Damien

Wondered if anyone had any ideas into an issue I am having. I don't know a lot about heating systems, pumps or how they all work so my terminology might be wrong.

In the airing cupboard, next to the big red hot water tank, there is a switch. I assume this switch is for the water pump? The water pressure is certainly almost non-existent with it off. However a quick Google suggests this switch is actually the immersion heater. The boiler also doesn't work with this switch on.

Anyway, as soon as this switch turns on it trips the fuse box. I am not even sure if this is an issue for an electrician or a plumber? Any ideas of what could be happening?

Thanks