Why is my radiator so noisy? Here are the most common reasons.

Reasons why and how to fix them

Radiators can make a lot of different noises which are very normal. However, some noises can indicate an issue. Here, we look at why your radiator is making a lot of noise, and what we can do to fix this.

Thankfully, some radiator noises are very normal. Regular radiator noises include:
• hissing
• dripping
• gurgling
• banging or knocking
• clicking

The most common reason why radiators make a noise is bubbles of air invading the system, slowing down your heating and potentially building some issues that really do require attention.
You should also ensure that the system has had an inhibitor added to prevent the water from reacting with the system’s metal components, which can cause corrosion and leaks.

Check out our guide below to see what may cause your radiator to ‘make this noises...or you can go straight to our online ‘How to bleed a radiator’ guide by clicking here.

Why is my radiator hissing?

A hissing radiator is not normally anything to worry about, as it’s probably the radiator’s thermostatic valve (TRV) doing its job - restricting hot water flow so that the radiator doesn’t exceed your setting on the valve.

If you are overly concerned and really do think it’s something to worry about, please do talk to a specialist and call us on: 0800 731 3344.

Why is my radiator clicking?

A clicking radiator is usually caused by thermal expansion, a natural consequence of the central heating system’s components expanding as they heat up or contracting as they cool – we often hear a car engine ticking as it cools down after a long run. The same phenomenon also affects electric radiators.

Why is my radiator gurgling, banging, or making a dripping noise?

All these louder noises can be due to the most common reason why radiators make a noise:


The more air there is displacing water in the pipes and radiators, the more vocal they are, and this may also be evident from boiler noise and cool spots that you can feel on your radiators.

Fortunately, you can bleed the air out easily using a radiator key – check out Swale Heating’s online guide, ‘Bleeding your radiators’ by clicking here.

We recommend bleeding your radiators at least once a year, preferably when you sense the weather changing for the long winter months ahead. This also enables any bigger issues to be noted and dealt with before you start to need your heating at its best.

But there are other culprits for why a radiator is gurgling, banging, or making a dripping noise…


A need for more frequent radiator bleeding may signal that the chemical inhibitor is missing or must be topped up, and its absence may have caused another major reason for noisy radiators – sludge.

More serious than air inside your central heating system, this suggests corrosion and will show up when you bleed radiators and dirty brown or black water starts to come out after the air has been expelled.

Other clues to corrosion and sludge:
• radiators failing to get hot at the bottom (the same problem at the top of a radiator suggests air and a need to bleed the system)
• boiler noises or grumbles
• radiator leaks

The best way to get your system tip-top again is a power flush and some new inhibitor. This ought to be done at least every 10 years. We can offer a range of boiler and central heating maintenance plans at very little cost - click here to have a look.


The South East has some of the hardest water in the country due to the amount of chalk and limestone structure in the county, which can produce a similar build-up in the central heating boiler that we see every day in our kettles.

This may restrict flow inside the boiler and heat the water higher than necessary– a process heating engineers call ‘kettling’ – causing banging noises and air bubbles that, as you will have read earlier, can cause radiator noises too.

The problem can be reduced by adding an anti-limescale agent to your system and you can get advice from us at Swale Heating about this.

Read about our boiler and central heating maintenance plans by clicking here, or call us on: 0800 731 3344.

Insecure pipes

The force of water flowing through pipes can make them bang and clang if they have not been properly installed or the clips have been tampered with for decorating or another purpose.

The standard advice is that vertical 15mm copper piping must be secured every 2 metres - every 2.5 metres for 22mm pipe – and every 1.5 metres and 2 metres respectively for horizontal pipes.

If this is the case, it’s best for you to have one of our Gas Safe registered engineers come to look at the issue. Click here to contact us today.

Pump speed

Adjusting the pump speed may be the answer to stopping radiator noise. This job is best done by a Gas Safe registered engineer.

Altering the pump speed may stop the noise, although it can mean that the system takes longer to heat up. If this is the case, something could be wrong, which would mean that a certified engineer would have to fix this.


Rushing and hissing noises from your radiators may suggest water is flowing through them too fast and, apart from the irritation to you, this may deny them the chance to heat up properly. It is most likely to affect rooms furthest from the boiler.

Water flow through a radiator is controlled by that unglamorous ‘other valve’ at the opposite end to the more familiar thermostatic radiator valve or TRV, which enables you to set the preferred temperature.

This is the lockshield, which is topped by a simple white cap rather than the larger head used for the TRV. Balancing can be a DIY job, using a lockshield valve adjustor or adjustable spanner.

However, this is quite a complex job so it would be best to request one of our Gas Safe certified engineers to come out to look at this – click here to contact us.

You can also call us on: 0800 731 3344.

Why choose Swale Heating?

We were founded in 1972 to focus on top quality installation with follow-up maintenance to the same standard.

Swale Heating is now one of Kent's largest installers of boilers and heating systems, completing thousands of installations each year, and keeping over 140,000 homes safe and warm, via our maintenance and repair services.

We understand that the failure of your heating system can leave you feeling anxious, which is why we're available 24 hours a day, 365 days a year. You can find out more about our boiler cover plans and use our online portal to book your repair or annual service. If you would like a quote for a new boiler, click here.