Reasons Why Your Boiler Is Making A Noise

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If you’re experiencing unusual noises coming from your boiler, it’s important not to ignore them. These strange noises could be indicative of underlying issues that may require immediate attention. At MML Plumbing, your trusted plumbing and boiler installation company in North London, we understand the importance of a well-functioning boiler. In this article, we’ll explore some common reasons why boilers make unexpected noise, and how our expert team can assist you with professional boiler installation and maintenance services.

Common causes of noisy boiler

Trapped Air in the System:

One common reason for a noisy boiler is the presence of air in the system. Air bubbles can cause gurgling sounds or banging sounds, disrupting the normal operation of your boiler. This can occur due to inadequate system bleeding or a leak somewhere in the system caused by trapped air. Our skilled gas-safe registered engineer at MML Plumbing has the expertise to diagnose and resolve air-related issues, ensuring your boiler operates silently and efficiently.


Have you ever noticed your boiler producing a sound similar to a boiling kettle? This phenomenon, known as “kettling,” occurs when limescale or mineral deposits accumulate within the boiler’s heat exchanger. As the water heats up and flows through these deposits, it creates a boiling-like noise. Kettling can lead to reduced efficiency and potential damage to your boiler if left untreated. MML Plumbing offers comprehensive descaling services to eliminate limescale build-up, restoring your boiler’s optimal performance.

Boiler Pump Problems:

Boiler vibrating noises can also stem from pump-related issues. If your boiler or malfunctioning pump emits a constant humming boiler whistling or vibrating sound, it could indicate a problem with the pump. This may be caused by a worn-out bearing or an imbalanced impeller. Our skilled engineers have the necessary expertise to inspect and repair faulty pumps, ensuring your boiler operates quietly and efficiently.

Faulty Thermostat or Controls:

In some cases, a noisy boiler may be the result of a malfunctioning thermostat or control unit. Rapid clicking or ticking sounds from a boiler’s pressure pump can indicate a faulty boiler thermostat, which can lead to inconsistent heating and excessive noise. At MML Plumbing, our team can assess and repair thermostat issues, ensuring precise temperature control and a quiet boiler.

Boiler Component Issues:

Various components within your boiler can develop faults over time, resulting in unusual noises. Faulty valves, heat exchangers, or fans can generate rattling, screeching, or whistling sounds. Another issue that can cause the boiler to be noisy is the frozen condensate pipe in the winter. Our experienced gas-safe boiler engineer can identify and replace faulty components, restoring peace and quiet to your boiler.

Gurgling noises

The low water pressure within your boiler can lead to various noise-related problems. When the water pressure drops below the optimal level, the boiler may produce a humming noise or vibrating sound. Additionally, water flow disruptions caused by low pressure can result in a gurgling or bubbling noise.

Pipe Expansion and Contraction:

As your boiler heats up, check the water pressure as metal pipes expand to accommodate the temperature increase. This expansion can lead to creaking or knocking noises. Similarly, when the boiler cools down, the pipes contract, resulting in additional clicking or popping sounds. While some level of noise is expected, excessive or sudden noises may indicate improper pipe insulation or mounting. Our skilled engineers can assess and address pipe-related issues, ensuring minimal noise disruption from expansion and contraction.

Ignition Problems:

A malfunctioning ignition system can contribute to a noisy boiler. Clicking or sparking sounds, accompanied by delayed ignition or repeated attempts to ignite, may indicate an issue with the ignition mechanism. Ignition problems can be caused by faulty electrodes, a blocked pilot light, or ignition failure from a defective ignition switch. Our team of professionals is adept at diagnosing and resolving ignition-related faults, ensuring efficient and quiet boiler operation.

Sediment Build-up:

Over time, sediment and debris can accumulate within the boiler, leading to various noise issues. Sediment build-up can cause a rumbling or vibrating boiler noise, commonly known as “rumbling pipes.” It occurs when water passes through the sediment, causing turbulence and disrupting the smooth flow. At MML Plumbing, we offer thorough system flushing and maintenance services to remove sediment and restore optimal boiler performance. Using a central heating inhibitor help to protect the heating system.

