Fitting new Direct mains system?

Postby jack_of_all » Sat Mar 17, 2007 3:57 pm

I am completely renovating my 1860 2-bed cottage and adding a kitchen extension and conservatory at the side of the house plus a new ground floor bedroom/study extension to the rear. I have my new roof and ceiling rafters fitted but am worried that the upgraded rafters may still not be rigid enough to carry the weight of the cold water storage tank. I dislike the idea of fitting a combi boiler but have noted your info on the Direct mains pressure system which also dispenses with the cold water loft tank. What regulations do I have to take note of when installing a mains pressure system and is there any advice you can give to enable a decision to be made. I intend to do as much of the work myself for financial reasons - I'm a retired electrician.
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Joined: Sat Mar 17, 2007 3:35 pm


Simply Build It

Postby stephen.s » Mon Mar 19, 2007 10:35 pm

Water regs and possibl building regs, depending what route you choose.

If you are completely re-doing the whole property and plumbing works, have you considered an un-vented cylinder? This is mains fed and mains supply to the taps but also gives a balanced hot and cold water pressure throughout the property of approx 3 bar to 5 bar dependant on manufacturer. although saying that, you do need to hold an unvented certificate (building regs part G3) to install but if you are good friends with any plumbers, they may be able to work out a "mates-rates" for you. you could do all of the plumbing etc yourself, just not install and/or commission the cylinder.

i live in a flat and have mains cold throughout and extremely low pressure hot water and it is an absolute nightmare, can't even install a shower unless i go for an elctric one which, as you probably already know, is crap. if you do go for mains cold throughout, without going for the unvented, you will need a hot water cylinder with combined cold water storage built in which will make you lose all head of water and thus give you a really low pressure on the hot water which causes propblems later like not being able to enjo a nice shower. not trying to scare you, but these cylinders also carry a greater risk of leigionairres disease than a traditional sstem in the home because of cold water storage temperatures being increased because it is in close proximity to the hot water - not nice.

so to sum up, the best advice if going for mains throughout is an unvented system giving balanced hot and cold... this will cost significantly more than a traditional vented system though!! If you dont want to spend the extra money on the clinder, make the ceiling stronger for the cold water storage cistern.

hope you find this useful, sorry i rambled on a bit
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Joined: Mon Mar 19, 2007 10:21 pm

Postby jack_of_all » Thu Mar 22, 2007 11:05 am

Thanks for the answer Stephen, indeed the "un-vented cylinder" system is what I intended however the "unvented certificate" is unknown to me - I lived and worked abroad from 1976 to 2002 so when I came back knew nothing about the hugely increased bureaucracy of Building Regs governing tradesmen, time was that proper apprentice trained tradesmen didn't need coercion from the local council to do the job properly, but that's another story!
5 bar, ummm, 70psi is a pretty high pressure, can I use ordinary compression fittings to comply with [b]building regs part G3 [/b]? Are there any 'push fit' plastic fittings which also comply?
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Joined: Sat Mar 17, 2007 3:35 pm

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