my ideal classic boiler constantly loses pressure and requires topping up every day, could this be due to evaporation in the system , there are no visible leaks in the system .could there be a problem with the expansion vessel/diaphragm. what should the air pressure be in the expansion vessel, and how do you re charge it.

frosty the broken boiler, December 2008

If you drain your system you can then put a pressure gauge on your pressure vessel and see if it correct - I believe they are normally around 12psi but I don't think it is critical. If you get water coming out of the valve your diaphragm has failed. Once that is correct you can refill the system, bleed it and then look for leaks. Don't forget to check the PRV in case that is dripping.

Richard, December 2008