At least once per year water starts dripping from my overflow pipe. Ballvalves etc get replaced and 6-8 months later it happens again. To me this doesn't seem normal however no-one can give me any recommendations as to what to do except keep replacing them!
In addition to that every few years the thermostat goes as well so either I am left with no hot water at all or scalding water.
Again the plumbers just replace it without recommendations.
To me it seems like a problem with the tank. It is a hard water area. Water is heated via economy 7 so only at night. The tak is square 1 foot 9 wide and 3 feet high. I/m in 2nd floor flat. Every plumber who has looked at it has said they haven't seen one like it!