Gainsborough 9.5KW Electic Shower - Strange Problem

This is a real strange one - about a month or two ago my 18 month shower started playing up - problem was very low flow/pressure when temperature turned up to warm (not even hot). Gainsborough sent me out a replacement engine (inside parts) which I fitted, but problem remained. Engineer then called to my house to fit another new unit but still same problem afterwards. He advised that I get the mains water pressure checked in case it is low, and said there was nothing wrong with the shower - so 3 in total all showed similar low pressure at average warm setting. When shower was originally installed 12 months ago the pressure was fine at warm temperature setting.
I called the water service to check my water pressure today. It turns out my mains pressure is very high at 7 bar (measured from garden tap).
Is it possible that electic showers do not operate correctly if the mains pressure is too high, and should I install a pressure reduction valve for my installation. Thanks for any help on this one, you can guess I am mystified.

I'm sure these have safety devices that cut heat output in certain conditions. Don't know if that is your trouble. Before you look at pressure reducing valve try reducing the pressure by turning your stopcock in the kitchen down or run the kitchen cold tap while you operate the shower.

It would probably be a good idea to fit a PRV anyway since such high mains pressure will tend to be noisy and splash a lot. It could well be the cause of the shower problem, but check with Gainsborough on that.

By the way, closing down the stop tap is not a very good way of reducing your pressure. It won't reduce the static pressure, only the pressure under high flow conditions, whereas the shower flow is quite low.

Sorry I didn't make it clear that the suggestions regarding stopcock and kitchen tap were to test the hypothesis that the problem was high pressure, not long term solutions.

As Chrishutt says high mains pressure results in a lot of splashing at the kitchen sink. If I was a male chauvenist I would suggest that you ask the female of the house if this is a problem

Managed to get to the bottom of this problem - some updates.

1. My mains pressure was checked and found to be 8 bar (no problems here).

2. Thought my pressure was too high so I partially closed the stopcock - made no difference.

2. Called Gainsborough service agent fitted another new unit, but I still had low flow problem through the shower.

At this stage I was pulling my hair out, and for some strange reason I decided as a last resort to swap the shower head with another showerhead we had in the house.

Guess what the problem was fixed by changing the spray head. The rubber membrane in the faulty spray head was not a good fit and water was leaking past the membrane and not though the pin holes - unbelievable (at least this was also missed by the service engineer so not too embarassing).

I ordered up a new spray head and fitted tonight. Got a good pressure at warm setting - everything back to normal I thought. Then I did something stupid. I turned the temperture control fully anticlockwise (cold) to see how good my new spray head was and the pressure was excellent, but then disaster the PRD activated, and water leaked from underside of shower!!!!

Does anyone know where I can get replacement PRD's or do I have to go back to Gainsborough (again). THanks.

You've probably got this sorted months ago but in case anyone else stumbles across this problem, you can order new prd's directly from gainsborough.co.uk . Make sure you get the right size (long or short) depending on your model.

I actually managed to fix my old prd by re-inserting the rubber ball - really simple.