On 03/03/2020 18:34, Chris B wrote:
I am going to have to fit a PRV in the cold supply for the benefit of a
new thermostatic shower mixer (max allowed pressure 5 Bar) current cold
pressure 7.5 bar and hot pressure regulated to 3 bar by a pressurised
hot water system.


If I do this, do I also have to fit a mini expansion vessel (as in 0.5
or 1lt - like the one linked below) into the cold supply?

https://www.advancedwater.co.uk/prod-775-147-0006.html

As I see it the water that has just entered the house at 3 or 5 C will
go through the PRV and be reduced to 3 bar.Â* It may sit in the cold feed
pipe for some hours and warm up to say 20C.Â* How is this expansion
accommodated?


By the expansion vessel you are going to fit..
Isn't there a way to take a cold feed also off the other side of the
mains pressure hot water?


--
€œThere are two ways to be fooled. One is to believe what isnt true; the
other is to refuse to believe what is true.€�

€”Soren Kierkegaard