Why is My Boiler Making Noise? 7 Common Reasons (2023)

Boilers, like any mechanical device, often exhibit certain symptoms when things aren’t running smoothly. Different types of noises — banging, gurgling, vibrating, humming — might indicate different types of issues. Here, we shed light on the seven most common reasons why your boiler could be making noise, and how to rectify these problems.

Top 3 Most Common Reasons a Boiler Starts Making Noise

  1. Type of Noise – Banging Noises | Cause – Thermostat/Heat Exchanger
  2. Type of Noise – Gurgling Noises | Cause – Trapped Air
  3. Type of Noise – Vibrating Noises | Cause – Pump Setting/Loose Parts

In the quiet of our homes, the sudden emergence of an unusual noise can be jarring. Especially when it’s your boiler acting up. The function of your boiler is indispensable, it’s what keeps your home warm and provides hot water, making life comfortable. 

So, when your boiler starts making noise, it’s crucial to identify the reasons behind it and seek remedial measures immediately. Now, it’s time for our deep dive into the 7 most common reasons for a noisy boiler, let’s dive in.

ℹ️  Having your boiler serviced will often prevent issues from happening in the first place. Consider your annual service a fundamental aspect of ongoing boiler maintenance.

1. Limescale Build-Up

Loud, unsettling banging noises from your boiler often suggest the presence of limescale or sludge build-up inside your boiler’s heat exchanger. The accumulation of such substances can cause your hot water to overheat and boil, creating a sort of mini explosion inside the boiler and producing an audible bang.

Calling in a heating engineer to examine your boiler thermostat and set it to the correct temperature could alleviate the issue. If the problem persists, a comprehensive central heating power flush might be necessary to clear the limescale or sludge from your heat exchanger.

2. Trapped Air

bleeding a radiator

A gurgling boiler is usually a symptom of trapped air in the system. The solution can be as simple as bleeding your radiators. Make sure to check the boiler pressure afterwards, as it may drop significantly during this process. Maintaining appropriate pressure is critical to avoid future complications.

However, if gurgling persists after bleeding the radiators, you may want to consult with a heating engineer. Low water pressure, a circulation pump running too quickly, or a blocked condensate pipe are other common culprits of gurgling sounds.

3. Incorrect Pump Setting or Loose Parts

If you notice a vibrating noise, this could indicate that the screws need tightening or that something is obstructing the boiler flue. 

Another potential cause is an incorrect setting on the pump, causing it to shake inside the boiler. Loose parts can usually be fixed with a screwdriver, but for obstructions in the flue or a faulty pump, it’s best to call a Gas Safe registered engineer. 

Built-up residue inside the boiler can be dangerous and may require professional attention.

Other Common Causes of Noisy Boilers

4. Kettling

Kettling is a phenomenon where a whistling sound emanates from the boiler, similar to a boiling kettle. This happens when water flow within the boiler slows down, allowing the water to heat rapidly and reach boiling point. 

Steam generated in the process becomes trapped, creating the whistling sound. A Gas Safe engineer should investigate kettling, as it can be a sign of severe issues, such as a leaking system, faulty thermostat, or poor system condition.

5. Loose Components or Faulty Valves

Rattling sounds are often associated with loose components or faulty valves. If you notice such a noise, bleeding your radiators or checking for unclipped pipes or open valves could solve the issue. If the problem persists, consider calling an engineer as you may have a faulty pump or valve.

6. Central Heating System Issues

A constant humming or droning noise may indicate issues with your central heating system. If the boiler pressure is too high or the pump speed needs adjusting, you’ll hear a humming noise. Sometimes, it could also be a problem with your boiler fan, which will need professional attention.

7. Ignition Failure

Clicking or tapping noises accompanied by difficulties in firing up the boiler could signify ignition failure. In such cases, you need to call a Gas Safe engineer, as this could be related to the gas supply to your property.

Types of Boilers Noise – Causes & Fixes

Why is My Combi Boiler Making a Whirring Noise?

A whirring noise in a combi boiler often indicates a problem with the fan or the pump. The fan might be running at an excessive speed, or the pump could be circulating water too quickly. These issues can cause a whirring sound. It’s advisable to contact a Gas Safe registered engineer to rectify these issues.

