Chauffe-Eau Heures Plein & Creuse

[Chancer]

The only losses from a ballon d'eau chaud are the heat losses at rest, they are very well insulated and mine take several days to cool down any appreciable amount, I can return after a week/10 days and still draw some warm water.

All the major manufacturers publish figures for this loss, its called something like "consommation de maintenance" or "déperdition thermique"

Here is a site that gives calculations http://www.bouilleur.fr/pertes_d_un_ballon_d_eau_chaude.html but they show figures well in excess of those of the reputable manufacturers, I guess the true figure is somewhere between the two.

To recap, there are no heating losses even with an element entartré, the losses are through the insulation, they are more consequent the higher the température in the ballon and so those left on permanantly like in my flats will lose more heat than one switched on for a timed period, why. because as soon as enough heat is lost to trigger the thermostat it will be replaced.

The savings on HP/HC are from using cheaper electricity to heat the water, however you pay a higher abonnement and you alos pay more for all of your other non HC consumption, many many people are now paying a premium for a claimed saving.

I would be interested to see your new measured figures ANO as the €10 per month (or was it week?) seems a bit light, the site above reckons you will use that much without drawing any hot water, from my own measurements when I have apartments empty there is only 20 watts drawn from the VMC's but if I switch on the ballon and take a few baths I can really see the consumption shoot up. For example one has been empty for the last month, the ony electric has been the VMC and the occasional lighting and vaccum cleaning, it has used 8kwh in the last month, in another similar empty period I took a few baths although heating the ballon from cold each time and the consumption was 50kwh. It was summer so there was no heating.

 

[Théière]

Chancer I will read/translate that later,  my horizontal tank is flanked by 100mm of polystyrene but not the lid which remains almost constantly warm.  I do wonder about placing a thermal break in the plumbing to as the current copper pipe does waste heat in conduction and I am just about to re site the tank so want to temporarily put it on flexi PER so I can move it as I need.

Planning to use reflective insulation next time as it cools down over 3 days to tepid.

[AnOther]

The only 'figures' I have are what I observed on the energy meter I had connected to it for several months after I installed the chauffe-eau.

It's a 200lt tank with a 3kW element and since I've had it we've never come close to running it cold even when we've had six people in the house so it's only ever topping up.

It's spec. says the heat up time from cold is 4h15m, in round numbers €10/mth works out to 73kWh or 2.5kWh per day it all sounds about right to me and not wildly at odds with the site you linked to.

[Chancer]

I think my biggest loss is in having uninsulated copper piping in my apartment, its maybe an 8m run to my kitchen sink and I have to run the hot water for ages, the shower and washbasin are right beside the ballon so not so significant, I have insulated the pipes in the apartments which have short runs anyway but wish in some ways that I had used PE instead of copper.

Your horizontal ballon that is not insulated on the top, is it a French one? All the ones I have seen have 5Cm of mousse all around except for where the element goes in, to me a horizontal ballon externally is like a vertical one on its side so shouldnt have a "lid" as such just the insulated curve of the body.

I have converted vertical ones to horizontal for the apartments, it wasnt 100% successfull, there is too much  mixing with the incoming cold water and also an air Pocket at the top which acts as an accumulateur, it means that a second bath will not have hot enough water, I am going to up the tempereature and fit a thermostatic temp valve in the future but for now its the reason that I have left them connected 24/7 so they can rapidly reheat, I have had no complaints to date.

[AnOther]

If you fit a mitgateur (as the regs require) that will limit your hot

water to 50c potentially worsening any problems you have. As you're

providing hot water on a commercial basis to third parties I don't think you can really afford to '

over look' fitting one.

I don't have one and the hot water coming out

of my kitchen tap at this precise instant is a measured 67c and that's after having been off since 6am and

having provided two good showers this morning, .

[suein56]

[quote user="powerdesal"]There are only two of us with 3 x chest freezers plus 2 x normal fridge / freezers.[/quote]

Juts a thought but I read somewhere that freezers, both free standing and as part of a fridge-freezer, can use much much more electricity than they should if they are not defrosted on a very regular basis.

Sue

[Pickles]

[quote user="Théière"][quote user="Pickles"][quote user="Théière"]There are some new tanks coming along with revelotionary  heating elements that use 50% of the electricity of the old immersion heater style tanks.  Also reported to not cause limescale to build up.

http://www.supergreenuk.com/whyinfrared.html[/quote]

Errr ... If this revolutionary new technology is heating water in a tank, how can it be more efficient than an immersion heater? Where are the losses in an immersion heater?

Or is it really just a high-power instantaneous water heater - ie an electric version of a single/multipoint water heater (like an electric shower)?

[/quote]

Point duly accepted and was also my first thought on the matter.

