Immersion heater replacement

It might prove a little difficult to undo and unscrew the faulty immersion element. How old is it? Any sign of additional sealant or corrosion? They can be very stiff to undo.

If you try loosening it - try first to see if it will move with a full tank of water so it has some weight to counterbalance the spanner force. The danger of that is that it might leak afterwards!

Last one I did came undone but distorted the tank slightly.

Unless she cant do without the immersion heater it might be best left until this virus bollyarks is over and done with -- just in case it wont undo and (worst possible case) need a replacement tank ?????

I had to resort to the method shown in this video

The quality of the spanner can also make a big difference. Those made from a stamped out flat piece of steel can easily distort before the fitting moves.

I replacd an immersion heater once, later for another reason the tank failed and I removed it. For fun I then tried to remove the immersion heater which was impossible without damaging the tank. Hard area. The local scrap merchant gave me some money for the old tank after weighing it. I always wondered how much of the weight was due to the hard water.

If I were the OP I would first make sure that I could buy a replacement tank quickly and that I could then fit it as many of the connections might be in a different position.

It is an internally insulated stainless steel high pressure tank, not a copper hot water cylinder. A blowlamp is the last thing to use on it

It is an insulated stainless steel pressure vessel and the lower thermostat is near the bottom of the tank so any attempt at removing it when the tank is full or partially full will most certainly produce an impressive leak.

If you manage to distort a high pressure tank at all it would need to be replaced.

Immersion heaters for pressurised vessels must have a built in overheat thermostat. The seal around the heater is usually made in the factory so you don't often have the problems of plumbers in the past slathering everything in sealant so removal isn't too difficult. Refitting must be done carefully making sure the gasket surfaces are absolutely clean. Make sure you know the refill procedure for the tank and expansion vessel before you start.

This cylinder did have a new expansion vessel fitted about a year ago (maybe more) and I watched the plumber do it (unless you know all the gotchas, I'm not sure I'd want to mess around with a mains fed hot water tank). The cylinder is about 15 years old. But what I don't recall is what the refill procedure was. Where would I find that? Is the procedure not the same across a lot of unvented cylinders?

Our Immersion heater has as an over heat cutout which once cut out. It is a little button under the cap that needs to be pushed down to be reset. It only did it once, I replaced the thermostat (which is removeable on ours, it slides into a 'tube' under the cap), on the assumption it was probably the reason.

You're right. It could be the thermostat. A few easy tests I can make once this covidy-bolloxy thing settles down.

To easily undo a traditional immersion heater. You need a hacksaw blade with one end wrapped in tape to form a handle. Use it to saw out the fibre ring, ie work all round the joint circumferentially until its cut right through (you can easily feel this)

Do NOT try to force things if the heater is tight (it probably will be) Use the saw trick You will heave to clean up the flange afterwards so take a file and emery paper. Put some Plumbers Mait on the new fibre joint.

Some stainless steel cylinders have non-traditional immersion heaters that your tradional spanner won't fit. You have to buy a heater for that particular cylinder. ~Expensive too.

Peter Parry has brought this to us :

All immersion heaters have to have the overheat stat now..

Brian Reay explained on 26/04/2020 :

That might have been the over-heat trip manufactured a bit low, with the main stat set a bit too high.

If only people would realise that it is the gasket that created the seal - the tread it sher to pull the faces together - and what about a smear of coppaslip?

Indeed. I'm not a plumbing expert, but that's how I understand the situation. The immersion manufacturers that I've read installation instructions for say you should only need to use the supplied gasket; no thread sealer is needed. One did suggest using PTFE as a lubricant.

Grumps snipped-for-privacy@here.com wrote in news:r87icc$avf$ snipped-for-privacy@dont-email.me:

So many plumbers and others seem to want to use sealants and gunks on all threads - perhaps it adds to the mystique of the trade and gives them more work in the future when things won't come apart. Same wit compression fittings. The thread is there to apply a clamping force. Cleanliness is the most important thing.

A quick Google suggests that this type of element is available at about £50. It should undo OK (I misread the OP) provided only the original gasket has been used. Check first, as mentioned, that the element is faulty - definitely open circuit, that the over temperature trip has not gone off and that the thermostat is OK.

While this is true, that doesn't stop limescale deposits forming in the clearance gaps between the non contact thread faces. My preferred fitting method on a heater that needs replacing every year or so (long story) used to be to put a thick layer of PTFE tape on the threads only. Excess extrudes and keeps the clearances filled, very much reducing the amount of deposits. More recently I have been using the soft sealants that claim to be "liquid PTFE" (although they are obviously not), for the same reason.

So I managed to visit and tested the thermostat and heating element. The over heat cutout had tripped and all it needed was to be reset. If it has tripped once, will it likely trip again? Anyway, bought a replacement to be safe, and will install in a few days.