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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Combi Pressure Loss https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1164190681 Message started by protier on Nov 22^nd, 2006, 10:18am

Title: Combi Pressure Loss
Post by protier on Nov 22^nd, 2006, 10:18am

Hi people,

Just found this forum looks great.

I am having a problem with my Vokera Combi Boiler. I have to re pressure it twice a day sometimes, but (Before you sat a leak) it only will loose pressure in windy or cold (Not sure which) Conditions. It has only just started since last year. Boiler is less than 2 years old.

It is releasing pressure out of the 'Overflow' I think its called? It is particurley windy at our house and I have a vertical flue, supplied from Vokera. Think thats everything.

Any help would be much appriciated.

Adam

Title: Re: Combi Pressure Loss
Post by thescruff on Nov 23^rd, 2006, 5:19am

You mean the pressure relieve valve that sticks out the wall behind the boiler.

Expansion vessel has lost it's charge, not been set up in the first place or duff.

Title: Re: Combi Pressure Loss
Post by CWatters on Nov 23^rd, 2006, 2:39pm

Interesting I assume the mechanisim is as follows...

If it looses it's charge it will fill with water when you try and restore pressure. Then, if there is any expansion (eg when the heating is switched on in cold weather) the excess is pushed out of the relief valve. Then when the heating cools down there is no pressure again.

Title: Re: Combi Pressure Loss
Post by thescruff on Nov 23^rd, 2006, 8:26pm

CWatters wrote on Nov 23^rd, 2006, 2:39pm:

More or less CW, water doesn't compress whereas air does.

The vessel takes up the expansion as the water gets hot.