Dishwasher on solar hot water (or gas, oil)?

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Christophe
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Dishwasher on solar hot water (or gas, oil)?




by Christophe » 24/05/11, 11:05

Everything is in the title, Why do not we systematically connect a dishwasher on the ECS (domestic hot water), preferably solar? This in order to save a few hundred kWh electric year round?

If it is solar (which is my personal case at 100% 7 8 month on 12), it is a heating power consumption cycle almost zero, if there is a cold prewash it falls well, the while the hot water arrives in the pipes ... it will be cold! If there is a cold rinse, it will be done hot and it will accelerate the drying! QED :D :D

So on the cycle of a dishwasher, a priori, it seems logical to me to do it!

If your hot water is gas or oil, economically it will always be interesting: the electric kWh costs more than 12 cents on average in France (25 in southern Belgium!), which corresponds to a fuel oil price of 1.5 € / L (with "boiler + transmission to appliance" efficiency of 80%) then there is still room!

The only question, is that we will necessarily over-use a few calories in hot water in all stages of the cycle where the water is not normally heated (or less heated), the question is to see if it is economically profitable to do !

Regarding the washing machine, here is a detailed subject that answers in detail to the question: https://www.econologie.com/forums/lave-linge ... t1435.html

If connected to the DHW, it would be impossible to clean the delicate clothes at 30 ° C and can even be 40 ° C (depending on the T ° of your solar DHW arrival).

So exit the washing machine (at least in winter when washing wool) ... but then on the dishwasher? What objections to not doing it?

While waiting to answer it, I will make some measurements of electric consumption of cycle of washing with the wattmeter on catch of this style:
https://www.econologie.com/shop/prise-el ... p-238.html
https://www.econologie.com/shop/wattmetr ... p-380.html

Then I will connect the dishwasher to the solar DHW and make a comparison of power consumption. A measurement on 2 cycles in connection with cold water ca seems sufficient to you?

If measures conclusive, I would do the same with the washing machine keeping the possibility to put on the cold water for winter woolen sweaters etc ... and ditto for the dishwasher if there are any surprises with when connected to ECS ...
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by Anthonyy » 24/05/11, 11:41

Such a connection is not likely to harm both the dishwasher and your dishes? Yes it can be beneficial but if it is for the dishwasher that is damaged and broken down more easily I do not know what is the best solution!
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by Christophe » 24/05/11, 11:49

Ben this subject is here to answer this kind of question.

Let's take a look at the possible risks of feeding a lava X in hot water rather than in cold water?

Damage the water solenoid valves? Maybe ... But I do not believe it too much: there is a margin of safety and we do not arrive with sanitary water at 90 ° C!

So, at this level of reflection, apart from a faster lime fouling in the "cold" zone (it settles faster when hot than when cold) I do not see ... and then:
a) not all waters are limestone (depends on your area)
b) the limestone that can be cleaned (every 10 years)

Do not believe the pub calgon: a scaled resistance has never leaked a washing machine (or dishwasher) ... at worst it blocks a solenoid valve but must already go!
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by Gaston » 24/05/11, 11:49

At home the dishwasher is connected to the hot water supply (gas boiler).

This is not a personal choice, but that of the previous occupant who put the water supply tap (maybe by mistake?) On the hot water pipe.

First important point: the operation of the dishwasher is not impaired.
As a precaution, I replaced the dishwasher water inlet pipe on which was marked "Max 30 ° C" :?

In terms of savings, I'm not convinced.
I operate the dishwasher mostly at night rate (8,64 ct / kWh) while the gas rate is 5,48 cts / kWh.
Given the efficiency of the boiler, losses (heating pipes between the boiler and the kitchen that make the first liters of water arrive cold ... and that the last cool in the pipe) ... if there is economy a, she is really minimal.

Finally for the quality of the washing ... I did not notice anything good or bad. The drying is not perfect, especially on some plastics, but it was already the case in the previous housing where the dishwasher was fed with cold water.
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by Christophe » 24/05/11, 12:19

Ah thank you super Gaston for this 1er back. Ok for the finish hose, I had not thought about it! I will check mine.

Has it been "running" like this for a long time?

Yes for the economy, but your case is special, if you take the national average rate (subscription included), the economy is there. What is the price of gas subscription included?

At home with 25 cents electric kWh (equivalent to more than 30 cents per kWh gas or 3 € / L oil !!!) and replaced by solar ECS, there is obviously not even to calculate: it is ULTRA profitable !!

Once again: why did I wait so long to do it? I must be a little maso ... and love, unconsciously, fatten the power companies ...

And then, to take your case, I still see a big advantage overall econological. This is positive because it limits periods of electrical peaks very expensive to the environment (and Edf for that matter)! It is not because the individual pays a fixed rate that it is true ...

