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Find the Cause of Your Noisy Boiler


All boilers make some noise but if yours has started making unfamiliar sounds, it’s time to find the cause and get it resolved. Our guide will help you to locate the issue causing the noise, getting you one step closer to a quieter heating system.

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Potential Causes of Strange Boiler Noises

There are a variety of noises your boiler might make when there’s a fault, which helps when trying to identify the cause. Use the table below to match the type of noise you’re hearing with the issue that could be causing it.

Type of NoisePossible CauseRequires an Engineer?
GurglingTrapped air in the system which could result in your radiators failing to heat up as they should. You should bleed your radiators.No – unless you don’t feel confident bleeding your radiators.
HummingA loud, noticeable humming suggests that there’s an issue with the heating element of your system.Yes
Kettle boiling (whistling)As sludge, limescale and other debris build up on the heat exchanger, your system can start to sound like a kettle, an issue known as kettling. A powerflush may be required.Yes
VibratingSome compartments might be open and simply need closing, or the brackets might need tightening. If you can see the boiler visibly shaking then a gas engineer will be needed to secure it. A third possibility is that the circulating pump – which circulates water through the system – might be set too fast.No – tightening the brackets can be done yourself with a screwdriver. Yes – to secure the boiler if the whole unit is shaking.
TappingA component has come loose and will need tightening. Sludge building up in the system, which may require a powerflush – this possibility depends where the tapping is coming from though.Yes
BangingDebris building up on the heat exchange which may require a powerflush to resolve.Yes
DrippingSuggests that there’s a leak somewhere in the system which can often be caused by the pressure being set too high or old boiler components wearing down.Yes

Not all of these potential causes require the assistance of an engineer but if you don’t feel confident enough doing it yourself then you should always contact one.

The Most Common Cause of a Noisy Boiler

A build up of sludge and debris on the heat exchanger, known as kettling, is one of the most common causes of a noisy boiler. In the table above, we highlighted that a powerflush would be needed to clear out any debris in the system, however, it can be prevented by having a magnetic filter fitted to your heating system. Magnetic filters collect sludge, debris and limescale before it has the chance to build up. By having a magnetic filter fitted, you’ll also benefit from a more efficient and longer lasting boiler.

Spotting a Leak From Your Boiler

A dripping noise is something that needs to be addressed urgently before it grows into something bigger. Start off by checking that the water pressure isn’t too high, but if that’s not the case then some components of your boiler are likely to be wearing down.

This tends to happen when a boiler has been heating your home for several years and is coming to the end of its life. It would be a good idea to consider replacing the boiler at this stage, rather than just addressing the fault, for ongoing peace of mind.

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More Causes of a Noisy Boiler

Still struggling to find the cause after looking at the table? Then there are still several more things to look into before contacting an engineer.

Low water pressure

You can check the pressure of your boiler by taking a look at the built-in pressure gauge. If the needle is below 1 bar then that’s too low so you will need to repressurise your boiler.

High water pressure Similar to the last point, if you spot that the pressure is too high then it will need to be lowered.

Frozen condensate pipe

Condensing boilers are fitted with condensate pipes which send gases outdoors rather than into the home. During the cold winter months, they’re susceptible to freezing and can cause your boiler to start making noises. You can resolve this by pouring warm (not boiling) water over the pipe to thaw it out.

Thermostat set too high

A thermostat that’s set too high could be what’s causing your boiler to make more than a normal amount of noise. Simply turning the thermostat down will be enough to resolve this but if you’re having to set your thermostat too low to enjoy a quiet home then it’s worth contacting a Gas Safe registered engineer.

Can’t Find the Cause?

If you’ve tried to find out what’s causing your boiler to be noisy but can’t find it then you should get expert advice from a qualified engineer. Receive up to 3 free quotes from trusted engineers in your area by visiting Boiler Guide today.

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