My Boiler is Making a Ticking Noise, What Could this Mean?

A ticking noise from your boiler is typically associated with the expansion and contraction of the boiler as it heats up and cools down. This is quite normal. However, if the ticking noise becomes very loud or continuous, it could indicate a problem. A Gas Safe registered engineer can help determine if there’s an issue.

My Boiler Has Begun Making a High-Pitched Noise, Why is it Doing this?

A high-pitched noise is more than likely a kettling issue (see section 4 above). However, if the cause is not due to kettling, it could be due to pump failure, a valve issue, air in the system or other pressure related concerns. You can check for damage to the valves and try bleeding the radiators to stop this noise. If neither of these fix the problem you should call out a professional heating engineer.

I Hear a Loud Clunking Noise When My Boiler Starts Up, is this a Problem?

Clunking noises can sometimes be heard when your boiler starts up. This could be due to a delay in ignition, which causes excess gas to build up. When the gas ignites, it results in a mini explosion, creating a clunking noise. This is referred to as ‘hard starting’ and it requires professional attention.

What Causes a Dripping Noise in My Boiler?

A dripping noise can usually be traced back to a leak somewhere in the system. This could be from the boiler itself, the pipework, or even the radiators. Leaks should always be addressed as soon as possible to prevent further damage to the system.

Why is My Boiler Making a Rumbling Noise?

A rumbling noise from your boiler could be a sign of ‘kettling’. This happens when the water flow within the boiler slows down, causing the water to boil and generate steam. This trapped steam creates a rumbling or whistling sound. If you notice such a noise, it’s best to get your boiler checked by a Gas Safe engineer.

Why Does My Boiler Make a Popping Noise?

A popping noise is often caused by the build-up of air in the system. This build-up can create pressure pockets that ‘pop’ when they’re heated. Bleeding your radiators can often fix this problem, but if the popping noise continues, it’s best to call a professional.

My Boiler is Making a Screeching Noise, What Does this Indicate?

A screeching or screaming noise from your boiler could indicate a serious issue, such as a faulty pressure relief valve or a pump failure. In such cases, it’s best to turn off your boiler and call a Gas Safe registered engineer immediately.

My Boiler Only Makes Noise When Heating

If your boiler only makes noise when it’s heating up, it could be due to a variety of issues, including a worn-out pump, a dirty burner or a faulty component. It’s advisable to have it inspected by a professional to identify and rectify the issue.

Additional Information and Causes of Noisy Boilers

My Boiler Has Started Making a Buzzing or Whining Noise – Why?

A buzzing or whining sound is typically a sign of worn pump bearings. If you hear your boiler making such a sound, it’s asking for help. The boiler needs immediate attention and professional repair.

Why Has My Boiler Started Making a Whooshing Noise?

If your boiler is making a whooshing noise, it could be due to a blocked circulation pump. Calling an engineer to check for any blockages and diagnose the problem is recommended.

Frequently Asked Questions (FAQs)

Why is My Boiler Suddenly Noisy?

Sudden noises from your boiler could indicate a variety of issues, from limescale build-up to a faulty thermostat, or even trapped air. It’s best to consult a professional to diagnose the exact issue and resolve it promptly.

Can a Noisy Boiler Be Dangerous?

While not all boiler noises indicate a serious problem, some can be a sign of potential hazards. For example, a loud rumbling or popping noise could be a sign of a dangerous pressure buildup. It’s important that if you’re ever in doubt about a noise your boiler is making, you should shut it off and contact a professional immediately.


Boilers are complex systems, and their functioning can be disrupted by a myriad of issues. It’s important to listen to your boiler and respond to its signals. If your boiler starts making noise, it’s trying to communicate a problem to you—whether that’s limescale build-up, trapped air, a loose component, or a faulty pump.

Always remember to act quickly when such issues arise. Early detection and resolution can save you from costly repairs down the line. If you’re unsure about any aspect of your boiler’s operation, don’t hesitate to call a Gas Safe registered engineer. They can provide the necessary professional help to keep your boiler running efficiently and quietly, making your home a warm, safe and peaceful place to be.

If you are in London, and require a boiler service or any kind of boiler repairs, get in touch with SP Boiler Services. We’ll service your boiler, repair it, or help you find the perfect replacement.

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