How To Cure A Noisy Central Heating System

Last updated: November 21, 2018

How To Cure A Noisy Central Heating System

What Causes A Noisy Central Heating System?

A noisy central heating system can be caused by a number of things, many of which you can fix up yourself.

In this guide. I’m going to cover a lot of different sounds that your boiler, pipework, radiators or central heating system may be making and help you to cure a range of noisy central heating problems.

Man in a purple shirt putting his finger sin his earsSo, if your heating is –

  • Gurgling
  • Tapping
  • Humming
  • Creaking
  • Clicking
  • Knocking

– let’s dive right in and cure that noisy central heating!

What’s That Awful Noise?

 

A cross section layout of a gas central heating system in standard house

Most of the components that make up your central heating system are made from metal, and metal – as you probably already know – will expand and contract as it heats up and cools down.

So it may be that the sounds you’re hearing your central heating make are just being caused by that natural process.

Because pipework creaks and groans as it expands and contracts, it can be something that you get used to – but if your central heating is making strange noises, it’s best not to ignore it.

More serious causes of annoying and loud central heating should be fully investigated and fixed by a qualified plumber, with the worst case scenario being that you have to part with a little bit of money to get it sorted.

But here at BestHeating, we like to give you the tools to fix things for yourself – so this guide is designed to help you identify the most common causes of noisy heating systems to help you to solve the problems without having to splash the cash on expensive repair bills.

Do You Have A Noisy Boiler?

 

Gas engineer fixing a faulty boiler

If you have a noisy boiler, it’s may be a sign that limescale has built up inside your boiler’s heat exchanger.

This noise is usually caused by hard-water build-up and is quite common in older heating systems.

To remove this excess scale, a descaler can be added to your feed and expansion tank.

Once you’ve allowed it to make its way around the system, you should flush your central heating with clean water and add some radiator inhibitor, to help prevent corrosion.

A noisy boiler could also be caused by a low water flow in the system. Modern gas boilers – and it’s important to know this – require a particular flow rate in order to operate properly.

Making sure this is correct will help you to diagnose the problem. You should be able to find the required flow rate in your boiler manual, or if you get really stuck you could contact the manufacturer and get them to provide the information to you.

If your boiler is not regularly serviced, you may find that noise begins to happen more often when you turn it on or when you are using your hot water. It may also be a good idea to install a Magna clean to help rid your system of sludge or debris; these are also good for reducing carbon emissions if fitted with an auto bleed valve.

Are Your Pipes Banging?

 

Pipework exposed under some floorboards

When you open the taps in your bathroom, do you hear a banging noise?

This is called ‘water hammering’ and can be caused by a number of things, from pipework not being secured properly under the floorboards to overheating or perhaps a little air in the system.

If you can hear your pipes making a thudding sound, the first thing you need to do is check the thermostat – either on your wall or your boiler.

To do this properly, turn your boiler off and allow the system to cool down. Once you’ve had it switched off for a while, turn your heating back on again and crank up the thermostat like you mean it.

You should hear a click when you do this, but if you don’t, call a professional engineer to come and diagnose the problem.

One of the most common causes of banging pipework is that the pipes under the floor are not secured correctly. Copper pipes need to be properly secured in order to prevent them rattling too much.

A simple solution, that should fix the problem of banging pipes, is to squash some felt around each pipe under your floorboards. Try and concentrate on every place where a pipe touches a joist or another pipe and wrap a little felt around it to create a snug fit.

If you’ve already had someone look into this for you and the problem still occurs, it may be worth your time investing in some plastic pipework, which is much more flexible and won’t make anywhere near as much noise as a copper alternative.

Why Is My Heating System Gurgling?

 

If your radiators are making a gurgling sound – like a kettle as it’s beginning to boil – it’s probably air trapped inside. This problem can be solved by bleeding the radiators – watch the video below to find out how.

And check out our How To Guide on Bleeding Radiators for some extra, in-depth help.

Why Is It Important To Get Rid Of Trapped Air In My Heating System?

 

It’s important to fix the issue of trapped air in the system as soon as you realise it is there.

