[platinum95]

Minor point, but the immersion is the heating element that extends to within the tank, short for "immersion heater".

The tanks generally also have a heat exchanger within that's hooked up to the wet central heating system, that way you can have 1 boiler so both central heating and water heating.

[beAbU]

Thanks, a foreigner here so I just parrot what the locals say :). I do have an oil furnace/boiler, which heats the water in the tank. My "immersion heater" then is so far never been switched on because I just run the boiler for 10 minutes a day.