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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Combi high pressure threatening old pipes https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1301992439 Message started by Jersiais on Apr 5^th, 2011, 9:33am

Title: Combi high pressure threatening old pipes
Post by Jersiais on Apr 5^th, 2011, 9:33am

I want to change my old gas boiler for a combi unit. My radiator system is 42 years old and SOME salesmen have told me that the copper pipes set in the cement ground floor would not stand the higher pressure and will need to be changed. Is this true? Is there any way around it - We could not put up with the upheval necessary?

Title: Re: Combi high pressure threatening old pipes
Post by CWatters on Apr 5^th, 2011, 2:58pm

Why a combi boiler? If you want mains pressure hot water you could get that with a mains pressure stored hot water system that retains the heating system as vented.

Title: Re: Combi high pressure threatening old pipes
Post by Jersiais on Apr 6^th, 2011, 7:02am

I thought that the Combi worked at mains pressure. If so the possible threat to the pipes would still exist

Title: Re: Combi high pressure threatening old pipes
Post by CWatters on Apr 6^th, 2011, 7:27am

Perhaps I missunderstand your question...

Which pipes are you worried about? Are you worried about both the heating pipes AND the DHW water pipes or just the heating?

If it's just the heating system that you are worried about there are ways to have mains pressure DHW and a vented (eg low pressure) heating system.

Title: Re: Combi high pressure threatening old pipes
Post by Jersiais on Apr 6^th, 2011, 1:14pm

You are BRILLIANT _ thank you very much

Title: Re: Combi high pressure threatening old pipes
Post by woodsmith on Apr 6^th, 2011, 4:00pm

With a combi boiler you normally set the pressure of the heating system to about 1 bar (which is equivalent to having the header tank 10 metres above the boiler), it is only the domestic hot water output that runs at mains pressure.

Title: Re: Combi high pressure threatening old pipes
Post by scotspark on Apr 6^th, 2011, 6:50pm

thats before you turn the heating on at wich time it will rise to about 1.5 bar

Title: Re: Combi high pressure threatening old pipes
Post by thescruff on Apr 7^th, 2011, 5:51pm

Buy a Combi boiler suitable for an open vented system, and ditch whoever is giving you bad advice.

Have a look at Intergas boilers.

I have one in doors, brilliant boilers.

Title: Re: Combi high pressure threatening old pipes
Post by Jersiais on Apr 7^th, 2011, 7:28pm

Thank you for your advice

Title: Re: Combi high pressure threatening old pipes
Post by thescruff on Apr 7^th, 2011, 8:39pm

Pleasure.

The Intergas boilers don't have all the usual problem parts that other do. If you contact them they will put you in touch with an installer near you.

The boiler of the future without any doubt.

http://www.intergasheating.co.uk/site.php?page=combicompacthre

Title: Re: Combi high pressure threatening old pipes
Post by greg on May 10^th, 2011, 6:03pm

TheScruff recommending a combi, what is the world coming to ;D

Title: Re: Combi high pressure threatening old pipes
Post by thescruff on May 10^th, 2011, 11:43pm

wrote on May 10^th, 2011, 6:03pm:

TheScruff recommending a combi, what is the world coming to ;D

Thescruff is trialing an Intergas Combi at home Greg ;D

Good piece of kit without all the usual problem parts.

Going on their training day with a load of guys from diynot this Thursday. 8-)

Title: Re: Combi high pressure threatening old pipes
Post by greg on May 11^th, 2011, 12:03am

Yes, saw the thread in the CC. Have a good day. There is talk in the thread that there may be a day arranged down this way.

Title: Re: Combi high pressure threatening old pipes
Post by thescruff on May 11^th, 2011, 6:04pm

wrote on May 11^th, 2011, 12:03am:

Yes, saw the thread in the CC. Have a good day. There is talk in the thread that there may be a day arranged down this way.

Yes Greg.

I'll ask Vince tomorrow about it. [smiley=thumbsup.gif]

Did you get my E.

Title: Re: Combi high pressure threatening old pipes
Post by greg on May 15^th, 2011, 6:19pm

thescruff wrote on May 11^th, 2011, 6:04pm:

wrote on May 11^th, 2011, 12:03am:

Yes, saw the thread in the CC. Have a good day. There is talk in the thread that there may be a day arranged down this way.

Did you get my E.

Going to check now.

Title: Re: Combi high pressure threatening old pipes
Post by london on May 28^th, 2011, 9:43pm

Copper pipes get corroded by cement