Apart from the obvious, a leek somewhere on the system which I've checked rads and connections
Where else is there to look...?

Paul from, January 2010

check pressure relief valve outside/when heating on does pressure guage go above 3bar.if so expansion vessell req recharging/or renewing all get gas.safe engineer 2 check inside heat exchanger as insulation pads will show deteiriation/or discolouring inside good/luck m8

patrick cronin, January 2010