can someone advise me on a hot water problem please ? i have suddenly lost hot water. if i run heating i can then get hot water. i have replaced cylinder stat, 3 way valve and programmer so i presume that it is not an electrical problem. i am starting to think that it may be a partialy blocked cylinder but can find no other cases of this on the internet. i have a ideal logic boiler which is 8 months old and the fault code is FD (water flow). would appreciate any advice thanks