How to Diagnose and Fix a Noisy Boiler

Is your boiler making noises? Whether it’s loud banging sounds or vibrating noises you’re hearing, you’ll want to know why. Furthermore, you’ll probably be looking for information about whether noisy boiler sounds are a cause for concern. Boilers work hard to keep hot water and heat running around our homes, so it’s important to remember that a boiler can make a noise on startup. In this helpful guide, we’ll help troubleshoot some common noises by showing you why your boiler might be making certain sounds. We’ll tell you how to make simple checks to diagnose a common problem yourself and help to fix any minor boiler issues.

Common Noises from Boilers

While some noises are typical and harmless, other loud sounds might indicate a more serious problem which will need to be fixed as soon as possible. Let’s look at the most common reasons for a noisy boiler.

  1. Humming
  2. Whistling or kettling
  3. Vibrating 
  4. Gurgling
  5. Loud banging 
  6. Clicking 
  7. Tapping
  8. Whooshing

Why is My Boiler Making a Loud Noise?

Persistent noises from your boiler can become irritating over time. Reasons for boiler noises include low water pressure, limescale build-up, and a clogged flue or air intake. Let’s break down these common boiler sounds. We’ll examine which boiler noises require further investigation and those you can solve with a little effort.


Humming is a common boiler noise and there are a couple of reasons for it, both of which relate to the pump. Humming could simply be due to normal operation. After all, the pump makes a humming noise, so it’s a good idea to check this first. The second potential reason might be that the pump is seized - or that a part on the pump has seized. Inspect the pump to see whether it is warm or hot. It should be warm. If it is very hot, it could indicate a seized part. You’ll need to call a qualified boiler engineer to deal with a faulty or seized part.

Whistling or Kettling

Whistling, or ‘kettling’ as it is also known, is a very common boiler noise. If your boiler is sounding like a kettle boiling water, it usually means there is air trapped inside the heating system. One way to remove the air is by bleeding your radiators. This can be done easily yourself and it’s a tried and tested method for releasing trapped air from the pipe system. Follow our handy step-by-step guide on how to bleed a radiator, here.

Another common cause of boiler kettling is the build-up of limescale. ‘Hard water’ is the term used to describe water that possesses a high mineral content. The build-up of limescale relates to the amount of calcium in the water. When limescale builds up, it restricts the flow of water. Over time, this can cause water to become trapped around the boiler’s heat exchanger. This can make the exchanger overheat, expand and produce steam - which creates a whistling sound. 

Other causes of kettling include a stuck pump and a build-up of debris or sludge collecting around the heat exchanger. Both of these problems can have a serious impact on the efficiency of your boiler. In fact, your boiler will need to work harder to get your heating and water up to temperature - which can push up the cost of your bills. You can treat sludge by introducing an inhibitor (to reduce limescale) into your boiler system to break down the collected sludge. You might also fit a filter to catch any debris travelling around the system.

If you have released trapped air from the system and are still concerned your boiler is kettling, call a qualified engineer who will be able to thoroughly inspect your boiler.


Vibrating sounds in your boiler are typically due to a bracket coming loose. If your boiler is making a loud vibrating noise, check the brackets around it. You can easily tighten them yourself with a screwdriver. If the vibrating noises don’t stop, call a certified engineer who will be able to help diagnose the cause.


Gurgling sounds come down to a few potential culprits. The first, and the most easily fixable, is a radiator bleed. Leaving trapped air in the system could lead to bigger problems, so it’s best to correct the issue swiftly. Here’s how to tell if your radiator needs bleeding. Thankfully, it’s not a big deal as bleeding a radiator system is an easy task.

In the winter months, the condensate pipe can freeze. You’ll usually find the condensate outside the house. Look for the white overflow pipe and gently tip over some warm water to thaw it. Use warm water, never boiling. If your condensate pipe has frozen over, you can read our guide on how to thaw and revive it.

Finally, it’s worth inspecting your boiler’s water pressure to ensure it’s giving the correct reading. Low pressure can cause your pipes to gurgle. Use your boiler’s manual to determine the precise reading, but as a general rule, if the reading is below 1 you’ll need to increase the pressure. Follow our step-by-step instructions to increase your boiler pressure, here

Loud banging 

You might hear your boiler banging when it’s turned on, or when the hot water’s running. Some boiler heating pumps are fitted with an airlock. These are common to a boiler’s system, and plenty of boilers have them. You can usually release a little air by adjusting the bleed screw that’s fitted to the pump - which in turn can relieve banging.


Clicking usually means ignition failure. Check your boiler is firing up properly. If it isn’t the chances are the noises you’re hearing are your boiler trying, and failing to ignite.


Central heating pipes can often be noisy. If yours are making tapping sounds while switched off, the issue will require an expert engineer to investigate the problem.


Whooshing noises coming from your boiler are either due to air intake pipe blockages or air filter blockages. The air intake pipe is located at the back of your boiler, and this eventually leads outside - leaving it susceptible to debris that can clog and block the pipe. By putting your hand over the entry point of the pipe you’ll quickly notice if you can feel any air. If you can’t then it’s likely the pipe is blocked. If you can feel movement then the air filter is probably blocked.

Air filters are located inside the boiler and are also subject to build-ups of dust and debris. Both problems require a certified engineer or boiler specialist to inspect your boiler and fix the issue.

How To Keep Your Boiler Quiet

While some of the noisy boiler sounds aren’t preventable, there are some simple measures you can take to ensure your boiler works as well as it’s designed to. Good boiler maintenance can be the difference between proactively preventing a problem or catching it early. Here are some quick and simple checks you can make:

  1. Regularly check your boiler for leaks, and inspect pipes for cracks and damage
  2. Fit a filter to catch sludge or debris - ask your qualified boiler engineer to clean the filter during every service
  3. Inspect the pump to make sure it hasn’t seized 
  4. Examine the heat exchanger for limescale build-up
  5. Regularly check your boiler’s pressure and flow rate - more on boiler pressure can be found here.

You can also test the boiler’s ignition cables to make sure they are functioning properly. If you are unsure, you can always ask a qualified boiler technician to help with this.

Boiler Still Making Noises?

If your boiler noises persist and you’re unable to identify the underlying cause, we recommend getting in touch with YourRepair. Old boilers or boilers that are out of warranty can make all sorts of sounds. While not necessarily a cause for concern, long term damage can occur without inspection. Old boilers can break down frequently, and every now and then they need replacing. YourRepair is on hand to fix and service boilers. We are the boiler experts and as specialists, we can help.

If your boiler breaks down, YouRepair can get you up and running again. We aim to get your boiler working and heat running around your home as soon as possible. We offer unlimited repairs to YouRepair plan customers, and plans start from as little as £8 a month. If you need affordable boiler cover, our plans offer immediate protection, which can help avoid any unexpected repair costs. Why not speak to one of our experts today?

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