You won't believe it: Save money by running your dishwasher on hot water? Full calculations!
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- Опубликовано: 29 ноя 2021
- Dishwashers usually only take on cold water, but what if I run it on hot water heated using gas rather than electricity.
The unit rate for my gas is about 5p but my electricity unit rate is about 23p per kWh so it makes sense that if some of the heating is done by gas then it should work out cheaper.
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We had a very cold toilet room and so I connected the hot water into the cistern and that kept the room warm in winter .True story .
If you run hot water out of the washer and keep the water in a large drum it keeps the house warm . We did that one cold day .For a dishwasher the food particles need to be considered as they might collect until it`s cold . A filter might work so the cold water can flow out easily
Owen, glad you included the rinse with hot water, you obviously have a hot water on demand (combi) type boiler to be able to quantify the gas consumption. Very interesting concepts and out come. It's not until you do the experiments that these factors become evident, splendid, cheers
Thanks Andy, yes, we have a combi. I was surprised by this experiment. I thought it would use a similar amount of energy, and that the difference in price would take care of any difference in energy, but I suspect that there are two rinses. I "invested" in a 1kW travel kettle that can boil a single cup. I have been doing some tests comparing it to our old kettle, that needed 2 cups to cover the element. Initially I got it to simply boil the water I needed, but then winter rolled in and all the hot water is coming off the range. But my comparison becomes redundant as the kettle takes less power, so the solar can probably run it in sunshine for free. But how to make a video of that?
I have a foggy double glazed unit that I am thinking of repairing, seems easy enough. ever done it?
@@bootsowen dishwashers are supposed to be cold fill only and heat their own water for hygiene reasons I read that somewhere
What are "Hygiene reasons"?
@@bootsowen Owen, the small 1 Kw kettle doesn't seem obvious to many people, ooh it takes too long, as if there time is that constrained!
Double glazed units: well the edging strip that keeps he glass apart is full of silica gel and has self adhesive strip on it. If you can split the unit with a Stanley knife between the glass and this strip then you could put this half somewhere warm to dry that out completely. Fine dust on the glass is the major problem when putting it back together. I suppose having the glass quite warm would then create a sort of vacuum when it cooled. What sealant would you use? cheers
I have seen a good video by @rlbob1. he does it all manually and fills the panel with welding argon. I have a bottle of that already. I have seen a website in the UK recommending Everflex 225 silicone. I don't mind giving it a go. I have a unit in the inside porch doors, they are 60mm thick teak double doors with full clear double glazed units, skip find, the appeared fine but when hung one has mist. Worst case scenario is that I lose my time and some silicone. Like you say a clean workspace. I have heard that you can dry the silica gel, or buy more on ebay.
As for the kettle, I haven't timed it, and I haven't died of thirst either!
In the USA (and Canada) dishwashers are always plumbed to the hot water line, probably for this very reason.
You could transform this dishwasher into hot and cold. Basicly you would have to make a device that switches to hot fill for for a few minutes after starting the machine(so dishwasher has time to fill itself with hot water) and after some time (a safe amount of time you would be sure that machine isn"t gonna add any more water) it switches back to cold fill. Simple timer based valve switch
The prewash will work better if the water starts off warm, but it needs to be running warm into the dishwasher. If it's cooled down in the pipework, it's the same as cold. So you may need to run the nearest hot water tap into a bowl, bucket or sink with a plug in until the water runs hot (you can save this water for another use).
If you can find a good dishwasher powder (or gel), you can fill both the prewash AND main detergent cups for even better cleaning. Best if you can do that along with using the hot water connection.
Have you watched Technology Connections video titled:
*Detergent packs are kinda wishy-washy (Dishwashers Explained)*
It's all explained in that video. 😎
You would be a dream maths/science teacher 👨🏫🤩 loved 💕 your clever whiteboard skills 🧙♂️
Thanks. Great work 👏 👍
nice experiment.
It'd be interesting how your calculations would fare if you had a heat pump and a hot water tank. Assuming a COP of just 2 for DHW, it seems that the heat pump would be cheaper via a hot fill. I'm guessing the normal COP for DHW is around 3 however which makes a big difference.
Perhaps this is why Miele are bringing the "hot fill" stuff back - Because of heat pumps
I reckon if I have hot water from solar over the summer it may be worth running it on hot water, that way the hot would be free!
@@bootsowen I guess this is why Miele have a "solar save" option
Good thinking Boots,I had a similar idea with the Bosch washing machine,I have plenty of hot water from the range in winter,so instead of using the leccy to heat the water....only snag being will the Bosch say noooo!!
That's the thing, if you have free hot water from wood or solar then you are ahead, I'm still burning gas so it's pricey!
Problem is machine does two or three rinses, which is a waste of hot water. If you could be bothered you'd have to switch to cold after the wash cycle's started (unless machine's hot and cold fill).
Another factor that plays a role is that when the dishwasher starts filling, water in the hose is cold. The hot water from the boiler needs time to get to the machine, so it might fill with water which is still warm.
General advice is that unless the gas boiler's a short run from machine it's not worth it because there's cold(er) water in the pipe and by the time the (combi) boiler's recognised a draw and started heating, a considerable quantity of colder water's already in the machine. Worst case scenario's that hot water never reaches the washer due to length of run but is wasted sitting in the pipe - so it's cost more than otherwise. You could run the hot tap to ensure the water got to the machine quickly, and lagged pipes help.
Calculations should assume a condensing boiler may be 90% efficient, whereas electric is 100% at point of delivery - thus you get 90% of the unit cost of gas but 100% of electric. This only makes a small difference given that electric is three times gas price.
Note that modern d/washers either don't have a heated drying cycle or allow deactivation to save electric. I find residual heat from the final hot rinse is perfectly adequate except for plastics.
American machines are normally connected to hot but the same observation applies above: how much hot water actually reaches the machine and how much is it boosting with its heater?
I don’t know if I agree with that general advice. If you hear your hot tank with solar or wood then it no longer applies.
We tried that when the heater on our bekos heater died and what happened is it didn’t pull enough water to actavate the boiler
No soundbar video for me ! 😧
I'm sad 🥺
How can I make a video about it? What would it do? Stir my coffee?
@@bootsowen And what can you not do with a soundbar !? Perhaps you can show me around take it apart or burn it break it in half I don't know the possibilities are endless