TOP OF HOT WATER CYLINDER

The top of the hot water cylinder gets very hot and expands. It also appears to get attacked with electrolytic action and can get very thin. When it leaks at the top there is little you can do, but to replace it.

I have seen people try to stick sealant on. If there is a manufacturer out there that makes something to cure this please let me know.

You will have the same problem if you want to replace the immersion heater. The copper is very thin and it does not take much for the whole lot to split open when you try to undo the heater.