Saving power on dishwashers and washing machines

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Saving power on dishwashers and washing machines

Postby bpratt » Thu Jul 03, 2014 7:48 pm

I just had a thought today, with all these new washing machines and dishwashers available with just a cold water inlet only, which heat the water up to 30, 40 or 60 degrees, would it be possible to utilise a tempering valve of an appropriate value ??

I'm not sure if you can get tempering valve of any value other than 50 degrees as you have on your solar hot water system, so my point might be moot.

Since dishwashers generally heat the water to 60 the machine is only then raising it 10 degrees instead of say 40.

In some situations, such as those on tank water, it could be a lot less than the normal ~20 degrees coming in via the cold tap.

Likewise a washing machine has many default washing settings, but if you want to do a load for more than 20 minutes, it now heats the water to 40 degrees. With a 40 degree tempering valve it won't need to heat it at all. As well the rinse cycle isn't done with hot water, but warm water.


I'm sure there must be some downsides here, otherwise everyone would be doing it.
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Re: Saving power on dishwashers and washing machines

Postby Tracker » Thu Jul 03, 2014 9:05 pm

.
Firstly, tempering valves are generally, infinitely adjustable..

Second ... with clothes washing, MOST all who I know use COLD water anyway..

Thirdly ..... dish washers and their soaps are generally designed ..
To fill with cold water and rinse the proteins off first.
Then to fill with cold water and release the soap and start heating whilst washing.
Remaining washes and rinses are irrelevant now..

The point is they are designed to use cold water..

If they have hot and cold connected, they use each as appropriate for the cycle part..

IMHO... connecting to hot, is a waste of time.. :?
when first operated, the hot usually takes soo long to get there, it imparts no real benefit.
Now, the cycle is so generally long, the water within the pipe cools, and when needed, it will need to be replaced yet again...

So, I don't see any benefit in what you are suggesting ... :cry:
..
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Re: Saving power on dishwashers and washing machines

Postby bpratt » Thu Jul 03, 2014 10:06 pm

Tracker wrote:.
Firstly, tempering valves are generally, infinitely adjustable..


That's good to know....

Second ... with clothes washing, MOST all who I know use COLD water anyway..


We do, however the automated nature of our front loader, quick wash up to 20 minutes is cold water, 30 minute wash cycle and it heats the water up to 40 (Samsung WF1752WPC). Last time I looked there was no way to change it to just use cold water only, if it did, I wouldn't be trying to find a way to give it warm water (don't want to give it 60 degree water all the time).

It has one mode that will heat the water to 90 degrees too !

Thirdly ..... dish washers and their soaps are generally designed ..
To fill with cold water and rinse the proteins off first.
Then to fill with cold water and release the soap and start heating whilst washing.
Remaining washes and rinses are irrelevant now..

The point is they are designed to use cold water..


I always thought most dishwashers always heated the water up to 50+ ? We don't have a dishwasher but considering one for our new house, so looking at options.

If they have hot and cold connected, they use each as appropriate for the cycle part..

IMHO... connecting to hot, is a waste of time.. :?
when first operated, the hot usually takes soo long to get there, it imparts no real benefit.


If it starts to fill with cold water that's still in the pipe, then it is doing what you said it needs to do, but depending upon length of pipe, it might start bringing in the heated water before it has finished that.

Now, the cycle is so generally long, the water within the pipe cools, and when needed, it will need to be replaced yet again...


With a total wash cycle of 30 minutes, I doubt the water would cool down too much.

