I have a Saunier Duval Thermaclassic F30E boiler. All was working ok until i bled the attic radiator. Since then the boiler has lost pressure each time it's used. I went away with work and my wife discovered the problem. To fix it i told her how to fill the pressure back up and that's what she has been doing. Now i'm home i'm not sure which bit is broken.
The boiler works if the pressure is refilled. When on water drips out of the discharge safety valve pipe. If i stop the boiler to see the current pressure then it gives a normal value for example if the boiler had been topped up and run for an hour then the reading would be 0.9 bar. This makes sense as water is being lost. But reading other peoples problems points at the Pressure Relief Valve or the Pressure Vessel. Not sure which one i should be looking at.
Help needed please!