Immersion extraction.
- Thread starter kaboom
- Start date
I've found a good box spanner and informing the customer that it may wreck the cylinder before work is carried out are godsends 
Tapping each side of the immersion with a hammer can help free the thred a little.
Tapping each side of the immersion with a hammer can help free the thred a little.
heat sometimes helps 
We've had this many times.
CHoices are:
Use box spanner and 24" stillson,
Use cast iron box spanner and hit it
Drill hole through centre then work outwards with dremel, hack, jig etc saw. Nicking the threads doesn't matter.
Heat always helps. You'll read that the washer can be cut with a hacksaw blade. I've never needed to.
Also leave the water in the tank. It won't stop the tank splitting but it makes it easier to hold still.
CHoices are:
Use box spanner and 24" stillson,
Use cast iron box spanner and hit it
Drill hole through centre then work outwards with dremel, hack, jig etc saw. Nicking the threads doesn't matter.
Heat always helps. You'll read that the washer can be cut with a hacksaw blade. I've never needed to.
Also leave the water in the tank. It won't stop the tank splitting but it makes it easier to hold still.
Just did exactly the same. depends how long the old immersion has been in place but:-
First of all I broke the seal on the immersion with the tank full!
Marked the flange of the immersion and the flange of the tank with a black felt tip. Used an immersion wrench and hit with a light hammer until the two black marks mis-aligned slightly. Once the seal broke I drained down the tank. Reason for keeping tank full at first was that the mass water inside the tank helps to stop the tank creasing.
Element was a complete mess - hard water area - so fitted an incalloy.
replaced, refilled, job done.
B*gger me it only lasted five minutes before it stopped working!!! Going to have to do it all again !
First of all I broke the seal on the immersion with the tank full!
Marked the flange of the immersion and the flange of the tank with a black felt tip. Used an immersion wrench and hit with a light hammer until the two black marks mis-aligned slightly. Once the seal broke I drained down the tank. Reason for keeping tank full at first was that the mass water inside the tank helps to stop the tank creasing.
Element was a complete mess - hard water area - so fitted an incalloy.
replaced, refilled, job done.
B*gger me it only lasted five minutes before it stopped working!!! Going to have to do it all again !
IMHO, a big, heavy wrench is a BAD idea.
The trick is to rotate the heater WITHOUT rotating the flange! To do this you need to keep the mass of the bit you're trying to move as low as possible, so that it accelerates fast. I've found a light, strong box spanner best - hitting the end of the tommy-bar with a light club-hammer.
Also, it sometimes helps to lightly hit it CLOCKWISE first (ie. TIGHTEN it) to break any seal on the threads.
The trick is to rotate the heater WITHOUT rotating the flange! To do this you need to keep the mass of the bit you're trying to move as low as possible, so that it accelerates fast. I've found a light, strong box spanner best - hitting the end of the tommy-bar with a light club-hammer.
Also, it sometimes helps to lightly hit it CLOCKWISE first (ie. TIGHTEN it) to break any seal on the threads.
Since this thread covers just about everything and has just been referred to, in answer to
I agree you don't want huge twist on the neck of the boss, but if someone has used old-style thread-seal, the immersion won't "crack" undone. But if it's heated up the compound will go sticky. A "moderate" force on a big spanner will undo it slooowly. 24" Stillson is only just big enough to hold a box spanner to fit.
By the way you'll always lose a cupful of water at least when the immersion is undone. Easy answer is a water-vac, unless the drain cock is unusually easy to use.
If you can't get the htr boss warm because of the water in the tank and there IS no drain cock, remove the top pipe fitting carefully (don't let the tank part rotate!) and syphon some water out.
I agree you don't want huge twist on the neck of the boss, but if someone has used old-style thread-seal, the immersion won't "crack" undone. But if it's heated up the compound will go sticky. A "moderate" force on a big spanner will undo it slooowly. 24" Stillson is only just big enough to hold a box spanner to fit.
By the way you'll always lose a cupful of water at least when the immersion is undone. Easy answer is a water-vac, unless the drain cock is unusually easy to use.
If you can't get the htr boss warm because of the water in the tank and there IS no drain cock, remove the top pipe fitting carefully (don't let the tank part rotate!) and syphon some water out.
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