So, I don't see any benefit in what you are suggesting ... :cry:


Thought it might be worthwhile over a number of years, initially the extra cost of tempering valve and extra tap for washing machine, and the same for future dishwasher, with them set to 30 and 45 respectively, with water from solar HW system could be a useful power saving (less drain on a offgrid system).
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Re: Saving power on dishwashers and washing machines

Postby davidg » Thu Jul 03, 2014 11:53 pm

lots or most of dishwashers provide a cold water input star rating and a hot water input star rating as well, most also assume that the external hotwater supply is being heated by something such as gas or grid electricity not renewable electricity or the sun ;) . so you could certainly offer a dishwasher hot water best if the tank to dishwasher is short they don't use much water anymore, our current one uses about 16 litres for a heavy or hygiene complete cycle and a normal eco 12 litres 45C temp if heating it internally. 8-)
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Re: Saving power on dishwashers and washing machines

Postby Tracker » Fri Jul 04, 2014 9:02 am

We do, however the automated nature of our front loader, quick wash up to 20 minutes is cold water, 30 minute wash cycle and it heats the water up to 40 (Samsung WF1752WPC). Last time I looked there was no way to change it to just use cold water only,


And that is a problem with some washers.... just too automatic.... it is frustrating that some models take choice from the equation...

Much of this is so variable. How cold, how hot..
The wife turns off the shower and ten minutes later, in winter, I wait for it to reheat..
It is all generalizations..

The bottom line is that IF the hot water costs you nothing, ie SOLAR... then using it MAY have a poorer (technical) performance (ie cooking egg yoke onto plates), but the faster cycle time WILL reduce the electricity powering the wash pump, whilst the heater is raising the temp. to 65c or 55c for ECO mode..

This is one of those situations where each case needs to be completely analysed ..

I DID use HW for the DW. (Long ago). But the long run and electric heating, proved pointless, so I fitted a cold tap.. and now use off peak power.
When the SOLAR EVT system is running, and I am off grid, i may switch back to hot (warmer) water.. again..
The more technically important DW wash cycle is the first rinse, and I suspect that will be Luke Warm, anyway..

Consider the so called theory, and then adjust plans to suit your situation.. :-)

And with the tempering valve... they come with a specail spanner.. that adjusts the temp.. not sure just how much adjustment there is.
I set the HeatPump temp. to 65c, and the tempering down to 55c and set the instant gas boost to 50c.
The gas would come on for a few seconds, until the HW arrives,and then shuts off.. until the stored water drops back to 50..
Ultimately, when the EVT is installed, it will control the stored water temp.. the Heat pump will run later into the day, to ensure 65c and so on, thus we assume we will have no shortage of free/cheap HW, and I'll go back to the hot tap for the DW.. :D

:evil: don't you have predictive text... always gotta go back and change..
..
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Re: Saving power on dishwashers and washing machines

Postby bpratt » Fri Jul 04, 2014 9:27 am

Thanks David, most dishwashers I have looked at only have one water input, and that's cold water only. That got me thinking why can't I with the help of a tempering valve provide the dishwasher through its cold water input some ~45 degree water, instead of tank water which might be as low as 15 degrees through winter ?

Water at ~15 degrees is going to take a lot more energy to get to whatever the dishwasher requires, than water at ~45 degrees is going to take. In our case, the hot water system is effectively on the other side of the wall to the dishwasher location.

The laundry is further away though, but I'm sure with a similar setup, there's no reason why I can't supply the washer with ~30 degree water, which certainly isn't hot.

Really my concern is why have a 315l SHW system, and still be having appliances heating their own water ?

To my way of thinking, a tempering valve draws solely from the hot water supply line until the temperature meets its setting, then 'bleeds' cold water in to the mix to limit that temperature ?
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Re: Saving power on dishwashers and washing machines

Postby Gordon-Loomberah » Fri Jul 04, 2014 9:32 am

bpratt wrote:... otherwise everyone would be doing it.


Aren't they? ;)

I use an adjustable tempering valve on the wall at the washing machine. It is adjustable from 25C to 55C, and with the Bosch washing machine I can adjust the temps of the various cycles from cold up to various 30 to 70C, or 90C on one of the cycles. I typically use the mixed cycle which can be set from cold (<10C at this time of year) to 40C, and if my cycling clothes have a particularly bad coating of meadow muffin material after a couple of hours MTBing, I'll turn the tempering valve right up for a hot wash. If I set the machine to cold it wont do any heating, which saves on electricity if required in cloudy weather.

