My Ferroli F30 combi loses water pressue, despite refilling using the fill loop the pressure guage will read zero after a couple of days, Yet when the system is pressurised to 1 bar and is started up the guage will read 3+ bar after about 20 mins. I have checked for leaks - none- is wter bing boiled off and how does noe pressurise the expansion vessel

Mike Gittins, February 2009