a sign of an issue occurring during the heating cycle. When you hear clicking from your furnace, you should contact an HVAC professional immediately, as this strange sound may indicate a faulty igniter or gas valve. Issues with these parts can result in a gas leak.

What does a failing furnace sound like?

While the screeching blower motor may just need some lubrication, it could also be "seized up." A screeching furnace sound is a good indicator that your heat is not blowing or will need emergency heater repair soon enough. We can't stress enough that routine check ups will help prevent these unbearable furnace sounds.

Why is my house making loud banging noises?

If you hear similar clanging or loud banging noise in the walls, it can be a sign of clogs or air pressure in the system called a water hammer. If you don't resolve the problem, it can cause damage to the pipes, so consult a professional.

How do I stop my heater from knocking?

It's easy to avoid this problem by regularly changing your furnace filter. Our HVAC technicians suggest replacing the filter once every three months or as soon as it's no longer a clean white color. If you have pets in the house, you need to change it every month.

How much is a blower motor for a furnace?

While costs can vary, homeowners can typically expect the following range: Standard Blower Motors: These might cost between $400-700, excluding labor. Advanced Multi-Speed or Variable-Speed Motors: These are generally more expensive, with costs ranging between $650-1250, not including labor.

Why is my furnace making a tapping noise?

Gas furnaces rely on a smooth ignition process to kickstart the heating cycle. Clicking noises during ignition could signify issues with the pilot light or electronic ignition system. Solution: Schedule a professional inspection to clean or replace the pilot light, ignition components, or flame sensor.

Why is my furnace making banging noises?

If your furnace is making a loud banging or booming noise when it turns on, the two most common causes are: Problem with the ignition system. Expansion and contraction of metal ductwork.

What is the banging sound in my HVAC system?

Banging Sounds Coming From the HVAC Ductwork

This type of noise usually occurs in quick, short bursts. It is the result of expansion and contraction in the duct walls as internal temperatures rise or fall. This type of noise can also be the result of pressure changes within the ducting.

How often do you need to bleed radiators?

You should bleed your radiators at least once a year, typically before winter arrives in order to ensure the efficiency of your heating system. Regularly checking for trapped air also helps to make sure that your system operates effectively and reduces energy consumption.

How do I stop my furnace pipes from banging?

Placing small pieces of foam near pipes that travel through wooden supports will prevent banging or other bumping sounds. If this does not fix the issue, seek professional help by hiring residential heating services. You don't have to live with heating pipes that bump and bang all night.

Why do I hear knocking in my vents?

Inside your air ducts, two processes occur—contraction and expansion. As temperatures rise, your air ducts' metal parts heat up. These parts will then move around, producing a knocking sound in furnace vents. Fortunately, this is entirely normal and generally doesn't signal an issue.

How to stop knocking noise from furnace expanding?

CLEAN, SEAL, AND INSULATE DUCTWORK

While it may cost some money, the most effective solution short of replacing your entire duct system is to clean, seal, and insulate the ductwork. This will reduce pressure differences and soften the effects of any expanding and contracting metal ducts.

Do bearings give warning before they fail?

This is reality, and can happen if you fail to notice the signs the wheel bearings are deteriorating and need immediate repairs. Your wheel bearing might be bad if you hear unusual sounds like humming, squeaking, or clicking. Some experts say a bad wheel bearing can sound like a bird chirping.

What is the number one cause of bearing failure?

The majority of bearing failures occur because of improper lubrication. Lubrication failure can occur if the wrong lubricant is used, if not enough lubricant is applied, or if the bearing has been exposed to excessive temperatures that have caused the lubricant to degrade.

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