I have the above boiler when its cold i put the pressure to 1.5 bar and after about 2 weeks if the heating has not been on it will slowly drop to 0.5 bar. However when I put the boiler on the heating system that is after the heating has been turned off the boiler drops to 0 bar and needs re - pressuring every time. I have checked all pipes and radiators and there seems to be no leaks can you help.

Mark, October 2007

Another place to check is the overflow pipe from the boiler (should go through an outside wall). If this drips (when the CH is on) you have found your problem. After you top up turn on the CH and watch the system pressure as it gets hot. It should not go up much. If it does , your expansion vessel needs recharging.
Search combi expansion vessel on this site or google.

c, October 2007

Hi mark it could be several things you say you have checked all pipe work can you get access to the pipe work under your house as a small leak would absorbe in to the foundation and not show any signs.Allso place a piece of tissue around each rad pipe of each rad just where they enters the floor and re pressure your boiler leave over night and check first thing the next day any leaks will show up tissue wet again a small leak here can run down pipe and under floor and might not even show damage to sub fllor..Other things to check there is a discharge pipe that comes from your boiler to the outside of your property adj to the boiler check to see if this has expeled water and combies suffer leaks at boilers look around and below the fittings at the boiler conections it I would not think there would be any leaks in side the boiler as you say leaving for a while the boiler still fires up hope this helps

Andy

Andy, October 2007