Mains Water Pressure

michaels

OK, current system has mains cold water in the kitchen and all other taps fed from large header tank (200l?) raised up to just below the roof apex in the loft with an indirect hw tank in the bathroom. When I moved in I fitted a 3 bar twin impeller booster which feeds the bath/shower thermostatic mixer only, all other hot and cold water is gravity fed. I suspect if you ran the shower long enough you could run the header dry.

In the kitchen I haven't had a problem with the pressure but using a volume by time measure gives 15l/min with the tap fully open. Obviously I could do something similar post extension with a big enough tank and a booster pump for the showers but this seems a bit old fashioned. I'm not a big fan of combi heat as you go systems but as far as I can tell without a large accumulator I won't be able to have a mains pressure system capable of providing a bath and one or more showers simultaneously.

For info every house seems to have its own stop c*ck on the street.

keystone

You say the mains pressure is low but I'm starting to get the feeling that you don't actually mean that at all. You say the kitchen tap delivers 15l/min and there is no pressure problem at this tap. Now it seems to be a reasonable supposition that you mean the cold (ie the mains) supply at this tap. Its normal in the type of installation you describe for the kitchen cold to be mains fed with all other taps both hot and cold being supplied from your CWST or HWC. Latter is, of course fed by the CWST in any event.

I have a feeling its the pressure and flow rate at all the other taps that is causing you a problem. Would that be the case? We do need to clear that one up first.

Where on the WIBNI svale of 1 - 10 does the requirement to have bath and shower at the same time fall?

Cheers

michaels

Thanks.

Currently there is no problem, kitchen tap and hose (both direct mains) take a while to fill a bucket but not the end of the world. Currently have one bathroom with pumped bath and shower, seperate WC with basin. Bathroom pump would almost certainly empty the cold header tank if you ran the shower or bath for long enough.

Post extension I will have 3 bathrooms all with bath and shower and separate shower room plus utility as well as kitchen. I will also be replacing the boiler. With this number of bathrooms I don't think it is unlikely that there will be simultaneous bath running and showering going on. the current cold water flow I would say was insufficient for direct bath filling anyway (for example if switching to a combi boiler or heatbank or megaflow mains HW system) so I am left with finding a way to boost the mains volume or keeping a large cold header tank and pumping the showers. Obviously it is nice if possible to have mains cold to all taps.

keystone

You'll need a very big tank to cater for that lot!

A combi won't suit your needs IMO.

It does rather sound like the approach is leading towards either an unvented installation or a [STRIKE]sludge bucket[/STRIKE] thermal store.

Its going to be quite complex working it all out and trying to do it remotely over teh interwebz will be counterproductive so I'm going to revert to my first post on this thread and suggest you really need someone on site to discuss it with you and draw up some plans for discussion.

The cold pressure actually being delivered by your water provider is quite key to the whole thing and needs measuring.

Cheers

michaels

Keystone, thanks for your input - I will get the pressure measured.