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The nature of washing appliances


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This morning, being bored, I amused myself by playing a favourite game of mine. It is called "where the heck is all that electricity going?" The sun had finally broken through the clouds, free power was raining down upon our roof and the batteries were getting the dregs whilst the house consumed nearly 3 kw.

What I found was the dish washer, washing machine and pool pump all running at the same time. What interested me is that the load was up and down for the next while. Being particularly bored I kept EZ manage running on my phone and did the rounds as the load changed.

So, my observation is that washing machines and dish washers seem to use lots of power when they are pumping water, not so much when they are washing or even spinning. Is this right? It seemed to me that the washing machine in spin mode used a lot less than right at the end of rinse mode when it pumped water out. Which means they use a lot, but in short bursts, the spinning seemed to use very little power. The dishwasher always is recognisable by a twin peak pattern on the load trace of the data my system generates. I assume this to be pumping water in early on, and then pumping it out again at the end of the wash. In between those two phases it seems to use a lot less.

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Our dishwasher has two heating cycles of about 10mins each over the 1h56 minute cycle. It then draws around 3kw to heat For around 10mins per heating cycle , and wash. Lg dishwasher.

I recently investigated a newer dishwasher and found that our 8 year old one is still pretty close to using around 1.2kwh and around 13 liters per wash. So the expensive dishwashers seem to get that down to around 1kwh and 6-8 liters per wash, so not worth the cost for gautengers, but if in the western cape may consider saving of 5 liters worth the R16k??

The lg automatic washing machine setup favorite wash program is a short “cold wash”, with 1400rpm spin cycle, total duration 39min 15 for spinning, weighing, spinning faster, etc.

 it seems to draw  around 3-400 watts during the spinning  which is set to 1400 rpm, to reduce moisture content and drying time.

pool pumps :) startup current is high and then The draw is around The size of the motor, so 0.5kw or 0.75kw etc no surprises here.

pool pumps are where one can save the most if running them from solar - from the house,  or if you go variable speed motors, or maybe even independently solar driven if you want to convert only your pump to solar. Personally I think that one should simply increase the solar on the house and use the additional power wherever needed rather than tying it to a single use like pool pump or pv panels dedicated to a geyser :)


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18 hours ago, Bobster said:

Ah! That is what is happening with the dishwasher - heating. What goes in is cold and immediately after the wash is finished the dishes are warm. 

As you figured out, the heating element is not inside the machine's cavity, it's inline in the pump loop. So when heating water, it is also pumping it. It (usually?) has two heat cycles, once during the main wash, and once towards the end of the rinse... to make everything (except the tupperware... loathsome things) nice and warm so it dries off and you don't have to dry it off manually (again, except for the tupperware).

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  • 2 weeks later...

If you have a new washing machine, chances are the drum motor is on a vsd. That will help in reducing the consumption of the wash and spin cycles. 1st with using slower speeds, second by using a smaller than usual motor to turn the drum. If it was on DOL then the motor would probably not get the drum going, but with a VSD it builds up speed and when it kicks inot hyper drive at the end of a spin cycle it already has some momentum going.

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