What is kettling in boilers & why is it making a noise?

The idea of your boiler making a sound that favours the noise from your kettle can seem quite peculiar. Nevertheless, many homeowners are confronted with what some describe as a whistling noise coming from their boiler system. This can be defined as ‘kettling’ and can seriously disturb the peace in your household, especially if your boiler is located in frequently used places such as the kitchen or bedroom. If your loud boiler is quickly becoming the bane of your existence, read on to discover the causes behind that unsettling noise and how we at HomeServe can provide you with the solution to your noisy problem.


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Why do boilers make this noise?

There can be many causes behind the loud, rumbling noise that your boiler is making. This can range from incorrect installation to inaccurate settings or a fault with your thermostat. The most common cause of boiler kettling however tends to be an accumulation of lime scale on the boiler’s heat exchanger. Within the UK, some areas tend to have ‘hard water’ which is a term used to describe H2O that possesses high mineral content such as calcium and magnesium. Places such as London, Bristol and Southampton are known to have a degree of hard water that ranges from hard to very hard.

Due to the presence of calcium, limescale deposits tend to build-up, making them insoluble which in turn restricts the flow of water. As a result of this, water can become trapped in the boiler’s heat exchanger which then makes it overheat, generate steam and expand. The whistling noise is a consequence of this process.

Other causes of kettling in boilers include sludge or debris collecting around the heat exchanger or if a pump has become stuck or needs to be replaced.

Kettling could have damaging long-term effects on your boiler by reducing its efficiency. The boiler will have to use more fuel to reach its desired temperature, which could result in a rise in energy usage and consequently increase your monthly bills. The fact that your boiler is being overworked could also reduce its lifespan, so you could ultimately end up paying to replace your boiler before its time.


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Prevention & Cure

Ensuring that your boiler is well-maintained and receiving an annual service could help prevent any of the usual causes of kettling. Here at HomeServe, we offer a range of services to help your boiler function properly for the utmost length of time, as well as providing you with solutions should your boiler reach a stage beyond repair. We provide our customers with services ranging from boiler health checks, singular and annual boiler servicing, and a variety of insurance cover options. So, whether you’re in need of some general advice or if you feel that your boiler is in need of some TLC, we can provide you with just what you need. Call us to speak with one of our trained advisors or alternatively we can send one of our approved Gas Safe registered engineers to your home to take a look at your boiler first-hand.

Our engineers are boiler professionals and can rectify just about any issue that could be the cause behind your kettling boiler. Here are some examples of what can be done to fix the problem:

  •  Add an all liquid inhibitor to the system

  • Fit a Magnabooster

  • Replace the heat Exchanger

  • Powerflush the system

  • Fit a Magnetic and Electrolytic Scale Inhibitor

All in all, if your boiler is making a loud, whistling noise or anything of the sort, rest assured that we at HomeServe can provide you with exactly what you need to get your heating functioning to a superb standard. Contact us and we’ll ensure that visitors will never mistake your boiler noise for you inviting them in for a brew.


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Information and other materials on this website are not intended to constitute professional advice and should not be relied upon. Please see our Terms of Use for further details.

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