An EdF electric kWh for heating rejects on average (taking into account the peaks) 180 gr of CO2 according to the ADEME: https://www.econologie.com/forums/nucleaire- ... t8139.html
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by Gaston » 24/05/11, 12:25

Christophe wrote:Has it been "running" like this for a long time?
A little over a year (with a dishwasher that was not new at first).

Christophe wrote:Yes for the economy, but your case is special, if you take the national average rate (subscription included), the economy is there. What is the price of gas subscription included?

At home with 25 cents electric kWh (equivalent to more than 30 cents per kWh gas or 3 € / L oil !!!) and replaced by solar ECS, there is obviously not even to calculate: it is ULTRA profitable !!


It is certain that with solar it is inevitably profitable (especially in the periods when the production of ECS is surplus).

Christophe wrote:And then, to take your case, I still see a big advantage overall econological. This is positive because it limits periods of electrical peaks very expensive to the environment (and Edf for that matter)!


Not really since I run it at night (just to benefit from the reduced rate).

I still have a question that I have not resolved: how much water is a filling of the dishwasher?
Indeed, when I draw the sink, I have about two liters before the water is hot.
If the dishwasher only takes 3 or 4 liters at a time, it is actually filled with lukewarm water :?
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by Christophe » 24/05/11, 12:46

Gaston wrote:Not really since I run it at night (just to benefit from the reduced rate).


The figures of the ademe are averaged over a year.
Don't you think that a cold winter night with all the heaters "full" is not a peak period?

Good I quibble!

Gaston wrote:I still have a question that I have not resolved: how much water is a filling of the dishwasher?
Indeed, when I draw the sink, I have about two liters before the water is hot.
If the dishwasher only takes 3 or 4 liters at a time, it is actually filled with lukewarm water :?


Absolutely, I mentioned this "thermal lag" above.

To know:
a) measure (on the jump) what goes out at the evacuation when the dish washer is emptying
b) learn about the precise internal cycle of operation (it must be)
c) more crudely: the standardized consumption (record) of a cycle will already give an idea (I do not know if the water really has time to cool between 2 levy? A voir ...). I will try to find the record of our ...
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by Did67 » 24/05/11, 13:59

My testimony and my thoughts:

a) I have since 2002 (I think), my washing machine connected directly to CESI; it's a Whirlpool all there is standard; to date, no problem related to this diet (I have experienced other failures that have nothing to do) ... It has 11 years in all.

(b) the record indicates that it can be supplied with hot water up to 60 °; this is good: my CESI is up to standards and has a thermostatic valve limited to 60 ° at the outlet (to avoid getting burned with hot water, it is obligatory but not always respected!)

c) as far as I know, on a LV, washing and rinsing are done with hot water; prewash: I do not use, I do not know ...

d) but beware, the LVs use very little water, so if the distance CESI - LV is long, the hot water has little time to arrive - the bigger one cools in the pipe; rebelotte au rinçage: hot water that has become very warm enters the LV, but is replaced in the pipe with hot water. Race results: the volume of hot water used is good = the volume of water consumed by the LV but the reduction of electricity is then minimal (because in the machine, we find mostly cold or warm water). In short, we pay twice !!!

Except for a CESI, where hot water is free.

So : small distance and feed with a pipe diameter 10 maxi !

NB: for the LL (washing machine), the water volumes are much larger, but the rinsing is done with cold water (generally 2 or 3 rinses). If no special "box" (alfamix - at 200 euros, depreciation period: 1 century) or no dual entry machines, abstain or .... risk of a cold shower because the LL will have almost exhausted the CESI reserve! And of course, wasting hot water when rinsing if it is not free (normally cold rinsing water is replaced by hot water). So an increase in the bill and the financial / carbon footprint ... I tinkered with a system with a mixer and by-pass, but you have to stay on the side! We must also change habits: one machine on sunny days and not a "laundry day" - with 3 or 4 machines = empty CESI = cold shower! It's not insurmountable, but hey, you have to know.
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by Did67 » 24/05/11, 14:09

Gaston wrote:
I still have a question that I have not resolved: how much water is a filling of the dishwasher?


The records revolve around 12 liters today, for one cycle (2 or 3 fillings ???).

This sheet : http://www.whirlpool.fr/digitalassets/W ... 01718F.pdf

indicates 4 l for a soak and 11 l for an eco cycle, so I think that each filling = 4 liters (and that there are 3 refills for a "normal" cycle called here "eco") ...
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by Did67 » 24/05/11, 14:12

Christophe wrote:
Do not believe the pub calgon: a scaled resistance has never leaked a washing machine (or dishwasher) ... at worst it blocks a solenoid valve but must already go!


Exact. I have water not enough limestone, slightly acid: result = resistance heating corroded in about 5 years! Limestone on it would have protected!
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