a hot water tank question

[mint]

Changing to a new electrics supplier has been a very good thing if only because it has made us reassess how we use electricity.

We have had lots of changes as from last year, now have a dishwasher, new washing machine and using all-electric cooking, heating, etc.

Now we no longer need basinfuls of hot water to wash up, I have been thinking that it doesn't make much sense to keep the very hot water in the tank day and night because that is how it's always been in this house, hot water tank on full-whack 24/7.

So, what I want to ask is this:

Is it better to turn off the tank, say, in the morning and turn it on before we hit the sack at night?  That's what we used to do in the previous house.  I don't really know whether you have to off-set the savings in usage costs against the "wear and tear" on the tank if you turn it off and on?

Is it true that the tank gets more worn out if heating and cooling with its attendant expansion and contraction were effected twice daily?

We live in a hard water area and I daresay that the tank wears out more quickly in any case.

Any advice, please? 

[Chancer]

If you are not on HP/HC then leave it on permanantly, the only electricity that is consumed is that to reheat the tank after you have drawn off hot water and a "maintenance consumption" which is the minimal heat losses from the very well insulated tank, if you want to argue over a few decimal places then there is a tiny bit more heat loss the hotter the tank is, better to turn down the thermostat than switch it off 20 hours a day, the goal is to have hot water when you need it not after 5 hours.

If you are going away for more than a week then there is an economic argument to leaving it switched off to avoid the heat losses but for less than a week its de minimus, mine still has hot water after a week unheated.

[mint]

Chance, I don't think you have properly understood my question.

I did say about leaving the tank on all night and switching it off in the morning when we get up.  After 12 hours or so, I should hope that there will be a full tank of hot water for what amounts to a shower each, a basinful or two for washing stuff that wouldn't go in the dishwasher and a bit more for general cleaning purposes.

I was NOT thinking of putting it on for 4 hours only and waiting 5 hours to have a shower, lol!!!

I thought that, in the context in which we use hot water, it seemed extravagant to keep the tank on all the time.

In our other house, we used to do that, switched it on during the night and off in the day, and we never ran out of hot water during the day.  Maybe, when we had visiters who wanted to take baths and wash their clothes, I'd leave the tank switched on.

Because I'd heard that the life-span of the tank could be shortened if it was off and on rather than left alone, I did wonder which as the better thing to do and that was all.

When I saw the amount of electricity we managed to use last year, I was a bit shocked and decided to overhaul the way we use the stuff in order to be less wasteful.

 

[vivienz]

Hello there, mint.  Our circumstances are rather different as our French place is only a holiday home rather than a permanent residence.  However, when there, we only heat the tank of water as and when we want it.  Generally, there is enough hot water for washing up and showers after about 3 hours.

The logical approach would be to find out how much a replacement tank (fitted would cost) and what the anticipated life span.  Compare this to the additional electricity cost of keeping the tank permanently heated over this period of time, and that should give you your answer.  Given the price of electricity in France, I would be surprised if it is cheaper to keep the tank permanently on than pay for a replacement every 10 years or so (pure guess!).

[mint]

Hi there, Vivienz, I see we are thinking along the same lines.

We don't know how old our tank is but the previous owner is due to visit us in the next few weeks, I shall ask him.

Then I'll speak to our electrician and ask him what he thinks.

It is not just the money, although there is that of course, but I don't like to be prodigal of resources generally.

[Chancer]

Because I'd heard that the life-span of the tank could be shortened if it was off and on rather than left alone, I did wonder which as the better thing to do and that was all.

 

N'importe quoi but what else do you expect to hear from someone that has probably been educated to believe everything that they are told and regurgitate it as fact even if it is n'importe quoi

When I saw the amount of electricity we managed to use last year, I was a bit shocked and decided to overhaul the way we use the stuff in order to be less wasteful.

 

You will not use (significantly) any more electricity by switching it on only at night or leaving it on 24/7, if you draw 50 litres of hot water per day for example which  will take lets say 2 hours to reheat it will not make any difference if it is reheated 10 litres at a time just after you draw the water off or all in one go when you switch the ballon back on in the evening.

