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Mains pressure cold water feed to shower valve

Postby davis10 » Tue Jan 12, 2010 12:35 am

Advise please for new en-suite.

Mains pressure cold water connection feeds toilet, basin and shower in new en-suite, then continues downstairs to kitchen, into back of fridge/freezer (with ice maker) then on to kitchen mixer tap and dishwasher.

Hot water for this en-suite comes from hot water tank about 20 feet away and 5 feet below new bathroom. It only feeds the basin, shower and kitchen mixer tap.

The shower is the problem. It is an Adams & Co 1922 exposed shower valve with 5 inch rain head above.

It was first recommended we put a restrictor into the cold water feed of the valve. The green, strongest restrictor was used. Shower still cold.

Salamander ESP CPV 80 was installed, pumping only the hot water. It works well, however the shower runs hot then cold, warm then cold again. It is better, but not right.

It is suggested that the shower valve is not coping with the different pressures and not mixing correctly.

Another plumber suggested that the pipework be exposed (tiles would need removing) and new pipe from c/w tank put in to shower. We would really like to avoid this.

We have had so much 'advice' from different plumbers, we don't even think of the money any more, we just want an en-suite shower that works!

Question: Does anyone know of a shower valve that will cope with different pressure cold & hot water feeds?
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Simply Build It

Postby plumbbob » Wed Jan 13, 2010 12:33 am

"Salamander ESP CPV 80 was installed, pumping only the hot water"

No, no, no, and no! There is absolutely no way you should ever have been advised to fit a pump on a hot side and mains pressure on the cold. It WILL NOT work! It could even be dangerous and may very possibly leak as pumps are not designed to work under these circumstances.

The best solution is to install cold feed from the tank but of course, both hot and cold will need to be pumped.

Recently, some new shower manufacturers, Bristan for one, supply valves that will work on uneven pressures. Generally with most showers, you find two restrictors (yellow and green) for balancing pressure differences associated with instant water heaters, but there is a third restrictor, a white one with a 2mm dia hole for your type of set up. They are available, but I have always avoided fitting them as I just don't see how they can work consistently.
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