Does anyone have experience of this?. I have read of this, but so far, have not managed to find some proper info on exactly what is involved, how easy it is to fit, and wiring it up. I know that an immersion heating element is essentially a big version of what you get in an electric kettle, so, in theory, quite simple!. The elements seem to be quite cheap, I have looked on ebay, so if it is do-able, it would make sense. After all, if the water in my 500l tank is warm in the morning when I leave the house, because it is such a large volume of water, it will stay warm for most, if not all of the day.