 

If in a year you draw say 20 m3 of hot water your ballon will have done exactly the same amount of heating (730 hours in the example above) whether its left on all the time or switched on only at night, whoever told you "what you have heard" is talking out of their orifice Mint.

 

There will be a tiny amount more of electricity used because the ballon is hotter more of the time so the heat losses, which are minimal anyway will be slightly higher but the amount will be de minimis.

[andyh4]

Mint

I have to agree with Chancer

if you are that concerned about profligate waste of electricity, then increase the insulation in your house.

Indeed improve the insulation on your hot water cylinder. This is easy and free. Just take an/several old blanket(s), or sleeping bags or duvets and drape them over the cylinder. When you come back tomorrow you will be surprised by how warm they feel next to your insulated tank and you may be horrified at how much heat is leaking away. In reality the heat leaking away is really quite small and all you have done is reduce the loss and for nothing apart from a few minutes to find the coverings.

[Chancer]

[quote user="vivienz"]
The logical approach would be to find out how much a replacement tank (fitted would cost) and what the anticipated life span.  Compare this to the additional electricity cost of keeping the tank permanently heated over this period of time, and that should give you your answer.  Given the price of electricity in France, I would be surprised if it is cheaper to keep the tank permanently on than pay for a replacement every 10 years or so (pure guess!).
[/quote]

 

And the extra cost would be? How are you going to calculate it?

 

I will give you a clue, the formula is 2/10 thsof 3/16ths of *** all [:D]

 

And why even consider replacing a perfectly functional ballon with a new one which almost certainly wont have as long a life as one made some years back? Oh of course because someone told me that it would save loads of electricity, when you have the EDF blindly spouting complete rubbish about an entartré'd element using massively more electicity to heat the water than the new ballon, no doubt fitted by one of their robbing partenaires, then its no surprise that the average French electrician who is conditioned never to say "why is that? Explain it to me!" will believe it and repeat it.

 

For the record a ballon with an encrusted element will behave no different to a kettle that needs descaling, it will take a few seconds longer for the initial heat to pass through the layer of calcaire (which compared to a heating time of 5 hours is nothing) to heat the water to the required temperature will consume exactly the same amount of electricity in exactly the same amount of time, the residual heat in the element will take the same few amounts of seconds to continue heating the water after the thermostat has cut out.

 

Yet you will read on loads of websites just how much extra electricity a furred up ballon uses, smany of them citing EDF rubbish comments, eemingly not one French person is capable of thinking for themselves and asking the question "if it does then where does all the extra heat go?"

 

Mint, there is no wear and tear caused to the ballon by switching it on and off.

 

[mint]

Thank you very much, Chance and Andy.

Will do the wrapping up and will also turn down the thermostat a degree or two.  So, not worth the trouble of trooping up and down to the sous sol to turn the thing off or on.

The tank shows a little bit of corrosion but there is no drip or anything at the moment to suggest the need for change.

[Chancer]

The corrsion that you can see is on the outer skin and as such cosmetic, if its in random areas then it will be condensation through being in the cave, however if its around the bottom seam and is actually a rust stan rather than corrosion its and indication that the inner pressure cuve is perforated and weeping, in that case get it changed pronto.

[AnOther]

After I fitted my balloon maybe 4 years ago for the first year or so I ran it through an energy meter and had it on a timer which gave it power for three hours per night (flat rate) with the thermostat set to max.

Worked out at €10 per month and cut my oil consumption in half !

[dave21478]

Mine is on a timer for three hours a night, which gives me plenty for my shower, dishwashing and my luxury hot-flush toilet. (...its a long story)

I am on a flat rate power tarif and the only reason I have it on at night is to stagger its power draw - I dont want it on during the day when I could have the oven, washing machine etc on, then pop out to the garage for a spot of welding and trip the power out by pulling too much juice at the same time.

[mint]

[quote user="AnOther"]After I fitted my balloon maybe 4 years ago for the first year or so I ran it through an energy meter and had it on a timer which gave it power for three hours per night (flat rate) with the thermostat set to max.

