How to Fix a Noisy Radiator – Eradicate the Noise

A noisy radiator

Last updated: July 20, 2021 at 11:29 am

The best thing you can say about the weather in the UK is that if you don’t like it, all you have to do is wait – it’ll change. It’s entirely possible to have temperatures of only a few degrees in June and be absolutely baking in summer.

That’s why if your radiator is making an annoying noise, it needs to be sorted as it’s not just a winter problem. Also, if you’re trying to soundproof a room, it doesn’t help having a noisy radiator ruining your soundproofing efforts.

Radiators can be responsible for a whole range of sounds including:

  • banging
  • gurgling
  • whistling
  • or hissing noises

Some are just part of the normal running sound of all radiators, and we’ll explain what these sound like. We’ll also discuss the most common reasons for the different abnormal noises and how you can fix them.

7 Common Noisy Radiator Sounds and Fixes

1. Normal Noises

Your radiator might make a quiet hissing noise as the room gets close to the desired temperature. The radiator will start to restrict water flow, and you’ll hear a quiet hiss.

Clicking and ticking are also normal sounds as long as you only hear them when your heating goes on or goes off. Metal expands and contracts as it heats or cools, so it will make a noise. You might also hear it in other areas because the pipes will also do this. There is no way to stop it, but it shouldn’t be loud enough or happen often enough to bother you. If your radiators start making this noise at other times, you should call in a heating engineer.

2. Banging Sounds

Banging sounds are almost always caused by your pipes. Either they haven’t been adequately secured to begin with, or over time they have come loose. If your pipes run outside your walls, then you can easily check them for any movement. If they have been hidden behind the walls, you’ll need to listen to determine where the sound is coming from.

Once you’ve done this, you’ll need to decide if the sound is annoying enough to cut open the plasterboard to fix it. This will cause dust and debris and will have to be put right at the end, so it isn’t a small job.

3. Running Water Sounds

If you hear a sound like running water using your radiators, it indicates that limescale and/or sludge have built up inside your central heating system. Sludge is caused by corrosion and is made up of various metal oxides. It creates a barrier that stops the water from flowing through the radiators properly. When the water hits the sludge, it bounces off the sides and creates a sound.

Sludge and limescale don’t just cause noise problems, it can affect the functioning of the radiator too. Here are some telltale signs:

Once the limescale and sludge have built up, the best way to remove them is a hot flush or a power flush. This isn’t something you can do yourself, so consult a suitably qualified plumber. There is a cost involved, but it’s worth it if you haven’t had this done in a few years.

Preventing a Build Up

Once you’ve flushed the system, the next step is to prevent the build-up from happening again. The first thing you should check is if you have a central heating inhibitor. This is a chemical used to break down any dirt or rust in the system, allowing your scale filter and your boiler filter to collect it easily.

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If you live in a hard water area, you should fit a scale reducer because it will prevent limescale from accumulating in future.

Finally, you can also get a boiler filter which uses magnets to prevent a lot of dirt, limescale and rust from making it into your central heating pipes and radiators.

4. Gurgling Sounds

Gurgling sounds are caused by air in the central heating. Air is one of the most common causes of unwanted noise from your radiators. Air in the system is caused by gases and oxygen bubbles building up inside your central heating.

The problem is that the air stops the radiator from completely filling with water. This means it won’t fully heat up, but rather than not heating at the bottom as you find with sludge, air will stop it heating at the top. You may also find it takes a very long time to heat up.

Bleeding Radiators

The first thing you should always do if you suspect air in the system is to bleed your radiators as this will fix a lot of problems, both noise and performance related. Bleeding the radiators is something you should do regularly, at least once a year at the start of autumn, when you start using your central heating again.

You will need a special key to bleed your radiators, but these can be picked up cheaply at any hardware shop. Simply fit the key to the small nut on the side of your radiator at the top and turn it. You will hear a hiss as the air is released from the radiator. It’s possible a small amount of water might also escape, so hold a cloth under the nut as you’re doing it.

If you find you need to bleed the radiators frequently, this indicates there’s a problem in your system. It might be missing the chemical inhibitor described above, for example. In this case, it’s worth getting a professional in to locate the source of the problem.

If your radiator is making a hissing noise that sounds like air escaping when you aren’t bleeding it, it may still be air. There are radiators that are fitted with air release valves or automatic bleeding valves. These valves mean you don’t need to manually bleed the radiators using a bleed key. The valves automatically release the air. This is a normal sound and nothing to worry about. It also shouldn’t happen frequently enough to annoy you.

5. High-Pitched Whistle

A whistle means there is a tiny hole somewhere, or you have not fully closed the valve after bleeding it. Check the radiators bleed valves are all tightly closed. If it persists, you might need a plumber to locate it for you.

6. Humming Sounds

If the pump in your boiler isn’t configured properly, it may run too fast or high. That will cause the water to flow too rapidly and can cause a humming sound when your central heating is switched on. In older systems, you might be able to fix it yourself as the pump will be accessible in your airing cupboard. Modern boilers have the pump contained inside the boiler, so you’d need to get a plumber to check it out for you.

7. Combined Hissing and Rushing Noises

If you can hear hissing or rushing noises in your radiators when they’re on, your system might not be properly balanced. Another symptom of this is if your radiators located furthest from the boiler aren’t as hot as those that are nearer. That will result in some rooms being too warm while others are still too cold.

The way to fix this is to have your radiators balanced. Balancing uses a small valve called a lock shield to control how much water flows into each radiator. Doing this ensures that hot water is distributed evenly throughout your central heating. This should stop any hissing and rushing noises from occurring.


Your central heating will always make some noise when in use, such as clicking or quiet hissing. Banging, gurgling, and rushing noises are not normal, though, and indicate there’s a problem. Always start by bleeding the radiators as this will fix a surprising number of issues.

If it doesn’t fix it, you may need a plumber to help correct the fault. Once the plumber has completed the job, remember to perform maintenance to minimise future problems. Replacing a central heating system is very expensive, so prevention is key.

On the other hand, a very old system may be so inefficient it’s costing you money. If so, it might be worth asking a plumber you trust for advice while he does your annual service. As well as being more efficient, it will be quieter, which is the point here. Only you can decide how much peace is worth to you.

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About the Author: AJ

AJ is a self-confessed soundproofing nut. He has written full-time on Quiet Living for the past 4 years, and has a wealth of knowledge about living a quieter life, soundproofing and fixing loud noises.

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