water pressure and flow to new loft room

Hi All,
I'm near the end of a loft conversion. During this the tanks were disposed of and now the plumbing is direct, no tanks, no megaflow.
The mains pipe from the road is still lead but the flow is quite good... so far. But I fear the pressure in the loft will be poor as its quite a long way up. All the piping from the new boiler appears to be 15mm.
So I was wondering would it be best to bite the bullet and go for an upgrade of the mains supply pipe, I assume the current one is a lead equivalent of old 3/4 inch - and get it upgraded to a new size in the blue plastic ? If so what size would be best.
Alternatively I understand that AquaLisa do a pump for showers that works off the direct supply - have I got that right? A plumber told me about it while installing the new boiler.
Thanks, Tom
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You'd loose about 1 bar of pressure for every 10 metres you go up, so pressure loss on a mains supply due to height probably isn't an issue.
(flow loss due to narrow pipes on long runs may be)
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Huh!
I have just said goodbye to a water board inspector who kindly measured our supply pressure. (done by removing the meter and connecting a gauge).
Result 5 bar or thereabouts. 8.45am so not exactly zero use static pressure.
My problem is that some tenants have installed an *under sink* water heater fed directly from the supply. For obvious reasons, these are fitted with a pressure relief valve which happens to operate a 6bar!
Late afternoon pressure clearly exceeds 6bar, grrr...
regards
--
Tim Lamb

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On 10/03/2010 10:15, Tim Lamb wrote:

If these are pressurised under-sink heaters, to they not require ( and come suplied with ) 3 bar inlet regulators?
Certainly, full-sized megaflos do.
--
Ron


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Apparently not.
This was installed by a plumber!
The cheapo Screwfix one I installed under our sink was made in Italy where the rules may be different. Same 6 bar relief valve but I wanted to use soft water to avoid clanging the thing up with lime and installed it in the hot water supply (vented).
Fitting a regulator would be easy enough.
regards

--
Tim Lamb

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As others have said, the height should not be an issue on a mains feed but any extra simultaneous usage in the house might lead to disappointing results, you'll need to suck it and see.
You're not allowed to pump water from the mains (unless you're the fire brigade).
--
fred
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Thanks for the replies.... I'll see what happens. Certainly an upgrade of the water supply from the road sounds like the best option.
Any idea what size pipe should be installed?
Rgds., Tom
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25mm MDPE pipe is the norm.
Pipe & fittings here: http://www.bes.co.uk /
--
fred
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Tom wrote:

I played this game a few years ago. Basically took out a gravity fed tank based system, and installed a combi boiler when I converted the loft. We had a 1/2" copper main that had reasonable pressure but slightly limited flow rate (about 18 lpm at ground level).
The extra height and pipe resistance made the shower on the top floor less powerful than then first floor one, but not dramatically so (after all the difference was only approx 9' of head less). Performance was well in excess of what one would achieve with an electric shower for example.

Unless there is a pressing need to get the pipe in now, because access later will be difficult, I would suggest you wait and see. You may find it adequate for your needs as is.
--
Cheers,

John.

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