!!! Worcester bosh 30si raise in pressure HELP !!!

[mike1991]

Hi i have a green star 30si combi boiler have recently changed the PRV valve as was leaking due to muck and grime that's all sorted. I have pressurized the expansion vessel and boiler system back up to one bar and when using the hot water gauge typically drops for a short period then goes back to normal.
However when putting the heating on radiators the pressure continues to rise until i switch off the heating (i switch it off as don't want to hit 3bar and fit another PRV) Can anyone help
No water comes out of the expansion vessel when i press the valve down to test. My filling loop is in the locked position but does leak about 1 drip every 5 mins?

hoping someone can help

 

[PrenticeBoyofDerry]

Have you checked if the filling loop is letting water in? It maybe wise to disconnect it from the CH inlet.
Also when you re-charged the expansion did you isolate and drain the boiler?

 

[mike1991]

hi i haven't checked the loop but don't think it is as the pressure only rises when the heating is on and not all of the time.
When re-charging the expansion I drained a rad until there was no pressure in the boiler i.e. gauge was reading 0 then pumped in 1 bar? is this the incorrect way if so can you please advise?... much appreciated

 

[jackthom]

Did you leave the system open (a rad bleed valve opened up would do) while pumping up the expansion vessel, to allow the air pumped in to displace some more water?

The charging operation is finished when no more water is coming out and the expansion vessel is steady at it's recommended charge pressure.

Then you can close the radiator bleed valve and refill the system to the recommended cold pressure.

 

[gigz]

Blockage between expansion vessel and system.
Leave a radiator half full of air and try the heating.