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Why is my boiler making banging noises?

Boiler making banging noises

‘My boiler is making a banging / clunking noise?’  You may have noticed this fault as you turn on your heating ready for the colder months. Your boiler may still be working while making the noise, which may tempt you to not take action. However a noisy boiler is highly likely to break down in the near future causing further damage.

What is kettling?

Kettling is when a boiler makes a banging noise.  This is usually caused by a disruption of water, causing the water to boil, steam and expand.  Often the cause of kettling is a build up of limescale or debris within the system.

The build up of debris can lead to a restriction in the flow of water, causing a reduction in boiler efficiency and heat distribution.

How can I stop the noise?

If the noise is caused by a build-up of debris, you will need to remove the debris within your system. Depending on your central heating system we would advise either a powerflush or a chemical clean.

A powerflush involves attaching a special machine to your heating system, which flushes out the debris. Water and special cleansing chemicals are pumped around your system to remove out the debris within your heating system.  After your system is flushed out a fluid called inhibitor is added which helps to keep the system clean in the future.

If you have microbore pipe central heating system, often a chemical cleanse will be more appropriate than a powerflush. A chemical cleanse involves inserting a special chemical into your heating system, this is left to dissolve the debris and limescale.  After two weeks your system will be drained and re-filled with clean water and a fluid called inhibitor.  Inhibitor helps to protect your system against future debris from building up.

After a powerflush or chemical clean you should notice your boiler quietening down and an increased efficiency for your heating.

Magnetic filter

You may wish to have a magnetic filter installed after your system has been flushed. A magnetic filter catches debris before it enters your central heating system, helping to prevent your boiler making banging noises.

Other causes of a noisy boiler?

It is very important that a qualified Gas Safe or OFTEC engineer diagnoses any fault with your boiler or heating system. It has been shown that 1 in 10 are in fact unsafe and that you should never attempt to carry out a repair yourself. Doing so can put yourself and others at risk.  As discussed this a noisy boiler is frequently caused by debris, however this may not always be the case.

For example, the noise could be caused by trapped air in the system, here the engineer will need to diagnose what is causing the air to become trapped.

Remember all work carried out on your boiler should ALWAYS be carried out by a gas safe engineer or OFTEC engineer if you have an oil fired system.

If you need to book an engineer or have any questions about your boiler, or would like to arrange a free of charge survey please call our office on 01258 472132 or fill out the form below.


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