DIY Doctor UK DIY Forums

The immersion heater in my 50gal. copper indirect vented hot water cylinder (approx. 50 years old) has failed, but I have been unable to unscrew the old heater in order to fit a replacement. I tried soaking the washer and (hopefully) the heater thread in penetrating oil every night for a week, but it's still stuck. I then tried tightening and then loosening the heater with the aid of a length of 28mm copper pipe added to the spanner, but even that failed to have any effect. I don't want to risk splitting the tank by using a hammer on the spanner, and am not sure what to try next. Any suggestions?

to be frank, fat chance if its been in that long.....better off to change tank (which will comply with current insulation standards) and then put in new immersion. The only other thing that may work is a bit risky....so take precautions.....drain cylinder.....remove insulation or anything flammable nearby and heat tank around heater (but not on it) in the hope that the as copper expands more than the steel around the heater the slight increase in the screw threads maybe enough.....but be careful as heat will travel through the cylinder.....