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What Does It Mean When Your Boiler Is Making A Loud Noise

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  • 15-09-2022
What Does It Mean When Your Boiler Is Making A Loud Noise

Do you need to find out what it means when your boiler is making a loud noise? We look at the common causes of a noisy boiler?

When you experience noisy boilers, you assume your central heating system is on the out, and you need a replacement boiler. That's not always the case! Keep reading this article if you have strange boiler noises and you want to know the damage. 

What type of noise is the boiler making?

A boiler making noises is concerning and definitely cause for a gas safe registered engineer to visit. While most noises are perfectly normal with a boiler, learning the difference between healthy and unsettling noises is essential. However, the first thing you should do when you notice a noisy central heating system is diagnose what type of noise it's making. 

Is It Worth Repairing A Boiler?

Any vibrating or rattling noises coming from your boiler could be as simple as a loose bracket that needs tightening. A thorough inspection from a gas safe heating engineer can ensure other tapping and strange noises are not resulting from another problem.

Once the brackets are secured properly, the vibrating noises should stop, as this is the common culprit, especially with older boilers. Your boiler casing could be loose, causing a vibration as the unit turns on or changes temperature. 

Electric water heaters, more than conventional boilers, can create a humming noise. While there may be rust, limescale or sediment in the cylinder, you can sometimes fix this yourself by tightening the heating element.

Rumbling noises can also come from high pressure, which means your incoming main water supply has too much pressure. Check the pressure gauge and readjust where appropriate. 

When your boiler is making loud banging noises, this is a sign of a build-up of debris on the boiler's heat exchangers or a faulty thermostat. Checking your boiler's thermostat can help remove this as a possibility, but you may need a qualified professional to inspect the unit further.

In the case of sludge build-up, you must contact a heating engineer as soon as possible to perform a power flush. This process uses highly pressurised water to remove blockages and clear pipes, hopefully eradicating your banging noises. 

Any gurgling noises from your boiler could be a result of trapped air, frozen condensate pipes or even low water pressure. Hearing a small amount of gurgling from the boiler is normal, but when it becomes constant and loud, you could have a bigger problem on your hands.

Air trapped in the central heating pipe must be dealt with by bleeding the radiators and removing excess air. Leaving air in the system can cause further troubles. If this doesn't work, check the water pressure and the circulation pump. 

In most cases, any buzzing or whining will come from worn pump bearings. These noises can also be caused by defective burners and vibrating fan bearings. You cannot diagnose these problems yourself and should contact a professional engineer, as they can install a new pump or pump bearings.

If you leave the boiler without replacement parts, it can cost more fuel to reach the desired temperature, meaning your heating bills and energy usage increase. 

Boiler kettling is the common term used to refer to the unusual noises produced by a boiler as a result of limescale build-up. The boiler can make whistling noises similar to a kettle boiling. As limescale accumulates on the boiler's heat exchanger, boiler whistling can occur.

Certain UK areas around London, Bristol and Southampton, have "hard water", which is water with higher mineral content like calcium and magnesium present. As these build up more, hot water flow is restricted, and the water becomes trapped in the heat exchanger. From there, it begins to overheat, generate steam and expand.

The whistling noise is a result of this process. Kettling can also result in your boiler pump becoming stuck or damaged, needing replacement. If you live in hard water areas, understanding how to keep your boiler best safe and clean is essential. 

Banging noises from your boiler system can either be caused by overheating, a faulty thermostat or unsecured pipes under the flooring. If the boiler is overheating, you should turn off the boiler and let the system cool down.

Turn it back on, with the thermostat turned up, and listen for a click. If it doesn't, you should call a Gas Safe engineer. You can tell your pipes are loose if you've always heard rattling or light tapping from the pipework. 

Where's the noise coming from?

The most important part of boiler repair is identifying where the noises are coming from. Whether you've got an old conventional tank or modern combi boiler, every system has different parts, and you should take time to find the component or area that is making the banging, tapping or whooshing noises.

If you can explain to a heating engineer not only the type of noise but the location of it, you're more likely to get the unit repaired quickly. 

Check the error codes.

It's fairly common for most modern boilers to be issued with digital displays, showing you fault codes when problems arise or internal parts are damaged.

These screens are more common on combi boilers, allowing you to control all the settings, timers and other features of your boiler. 

Checking your boiler pressure gauge can also identify what the issue may be and where the problem lies in the system.

Correlate these error codes with your boiler manual, which you can find online if you don't have a hard copy.

These manuals should be kept close by and studied when a problem arises, as they can guide you to the right solution. 

What Does It Mean When Your Boiler Is Making A Loud Noise?