Loose or Faulty Components:

Loose or damaged components within the boiler can produce rattling, clanking, rattling noises or making loud banging noises or sounds. Loose pipes, valves, or heat exchangers can create noticeable noise when the boiler is in operation. Additionally, a faulty fan or motor can result in grinding or whirring sounds.

Water Hammer:

Water hammer is a common issue that causes a loud banging or hammering noise in the boiler. It occurs when water flow is suddenly stopped or redirected, causing a shockwave that reverberates through the pipes. Water hammers can result from factors such as high water pressure, improperly secured pipes, or faulty pumps or valves. MML Plumbing’s professional gas-safe engineer can assess your system, install water hammer arrestors, and adjust the water pressure to eliminate this disruptive noise.

Boiler Scaling:

Scaling refers to the accumulation of mineral deposits, particularly limescale, within the boiler. This buildup can lead to a variety of noise-related issues, including kettling noises, rumbling, or hissing sounds. MML Plumbing offers professional descaling services to remove stubborn scale deposits, ensuring optimal boiler efficiency and reducing noise levels. Our experts can also provide advice on water softening options to prevent future scaling and maintain a quiet, well-functioning boiler.

Uneven Distribution of Water:

A noisy boiler may indicate an imbalance in water distribution within the system. Uneven flow or blockages in pipes can cause rattling, clanking, or even gurgling noises from boiler sounds. These noises are often more noticeable when you turn on specific taps or appliances. MML Plumbing’s skilled professionals can inspect and rebalance your system, ensuring a smooth and quiet water flow throughout your home.

Faulty Diverter Valve:

A malfunctioning diverter valve can lead to disruptive noise in your boiler system. The diverter valve controls the flow of hot water to either the central heating system or the domestic hot water supply. If the valve becomes stuck or damaged, it can cause loud banging noise, whistling noises, or clicking sounds when switching between modes. An expert gas-safe engineer can diagnose and repair or replace faulty diverter valves, restoring quiet and efficient operation to your boiler.

Incorrect Boiler Sizing:

In some cases, a noisy boiler may be the result of an incorrectly sized boiler for your home’s heating needs. An undersized boiler may strain to meet the demand of central heating pipes, leading to excessive noise and reduced efficiency. On the other hand, an oversized boiler may cycle on and off frequently, causing loud banging, tapping noises, or clanking sounds. MML Plumbing’s professionals can assess your heating requirements and provide expert advice on selecting the right-sized boiler, ensuring optimal performance and noise reduction.

Transform Your Noisy Boiler into a Whisper-Quiet Powerhouse with MML Plumbing

Experience the MML Plumbing difference today and say goodbye to noisy boilers once and for all! Our team of expert gas-safe engineers are ready to provide you with reliable assistance and proven solutions that will transform your boiler into a whisper-quiet, efficient powerhouse. Don’t settle for disruptive noises – contact us now and experience the confidence of a perfectly functioning boiler. Get in touch with MML Plumbing at 02083550840.

FAQs About Noisy Boilers

Why is my boiler making a humming sound?

A humming sound coming from your boiler circulation pump in your boiler could indicate a problem with the pump, such as worn-out bearings or an imbalanced impeller. It’s advisable to have a professional heating engineer inspect the gas boiler and repair the pump if necessary.

What causes a banging noise in my boiler?

Banging or knocking noises are often caused by trapped air in the system or pressure drop issues. Bleeding the air from the radiators can help you reduce the noise in the heating system resolving water pressure problems and helping eliminate the banging noise.

Why does my boiler sound like a kettle boiling?

This phenomenon, known as “kettling,” is typically caused by limescale or mineral deposits in the heat exchanger. Descaling the heat exchanger system can effectively remove the buildup and reduce the kettle-like noise.

