my baxi 105HE combi bolier loses pressure constantly! can anyone help?

I have the same problem with my Baxi 105HE and the local installer has said that I must have a leak around the heating pipework and to check the radiators. I have checked them all, and no leaks are evident. There is no water coming out of the overflow pipe but there is out of the condensate pipe - which I have been told is normal. I have to fill up the pressure to at least 2.0 twice a day to get the boiler to start and it drops down to 1.0 after a few minutes and remains there until heating goes off and gradually drops down to zero, so effectively will not come on via the timer. If the unit is set to Hot water only, you can see the needle dropping down gradually until it reaches zero. If the hot water is used it goes up a few small notches but then drops down to zero again and then eventually will not come on for water until it is topped up. Does anyone have any clues on this one yet ??

Phil P
December 2008