My Ariston microgenus 27 mffi.is losing pressure through the safety valve(3 bar). when the central heating is on the pressure gauge rises to 4 bar and the water is released.the system then has to be re-filled daily .adjusting the CHW knob to minimum helps ,but the pressure still rises to over 3bar .Operation of domestic water supply is fine.any ideas of where to look for this problem will be appreciated .

steve nicholls, September 2008

Thanks for the info chaps I have re-pressurised the EV and the boilers fineexcept for asmall leak on the safety valve ,which is now on order.

steve, September 2008

expansion vessel lost charge,new exp valve will probably be required, contact good corgi engineer.

gray, September 2008

expansion vessel has zero charge, could be flat but more than likely knackered

iain, September 2008