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spring fed water supply -i need constant water pressure

Postby simma55 » Sun Jul 19, 2009 9:11 pm

Please can anyone help. We have a private spring fed water supply that is fantastic quality and pressure however we have the problem of poor pressure when showering if any other appliance etc is turned on. We have installed a worcester combi boiler (the largest we could get) but the problem renmains .We are about to extend the property and install 2 en-suite bathrooms and had heard that a pressurised system would do the trick but i cant find any info. Any suggestions would be greatly appreciated.
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Postby htg engineer » Mon Jul 20, 2009 6:35 pm

It's always the same with combi boilers they'll run one shower/tap and that's all, as you say you have excellent pressure normally, then it should give a good shower as long as no other taps are used. Basically try not to use taps, washing machine, dishwasher etc when the shower is being used, not much else you can do - without saying bye the combi and more money on a new heating system!

'We are about to extend the property and install 2 en-suite bathrooms'

More than one bathroom - a combi's no good for this setup - as the installer should have explained. If you want to use more than one bathroom at any one time, then say bye to the combi.

Sorry if it's not what you wanted to hear - but to use more than one bathroom the only way round it is to used stored hot and cold water, so back to a system boiler with cylinder.

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Postby plumbbob » Mon Jul 20, 2009 10:52 pm

You have a pressurised system now. That's how a combi works - you don't have header tanks in the loft??

Maybe you are describing a pressurised system with a hot water store with a system boiler rather than an instant water heater (combi)?

You have got to take Htg's comments on board, but it may be worth checking the cold water supply pressure from the spring to make sure it is not dropping unduly when both the shower and another tap is turned on.
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Postby chris_on_tour2002 » Tue Jul 21, 2009 9:46 pm

unfortunately that's the one great limitation of a combi system, it will only service one appliance at a time, be it tap, shower, washing machine etc.

further to htg and plumbbob's comments, this problem will occur even if a demand on the cold side is made whilst shower is running, eg cold tap running, toilet flushed as the boiler will be starved of water to heat.

only real cure is to install a hot water cylinder large enough to cope with the demands - this does not necessarily mean that you will have to change the boiler.
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Postby plumbbob » Wed Jul 22, 2009 5:15 pm

Can you fit a hot water cylinder in a combi boiler system then Steve?
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Postby chris_on_tour2002 » Thu Jul 23, 2009 9:43 pm

from a combi boiler, yes - from a combi system a little more complicated. i have come across a set up where the combi boiler was heating a gravity fed hot water cylinder to supply two pumped power showers in the house, all other DHW from the combi side.
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Postby stuart_craigon2003 » Wed Aug 12, 2009 12:09 am

I'll try to help here if i can, what i suggest you do it change the water supply to the boiler and put in a new supply from the spring to the boiler that way when you flush a loo or use a tap the boiler isn't being starved of water or pressure.

I own several hotels and restaurants and i am having a new one built. I have had a combi put in but i have had two main supplies put in, one to serve the boiler and one for general use, this way (like i said above) the boiler won't be starved of pressure because all the mains lines coming from the street main are the same pressure and the same flow rate regardless of how many houses or what it is contacted to.

We have had to install two double none return check valves (one as the mains enters the site and one at the boiler) to keep the water company happy and to prevent the water from running back out of the boiler and back into the mains supply!

I hope this helps.

P.S. - before you go to the expense of installing a new pipe use a garden hose as your boiler feed for a while and see if it makes any difference! - I'm not a plumber so don't take any of this as gospel. get professional advice if you have to, it might invalidate your boilers warranty or even your house insurance! Take care and all the best!
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