PRV or mini expansion vessel?

[rgate]

I have a Mira Thermostatic Mixer shower valve which is very stiff to turn on and off. If I turn on the cold water tap at the sink first, the valve will turn easily. I have therefore concluded it is a water pressure problem.
The problem has worsened since I had a new supply to the house installed to fix a poor flow rate in the supply.
I have conflicting advise as to the best solution, either a pressure reducing valve inserted in the cold feed to the shower, or a mini expansion vessel.
Can anyone shed some light as to which is best and why?

 

[oilman]

You will need a pressure reducing valve whether you have an expansion vessel or not. The expansion vessel must have a set pressure to work, and mains variations need to be removed first. You probably won't need an expansion vessel.

 

[ChrisR]

I'd be on the phone to Mira, with the model number, for their advice.

 

[rgate]

Thanks Oilman,
Fitted a PRV preset to 3 bar, shower turns on and off smoothly now, problem solved!