low mains cold water pressure

[forexander]

Hi
I visited a house where when someone opens cold water tap anywhere in the property flow to the electric showers stops completely. They have big tank in the loft which gets filled up with cold water like your toilet cistern. They also have got combi boiler installed, no hot water cylinder. What can be done to increase mains cold water pressure? Is the pressure low because house gets gravity cold water feed from the tank in the loft?
Your answers will be much appreciated. Thank you in advance!

 

[Charnwood]

Your title says 'low mains water pressure'. The only things I deduce - from your description - that are fed from the mains are the hot taps via the combi boiler, the electric showers and the header tank in the loft.

Is this correct?

 

[wrathkeg]

we had this situation (almost: the shower didn't stop completely, but reduced enough for the shower to only put out a trickle of stone cold water when someone turned on any water elsewhere). The problem in our case was a lead pipe from the road into our house. Having that replaced with 25mm plastic pipe solved the problem: much better flow of water, ability to use shower and dishwasher at the same time etc. Quite expensive to have done, but well worth it.

 

[TicklyT]

If the flow is adequate through any single tap, the problem is restricted flow, which is nothing to do with the water pressure.

First check that all stoptaps and service valves are fully open - people often half close them in the mistaken belief it reduces the water pressure, but all they are doing is reducing the maximum flow rate. The static pressure remains exactly the same.

 

[forexander]

Thanks Guys, I will have a look at the things you have mentioned and see what problem we have got. I will keep you posted.

 

[forexander]

Your title says 'low mains water pressure'. The only things I deduce - from your description - that are fed from the mains are the hot taps via the combi boiler, the electric showers and the header tank in the loft.

Is this correct?

Yes thats correct, I was thinking of installing pressure booster pump on the outlet of the tank but other guys here suggest that it may not resolve the problem as it is the flow problem not pressure.

 

[wrathkeg]

it might be worth checking that the electric shower really is filled from the tank in the loft. in our set-up the electric shower was fed from a pipe going through the loft, but these actually came from the mains even though we had a tank in the loft too. that might help you work out whether the problem is with the mains supply, or the system in the house.

one way to estimate what the flow is like is to see how fast you can fill a container of known volume with cold water from a tap coming out at max. before we had the lead pipe replaced, it took about 5 seconds to fill a pint glass (flow of about 6 l/min). After the work, we could fill a pint glass in about 2 seconds.

I seem to remember the water company coming out and doing a survey and saying that although the flow was less than it should be (due to the lead pipe) the pressure was correct.