I have a ravenheat rsf 820 -20 combi boiler, the hot water was intermitent, called in an ex BG eng`, who replaced the diverter valve, worked for a short while, but not as it should, then a rumbling noise was heard , called eng` back who replaced the fan. All went well for a couple of days when the hot water was continously luke warm again as per original problem, called eng again who basically didnt want to know, leaving me with, IT COULD BE ANYTHING, and would be cheaper to buy a new boiler having already charged me £529 for the two jobs. Could anyone suggest what the problem might be, as I cant afford to replace the old boiler, thnx in advance, Edna