I also supply the dishwasher with the regular tempered water at 50C, although the first rinse fill will be much less than that if I haven't flushed the cold water from the pipes first. Regarding removing protein with cold water- IME if you have soft egg stuck on a plate, hot or cold makes no difference, it has to be removed by hand before going into the dishwasher.
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Re: Saving power on dishwashers and washing machines

Postby bpratt » Fri Jul 04, 2014 9:42 am

Tracker wrote:
We do, however the automated nature of our front loader, quick wash up to 20 minutes is cold water, 30 minute wash cycle and it heats the water up to 40 (Samsung WF1752WPC). Last time I looked there was no way to change it to just use cold water only,


And that is a problem with some washers.... just too automatic.... it is frustrating that some models take choice from the equation...


Even if it was changeable, my 84 year old mother would not confidently be able to do it. Yes, mum does all the washing here and I don't. She likes to have something to do, and I'm more than happy to let her do it whilst she is more than capable of doing it because it keeps her mind active.

The bottom line is that IF the hot water costs you nothing, ie SOLAR... then using it MAY have a poorer (technical) performance (ie cooking egg yoke onto plates), but the faster cycle time WILL reduce the electricity powering the wash pump, whilst the heater is raising the temp. to 65c or 55c for ECO mode..


That's the intention, having SHW means hot water is effectively free, rather than having the appliance use electricity either off the grid or batteries.

I DID use HW for the DW. (Long ago). But the long run and electric heating, proved pointless, so I fitted a cold tap.. and now use off peak power.


If you are ToU tariffs, then letting the DW work during off peak is a good way around it. If you are on flat rate, then using tariff 11 (peak) it seems wasteful when I've got so much hot water 'kicking around'.

And with the tempering valve... they come with a specail spanner.. that adjusts the temp.. not sure just how much adjustment there is.


That's good to know. Of course how much you can adjust the temperature by is something different. I imagine only by a couple of degrees though. :( Hopefully there are different models that work at different temperatures. The more I talk about this, the more I'm seeing ~45 for DW and ~35 for the WM.
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Re: Saving power on dishwashers and washing machines

Postby bpratt » Fri Jul 04, 2014 9:50 am

Gordon-Loomberah wrote:
bpratt wrote:... otherwise everyone would be doing it.


Aren't they? ;)

I use an adjustable tempering valve on the wall at the washing machine. It is adjustable from 25C to 55C,


Great news, sounds like I'll be able to do what I've been thinking about.

and with the Bosch washing machine I can adjust the temps of the various cycles from cold up to various 30 to 70C, or 90C on one of the cycles. I typically use the mixed cycle which can be set from cold (<10C at this time of year) to 40C, and if my cycling clothes have a particularly bad coating of meadow muffin material after a couple of hours MTBing, I'll turn the tempering valve right up for a hot wash. If I set the machine to cold it wont do any heating, which saves on electricity if required in cloudy weather.


Sounds like when it is time to replace the machine (it's only 1 year old, so hopefully a while away), I should do a lot deeper research on what's available at the time, so that I can get one that can be configured that way.

I also supply the dishwasher with the regular tempered water at 50C, although the first rinse fill will be much less than that if I haven't flushed the cold water from the pipes first. Regarding removing protein with cold water- IME if you have soft egg stuck on a plate, hot or cold makes no difference, it has to be removed by hand before going into the dishwasher.


Might save on the tempering valve then if I can get away with the already tempered 50 degree hot water. Seems like 50 degrees doesn't really 'cook' the food on to the plates anymore than the flushing of the water removes it.
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Re: Saving power on dishwashers and washing machines

Postby Gordon-Loomberah » Fri Jul 04, 2014 10:01 am

The adjustable tempering valve at the washing machine takes its hot from untempered hot, ie, before the tempering valve that supplies shower and sink in bathroom and kitchen sink and dishwasher.

BTW, you may have forgotten about this thread where I posted some graphs:
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