advice on draining electric water emersion

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Andy1
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advice on draining electric water emersion

Post by Andy1 » Sun 22 Oct 2017 22:24

I have a electric water emersion that supplies hot water to taps and shower. The flat insurance policy requires it to be drained in the winter months, i have been looked for a drain from the tank but have failed. My DIY skills are poor.
so I must ask for help. Im sure its very obvious when shown but my water heater hasn't got a drain port on the main tank!

Can anyone advise me of someone who could call in one day next month and drain the tank plus show me how to do it properly.

Thanks in advance

Webdoc
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Post by Webdoc » Sun 22 Oct 2017 22:48

The only reason I can possibility imagine to drain the tank in winter is to prevent freezing and consequent bursting over a prolonged cold period. In this region, and in a block of flats where others may be occupied and heated over winter, the risk is miniscule.

I remember from O-level geography that Mediterranean Weather is very different from Continental Weather. A friend bought a house in the Dordogne which froze over winter and burst all his pipes because no-one told him to drain it down, but I can't believe that would happen here.

I routinely turn the water main off when I leave my house here but never drain it down. I also isolate and drain the outside garden tap but that's my OCD showing through.

I wonder if your policy is designed for properties in central France?

Does anyone else drain their tank?

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Post by Webdoc » Sun 22 Oct 2017 22:52

Oh, and there will be a drain underneath the tank, otherwise you could never change it as it would weight a ton. It's probably tucked round the back because you only need it every 30 years or so.

martyn94
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Re: advice on draining electric water emersion

Post by martyn94 » Mon 23 Oct 2017 16:08

Andy1 wrote:I have a electric water emersion that supplies hot water to taps and shower. The flat insurance policy requires it to be drained in the winter months, i have been looked for a drain from the tank but have failed. My DIY skills are poor.
so I must ask for help. Im sure its very obvious when shown but my water heater hasn't got a drain port on the main tank!

Can anyone advise me of someone who could call in one day next month and drain the tank plus show me how to do it properly.

Thanks in advance
Webdoc is entirely right about the risks of suffering serious damage from freezing in a multi-occupied block of flats in St Cyp. But the immediate moral is to find yourself a new insurance company which doesn’t impose such absurd conditions: if you haven’t shopped around for a while, it will also probably be much cheaper. Failing that, just ignore the insurance conditions: everyone else does, and mostly come out alive.

If you really need advice about draining, ask again: it can sometimes be dead easy and sometimes a pig, depending on how your plumbing is laid out. But the fact that plumbers round here don’t try to make it easy speaks for itself.

martyn94
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Post by martyn94 » Mon 23 Oct 2017 17:50

Just an afterthought to explain why I am warning you off the project. The point about French water systems is that they are sealed once you turn the mains supply off (as you evidently have to do). It’s useless to find a drain cock at the bottom of your ballon (which may well not exist, anyway) unless you can find a way of getting some air into the top of your ballon to replace the water flowing out (and that may not exist either, in a convenient form). Otherwise you just get a vacuum and nothing happens.

There’s always a workaround, but how tiresome and messy it would be depends on how your plumbing is laid out. And it’s wholly unnecessary until your ballon packs up.

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Post by Allan » Mon 23 Oct 2017 20:28

martyn94 wrote:Just an afterthought to explain why I am warning you off the project. The point about French water systems is that they are sealed once you turn the mains supply off (as you evidently have to do). It’s useless to find a drain cock at the bottom of your ballon (which may well not exist, anyway) unless you can find a way of getting some air into the top of your ballon to replace the water flowing out (and that may not exist either, in a convenient form). Otherwise you just get a vacuum and nothing happens.

There’s always a workaround, but how tiresome and messy it would be depends on how your plumbing is laid out. And it’s wholly unnecessary until your ballon packs up.
Surely you just open the hot tap which after all is fed from the top of the cylinder.

To drain the system it might be as simple as opening all taps, depending on how high the cylinder is. If not there is usually a sprung tap on the expansion valve of the cylinder.

I agree with your comments about the need for it but 4 or 5 years ago winter was freezing.

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Post by martyn94 » Mon 23 Oct 2017 21:47

Allan wrote:
martyn94 wrote:Just an afterthought to explain why I am warning you off the project. The point about French water systems is that they are sealed once you turn the mains supply off (as you evidently have to do). It’s useless to find a drain cock at the bottom of your ballon (which may well not exist, anyway) unless you can find a way of getting some air into the top of your ballon to replace the water flowing out (and that may not exist either, in a convenient form). Otherwise you just get a vacuum and nothing happens.