How can I stop my boiler from making a whistling sound?

Whistling sounds can be attributed to faulty components such as valves or fans. A professional heating engineer can identify and replace these components, resolving the whistling noise.

Is it normal for my boiler to make some noise?

While some boiler noise is normal, excessive noises can indicate underlying issues. It’s best to have a professional assess your boiler if you’re concerned about the noise levels.

Can a faulty thermostat cause boiler noise?

Yes, a malfunctioning boiler fan thermostat can cause clicking or ticking sounds as it fails to communicate effectively with the boiler. Repairing or replacing the faulty boiler pressure thermostat can help eliminate the noise.

What should I do if my boiler is making a rumbling sound?

Rumbling sounds can indicate sediment buildup or a faulty burner. It’s recommended to have a professional heating engineer clean the system and inspect the burner for any issues.

How can I prevent air in my boiler system?

Proper bleeding of air intake in the system during installation and regular maintenance can help prevent air from entering the boiler, reducing the chances of noise-related problems.

Can boiler noise be a sign of a dangerous issue?

While not all boiler noises indicate dangerous issues, it’s important not to ignore any noises. Some problems or humming noises, if left unaddressed, can potentially lead to more severe malfunctions or safety hazards.

How can MML Plumbing help with my noisy boiler?

At MML Plumbing, our expert gas-safe registered engineer specializes in diagnosing and resolving boiler noise issues. We offer comprehensive gas supply services, including repairs, maintenance, and installations, ensuring your boiler operates quietly and efficiently.

When should I worry about boiler noises?

When it comes to boiler noise, it’s important to pay attention to certain factors. While some boiler noise is normal, there are instances where you should be concerned. If the boiler making noises are sudden, excessively loud, or persistent, it may indicate underlying issues that require professional attention. Additionally, if the noises are accompanied by other problems such as reduced heating performance or leaks, it’s advisable to seek assistance from a qualified gas-safe engineer. Addressing the issue early can prevent further damage and ensure the safety and efficiency of your boiler.

Is it normal for boiler pipes to make noise?

Boiler pipes can make some noise during normal operation due to the expansion and contraction of the metal as the system heats up and cools down. Mild clicking or ticking sounds are generally considered normal. However, if the pipe noises are loud, persistent, or accompanied by other symptoms like reduced heat output or water leaks, it could indicate an issue with the pipes, such as loose fittings or inadequate insulation. Seeking professional advice can help identify and resolve any underlying problems to ensure proper functioning and minimize disruptive pipe noise.

Why is my boiler so loud at night?

There can be several reasons why your boiler is particularly loud at night. One possibility is that the reduced ambient noise during nighttime makes the boiler noises more noticeable. Additionally, certain factors like lower water pressure or reduced flow rates during nighttime usage can contribute to increased noise levels in annual boiler service. It’s worth having a professional heating engineer assess your boiler to determine if there are any specific issues causing the nighttime noise and provide appropriate solutions for a quieter operation.

What does an airlock in a boiler sound like?

An airlock in a boiler can create distinct sounds that can be described as a gurgling noise, bubbling, or whistling noise. These noises occur when excess air becomes trapped within the system and disrupts the normal flow of water. If you suspect an airlock in your boiler, it’s important to have it addressed promptly. A professional technician can help release the trapped air and restore proper water circulation, eliminating the noise and ensuring optimal boiler performance.

Why is my boiler making noise even when off?

If your boiler is making noise even when it’s turned off, it could be due to a few possible causes. One common reason is the residual expansion and contraction of the system as it cools down, which can create creaking or ticking sounds. Another possibility is that the boiler’s controls or valves are malfunctioning, causing unintended noises. It’s recommended to have a professional technician inspect the boiler to diagnose and resolve the issue. Identifying the root cause will help prevent any potential damage and ensure a quiet operation, even when the boiler is not in use.


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