What Are Common causes of a noisy boiler?

There are a few common reasons why your boiler produces unexpected noises, many of which can be fixed either by yourself or a boiler engineer. Here are our 10 top causes of a noisy boiler and how you can fix it.  

Limescale building up on the heat exchanger, internal pipes and connections to the boiler is one of the main reasons of a noisy boiler. When limescale is present, you can hear boiler kettling and whistling, but also banging and clanging. As water circulates throughout the heating system, hotspots will appear where higher temperatures are achieved.

This creates steam bubbles, which pop and produce the whistling noise from within. In most cases, you may have to replace your boiler's heat exchanger or even the boiler itself, depending on the severity. After speaking with a Gas Safe heating engineer, you should invest in a central heating inhibitor, dose the system and flush it out.

If old limescale deposits have built-up and hardened, these may remain, and gurgling sounds could continue. 

It's normal for boiler components, radiators and pipework to deteriorate over time, becoming heading sludge and attaching themselves to parts of the boiler. Sludge is responsible for creating tapping, clicking or even trickling noises as it travels around the system. The solution? You will require a hot flush throughout your boiler.

Power flushes are common for many heating engineers, and most boiler warranties and manufacturers will not let you complete one yourself. A power flush removes most sludge and limescale from the system, helping the boiler run more efficiently. You should also ask your boiler engineer to fit a boiler filter and clean this out at the end of each service. 

Low water flow and low pressure is another common cause of banging and clanging in your boiler. A lack of circulation and pressure followed by a sharp boost of pressure will create noisy clanging and banging. This is similar to water hammering. If your boiler has lost pressure, there's most likely a leak.

Low water flow rates could be due to heating pumps being on a low setting. Check your pump for the flow rate setting it's currently set to, as you can increase the flow rate and stop the unwanted boiler noises. On the flip side, if your pump is running too fast, humming can begin. Try setting it to a lower speed and seeing how that affects the noise and prevents further damage. 

Banging noises could be caused by airlocks in the central heating system, which are common. When you start running hot water, or you turn your boiler on, you can hear banging due to this airlock. After inspecting your boiler for other damages, check for a bleed screw on the pump, as you can release the air from here, typically stopping the boiler banging.

A malfunctioning pump will need replacing from gas safe qualified engineers. Leaving faulty pumps without care can cause more problems with your boiler, with your energy bills increasing over time. For other trapped air, open all the radiator valves and run your heating at full temperature for around ten minutes. 

If you hear a clicking or light tapping, your boiler could be experiencing ignition failure. When there's a problem with the boiler working or even firing up, this ignition fault will require a boiler engineer to check the system.

There could be a fault in the ignition leads or probe or perhaps a lack of gas supply to the unit. A dirty pilot light can also be the reason for many tapping sounds, so maybe check that. 

A seized boiler pump can cause vibrating and humming boiler noises, with the pump increasing in temperature as the vibration increases. If the pump is hot to the touch, there is a seized component. While the pump should be warm in a working boiler, with some vibrating noises also being normal, you should know when this is above the typical operating level.

For a temporary fix to the noise, tap the pump gently, freeing any components and letting the motor continue running. This can stop the boiler from making a loud noise. In most cases, the pump will need cleaning from sludge or limescale (or perhaps even replacing).

Be sure to check your pump is not set too high, either, as this can cause heated water in your central heating system to travel around the pipes too quickly.  

If the boiler is switched off and has been for a few hours, yet you hear tapping, banging or knocking, this is a sign of pipework problems. The heating pipes could simply be cooling down, in which case expect noises, but anything aggressive, loud and continuous should be reported to a gas safe registered engineer.

If your boiler and heating system has too high a pressure, you could also experience noise with the valves inside your home. These can start to hum and make other strange noises. 

Any vibrating or whooshing sounds can come from the air intake or flue. You should regularly check the air filter to ensure there are no blockages, as fluff and other foreign objects can easily build up and cause a disruption to air movement.

Similarly, the boiler fan itself could have a fault or be blocked by dust and sludge. 

When you've bled your radiators to stop rattling noises, but the noise continues, this could be due to a loose valve. Tightening your radiator valves can sometimes help prevent this problem.

Follow any pipes that haven't been clipped correctly, as unclipped pipes can often cause those kinds of noises. Loose brackets are an easy and inexpensive fix if you know what you're doing. Bleeding radiators is also a straightforward procedure but should only be done when they are cool to the touch, and you feel comfortable doing so. 

Do you need a boiler servicing in East London? 

Contact us for boiler repair services in Docklands, Waltham Forest, Tower Hamlets, Lewisham, Newham, Hackney, Southwark or Greenwich.