Heat will have a difficult time reaching where it needs to be if air is preventing it from travelling to certain areas of your home – and if you get really unlucky, your boiler might not start at all and then you’ll really be in trouble.

Another cause of gurgling in a heating system – particularly in colder weather – could be a frozen condensate pipe.

Colder weather can cause pipes to freeze, stopping water from circulating through the system.

image of a condensate pipe being warmed up with a jug of water

Your condensate pipe is normally a white overflow pipe that drains to the sewers outside of your home – and is usually found on an external wall outsode of where you boiler is.

If your condensate pipe is frozen, it is normally at the most exposed external point – at the end of the pipework and near to the drain.

As in the image above, you can normally thaw a condensate pipe out entirely with a little warm water.

Using a suitable container – like a jug or a watering can – simply pour a little warm water onto the surface of the pipe to slowly thaw it out and remove the blockage.

Be sure NOT to use boiling water, as this can cause more harm than good, and once the contents of the pipe have fully drained and the blockage has been removed, restart your boiler.

PLEASE NOTE: Always follow the manufacturers guidelines to restarting your boiler, and if you’re unsure, give them a call.

Why Is My Central Heating Making A Tapping Noise?

 

A tapping – or gurgling sound like the one described above – could also be caused by a build-up of limescale within the pipes and radiators. If you suspect this is the problem, use a non-acidic cleaner to flush out the system when the heating is turned off.

The type of chemical cleaner you’ll need is dependent upon the age of your radiators and your boiler – discover how to choose the best one here.

Older central heating systems may need a much stronger solution than newer installations, so don’t just go and pick one off the shelf at the local plumber’s merchant – be sure to ask them which chemical cleaner is best for the age and condition of your system.

sludge in a cross section of pipework from a central heating system

Why Is My Central Heating Humming?

 

A humming sound coming from your heating could mean that the heating elements in your immersion heater are not functioning properly.

First, check that the thermostat is working correctly. If it is, turn your attention to the central heating pump; this may be set too fast and need slowing down.

If you think it’s necessary, turn the pressure down too, as too high a setting can result in pipe damage and clanging sounds.

If you have recently refilled your heating system, it could be that you’ve left the filling loop open slightly, or forgotten to disconnect it – as this is what the regulations state should be done. Or you might have knocked the valve accidentally and it may have become loose, allowing a constant flow of water into the system. Be sure to check that this isn’t the case.

You can reduce the pressure in your boiler by bleeding your radiators, check out this infographic for an easy guide, or by using the pressure relief valve in your boiler.

Why Is My Central Heating Making A Knocking Sound?

 

As water in the system heats up and flows through the pipes, it causes them to expand – and contract again once cooled.

If there’s insufficient room beneath the floorboards for this to happen, then noises will occur.

Check the position of the pipes and make any necessary adjustments if you find they are too close to the joists or floorboards – you can just use a saw and a chisel to make more room.

If the pipes have room to expand but are still making a noise, pack some light insulation around the pipe as that should help to limit movement and dull the sound.

Could My Pump Speed Be Making A Noise?

 

boiler-pump

If you’ve exhausted all avenues above – and you’re still hearing an annoying hum – it’s very likely that the root of your problem is your heat pump.

A common cause of humming is the vibration of the unit itself. If you find that this is the case, your pump will need securing in place and you could install simple brackets to make it more secure.

You could also try turning down the speed of the pump, but just be aware that this may lead to your radiators taking a long time to heat up. So if the problem persists, be sure to contact the professionals.

Good Luck Curing Your Noisy Central Heating!

 

There’s usually a simple solution to the noise coming from your boiler or radiators, but if in doubt, give a local engineer a call and ask for some advice about your radiator or boiler installation.

If you’ve had some success with these tips and managed to cure your noisy central heating, don’t forget to leave a comment and tell us all about it – you never know, you might help someone else with their problem.

For more help, advice and info on many heating issues, visit us on Facebook, Twitter and Pinterest.

