Thermostatic Mixer and Noises from Pipes

[watsonwumba]

I've just had a new bathroom installed and pipework has been moved. Every time I use the newly installed thermostatic mixer tap there is a screeching noise from the pipes. The mixer is a Sagitarius Atlantis product.

Thanks in advance

 

[kevplumb]

and the hot water system is
and the cold water system is

 

[watsonwumba]

Hot water - mains
Cold Water - mains

 

[watsonwumba]

Forgot to mention , boiler is a combi.

Thanks

 

[kevplumb]

so is the mixer for mains pressure

 

[watsonwumba]

Yes it's for mains pressure