When I switch on the gas water heater the water no longer gets hot but the radiators do, the day before this started the water company switched of the mains supply for a few hours while I was at work, what's going on? Dave

Ok, you have a boiler that heats the house, and it has a coil in it to heat the hot water? Does the whole system have a circuit board that controls everything? If so, shutting the power off and back on may have fried the logic on the board. Post back with more details. I am going to suggest to the moderator that this is switched to H&C. Our best plumber lives in Florida and suggest taking heating questions to H&C

A day after it stopped heating th water it started to work OK for two days, it has a new (less than a yearold) control box with digital readout with which the central heating and water heater on/off times are controlled, don't know about a coil, there is fortunately an electric water heater I now use which appears to work the same as an electric kettle, an heating coil inside the tank