Stay Safe and Happy Heating

43 responses to “How To Cure A Noisy Central Heating System”

  1. Hayden McBryde says:

    Hi John!!
    Central Heating System is a most important thing nowadays and people are also facing the issues regarding it so you have provided or highlighted such an important topic with helpful guidelines.
    Your post will really help a lot of people.
    Thanks and carry on with such informative posts Good luck!!

  2. Ella Spice says:

    These are some really great tips.
    I got my dad to put some cotton wool around some of my pipes and I’ve had no issues with noise for ages!
    Thanks for the help 🙂

  3. Kevin Taylor says:

    Hi just recently had a new boiler fitted and one rad in the bedroom sometimes sounds like next door is drilling how can I resolve this noise without calling an engineer?

  4. Paul says:

    Hi,

    One radiator has started making a noise, the only way I can describe is that you can hear it working.. but like a sound you didn’t use to be able to hear.. any ideas???

  5. Jade Brunet says:

    Our furnace keeps making strange sounds which causes our dog to bark at night. It is good to know that if you have a noisy boiler, it is often a sign that limescale has built up inside the heat exchanger. I did not know that this was usually caused by hard-water build up. We will have a professional come inspect the system to resolve the problem and hopefully allow my dog to sleep at night. http://www.WintersHVAC.com

  6. Amelia Murray says:

    Hi,

    We have just come back from our holiday and noticed that the heating is making a really loud humming sound, which we can hear through the whole house. We have recently had the wardrobe in front of the water tank removed and wondered if the sound could be due to now having less insulation? But should it be so loud? My daughters are a bit worried about explosions!

    • Hi Amelia, sorry for the late reply on this. That’s a little strange. It could be down to the removal of the wardrobe and perhaps its a noise you could get used to – not that you would want to. But it may also be an issue with the pump in your boiler. I have an old immersion heater that often makes noise like this. It could be the age of the system. Have you had it for a while, or is it a new boiler?

  7. Carolyn Leader says:

    Hi, I hope you can help. One of our radiators has started making the strangest noise. It sounds like a paper bag being scrunched and always happens just after the hot water tap is turned on, and sometimes happens when the water tap isn’t on. Do you have any idea what this could be? Thanks Carolyn

    • Hi Carolyn, most noise from a radiator is usually caused by air in the system. Perhaps look at bleeding your radiator and see if that helps. We have a guide on how to do it here – http://www.bestheating.com/info/blog/how-to-bleed-a-radiator/. If the problem persists though, it may be that you have a build-up of sludge inside it, which sounds worse than it actually is, and can be solved by flushing the radiator out. Try bleeding it first and if it still makes the noise, there are plenty of video guides online that can help you to flush the radiator out and get rid of any sludge that has built up over time. If you’re still having issues after that, feel free to come back to me again. I hope this helps.

  8. Jill says:

    Hi, I have an intermittent noise coming from my boiler. It is just 3 years old. The noise is really irritating. It is a constant rhm—rhm—rhm—rhm, and has been going on all day today. It has been happening for sometime now over the last year or so. I did have it serviced last year, but cannot understand if this noise is normal or not. I only have my central heating on for about 4-6 hours a day could this be something to do with it? Extremely exasp,erated…. Thank you in advance, Jill

    • Hi Jill, that is a little strange.
      Sadly with not much to go on, it’s hard to pinpoint the issue.
      Ideally, having an engineer look at it (or listen to it) would be best. If I had to guess, I would say that it was the pump that was making the noise, but on a system that is so new, that would be a weird one. I wish I could offer a little more insight, but having someone on site to hear it would be the best option and they can then hopefully diagnose the issue for you.
      Sorry I can’t be of more help.

  9. Duncan says:

    Hi, We have just added radiators to the living & dining rooms but not getting hot like the others. Also rads that use to get hot & stay hot have started to turn themselves off. Any advise please. And what size pipes should be under the floorboards????

    Duncan

    • Hi Duncan.
      Firstly, which rads did you buy?
      Secondly, did you check that your central heating system was large enough and powerful enough to accommodate new radiators?
      Thirdly, if they are designer style radiators you may need a baffle – depending upon the connection.
      And lastly, the pipework size will depend upon the size of the system and whether you live in a ‘normal’ house or a HUGE mansion.
      I recommend checking out our blog on how to balance your radiators – http://www.bestheating.com/info/blog/a-best-heating-guide-how-to-balance-radiators/ – and seeing if there is anything in there that could help.
      Good luck.

