Stuck immersion heater boss - digging out fibre seal

[AndyI]

Evening all.

You're such a helpful lot, I was wondering if I could trouble you again.

I have a very old hot water cylinder which has never had an immersion heater fitted (I now know why), and I was going to treat it to one - the other half thinks not having hot water in summer is a bit off.....

Problem is, the blank boss in the immersion heater hole is well and truly stuck. I've applied all the torque I feel I can risk with an array of tools, have tried heating the cylinder, have tapped, banged and bashed, chiselled, prodded and poked, filled and emptied and refilled. The thing is stuck. Well, it is 20 years old.

On removing some of the lagging, I now see that there's a reasonably chunky fibre or leather seal, 2 or 3 mm thick, and I fancy my chances of digging that out much better than my chances of drilling out the copper boss (which I started on, but looks like a serious, serious pain). It looks like there's some sealant in there too. I've applied penetrating oil and it's getting a tad softer, but will still take forever to get out (that forever is a shorter forever than the forever it will take to drill and saw the boss).

Any tips for digging out a fibre seal? Or am I kidding myself?

Cheers all,

Andy

 

[Rob]

I dont think digging away at the washer/seal that you can see is going to acheive much.

The best technique is one you have apparantley already tried and that is to HEAT it up! This only works if the surrounding area is completly dry, you also dont want to be trying to undo it on an empty cylinder so draining about a 1/4 of the tank is what i'd be trying to do before getting the MAPP out!

 

[namsag]

Use a hack saw blade and a small strong bladed electricians too pick it out, once washer is out plug should loosen quite eay,,,, before doing that try tightening plug to break seal then undue this sometimes works

 

[Softus]

The thing is stuck. Well, it is 20 years old.
.
.
.
Or am I kidding myself?

Yes. Get a new cylinder.

 

[Soggy_weetabix]

No, a new cylinder is not required.

Lots (and I mean lots) of heat will allow it to turn. MAPP gas required here.

Patience is required.

David

 

[AndyI]

Thanks everyone.

Having counted the votes, I'll give the heating more of a go, but... MAPP? Is that a blowtorch or something? Should a hot air paint stripper be good enough?

Failing that, it's hacking away, then when I've broken the cylinder, it's new cylinder time. I like to learn the hard way.


Thanks again.

 

[ChrisR]

I've used a jigsaw on two. Lots of foam about so heat a bit of a problem. Drill 8mm hole, saw as far as poss, then hand padsaw. You can break the last of the brass quite easily. Do realise that you can saw into the thread, but not the top flat ring surface, though a bit of LS-X would seal it if you did.
The second one I did only took a minute or so, having worried and fussed unnecessarily with the first!

 

[AlanE]

Should a hot air paint stripper be good enough?

It needs to be HOT. A paint stripper will only make it warm!

MAPP is a type of gas that burns hotter than a standard torch gas.

 

[AndyI]

Thanks again, everyone.

I went with the drilling and sawing option - have adjourned after a few hours' hacking, but I think I'll get there in the end! Big hole in the centre, trying to cut into the thread at the mo - tracking down a better tool for the job.

 

[AndyI]

Update - finished the job successfully, much slower than ChrisR's record, but that's to be expected!

No jigsaw to hand (unlikely to need one again in the foreseeable future, and tight too), so drilled a ring of holes towards the outside of the plate (8mm titanium bit - a proper metal-drilling bit was crucial!), cut the links between the holes with my improvised jigsaw (a metal-cutting jigsaw blade string-bound and taped into a pipe - ). Having removed the central chunk, it was a case of bodge-jigsawing, filing and (yes) drilling three cuts to the edges. As suggested, I needed to cut well into the thread, and the washer allowed me to cut through the front without damaging the tank's sealing surface. First two cuts about an inch and a half apart to remove a small segment, then another cut opposite to get the rest in two big sections (needed a knock with hammer and chisel). Scrubbed the sealing surface and threads with soft scourer and toothbrush, then fitted the heater.

A bodge job in typical style, and lots of sweat but it worked. Thanks for all your input. Oh, and lessons: digging out the seal would have been tougher, and a jigsaw would have helped a lot. Now looking for a way to replace lagging.......

Happy plumbing!

Andy