"I replaced a 40 year old immersion heater at the weekend - the thermostat was in Fahrenheit !, I read about how to do the job and with limited space bought this.
What a job! Heated the joint after removing the water, froze the joint - it would not budge. Added an extension to the bar - which started to bend!.
Eventually got my son to lie on his back bracing the cylinder with his feet so it would not move at all . I then used the extension (a hollow car jack handle which fitted over it) and applied all the force I could. It suddenly moved very slowly for one full turn and then came away easily.
So it works well in confined spaces and tolerates a large amount of force. Just the job.
"Although this is slightly more expensive than the flat ring spanner I would thoroughly recommend this. It feels like it will last a few generations. It undid my old immersion heater with ease. I managed to thread the mains lead through the socket and still undo it so no need to remove the cabling first - once unplugged! This is twice the price for 10 times the quality."
"removed my heater in no time. fitted the new one. In all it took me about five minutes excluding draining tank. you always get someone who expect something for nothing and then moan about it !!!!!!!!!!!!!!"
"Spanner fitted perfectly after a few burrs were lightly filed off. Much stronger than a pressed steel cranked spanner, it removed the old heater and replaced the new one on a foam insulated cylinder with no trouble at all.
"Fitted well - I have tried the flat spanners before and they do not work and you have to cut away a lot of the tank insulation. The tommy bar is not really long enough - we are in a hard water area and the old heater had been there 20+ years. But using a long pair of heavy-duty grips to hold the box spanner got it moving. I read that it is best to leave the water in the tank while trying to get the first movement on the spanner - water adds to structural strength of tank and reduces risk of damaging it - of course drain before taking it right out!"
"Very good bit of kit, bought this to try & remove my old immersion heater, unfortunately the heater was well & truly stuck to the point on bending the “tommy bar”. However this is a great tool at a reasonable price and will not damage the cylinder lagging, unlike the spanner type."
"I try this box spanner after buying Ring spanner to remove Heater. Has they was no room to turn Ring spanner and was bend the top of tank the box spanner was larger than the ring spanner by 1mm and slip round heater nut till filling gap with 2p coin one of the flats work great after that"