Water Pressure Problem!?

Question

OK this is a bit of a complex problem but I will try and explain my problem as best I can.

I am fitting a jacuzzi/power shower in my down stair bathroom, the bathroom only had a cold water supply.

I have run a hot water supply from upstairs and tried to fit a single booster pump to up the hot water pressure.

I live at the bottom of a hill and as a result the cold water pressure is very high (Above 3bar). The hot water is supplied from a gravity fed boiler and has very low pressure.

When I turn on all the water supplies it appears that the high pressure cold water it crossing over the thermostatic shower control and pressurising the hot water supply.

As a result the "O" ring seal on the pump blew out of the pump housing. Also when you try to run hot water all you get is cold.

Is there a way to reduce the high cold water supply without reducing the flow rate?

Do I need to fit an NRV to the hot water feed after the pump?

Do I need to service the Thermostatic mixer valve?

I am really pulling my hair out with this, so any advice would be appreciated.

Jason

Answer 1

If the resistance remains the same the flow rate will go down if you reduce the pressure - thats basic physics.

fit a pressure drop valve on your cold to the bathroom.

The BEST solution would be to fit a main pressure sealed hot water system and solve the problem for the whoel house. We have a megaflo and our hot and cold is all at 3 bar - we run 2 whirlpool baths and 4 showers - all at fantastic pressures and flow rates

Answer 2

I would think you can connect a pressure reducing valve to the cold water without bringing its flow down below what the hot water is supplying. It would also be adjustable, so you can tweak the reduced pressure setting to match it with your hot water supply.

Remember, that the line pressure will equalize on each side of the PRV when you don't have any flow. While it should resolve itself quickly, you might consider a check valve on the hot water side just in case.

Answer 3

you definitely need a regulator. probably on the cold. to reduce pressure.

make sure it is sized correctly.  get a decent spray going with cold water, then time a 5 gal bucket or some other known volume. the reg capacity should include that gpm figure in it's range for the pressure your HW pump can deliver.

Answer 4

Ja, This is more of an FYI but could be a solution.

I was faced with this as a possible problem with our new downstairs wet room. To avoid any problems I first fitted an unvented hot water cylinder. So hot an cold are both at the same pressure and no pumps or PRV's.

As it's mains fed I was able to install it in the loft, I also converted the heating to a seal system and did away with the feed and expansion tank as well.

http://www.screwfix.com/prods/86599/Plum...

Edit

Alternativly run the cold supply from the head tank, put hot and cold through a double ended pump, then both your inlets and discharges are at the same pressure.