  10. Adrian Peacock says:

    Hi we have had some extremely loud banging/vibration noises, they are random and mostly happen during the night when heating and water is off, last up to 10 seconds so it is difficult to ascertain exactly where they are coming from Anglian water has checked the water supply and found nothing, heating enginer is currently puzzled by it, so loud at times that you would think there was an earth tremor, any ideas, thanks

    • Wow, Adrian, that is a bit of a puzzle. When you say the heating is off, is this happening as the system is cooling down? It may be the pipework contracting when cooling, but it’s tough to tell without hearing it. I wish I could proffer a better helping hand, but it’s a bit of a weird one and if the engineer on the ground and in the house is puzzled, I’m at a complete loss. Sorry.

      • Adrian Peacock says:

        Thanks John, no heating is not cooling down occurs completely randomly, middle of night, early morning etc, engineer coming back today

        • Well that is strange and not something I’ve come across before. Let us know what they say when they’ve come to have a look. I hope you can find some kind of resolution.

          • Adrian Peacock says:

            Current thinking is that there’s a 70% change its the combination valve, if that doesn’t work it looks like the megaflo

  11. Laura partner says:

    My sons rad has been turned off for nearly 4 days…turned it back on today ..was a bit gurgly..bled it , fair bit of air came out till water spluttered out…still making gurgly noise occasionally !

    • There may be sediment inside. With it being off for a few days, it may have settled at the bottom of the rad.
      If it doesn’t get hot all over when you turn it on – or is colder at the bottom than it is at the top – this could be a sign that there is a build up of gunge in the radiator and this could be the cause of the noise.
      It may be an idea to add some anti-corrosive into the system – but it may also be too late for this.
      One thing you could try is to remove the radiator altogether and flush it out.
      We have a video about how you can get it off the wall here – https://www.youtube.com/watch?v=vgGmY67xJJk
      Then, just get a hosepipe and power some water through before reconnecting the rad – you’d be surprised by just how much rust and gunk can build up.
      Then, when you have it back on the wall, add some corrosion inhibitor to the top of your system. You can get this from virtually any hardware store.
      I hope this helps, but as with most noises, it’s easier to diagnose when I can actually hear it.
      Good Luck
      John

  12. Beard2bfeared says:

    Hello guyz,

    The rad in our bedroom has recently started to make a loud banging noise every 2 secs when the heat comes on, we have a combi boiler so we set the temp we want the house to be and leave it on manual, as the house heats & cools the heating turns on and then clicks into a slow burn. Recently however this noise has been enough to wake us from our sleep on more than a few occasions throughout the night. The last time was last night when I got up and I rested my hand on the pipe from the floor going into the rad and I could feel the vibrations travelling up the pipe when the banging happened. Any ideas on how to fix this please, I had to turn the heat off as the noise was keeping us both awake!!!!

    • Hi Beard2bfeared (brilliant name),
      It sounds to me like there may be a little air in your system.
      This can happen if you’ve had the system switched off for a while.
      We have a great guide on how to bleed your radiator here – http://www.bestheating.com/info/blog/how-to-bleed-a-radiator/
      The best way of going about it is to bleed the radiator at the highest part of the system, this is normally your bathroom radiator or towel rail.
      Banging like this is often just a little air in the system. Once you’ve bled the rad, it should get rid of the noise.
      I hope this helps, but it’s hard to tell exactly what the problem is without hearing it.
      Good luck.
      John

      • Beard2bfeared says:

        Hello John, it’s my Xbox handle lol, cheers for the advise, let me just check I’ve got this right, to fix the banging noise in my bedroom rad I have to bleed the rad in my bathroom, is that correct lad ???

