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?



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.

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Stay Safe and Happy Heating