Water heaters: the big waste?

[chlemagne]

Hello,
I think I'm going to smash old open doors.

Every morning, I take my shower whose hot water is provided by an electric cumulus of 300 liters.

Knowing that it is the cold water that pushes the hot water towards the taps, I told myself that it made a sacred beautiful gachi.

This amounts to putting in the cumulus tank, as much cold water as hot water taken. Which "warms" the remaining hot water and so on each time I draw hot water.

So, with my 300 liters, I can only take three showers in three days if I stop heating after the first heating.

Three small showers are not 300 liters !!! Oh, go with two dishes, no more.

You will tell me that we pay half the price per night Kwatt.
But this is a view of the EDF spirit, because overall all French users pay the entire French consumption of electricity.
Which makes a kind of average price that all French people pay.

It will not occur to me, to put in my bathtub as much cold water as hot water if I had to heat it other than with an electric cumulus !!!

I come to think that this is a system which was well suited to the EDF for distributing the production of current at night or less industries are demanding.

But from an energy point of view, it's a big waste, if you think that my little experiences are multiplied by 50 million consumers while we are looking to save the slightest KW or make them with derisory means (photovoltaic wind turbines).

I leave it to your repairs

[Philippe Schutt]

300L for a shower and dishes per day ... a little oversized?

Cold water is diffused horizontally in the tank, so it does not really mix with hot water. If you pulled 300L at once you would see that it stays very hot 80 to 90% of the flow, and then it quickly becomes frozen.
By cons, once cold water in the ball, it will become uniform in the long run, and 3 days is long. Without counting the loss by the external envelope, or the reduction in volume due to lime.

With such a low water turnover, watch out for legionellosis.

[chlemagne]

With such a low water turnover, watch out for legionellosis

.

I have the choice between cold water and legionellosis

For 50% of my bill !!

Boujou well as they say at home !!

[Christophe]

I did not understand everything ... what is the idea exactly ???

Water has to be heated in one way or another, and for that you don't have 36 solutions, there is even only one: provide it with calories ... after the calories can be different types: electric (nuke or fossil), fossil (gas or fuel oil), solar thermal, wood ...

Solar and wood are the most economical ... I imagine you can't put a solar system at home?

About the losses of a balloon, if the balloon is recent, they are very low therefore lowering the T ° of the balloon too much is not interesting with regard to the (low) health risk.

See:
https://www.econologie.com/forums/chauffe-ea ... 10350.html
https://www.econologie.com/forums/chauffage- ... t4934.html
https://www.econologie.com/legionellose- ... -3794.html

[dirk pitt]

I think you have not really understood the phenomenon of stratification in a water heater.
when you have 300L of water at 60 ° and you draw 50L, you bring in 50L of cold water of which only a small part mixes with hot water thanks to stratification (cold water tends to remain down because heavier and hot water to go up.)
more water being a step too bad thermal insulator (lambda 0.6) the area between cold water and hot water is self insulating.
your 50L of cold water will stay cold and the 250L of hot water will stay hot if the water heater is off.
I no longer have the figures in mind but I think we should be able to draw about 80 to 90% of water at maximum temperature.
see this document for info HERE

[chlemagne]

Hi Christopher,

It is only a question of principle, or of technique.

When you have heated water to 60 °, isn't it silly to go and put cold water in it?

We would have to find another way to push hot water to the taps, before filling up with cumulus water !! Flexcon style (to invent)

The instantaneous water heater, which has many other disadvantages, I suppose, does not put cold water in hot water !!

Paying less at night with a clock does not excuse the gachi from spending electricity.

Here, I hope to be clear

[Christophe]

When you have heated water to 60 °, isn't it silly to go and put cold water in it?

Well not too much because thermally, neglecting the increase in losses between 40 and 60 ° C (low), well it's exactly the same thing: what matters is the T ° and amount of water used at final.

Example, the thermal balance of the following 2 cases is strictly identical:

50L of water at 40 ° C = 25L of water at 60 ° C mixed with 25L of water at 20 ° C

You will need the same energy to heat these 2 scenarios starting from the same cold temperature.

Here, I hope to be clear

Uh ... Bad ...

[chlemagne]

I do not really agree with this description of the stratification phenomenon.

Note copied:
If the stratification does not exist or is strongly disturbed by the draft, we will eventually have 100 liters of more or less lukewarm water between 20 and 30 ° C. There yes.

The figures are convincing but I note that 300 L does not make me more than three days without warming up with 3 showers and 3 dishes. QED

I think that cold pressurized water swirls when entering the balloon and warms the whole. Hence a big drop in T °

[Christophe]

Uh ... except losses, the electric energy that you put in the ball, goes in your water ... point bar, there is no quibbling about it.

Whirlpools or strata will not change anything! Then you have to do an energy balance if you want to know your losses. Do you have an on-board econometer to do an energy balance?

Otherwise here are 2 models:
https://www.econologie.com/shop/wattmetr ... p-380.html
https://www.econologie.com/shop/prise-el ... p-238.html

3 showers too, it is not a very precise value: they are showers of 5 min all inclusive or 15 minutes?

For your doubts, I think I understand a little ...

The only case where a balloon would not be suitable, it would be a balloon on which we draw continuous DHW: the stratification does not have time to be done ... and indeed the cold water could come out not hot but lukewarm ...

But manufacturers have tips against this and to improve the cold / hot mixture: ours (2 exchangers) has for example a horizontal plate in the middle ...

[chlemagne]

It is not a matter of making a fool of it, it is a 5 min shower. But 300 L is 300L and three days is 3 Days.

Come to my house, if you don't believe me

You will eat "Camenbert" and apple sugar.