        • You can bleed them both if you want to.
          Air will normally find it’s way to the top of the system (that’s a bit of science for you there lol), so it is normal to bleed the rad at the top of the system.
          If you bleed one further down the line in the system – working back to your boiler – you may introduce more air into the system, which is why it is normally best to bleed the rad or HTR at the top of the system.
          I hope that makes sense.
          Great Xbox handle

          • Beard2bfeared says:

            Hello John, just finished doing that lad, I’m about to top up the boiler now as it’s low in water and I’ll let you know how I get on, if it’s still doing it then I will record the noise and send you a link so that you can hear it, quite a bit of air came out of the bathroom rad, hardly any from the bedroom and now the rad in the bathroom is making a sort of bubbling noise lol

          • The water may take time to settle, and you might have to bleed it a few times. You’ll get there. I bet it’s just a bit of air. Let me know.

  13. jamesem says:

    Hi..My Potterton Suprima has started to make squealing noises, a bit like an old fashioned whistling kettle. Any ideas guys? James

    • Hi James, that sounds like it could be an issue with the pump, but let me have a chat with my technical friend when he lands in the office to see if he can proffer a more learned answer. I’ll come back to you soon, but, I will add, without hearing the sound it can be tough to diagnose an issue, but I’ll see if I can shed some light for you very soon.

      • jamesem says:

        Thanks John.

        It sounds like (and I’m only guessing from experience of another one years ago) that the fan might be on the way out?

        But any thoughts you guys could offer would be great.

        Cheers!

        James

        • Hi James, sorry I didn’t get back to you yesterday.
          We were thinking the same thing. But my more learned friend agrees with me, it could be the pump, so it is probably best to have an engineer come and have a look and a listen to be on the safe side.
          Sorry we can’t be more helpful.

  14. Beard2bfeared says:

    Morning lad, didn’t work lol, there was nearly murder last night, I’ve managed to record the noise so you can listen and perhaps bring an end to this once and for all lol

    https://1drv.ms/v/s!AsnN9vAi_zeTgeUu_V985bkB2LzL6w

    Cheers lad

    • Bloody hell, that’d drive me mad too. I’ll share this with my technical maestro when he gets into the office and see if we can offer a better diagnosis for you. I don’t know when he is in today, but I’ll try my best to come back to you as soon as I can.

  15. Ok then Beard2bfeared,

    I’ve had an in-depth chat to my colleague and we have come up with a list of potential issues and fixes that may or may not be useful, based on the sound you’re hearing.

    First up, the temperature of your boiler/water in your boiler may be too high.
    If you haven’t had the heating at that high setting before, it could be that the pipes are expanding a little too much under the floor and may need clipping down or could benefit from some padding where they meet the joists under the floor.
    I personally think it might be this, based on the video you posted – cos it looks like the noise is coming from the floor.
    If you can get your carpet and boards up without too much trouble, try to do it where you’re hearing the noise and test to see if you can pinpont the problem.

    Secondly, it could be that there is dirt in your system and the pump in your boiler is causing the sound when it pushes the water through the system, that could be the cause of the vibration and noise.
    You could try and test if that is the case if you know where your pump is in your boiler – some pumps have a switch that can be turned to slow the flow down, so check the guide for your boiler if you have it, or look for the model number online to find any info.

    Thirdly, it could just be air, still in the system.
    To help you and to save time, you could invest in an auto-bleed valve that you can connect to the radiator at the top of the system.
    This will allow you to get some time back for yourself and mean that whenever there is air in the system, the valve will automatically bleed it for you – that means you won’t have to do your own nut in by manually bleeding it all the time (is there really anything more boring than bleeding a radiator?)

    And finally, and this is the ‘if all else fails’ tactic, you could powerflush your system or the radiator that is making the noise (if it is a radiator).
    You would normally need a professional to do this, but if it is just one radiator that appears to be causing the issue, you could isolate it by closing both valves on it, removing it and then powering a hosepipe through it at a high pressure to try and flush out any rust or debris.
    When you put it back on the system, be sure to add some rust inhibitor to the top of your system before you refill it from your boiler.

    Short of any of those working, it would be a case of calling in the pros and seeing if they can diagnose on the ground, in the room and by your side.
    I wish I could give you more insight, but if the above fails on all counts, it’s time to get the Yellow pages out!

