Ok, got a problem with my Ferroli F30 boiler and its doing my head in. We had a slow leak on the central heating pipe which we got sorted. All happy, pressure on the ch reset to 1 bar. As heating kicks in, the pressure goes up to 1.5 – 2. After heating is switched off, the pressure drops down to 1.2, again after each time the heating kicks in and then switches off, the pressure climbs higher. When it got to 2 bar , think this isn’t right…have. A google, and learn about checking the pressure on the expansion chamber. Drain the system right down, pressurize the EC, refill the system.

But again, pressure climbs up to 2.5 bars over several days. Redrain system, check EC value to see if any water in due to leaks..nothing. The air valve is at the bottom of the EC so any leaks would be apparent.

Any other causes / checks to consider before I commit to a plumber?

Cheers..