Noise when running hot taps and shower

[Cruddace]

Hi - last couple of days noticed loud noise starts when turn hot water and shower on. Not the pipes banging as heard this before. Any ideas what could be causing it
thanks

 

[JCplumb]

Do you have open vented hot water with a cylinder you need to heat up before you get hot water- i.e. the old fashioned system, not a combi or an unvented cylinder?
If so the likely culprit is the float valve in your cold water storage tank.
Simple enough job for a plumber if access is OK, not so simple if you're doing it yourself and don't have experience of such things.