Reducing mains water pressure for a shower?

[DavidM]

I've been asked by a friend about installing a thermostatic (bar type) shower in his bathroom above the bath, plumbed into the hot and cold supply pipes to the bath. The hot supply is from an indirect cylinder fed from a header tank, and the flow rate/pressure seem adequate for a shower. However the cold supply is direct from the mains, at a much higher pressure (I couldn't stop the flow from the tap with my thumb, whereas I could with the hot tap).

There's no easy way of getting a low pressure cold feed from the cylinder or header tank, and he doesn't want to spend a lot now because the whole bathroom will be gutted and rebuilt in a year or twos time. Similarly no easy way of getting a supply cable in there for an electric shower. In fact the whole property (listed building) will be replumbed and rewired, so this is just a stop gap until he can get that work done.

So I was wondering about putting a pressure reducing regulator in the cold feed to the shower thermostatic valve, to reduce the pressure to something close to the hot water supply, which I'm guessing is about

7m head (0.7 bar?). I'll measure it more accurately in due course.

Is this the right path to go down, and is there anything I need to be aware of when sourcing and fitting a regulator? Can anyone recommend a source for the regulator?

Thanks for any help. David

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember DavidM saying something like:

It'll work fine. It's exactly what I did with a shower of mine, years ago. Get one online (bes) or at your local plumbers merchants.