The element is around the outside of the tank heating inwards not as conventional heating out wards causing energy to be forced out is part of it.  Also the element is totally different transferring heat more efficiently and at a tighter infra red frequency so energy is utilised more effectively. 

http://infraredtechnologies.co.uk/carbon-boiler

Some are direct instantaneous water heaters others are actual cylinders like we use now at mains pressure.

[/quote]

Thanks for the link, but I really AM confused now as to how the heck they think this is supposed to save electricity, other than by using the control system to avoid heating when it isn't necessary (and you could fit the same control system to any immersion heater). The heating area is, I accept, larger. Hence the heat transfer rate could be higher. Except it isn't, because the largest of them is only rated at 1.8 Kw, as opposed to the 3Kw of the typical household immersion heater (and the heat transfer rate doesn't have much impact on the calculations below).

I do not understand what they mean by saying that "carbon fibres cut energy demand by 40% for the same target temperature" - it just doesn't make any sense. How can they possibly do that?

Then there are the numbers that they give in the table. I don't really understand why the temp for 1 person is 45 C and for 4 it is 65 C.

Every kilogram of water requires approx 4200 Joules of energy to heat it by one degree celsius.

So, taking the last line from their table, and assuming that the input water is at 15 C (I suspect that you'd normally assume 10 C, but I'm in an unaccountably generous mood today), and making the assumption that 1 litre of water has a mass of 1kg thoughout the range of temperatures under consideration:

245 litres of water heated from 15 C to 65 C requires 245 x 4181 Joules x 50 =  51 megajoules.

To convert this into Kwh, we need to know that 1 Watt= 1 Joule per second.

Therefore 1 Kwh = 60 (seconds) x 60 (mins) = 3600 Joules

Therefore energy required to heat up 245 l of water from 15 C to 65 C = 51,000,000/3600 =  14 Kwh

Where does their 6.25 Kwh come from?

(Even their figures for 1 person, heating only to 45 C, seem wrong, because using the same calculation as above it would require over 3 Kwh).

Am I missing something here?

[Chancer]

I dont think that you have missed anything, it seems to be the same old "snake oïl" claims but you cannot argue with physics and thermodynamics.

ANO, re the mitigeur, I have 150l ballons due to the orientation and the excessive dilution from the incoming cold water let us say that I can only draw 100l of hot(tish) water before its too cold to refill a bath, if I fit a mitigeur and crank up the temp of the ballon to the maximum then less will be drawn from the cylinder as it will bleed in cold water to keep the temp down to 40° or whatever it is thus making more hot(tish) water available, thats my rationale anyway, as you say its a good thing to fit in any case.

[AnOther]

Well it sounds like a plan, let's hope it works !

[Théière]

[quote user="Pickles"][quote user="Théière"][quote user="Pickles"][quote user="Théière"]There are some new tanks coming along with revelotionary  heating elements that use 50% of the electricity of the old immersion heater style tanks.  Also reported to not cause limescale to build up.

http://www.supergreenuk.com/whyinfrared.html[/quote]

Errr ... If this revolutionary new technology is heating water in a tank, how can it be more efficient than an immersion heater? Where are the losses in an immersion heater?

Or is it really just a high-power instantaneous water heater - ie an electric version of a single/multipoint water heater (like an electric shower)?

[/quote]

Point duly accepted and was also my first thought on the matter.

The element is around the outside of the tank heating inwards not as conventional heating out wards causing energy to be forced out is part of it.  Also the element is totally different transferring heat more efficiently and at a tighter infra red frequency so energy is utilised more effectively. 

http://infraredtechnologies.co.uk/carbon-boiler

Some are direct instantaneous water heaters others are actual cylinders like we use now at mains pressure.

[/quote]

Thanks for the link, but I really AM confused now as to how the heck they think this is supposed to save electricity, other than by using the control system to avoid heating when it isn't necessary (and you could fit the same control system to any immersion heater). The heating area is, I accept, larger. Hence the heat transfer rate could be higher. Except it isn't, because the largest of them is only rated at 1.8 Kw, as opposed to the 3Kw of the typical household immersion heater (and the heat transfer rate doesn't have much impact on the calculations below).

I do not understand what they mean by saying that "carbon fibres cut energy demand by 40% for the same target temperature" - it just doesn't make any sense. How can they possibly do that?

Then there are the numbers that they give in the table. I don't really understand why the temp for 1 person is 45 C and for 4 it is 65 C.

Every kilogram of water requires approx 4200 Joules of energy to heat it by one degree celsius.

So, taking the last line from their table, and assuming that the input water is at 15 C (I suspect that you'd normally assume 10 C, but I'm in an unaccountably generous mood today), and making the assumption that 1 litre of water has a mass of 1kg thoughout the range of temperatures under consideration:

245 litres of water heated from 15 C to 65 C requires 245 x 4181 Joules x 50 =  51 megajoules.

