On 21/01/2011 10:53, Lobster wrote:
On 20/01/2011 21:15, Ron Lowe wrote:
On 20/01/2011 20:10, Lobster wrote:

The system has been in for about 10 years with no problems up to now.

The expansion vessel has lost it's air volume.



Thanks for the responses. Just checked, and upon depressing the
Schraeder valve I'm rewarded with a barely perceptible little fart -
that's it - just enough to know that the valve was actually depressed.
I'll give repressurising a go first but presumably it'll need replacing.

If you got a small air volume, that's good. It probably indicates the
thing is not ruptured. It's just lost it's ait volume, and over 10
years, that's not bad. Just pump it up and see how it goes.

The 4 bar is a pre-charge pressu ie the pressure in the bladder
without eny external water pressure. So shut off the cold water inlet
to the cylinder, then open the lowest hot tap. Since there's no air
volume, it will stop running fairly quickly.

Pump it up unter these condtitions.

Shut the tap, and turn on the cold supply.

Isn't it a bit odd that my system works though? Have had CH and HW on
all week with no problems at all except apparently for the one
'overflow' issue.



No, the symptoms you describe are totally normal for this failure mode.

--
R