There’s always a workaround, but how tiresome and messy it would be depends on how your plumbing is laid out. And it’s wholly unnecessary until your ballon packs up.
Surely you just open the hot tap which after all is fed from the top of the cylinder.

To drain the system it might be as simple as opening all taps, depending on how high the cylinder is. If not there is usually a sprung tap on the expansion valve of the cylinder.

I agree with your comments about the need for it but 4 or 5 years ago winter was freezing.
Once you’ve turned the mains off, it’s no advantage that the feed comes off the top of the cylinder, rather the contrary, gravity being what it is: the system is no longer pressurised. [on second thoughts, I think it depends on how the pipe runs lie: I was never any good at fluid mechanics, but I did just fluke the exam]

If you are lucky enough to have a tap higher than the top of the ballon, and another one lower than the bottom of the ballon, you might drain it by just using taps. But it’s not obvious in a flat. Otherwise you need a spanner, and lots of buckets, and lots of things to mop it all up with. That includes using the safety valve on the ballon: it works, and I’ve done it, but it makes an awful mess, and takes a long time to shift 200 litres.
Last edited by martyn94 on Mon 23 Oct 2017 22:20, edited 1 time in total.

Allan
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Post by Allan » Mon 23 Oct 2017 22:14

martyn94 wrote:
Once you’ve turned the mains off, it’s no advantage that the feed comes off the top of the cylinder, rather the contrary, gravity being what it is: the system is no longer pressurised.

If you are lucky enough to have a tap higher than the top of the ballon, and another one lower than the bottom of the ballon, you might drain it by just using taps. But it’s not obvious in a flat. Otherwise you need a spanner, and lots of buckets, and lots of things to mop it all up with. That includes using the safety valve on the ballon: it works, and I’ve done it, but it makes an awful mess, and takes a long time to shift 200 litres.
My comment about opening the hot tap was to release the vacuum to replace the water flowing out and of corse it will do that, irrespective of the height of the tap.

To drain it, you either need a cold tap lower than the cylinder or a drain valve. Or use the tap if there is one on the expansion valve which will always be fitted in a pressurised system.

Every expansion valve I has seen is directly connected to a drain outlet, otherwise when the water heats and expands it will flow over the floor.

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Post by martyn94 » Mon 23 Oct 2017 22:26

Allan wrote:
martyn94 wrote:
Once you’ve turned the mains off, it’s no advantage that the feed comes off the top of the cylinder, rather the contrary, gravity being what it is: the system is no longer pressurised.

If you are lucky enough to have a tap higher than the top of the ballon, and another one lower than the bottom of the ballon, you might drain it by just using taps. But it’s not obvious in a flat. Otherwise you need a spanner, and lots of buckets, and lots of things to mop it all up with. That includes using the safety valve on the ballon: it works, and I’ve done it, but it makes an awful mess, and takes a long time to shift 200 litres.
My comment about opening the hot tap was to release the vacuum to replace the water flowing out and of corse it will do that, irrespective of the height of the tap.

To drain it, you either need a cold tap lower than the cylinder or a drain valve. Or use the tap if there is one on the expansion valve which will always be fitted in a pressurised system.

Every expansion valve I has seen is directly connected to a drain outlet, otherwise when the water heats and expands it will flow over the floor.
Yes, but mine is not sized to drain the whole tank very quickly. And it’s crooked, so it leaks anyway.

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Post by martyn94 » Mon 23 Oct 2017 22:59

Allan wrote:
My comment about opening the hot tap was to release the vacuum to replace the water flowing out and of corse it will do that, irrespective of the height of the tap.
Or of corse maybe not, though fluid mechanics was never my strong subject.

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Post by Allan » Mon 23 Oct 2017 23:20

martyn94 wrote:
Allan wrote:
My comment about opening the hot tap was to release the vacuum to replace the water flowing out and of corse it will do that, irrespective of the height of the tap.
Or of corse maybe not, though fluid mechanics was never my strong subject.
Or even of course. Clearly spelling or rather typing with one finger on an iPad is not mine.

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Post by Allan » Tue 24 Oct 2017 09:39

Plan B - the fluid dynamics solution

Leaving the mains water turned on, unhook the shower hose from the wall and place it as low as possible in the shower tray.

If the shower spray head is detachable at the end of the hose then take it off. It is important that the hose outlet is as low as possible.

Turn the shower tap so that ONLY COLD water comes from it. Make sure the waste water stays in the shower tray and flows down the drain.

Open the highest Hot tap elsewhere. Make sure all other cold taps are turned off

Turn off the main stop valve to the property.

