Thudding from boiler when cold tap turned off

[usernothername]

Hi, recently I started hearing a subtle thud from inside the combi gas boiler whenever we turned off any cold tap. Turning on a cold tap and running it makes no noise, only when it is turned off again. We've had no work done recently on the plumbing system at all. People have posted similar questions here before and the answers have been about replacing toilet valves or fitting arrestors, but everything has been fine with our system for years so not sure what could have changed. Thanks

 

[mikeey84]

Might be worth asking a mod to move to the plumbing section

 

[Madrab]

Mains water pressure may have changed that or the flow valve in the boiler may be getting older (boiler dependent)