Wild swings in water pressure - Ariston Combi

1 Dec 2003
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United Kingdom
I have an Ariston EuroCombi (SX 20 MFFICE) installed, and I am experiencing significant fluctuations in water pressure. I.e. swings of +3bar to 1 bar over several hours, sometimes resulting in water being dumped through the pressure release valve.

As an interim, I have re-pressurised the system each time. The radiators have been bled and have checked for possible leaks in the central heating system, but found none.

Any suggestions?
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You have the same problem that I have - see "High Boiler Pressure" in the Plumbing section. The advice I was given was that it may be to do with the expansion vessel - either needs re-pressurising or is faulty in some way.
Thanks Ian,

It sounds quite plausible. I shall have to dig out the manual to see how I can re-charge the vessel, if at all. Presumably if I have a leaky valve in the pressure vessel, then it should be leaking water (out of the valve) as well?

Pressure vessel is knackered, depending on how long its been like this determines if you will get away with just pressurizing it!!!
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Thanks for the sound advice Ian & GasMan. I’ve re-pressurised the expansion vessel, and put the boiler through a number of hot ‘n cold cycles – so far, so good!

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