On 18/02/2014 13:21, wrote:
Thanks - I thought that if the vessel had failed then the pressure
would shoot up over 3 bar and water would be ejected? I'm pretty
sure there no rad full of air to absorb the increase either.

If it had failed completely, then yes. If however its just lost
pressure, then the normal "cold" pressure of the system may be taking up
most of the expansion room in the vessel.

(note see my reply to Roger, I think he is correct - I over stated the
"relaxed" pressure)

I checked the pressure vessel with the water pressure out of the
system and it's 9psi - the manual says it's set at 0.5 bar initially

Yup that seems reasonable.

WRT the neighbour's system, they may have a rad full of air. Also are
they running lower flow temperatures than you?

although there's a table (9) in the manual that doesn't makes sense
to me (I can't tell which is the pressure vessel setting and which
is the water presure setting).

To be fair, the default setting is normally fine unless you have a
particularly large water content system.


--
Cheers,

John.

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