I have a Ideal C80FF combi boiler that is playing up. The problem is the presure keeps droping down to zero but when I presurise back up to 1Bar it runs ok but the preasure soon rises up to 3bar I then turn the heating off and it soon drops back down to 1Bar and below. Any Ideas?[/b]
Check the expansion vessel, it has a schrader valve,check pressure in it.
It should be 0.8 - 1 bar, diaphragm could have failed.
Don't be too worried about the 3 bar pressure the PRV will dump the water outside.