advice needed ref replacement of immersion element

DOES ANY ONE KNOW HOW BIG A JOB IT IS TO REPLACE THE ABOVE? I RECENTLY TURNED ON THE SWITCH FOR THE IMMERSION TO HEAT THE WATER FOR A SHOWER, BUT THE WATER NEVER HEATED, THE LIGHT WAS ON, TO INDICATE IT WAS WORKING....HOWEVER NO HOT WATER?
i HAVE HAD ONE OF THE ELEMENTS REPLACED, IT WORKED FOR A WEEK, BUT IT HAS HAPPENED AGAIN i DON'T KNOW WHETHER I NEED A PLUMBER OR AN ELECTRICIAN?

If it has failed twice within such a short space of time I would think there is something else wrong with the immersion heater and would probablly replace the whole heater.

The electrical side of replacing an immersion heater is generally pretty trivial. IIRC it can sometimes be difficult to unscrew them without damaging the tank though.

many thanks for your reply, it has been most helpful!

if it failed shortly after being fitted there is a chance that there was a loose connection. loose connections burn away under sustained load. I would expect your plumber can recognise and correct this IF that is the problem (overheated copper wire has to be cut back, as it will not make a reliable connection in future due to the heat damage) The heat also damages terminals in the switch or wherever it was loose, which also needs to be replaced. plumbers might not be as familair with this damage as electricians, but most of the work in getting an element out is plumbing work.

You need to see why the latest element failed. I've seen them bent to fit in a cylinder because the one the electrician brought with him was too long. Where it was bent was a weak spot.

If you do change it yourself, don't bother with one of those large ring spanners, as they slip off and tend to twist to one side when applying pressure. Buy a box spanner type. That way with a bar you can put equal pressure and less chance of slipping off.

As said previously, it's mostly plumbing work.