Have an ideal logic 24 boiler, installed in 2011. over the past week its been losing pressure on a daily basis, upwards of a bar in pressure. there are no obvious leaks on the system, all rads bled and heat up fine and dhw works well. I would assume there would be an obvious leak losing that amount of pressure. I phoned a plumber who said this was a known fault and quoted upwards of £500 to repair. is this a boiler problem, and anyone know what this known issue is. I have done some testing, filled the system to 1.5bar yesterday and switched off heating whust we were out. I put a bag over the prv and the condensate pipe as I assumed as there is not a pool of water under the boiler these are the only other outlets. when we came back after 4hrs, the pressure was at 1bar and there was around 300mls of water in the bag under the condensate pipe. the prv was bone dry. anyone any ideas, as I dont want to start chucking cash at this if its not economically viable.