Why is my radiator making a noise

One of the most common noises you will hear coming from your radiator is air. You should bleed the radiators in your home at least once a year

Radiators are an important part of your home’s heating system, so when they break down or start misbehaving, it can stop your life from running as it is supposed to. Noisy radiators can be a source of worry for many homes across the UK. No one wants a radiator that gurgles in the night or clanks and groans throughout the day, but a lot of the time this is a completely natural occurrence. 

What causes a noisy radiator?

Radiators can make all sorts of strange noises, and many of these can make it seem like your appliance is on its last legs. However, many of these noises are completely normal. For example, a hissing sound coming from the radiator may be as simple as your thermostatic valve restricting the flow of water to make sure it doesn’t exceed the desired heat setting. 

On the other hand, there are some radiator sounds that could be an indicator of a more serious problem, these could include; banging, clunking, gurgling, and vibrating. 

Firstly, there should only ever be two things inside your heating system; water, and a central heating inhibitor. A central heating inhibitor is a chemical that stops corrosion by preventing the water from reacting with the metal of your radiators. If there is anything else put through, it is likely to have an adverse effect on your system – this can manifest as many of the noises you hear. 

Causes of radiator noises

Air – One of the most common noises you will hear coming from your radiator is air. You should bleed the radiators in your home at least once a year to prevent oxygen bubbles and other gases from forming inside your central heating system, thereby taking up space that could be occupied by hot water to effectively heat up the radiator, and by extension, your room. 

If your radiator does not get hot at the top or takes a long time to heat up, bleeding it could be the fix for the source of the noise and is something you can do yourself. If you’re finding yourself having to regularly bleed your radiators, this could indicate another, more complex issue, such as a lack of chemical inhibitor. 

Sludge – If you have an old heating system, you may have corrosion in your pipework. Corrosion is made up of metal oxides that range in colour from dark brown to deep black. Some of the signs of sludge in your pipes include:

  • Radiators that don’t heat up at the bottom

  • Excessive noise coming from your boiler

  • Dirty or discoloured water inside your heating system when you bleed your radiators

An effective way to remove sludge from your radiators is getting a power flush performed by a Gas Safe heating engineer. This is also worth doing if your system is over 10 years old. It is worth adding a central heating inhibitor into your system after a power flush to protect against corrosion in the future. This will also help to prevent gases from forming in the system, as hydrogen is one of the by-products of corrosion. 

Pipe Warping – Pipe warping is another potential cause of noise coming from your radiators. When metal gets hot, it expands, and this is no different from your pipes. Whilst they might only expand a small amount, it can still cause some creaking and groaning. If your pipes expanding is to blame for creaks, groans, and clicks in your home, your best solution might be cushioning your pipework. There are various ways to do this, such as; expanding foam, or even just moving the furniture your pipes are expanding against. This should quieten things down in no time. 

However, if your pipes have been run through wooden joints, this is more serious. This means it is likely making noise due to the tension and eventual breaking of wood and metal. 

Pump speed is too high – If your central heating pump is improperly configured, setting it too high can cause noisy radiators. Lowering the speed setting could potentially solve the problem, although this does mean it will take longer to heat up and may not be possible for those with a combi boiler. 

Your radiators need balancing – If you find that the radiators furthest from the boiler don’t get as hot as the others, or reversely if you have rooms that get too warm and others that don’t get warm enough. Too much water flowing through can cause the water to take the shortest route back to the boiler, effectively bypassing the radiators furthest away. By using a lock shield valve, you can control how much water flows through and ensure the hot water is evenly distributed throughout your heating system. 

Improperly secured pipes – As water flows through your pipes, resonance can cause vibrations of the metal. If your piping isn’t properly secured, the pipes will rattle against the clips, causing vibrating or even hammering sounds, depending on the severity of the resonance. Vertical lengths of 15mm pipe should be clipped every 2 meters or 2.5 meters for 22mm pipe. For horizontal lengths, 15mm pipe should be clipped every 1.5 meters, and 22mm pipe should be clipped every 2 meters.

Limescale – Like sludge, limescale is a build-up of debris that forms in your radiator and pipework over time. Similarly, this can also produce air into the system. Limescale deposits that form inside your boiler can restrict the flow of water so much so that the water gets too hot, and can potentially start to boil. As a result of the water boiling, air from the water vapor forms in the system and begins to circulate, causing noises in your heating system. Limescale remover solutions can be added in much the same way as adding inhibitor fluid. 

How to fix these problems?

For certain issues causing sounds in your heating system, the solutions can be quite simple, and things you can do yourself. Other issues might require a more complicated solution, which may involve calling out a professional engineer to come and investigate the problem, which is recommended if you think the issue may be serious, or even if you are generally unsure. 


Radiators need to be kept in good condition to keep them working properly and lasting for a long time. To keep your radiators and heating system in the best condition, it is recommended that you protect your appliances with boiler insurance cover, such as Smart Cover’s boiler breakdown insurance. With this cover, should the worst happen and part of your system breakdown, a qualified engineer will be sent to your property to investigate the problem and have you back up and running as soon as possible.


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