replacing immersion heater element

I want to replace the economy 7 heating element in my immersion heater and need advice. I don't seem to be able to drain the tank, do I need to? I dread the thought that i will unscrew the element to find water gushing out. Any help appreciated.
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You do need to drain the tank. Sorry. There should be a drain valve on it, or, perhaps, on the cold water entry pipe right at the bottom. If there isn't you may have to add one, which can be done with one of these screw onto existing pipe type devices.
However, loosen the immersion with the thing full, as it will help prevent the cylinder wall buckling.
Christian.
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Does it really? Surely the pressure is only a few metres of head and that can't do much to prevent the copper tearing.
It can be hell's delight to get them out and I normally use a big stilson gripping the copper ring and a box spanner on the heater. That way the torque is not carried by the tin copper of the tank.
Spread a little vaselene on the new heater to make life easier when yo ucome to remove it.
Robert
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Robert Laws wrote:

I must try that next time - hold on - that would only work with the really old sort of HWC which has a raised tube into which the heater goes.
I do find heat helps - the old immersion is f****d anyway.
The internal pressure certainly does help to keep the tank from buckling under stres.

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Ed Sirett - Property maintainer and registered gas fitter.
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and the weight helps to stop it moving, so you can apply a shock load
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Christian How do I tell if it's the thermostat and can you just replace it? thanks for advice.

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Assuming you cut off the water supply to it, you only need to drain it down to beneath the level of the immersion opening - ie not a lot.
--
*Money isnt everything, but it sure keeps the kids in touch

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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On Thu, 18 Sep 2003 23:09:43 +0100, Dave Plowman

OP mentioned Economy 7. They often used twin horizontal immersions, with the cheap-rate one at the bottom to heat the whole tank, and a daytime heater high up for on-demand sinkfuls.
I buy old tanks as a source of cheap copper sheet. Haven't yet been able to unscrew an immersion before I reached for the plasma cutter instead.
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Indeed.
You've pretty well got to have the tank full to loosen them.
--
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Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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This is how my recent immersion heater element-change went. Some bits you will want to emulate, others not. You can decide which.
1. Puzzle about how to drain the tank for a while. Eventually locate drain-cock hidden away at the back of the cupboard.
2. Turn off cold feed to tank. Open hot taps for initial draining. Drain a few more litres out of the newly-found drain-cock via a hose pipe into a bucket. It's only necessary to get the water level below the immersion opening at this point.
3. Remove wiring to immersion heater. Apply newly purchased immersion spanner. Not a hint of movement.
4. Spray WD40 liberally. Wait for a few hours.
5. Apply spanner. No movement. Employ tactic of giving short, sharp blows to spanner handle to loosen immersion. No movement. Increase blow strength.
6. Notice asymmetry developing in shape of the top of the tank. Notice water starting to leak from split appearing in tank below immersion boss.
7. Retrieve extra-large box of swear words.
8. Obtain new tank from B&Q.
9. Drain old tank via drain-cock. Takes a very long time messing around with syphons (tank on ground floor).
10. Remove old tank.
11. Insert new tank.
12. Revisit B&Q for fittings not previously obtained.
13. Dutifully apply PTFE tape to everything in sight.
14. Fit fittings and fill tank. Note leaks. Tighten everything. Continue to note leaks.
15. Empty and remove tank (long, slow process: see 9).
16. Repeat steps 13-15 a couple more times. Give up and go to bed cursing PTFE tape.
17. Dream about a fantastic idea for sealing leaking tank-fittings: silicone sealant!
18. Revisit B&Q. Discover Fernox-LSX already exists. Dreams of fortune-making patent shattered, but nonetheless leave happy.
19. Apply Fernox-LSX liberally to every fitting. Wait for required hour. Refit tank. Observe no leaks. Grin broadly and congratulate self. Wire up new immersion.
20. Enjoy nice hot bath.
Total time taken: best part of two days. Total cost: about 150 including some new tools.
But cheaper than getting a plumber in!
Hope your attempt goes better 8^)
Ben
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Ben Edgington wrote:

Fernox-LSX is brilliant stuff - much better than runny putty and frayed string. It's a shame the tube and cap aren't made to the same quality standards as the contents. The threaded end of the tube has a tendency to punch its way through the cap, the sealant then sets in the neck of the tube and the next sqeeze forces the contents out through the back. Believe me - I've done it!
Roger.
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Stinks to high heaven whilst curing though!
Pete
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Err..yes..
I've seen that dome where it tears the copper sheet of the tank!. Sometimes a little heat can work wonders. In these difficult to remove circumstances one should also budget for a new tank plus the downtime that entails, should it let rip!...
--
Tony Sayer


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