Jaguar 28 kw .I have to refill to bar setting after each central heating program which shows FO , before I can get domestic hot water by turning on the filler loop, Please advise , ( no leaks in rad system and I don,t have to bleed system etc.)

jonjostan, December 2009

I have exactly the same boiler and have had the same problem. It appears as though it is the expansion vessel with my system.

10clamp, January 2010

with the system a ZERO pressure,test what pressure you have in the expansion vessel ,
NOTE if water comes out when you depress the valve core
the pressure vessel internal diaphragm has failed the pressure vessel will need to be replaced.
if no water comes out re inflate pressure vessel to about 1 bar MAX using a car pump ,then refill system with water via the filler loop

wirecutterman, December 2009