Plumbing Question

Water pressure problem, gravity tank + shower booster pump solution?

I just bought an upper 2-floor maisonette flat and upon taking my first shower realised there is no cold water pressure from the shower head, only hot. The bath nozzle has some (weak) cold water pressure. Please see the attached diagram.

I think the explanation is that the gravity cold water tank in the airing cupboard (no loft access, it’s fully insulated and blocked off) is below the shower head, measurement ‘x’ in the diagram. This would explain why the bath gets some cold water as it’s below the tank, measurement ‘y’ in the diagram.
What is the best way to resolve this problem?

One solution I’ve designed is attached. I wonder if I piped the cold water tank down to the lower floor, into a shower booster pump, and back to the upper floor shower – would that give me additional cold water pressure? Notice it would have to pump beyond the height of the cold tank to reach the shower head, distance z + x. Would this mean I’d require a negative flow pump? If the height of x is about 1m, could a standard pump do the job?

Thanks for your help.

existing system:

proposed solution:

2 Answers

Best Answer

Hi why cant you redirect the mains feed to the pipework to the bath and shower? What pressure do you get from the incoming main? You could fit a negative head pump with a flow switch the pump would have to be able to pump about 8 meters worth of head.

Answered 11th Feb 2013

Southport Bathrooms

Member since 11 Feb 2013

I don't understand why you have hot at the shower, if the hot is tank fed the hot and cold would be the same pressure. It sounds to me the hot is maybe from a combi boiler if that is the case you could not pump the hot but you could put a negative head pump on the cold or supply the cold from the main.

Answered 13th Feb 2013

chris tomlin

Member since 28 Mar 2012

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