Why is My Boiler Making Banging Noises?

Posted on by Daniel, VHL

If there are mysterious banging or knocking noises coming from your boiler, it could be for a number of reasons. Before you call out a professional to inspect your system, there are a few steps you can take to try and determine the problem for yourself.

If you are not familiar with how to flush your system, consult a professional or the instruction manual provided by the manufacturer to get a clearer idea of how to do it. A central heating system, connected to the gas mains should not be tampered with, if you are not familiar.


Check 1 – Chugging Noise

Copyright of s_p_a_c_e_m_a_n on Flickr

‘Kettling’ is the name of the occurrence of a chugging noise from the boiler. This often happens when the pilot light is first lit, so the best course of action begins with shutting off the power to the boiler itself.

The cause of this issue could be a build up of limescale on the heat exchanger, blocking the flow of water, which in turn can cause it to boil, steam and then expand.


Check 2 – Whistling Noise

Releasing air from boilerFind the air bleed screw – this is located on the pipework near the cylinder. Turn this screw and ‘bleed’ the air out of the piping, and this will hopefully resolve the problem. A way to tell if your boiler is suffering from this issue is a whistling noise being emitted from it.

Once the problem has been rectified initially by bleeding the air from the system, inspections should be carried out to determine what caused the trapped air in the first place, so the root cause can be eliminated.


Check 3 – Dirty Water When Bleeding The Radiator

Bleeding a radiator

There could be a build-up of sludge in your boiler’s tank, which may be located in your loft or a separate airing cupboard. Check for any aforementioned build up in the tank – if there is a build-up, remove it by flushing the system. This sludge can affect the amount of water that is entering the tank, which in turn can hamper your boiler’s performance.


Some other noise

A banging noise from your boiler does not always result in a clear diagnosis – as mentioned above, the noise can be a result of a number of problems. These steps are intended to help you determine where the issue is coming from. However, if you are not confident in your ability to inspect your boiler, you must contact a registered, accredited plumber to visit your premises and inspect your boiler for you.



Here at VHL, we are proud to offer a wide range of plumbing services. Whether you are experiencing a problem with your boiler or you have a leak in your home, our experts can be on hand promptly to inspect your system and provide a permanent fix.

For help, get in touch with us today!

About Daniel, VHL

VHL's Technician of the Year +Daniel Chambers View all posts by Daniel, VHL →