Brand new bristan sonique shower squeeling

[TCCHeating]

Just fitted a new sonique thermostatic mixer shower for a cutomer as a direct replacement. ( cutomer decided to get the whole shower instead of just the cartridge as it was not much more money). Problem is it is now making a high pitched noise when it is running. It is running off a combi and pressure is about 4 bars, which is within limits. Flow restrictors are correct according to instructions. We called briston and they are sending an engineer out to look at it but they will charge if its an installation fault. Is there anything else i should have checked? Just dont want the engineer to say its my fault for any reason. Old valve never made this noise, just leaked, which is why it was replaced! Cheers for any help

 

[Madrab]

Sometimes the thermo valve can make this noise if the pressures too high or not balanced correctly but you say you have fitted the flow reducers. Is the cold and hot water pressure similar?
I take it the noise is coming from the valve body? If you have iso valves on the inlets, if you close them slightly does the noise reduce/change?

 

[TCCHeating]

Its running off a combi so pressures should be balanced. No iso valves fitted either. Flow restrictors were fitted as standard, mi's say remove them for low pressure so i'm presuming these are ok. Just worried as the shower is the exact same as previous one, and previous one never had this problem

 

[JohnD]

is this model available with either a high-pressure or a low-pressure cartridge? usually identified by a coloured part or ring?