To convert this into Kwh, we need to know that 1 Watt= 1 Joule per second.

Therefore 1 Kwh = 60 (seconds) x 60 (mins) = 3600 Joules

Therefore energy required to heat up 245 l of water from 15 C to 65 C = 51,000,000/3600 =  14 Kwh

Where does their 6.25 Kwh come from?

(Even their figures for 1 person, heating only to 45 C, seem wrong, because using the same calculation as above it would require over 3 Kwh).

Am I missing something here?

[/quote]

No I don't think you're missing anything and out of interest I have contacted the company for further information. Thus far it seems the biggest saving is through the running of the cylinder for keeping the water topped up hot which uses a low setting on their element rather than switching on and off a 2.2kw or 3kw element. There has to be more to it than just that to justify the higher price tag otherwise fitting multiple elements as in a Megaflow cylinder etc would work just as well.

[Chancer]

The" biggest saving"?

That implies that there is more than one whereas I am very sceptical if there is any saving whatsoever.

Their claimed saving is allegedly through using a smaller element.

A 500 watt element used for 4 hours produces the same heat and consumes the same electricity as a 2kwatt element running for 30 minutes on my planet.

I can understand why a microwave oven may use a small amount less electricity to boil a pint of water compared to a pan on an electric ring but its not due to the microwave having less power but to the heat lost in the inefficient transfer from the element, through the hotplate through the bottom of the pan and of course all around it, there is no insulation.

Ballons are very well insulated and there is precious little heat that escapes around the element while heating unless theirs have a different construction.

Still these wild claims persuade many people to buy radiators à inertie, halogen heaters etc, on my planet all forms of electric heating are close to 100% efficient.

P.S. Pickles I agree with your calculations but think that the final figures should be in kilowatts not kilowatt hours but I'm sure you know that and I apologise for my pedantry but it might have confused some people.

[Théière]

Yes Chancer I agree, at the moment I can't really see where the saving would be over the investment in a rather expensive cylinder.  Pickles brilliant breakdown is on the money.  Their construction is different insofar as the water is heated by a larger element around the peripheral of the inside of the tank and the water passes in a sleeve arrangement so quicker heat up considering the smaller element used but at the end all I can see is the amount of energy used is much the same because of the law of thermodynamics. I received their info and will respond to them but unless I see something that is really plausible "I'M OUT" as the dragon's say.

On your planet, have you had a chance to view the panel heaters using a tight frequency of Infra Red?  Now that is something that would be more (can't use efficient) but effective at heating and keeping us warm.  It heats us and the objects around us not the air so in essence like a microwave heats objects not the space as in a conventional oven (obviously microwave is the analogy and they use IR)  same as sitting inside when the sun is shining on the double glazing, you can get silly hot but the air temp doesn't rise to the same degree. 

That's worth something for heating purposes.

[Chancer]

Yes they are Worth considering, I have used them in a body shop and they are good for heating the object and not the air around it like a mico-onde.

We will have to find another term for efficient, let us use effective.

I have found two very effective means of heating, my uderfloor heating is very effective as you get the impresson that the rooms are warmer than they actually are and I have the thermostats set lower, using an infr red temp gun I find that I can have a room 4°c colder than with other heating.

The other is my heated underblankets, they save me loads of money and I get a better nights sleep, they only need to be on 20 minutes and at 100 watts or so consume very little, I no longer heat my bedrooms.

[Théière]

Yes my first ever underfloor heating I thought the same, lower temperature than central heating but your feet send a message to your brain that you are warm.  The reverse is also true, BIL's house fully tiled no insulation or U/F heating and your feet and calves tell the brain you are cold. Lifting feet oof the floor and onto the sofa almost immediately made you feel warmer but not much real difference in heat over the 300mm distance.

[Pickles]

We have electric underfloor heating in our primary residence in the UK and I really like it - as you say it's not about the air temp but how you perceive the heat. Similarly, I like the idea of the IR devices, particularly the ceiling-mounted one that you linked to. I haven't any experience of them (other than the space heaters used in some large buildings such as churches, which are different in that they also put out a lot of light). The ones that I have a theoretical problem with are the low-temp ones which I can't see putting out much perceptible heat: I think that to be working effectively they have to be too hot to touch and therefore need to be kept away, out of reach of occupants.

[Chancer]

The underfloor heating that I used on my UK pied à terre gives me a double benefit as before it was a cold uninsulated floor, now its a warm slightly insulated one.

In France I have cold tiled floors, the rooms are warm but my feet always cold, in winter I wear gore-tex boot liners permanently over my socks.

too much work to remove, insulate and replace the tiled floors with UFH, its my tenants that have the benefit of the underfloor heating in their apartments.