Chrome 3/4 non return valves?

[plumber89]

hi been called out to a problem with a shower , is a normal thermostatic bar valve,
running of cold main and tank fed hot with about a 4 metre head-ish when running the shower will only run medium warm, i guess this is the cold main is to powerful and overpowering the hot, as i can get the shower hot if i turn the cold on at the basin
just wondering if you can get chrome 3/4 non return valves, that i could put behind the ,bar valve ,as there is a 3/4 male fitting that this bar valve goes onto, so a 3/4 non return valve that has a female thread one side and male thread the otherside in chrome,
Or i could put a PRV on the cold entering that bathroom, this means taking up floors etc,
Any advice
Cheers

 

[barryplumb]

PRV on the cold supply will work, why do you think non return valves will balance the supplies? they are just for backflow prevention.
Cant say I have ever seen nrv's with female on one side and certainly not in chrome.

 

[barryplumb]

Is there a way of supplying cold to the shower from cws?

 

[anz]

Is there a way of supplying cold to the shower from cws?

Do this.

 

[josh]

I agree, could also use one of them pressure equalisers but will never beat proper balanced supplies. Customer may complain that the pressure/flow rate are less but atleast it will work properly.