Thermoststic Shower - Hot Water Pipes Bang

[BumpyPipes]

Hi folks I have a problem.
Our shower is a Triton thermoststic run from an Alpha combi boiler.
The pipes began making a noise when the hot water was turned on (any tap) and we realised if the shower thermostat was turned to coldest setting this resolved the noise.
But .... now the hot taps (any) are running warm unless the shower thermostat is turned up - then they run hot - but are noisy!
Any suggestions?
(heating is fine)

 

[steadyon]

First place I'd look would be the non-return valves in or for the shower. Could well be caused by cold overcoming the hot via a stuck / failed valve. If its a bar type mixer, turn off hot and cold, remove shower from wall to reveal non-return valves / filters in wall outlets / shower inlets.

 

[BumpyPipes]

Its just a dial coming out of the wall with outside controlling water and an inner thermoststic temp. adjuster.

 

[steadyon]

Look up make and model and try and find installation instructions. Still likely to have non-return valves and filters.