Water should continue to flow through the shower hose (a symphonic effect) until the cylinder is empty.

No spanners, no buckets, just good old fashioned theory. Of course like most theories it might not work, but worth a try.

martyn94
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Post by martyn94 » Tue 24 Oct 2017 11:20

Allan wrote:
Water should continue to flow through the shower hose (a symphonic effect) until the cylinder is empty.

No spanners, no buckets, just good old fashioned theory. Of course like most theories it might not work, but worth a try.
Surely not a symphonic effect: it must be Handel’s Water Music. Apologies in advance: I hate autocorrect too.

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Post by martyn94 » Tue 24 Oct 2017 19:53

Allan wrote:Plan B - the fluid dynamics solution

Leaving the mains water turned on, unhook the shower hose from the wall and place it as low as possible in the shower tray.

If the shower spray head is detachable at the end of the hose then take it off. It is important that the hose outlet is as low as possible.

Turn the shower tap so that ONLY COLD water comes from it. Make sure the waste water stays in the shower tray and flows down the drain.

Open the highest Hot tap elsewhere. Make sure all other cold taps are turned off

Turn off the main stop valve to the property.

Water should continue to flow through the shower hose (a symphonic effect) until the cylinder is empty.

No spanners, no buckets, just good old fashioned theory. Of course like most theories it might not work, but worth a try.
I can’t work out why it doesn’t, or might not, stay air locked. If it does, just take your adjustable spanner and slacken off the threaded connection at the top of the ballon (and tighten it up afterwards).

But the best advice remains “Don’t botherâ€￾.

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Post by Allan » Tue 24 Oct 2017 21:53

martyn94 wrote: I can’t work out why it doesn’t, or might not, stay air locked. If it does, just take your adjustable spanner and slacken off the threaded connection at the top of the ballon (and tighten it up afterwards).

But the best advice remains “Don’t botherâ€￾.
Because water is siphoned out from the bottom of the tank and replaced by air drawn in through the open hot tap into the top of the tank.

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Post by martyn94 » Wed 25 Oct 2017 01:45

Allan wrote:
martyn94 wrote: I can’t work out why it doesn’t, or might not, stay air locked. If it does, just take your adjustable spanner and slacken off the threaded connection at the top of the ballon (and tighten it up afterwards).

But the best advice remains “Don’t botherâ€￾.
Because water is siphoned out from the bottom of the tank and replaced by air drawn in through the open hot tap into the top of the tank.
OK, I think I get it, at long last. But your siphon is doing a lot of work, depending on the layout and the losses in the system.

It would be interesting to know from the older inhabitants on the forum (and down on the coast) whether anyone has ever suffered serious frost damage?

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Post by Florence » Wed 25 Oct 2017 18:04

We used to have the tank in the loft. We did have a problem once when we were away for a few weeks in winter and the house wasn´t heated. But it was the pipe that froze, the tank was OK. We´ve since moved it down to the garage and put a cover on it. No more problems now

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Post by Allan » Wed 25 Oct 2017 18:40

Florence wrote:We used to have the tank in the loft. We did have a problem once when we were away for a few weeks in winter and the house wasn´t heated. But it was the pipe that froze, the tank was OK. We´ve since moved it down to the garage and put a cover on it. No more problems now
You were lucky, a tank or hot water cylinder will rarely freeze but if a pipe freezes it can split.

Once the pipe thaws, the water in the tank can empty through the split.

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Post by martyn94 » Sun 29 Oct 2017 17:29

Allan wrote:
Florence wrote:We used to have the tank in the loft. We did have a problem once when we were away for a few weeks in winter and the house wasn´t heated. But it was the pipe that froze, the tank was OK. We´ve since moved it down to the garage and put a cover on it. No more problems now
You were lucky, a tank or hot water cylinder will rarely freeze but if a pipe freezes it can split.

Once the pipe thaws, the water in the tank can empty through the split.
I’m not going down to the cellar to look, but I recall that my cylinder has a little red stop cock near to, or built into, the pressure release valve. It won’t stop your cylinder freezing up (in a thousand-year freeze, down here) but it might stop it dumping 200l of water all over the floor. It would be my cellar floor in my case, so I don’t much care. But it might be worth switching it off before you leave, if you are leaving in the cold months,

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Post by Richard and Sharon » Mon 06 Nov 2017 09:47

If you want a plumber to sort it out, I can recommend Christophe Docus. He is a fairly local to you, very helpful, speaks English and his rates are very reasonable. His contact details are jcdocus@bbox.fr or call 06 43 00 28 40

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