Worked out at €10 per month and cut my oil consumption in half !

[/quote]

Do you have a "proper" switch for it then?

With ours, you could only switch it off at the board.

[Chancer]

Yes, you both have given a very good reason for heating the ballon only at night even on standard tarif, in fact I do exactly that with my French ballon in the UK yet had forgotten.

 

Here in France my heavy demand is at night with storage heaters and the ballon, hence the HP/HC abonnement, just as well as the tumble drier that I use for the business takes 6kw [:-))] yet another thing which I loudly and repeatedly said I would never ever own or use as long as I draw breath [:P]

 

I have still resisted the dishwasher and smartphone though!

 

Hot flush toilet, that has got me thinking Dave, the toilet that came in my UK house when I bought it had a high water level in the bowl and used a lot of water to flush compared to modern ones but it had the advantage of remaining clean except when I had Giardia (long story!) all the others need cleaning with a brush every flush, now a hot supply to my toilets with cisterns would be of no use as the water would cool but in my UK pied à terre I have a n integrated macerator toilet which is the worst in regard of cleaning but it is right beside the ballon and would benefit from a hot water flush, also the pipes are not buried deep enough, another long story and risk freezing in winter, I think that I am going to give it a go.

 

Did you just accidentally connect to the hot pipe Dave or was it one of your  inventive and imaginative solutions to a gêne that most others just accept and put up with?

[dave21478]

It was a screw-up on my part.

This house had no bathroom when I moved in, so one of the first tasks was to build one. I partitioned off a room and started. Behind this room, through a thick stone wall is an empty space where I could run pipes from the kitchen. I fitted the usual T-pieces etc inside the bathroom for bath, sink and toilet connections. I somehow convinced myself that France had the hot and cold taps the "wrong" way round, so piped accordingly. I tested for leaks and once done, plastered, tiled, fitted furniture etc.

My thermostatic bath tap appeared to be faulty out of the box, but some fiddling revealed I had plumbed it the wrong way round. I then realised my mistake.

Unwilling to give up a thermostatic tap I cut the feeds to the bathroom on the empty space behind and swapped over the pipes so the thermo tap worked. The sink was now the "wrong" way again, but easily solved by swapping the hose tails on the tap round, but the toilet now flushed with hot and would require removing tiles and cutting through the plaster to get at the relevant connections to swap it back to cold so I left it.

It has its ups and downs. Its a long pipe run from the kitchen so using the toilet before a shower draws the hot water through, saving some waste instead of just running the tap. I seem to get a bit more limescale in the bowl than I would expect, but I dont know for certain if thats related to the hot flush.

I never get condensation on the cistern now.

Its a waste of energy, I suppose; but in winter time the hot cistern will add its warmth to the bathroom, reducing the need for heating slightly so its not completely wasted.

[woolybanana]

One is fascinated by the thread; people having 'hot' tanks and now 'hot' loos. Where will it end, I ask, 'hot', shaped hotwater bottles, vibrating barrels, gites with 'hot' appliances..... the choices are endless.

[Rabbie]

Provided your hot water tank is well insulated then there should be very little difference in costs regardless of which option you choose. We always have the HW heating on and the costs are not more than when we only had it on at certain times. There was no increase in the amount of oil used when we changed. Having it on all the time has the advantage that there is always hot water when we need it. Nothing more irritating than loosing the hot water halfway through a shower

[mint]

[quote user="dave21478"]

Its a waste of energy, I suppose; but in winter time the hot cistern will add its warmth to the bathroom, reducing the need for heating slightly so its not completely wasted.[/quote]

When the room is cold in the winter and you flush the loo and produce all that steam, do/can you use it as a sort of Turkish bath or Scandinavian steam room by flushing the loo every so often?[:D]

[AnOther]

[quote user="mint"]Do you have a "proper" switch for it then?[/quote]It's plugged into a normal socket with plain old mechanical timer.

Just because it's wired into the HC relay.in the main fuse box doesn't mean you have to leave it there.

[mint]

Thank you very much, Erns.