Removing immersion heater

[gtkingsley]

I need to replace my immersion heater. In theory not a hard job BUT I can't unscrew the existing one (probably scaled up inside, I expect, and maybe installed with bosswhite or similar which is now well cooked). Don't dare use too much force for fear of bending the tank or damaging the pipe connections. Any ideas for loosening it?

[j2buttonsw]

Put pentrating oil (WD40) around the joint and leave it overnight. Or try heating it up with a blow torch. I've bent an immersion heater spanner before trying to get one off!