Thanks for your comments guys, It is an Isar. The manaul is for HE24, HE30, HE35 not sure which it is. If it is the valve fault you mentioned should that be covered by the breakdown insurance?
I know very little about plumbing or central heating so I'd be very grateful if someone could exlain whats up with my mums central heating. She has an Ideal boiler which was installed about 5 years ago when she moved into the house which at the time had no working central heating. For a long...