just went upstaires to have a look at my 28i junior combi(please look at my other thread with the problem in having with it) and noticed a loudish bubbling type of noise coming from it when i had the ch on?so now ive turned it off untill i find out what it is or if its safe to carry on useing it.so if anyone could please help asap as ive got 4 kids in the house and no heating