    Good luck.

    John

  16. Max says:

    Hi John,
    I have the exact problem as user above.
    I had a property renovated and the rads upgraded to modern more efficient ones, the boiler in the property was only replaced new 3 years back anyway.
    so everything was connected up, flushed and working when we moved in. 4 weeks or so in one of the upstairs rads was only half hot.
    I bled the rad until all sorted, however since that point we have experienced a ticking noise through the night, always in said rad and pipework leading to it.
    I have tried to bleed the system further in case of trapped air and have topped up the pressure to 1.5bar since also.
    Is there any other way of forcing the air out of the system?
    Would pushing the rads temp up force any air in the pipes into the rads where i could bleed it out?
    Please help, 3am wake up calls are not the one! haha!

    Thanks

    Max

    • Max, if all was working when you moved in, perhaps they didn’t add any inhibitor to the system.
      If they didn’t, the chances are that after a few weeks of use, there could be a build-up of sludge in the rads that is causing the problem.
      Perhaps try removing the problem rad and flushing it out with a hosepipe and when you put it back, add an inhibitor like Fernox – https://www.fernox.com/inhibitors-protectors/protector-f1-500ml to the top of the system. Bleed the system to remove air and see if that makes a difference. Tbh, we’re all a bit stumped here…sorry.

  17. Mark Ault says:

    Great piece of information

  18. Waseem says:

    First thank you for accepting my Invitation on LinkedIn! To be honest i‘m looking for a consultation and i hope you can help me on this Regards.

    Recently i installed a VRF System in my house. The problem that the company that responsiable for this VRF System didn’t‘t know how to fix my problem. They are trying to find solutions but until now they didn’t succeed. Thats why i’m trying to contact you at this moment.
    I have one outdoor unit 10 ton and a 6 wall mounted units. i‘m experiencing following problems:

    When i switch on one of these wall mounted units on the heating mode, i hear a loud Gas-voice passing through the others switched off units. Its like that the Solenoid Valves are not closing on each units. Its noisy and loud. I tried to touch these units from the top of them, they were hot, despite they were swiched off. Is this normal. I asked the company why these turned off units are hot while there are switched off they answered me that this is the coil, and Gas passes into this coils making them hot. Is this really normal? Other big concerns i’m facing is the loud voices! It should be no voices comes from units are already not switched on. Whey to hear that voice from them and why they are hot. I called some friends that they have same VRF and they told me that they have no such voices. This is weird!!!

    Beside that the company told me that the Solenoid didn’t close in the heating mode. But in the cooling mode it will close and open. This is also not logic to me?? Is this also right?

    How can i prove to this company that i have something wrong? Please Advice!!
    Thank you!!

    • Hi Waseem, we couldn’t really proffer any direct help, unfortunately. It is difficult for us to do so through a blog without hearing what the issue is directly. Also, we are a radiator retailer and not installation specialists – each of our blogs are designed for guidance only – so if you require a direct professional opinion on the matter, we would recommend contacting a local engineer that could perhaps give a more accurate overview of any issues you may have been having. I’m very sorry that I can’t help any more than that, but it is quite difficult to ascertain any problem through the medium we are using here. My advice would be to seek a second opinion from a professional that can actually come and take a listen to what is actually going on, there on the ground. John

  19. Waseem says:

    This was my last massage to the one of best Ing. Nobody until now helped me on thos regards.

  20. polaris7 says:

    could it be dangerous for our health this air flow that come out while humming in the room cold air is coming from the ceiling this is a 42 apt building and i wonder if a fan on the roof could cause that noise this outside fan being on the top of my apt it is a gas heating system build 60 years ago and not very well supervised by the owner this noise happened at nite around 10 pm very difficult to sleep with this noise

    • Hi Polaris7,
      I would say that if you are getting any kind of vented exhaust air coming into your building that it most certainly is dangerous. Without being there on the ground, I really couldn’t comment further, but any exhaust gas making its way into any building is a big no-no. I would recommend having a serious chat with the building supervisor. I’m sorry I can’t really offer any more advice than that. John

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