Noisy boilers and how to fix them

Common causes of a noisy boiler

Here are the most common causes of a noisy boiler:

• Limescale
• Air blockage
• Overheating
• Insufficient water flow
• Faulty thermostat
• Low water pressure

Diagnosing a noisy boiler

Step 1: Identify where the noise is coming from

Firstly, it’s important to identify exactly where the noise is coming from. Is your boiler making a loud banging noise, or are the unusual sounds coming from a radiator or central heating pipe? If you can hear a creaking noise, it may just be the sound of pipes changing temperature – this is perfectly normal.

Once you’ve identified where the noise is coming from, you’ll be able to diagnose the problem.

Step 2: What type of noise is the boiler making?

The next step is to identify what type of noise your boiler is making. If you react quickly to these unusual noises, then the steps to fix the issue could become less complicated and more cost-friendly. You may even negate the need for a new boiler.

You will need to call in a Gas Safe Registered engineer to repair the issue, but here are some steps you can take to discover the root of the problem first.

Vibrating noises

A boiler that’s making vibrating noises could be the result of loose brackets that need tightening. You’ll be able to tighten the brackets yourself, but a Gas Safe registered heating engineer will need to diagnose the issue if this doesn’t stop the vibrating noises.

Loud banging noises

If your boiler is making loud banging noises, it may be the result of a faulty thermostat or a build-up of debris on the boiler’s heat exchanger. If debris builds up, you’ll need a qualified professional to carry out a powerflush. A powerflush removes the sludge in your system, preventing blockages and heating inefficiency.

Gurgling noises

Gurgling radiators could be the result of trapped air in the system, low water pressure, or a frozen condensate pipe. It is fairly common for a small amount of gurgling within the boiler, however, it’s important to investigate further if this becomes loud or constant. There are simple fixes that can be carried out at home yourself, depending on the issue.

Read more below to diagnose the problem:

Check if the system needs bleeding

If there is trapped air in the system causing the gurgling you could bleed the radiators to release this air. Leaving trapped air in the system could lead to further troubles, so it’s best to deal with it straight away. Read more about bleeding a radiator.

Check the water pressure

Check the pressure gauge on the boiler in case you have low water pressure causing the gurgling noise. Always refer to your user manual, but typically if the reading on the display is below 1 bar, this is a sign of low pressure. To increase the pressure to the correct level follow our step-by-step guide.

Check for frozen pipes

You can usually locate your boiler’s condensate pipe outside of your home, it’s usually a white overflow pipe. You should be able to thaw it with some warm water (not boiling).

Whistling or kettling noises

Does your boiler sound a little like a kettle? If so, this particular issue is more commonly known as kettling.

The most common cause of boiler kettling tends to be an accumulation of limescale 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.

Does your boiler sound a little bit like a kettle? If so, this particular issue is more commonly known as kettling.

Banging or tapping pipes

If you can hear your pipes banging when you turn on a hot tap, this could be due to overheating. Check your boiler’s thermostat by turning off the boiler and cooling the system down. Once cool, turn it back on again and turn up the thermostat. It should click. If not, it may be time to call for a Gas Safe Registered engineer.

Sometimes, banging pipes are simply due to pipework not being secured properly under the floor; if you’ve always heard rattling noises, then this may be the case. This can make them rattle around when water is flowing through them. One of HomeServe’s engineers could help solve this problem, simply contact us to arrange an appointment.

Step 3: Help to fix your noisy boiler

If you’re still experiencing problems with your noisy central heating system, don’t hesitate to get in touch with us. One of our Gas Safe Registered engineers could visit your property and examine your system to identify and rectify the issue.

All of our engineers are Gas Safe registered and fully qualified to diagnose and fix your central heating problems, so whether you know what the problem is or not, you can book an appointment with a local expert to diagnose the issue and get your heating back up and running effectively again.

HomeServe’s tips

Boiler error codes

Your boiler may show an error code, helping you diagnose the issue quickly and efficiently. Some problems may be easy enough to fix yourself, whilst others will require the assistance of a Gas Safe Registered engineer. Remember, not all issues will generate a boiler fault code so the above steps may still be necessary.

If you don’t have access to your boiler manual, you should be able to locate it online. The following guides cover the most common boiler fault codes:

• Ideal boiler fault codes
• Vaillant boiler fault codes
• Worcester Bosch boiler fault codes

Learn more about what to do if your boiler controls are not working.

If you have a noisy boiler, and require assistance to fix it, contact HomeServe today. We’ll aim to book you an appointment with one of our friendly, local engineers at a time that suits you.