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GlowWorm 24ci boiler high pressure fault?

With the boiler left on, i.e. no demand for DHW or CH, the pressure will remain constant, set at 1.0 bar.
When demand for DHW the pressure is not excessive but the PRV will operate correctly and release this excess pressure, but the pressure is not great enough to shut down the boiler, 1.5 bar.
When demand for CH is at a low temp. setting i.e. roughly half way between summer and maximum setting, again the PRV will operate correctly and release the excess pressure, but the pressure is not great enough to shut down the boiler, 1.5 bar.
When demand for CH is at a high temp. setting i.e. 3/4 to full, the PRV operates and within 5 mins the boiler will indicate a fault by flashing on the display the pressure at 2.5 bar at which point the demand for CH is manually switched off. The PRV then reduces the pressure below 0.7 bar and error F4 is displayed to indicate low system pressure which then requires re-pressurizing via the filling loop.
On visual inspection inside the boiler there are only signs of water leakage around the auto air vent which I assumed to be expected since the system has been re-pressurized due to the pressure loss and in the process of expelling the air it is also losing very minor water drops which I'm sure is of no concern.
What checks can be made to assist troubleshooting?
Any help greatly appreciated!

Robert
October 2010

Heating, Home Heating Systems Glowworm Boiler Pressure

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

OK, so I drained the boiler, briefly released the expansion vessel valve and a quick shot of water expelled but only slight. Still nitrogen/air present.
Re-pressurized xp vessel to manuf. recommended 0.5 bar (roughly 10psi), pressure remained. Re-pressurized boiler again to recommended 1.0 bar, powered up and still the same fault persists.
If I were to completely deflate the xp vessel and repressurize with the drain valve open wouldn't there be air coming through the drain valve if the xp vessel had a leak/burst plus the vessel would not maintain pressure.
Would a blockage to the vessel account for over pressure also?

Robert
October 2010

Expansion vessel needs re-charging/replacing.

Carefree
October 2010