OK, here goes.
If you have a similar problem check the simplest of things first i.e. vessel and hose.
1. drain system according to manual
2. flush system through as a matter of course and good practice
3. check xp vessel hose is not blocked or kinked, my hose had a tight bend and by wiggling the bend of the hose managed to release blockage or it just loosened the kink and more water drained from the system, quite a bit more
4. check xp vessel pressure is at the recommended bar/psi(refer to manual), but be sure to drain system first and that the xp vessel has in fact drained, if theres a blockage in the hose it will not have drained and you may be reading an incorrect vessel pressure. Re-pressurize vessel if required. Refer to manual for water capacity to check against the amount actually drained, if its nowhere near and only a trickle you may well have a blockage.
5. Re-fill system and test its working correctly.
All this was performed with the boiler still attached to the wall and there was no need to remove it from the wall but to replace the xp hose I don't see a way of removing/replacing without first having to take the boiler down, the boiler will then require re-connection by a Corgi guy due to gas work.
The issue I had was a case of a blocked/kinked xp vessel hose, as the pressure had nowhere to release,
consequently the temp and pressure increased at a rapid rate and the boiler safely shut down/lock out. The PRV correctly released the pressure, hence the expelled water.
Hope this helps others in the future, all so often forums never have follow ups to provide how the issue was resolved.
Robert
October 2010
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