the boiler keeps lossing pressure. everytime i switch it on i need to open up the black tap to fill it up with water. as a result the radiators are only warming up half way. i've tried bleeding them all but nothing is working any ideas.

mike, November 2007

I have a worcester CDI 30i with the same problem so I would be very interested if anyone has any ideas. I cannot find any leaks in radiator system but I have not ruled this out completely as I have not checked all the radiator joints under the floor boards.
Please any help

DOM, November 2008