That seems way less efficient and more prone to issue than just having a central appliance that’s responsible for making hot water.
Comment on Heat-pump water heaters are a winner for the climate — and your wallet
Taringano@lemm.ee 7 months agoI think it’s everywhere but in the US the water comes already hot, in Europe the dishwasher heats it up from the regular cold water.
Zron@lemmy.world 7 months ago
Mamertine@lemmy.world 7 months ago
It is, but the dishwasher has to have a water heater in it. It has to heat water to a temp that you shouldn’t keep you got water tank at and heats throughout the cycle.
Your clothes washer (generally) also has a built in water heater.
Squizzy@lemmy.world 7 months ago
My tank is 60° and my washing machine is 40° and dishwasher is 70° at a maximum. A lot more efficient to have a hot water feed to these that have them increase the temperature 30-50°.
sunbeam60@lemmy.one 7 months ago
In most places in Europe, hot water that’s been stored is treated with some suspicion. Besides, having a heating element is probably the least error prone thing you could make.
Mr_Blott@lemmy.world 7 months ago
A lot more efficient
Hundreds of engineers and scientists who designed modern dishwashers disagree with you
Zron@lemmy.world 7 months ago
Do they not have mixing valves where you are?
wax@lemmy.wtf 7 months ago
That probably means that the hot water tank needs to be larger though. Guess it depends on the heating source though
Peppycito@sh.itjust.works 7 months ago
Dump a kettle of boiling water in the dishwasher before you start the cycle.
burrito@sh.itjust.works 7 months ago
That wouldn’t work with every dishwasher I’ve ever had. They all start the cycle by draining any liquid in the dishwasher before they fill to run the first pre-wash cycle.
Peppycito@sh.itjust.works 7 months ago
Oh. Admitably I’m not an expert, I’m still ony first ever dishwasher. I did that when our water heater died and it seemed to help.
Squizzy@lemmy.world 7 months ago
Yeah the hot water way seems better.
Mr_Blott@lemmy.world 7 months ago
It’s because our dishwashers are massively more efficient and environmentally friendly.
They use very little water, which they heat up themselves to save energy
The only drawback is they take longer to clean the dishes, up to three hours
But nobody would be so selfish as to demand their dishes be done quickly over preserving our environment, would they?
Nollij@sopuli.xyz 7 months ago
Why would that save energy? It’s going to be resistive heat, which at best matches the water heater. Some models in the US include a heating element, but it’s more of a convenience. The vast majority are simply connected to the hot water line, since that’s why it’s there.
Also, let’s talk numbers. From what I could Google, EU dishwashers use 1-1.5KWh/load, while US dishwashers use an average of 1.15KWh/load. Certainly there are more efficient models, but this shows that there isn’t a significant difference in energy usage between them.
orrk@lemmy.world 7 months ago
your energy calculations are forgetting the energy cost of the pre-heated water, it’s the appliance equivalent of an offshore tax haven!
Mr_Blott@lemmy.world 7 months ago
Your system - Add cold water to water heater and heat (using energy). Keep at required heat until needed, could be a whole day or more (using energy). Pump hot water through cold pipes to dishwasher, losing energy. Reheat (using energy)
Our system - add cold water to device directly. Heat (using energy)
Squizzy@lemmy.world 7 months ago
I’m confused, our as in European dishwashers are more efficient and environmentally friendly?
But wouldn’t it be even more so if the hot water that was stored and not being used was the feed instead of cold water? That was the temperature increase is minimal and a lot more efficient.
The eco wash is the best wash on my dishwasher.
Mr_Blott@lemmy.world 7 months ago
The majority of our hot water is on-demand so no. Also, is it more efficient to heat the water, pump it through a potentially cold pipe, only to have to reheat it again? Nope,just heat it where you need it, and with a lower wattage heater
Rivalarrival@lemmy.today 7 months ago
It has nothing to do with energy efficiency, and everything to do with UK plumbing. A building’s hot water system is presumed to be subject to environmental contamination, and not considered potable. Only the cold water supply is considered potable.
It’s the same reason why they have separate taps for hot and cold water, while the US uses mixing taps almost everywhere.
Rivalarrival@lemmy.today 7 months ago
No.
The reason your dishwashers use cold water is because your hot water supply is not presumed to be potable water.
EU regulations allows for gravity-fed hot water tanks in certain jurisdictions, open to atmospheric pressure, and thus possible contamination. They did this to prevent the possibility of exploding boilers.
Since the building’s hot water supply is presumed unsafe, dishwashers are required to use the safe, cold water supply to generate their own safe, hot water.
US regulations do not allow hot water to be held at atmospheric pressure. We use T&P valves to limit boiler pressures and prevent explosions. Our hot water is not exposed to environmental contaminants, and is presumed potable.
Mr_Blott@lemmy.world 7 months ago
Ha ha ha that’s about 50 years out of date bud 😂
theragu40@lemmy.world 7 months ago
I’m so confused. Whose dishwashers are you talking about? I’m in the US, you’re describing every dishwasher I’ve ever had, except that we always hook it up to the hot water line. Our unit takes very little water, it takes hours to run a load due to efficiency features. It has a heating element inside to take whatever water it gets and keep it hot for the cycle.
I don’t really see why it’s any less efficient to use the hot water we are already heating with our water heater (which heats much more efficiently than a small electric heater would). The water originally arrives to my house cold, it has to be heated one way or another. My dishwasher is less than 10 feet away from my water heater, water is not losing appreciable heat on the way to the dishwasher.
sunbeam60@lemmy.one 7 months ago
It depends. Spraying your dishes with water that is prone to legionella doesn’t seem super safe to me. But even assuming that, I have dishwasher programs than run at 70C, which is above what my hot water tank produces.
Besides, isn’t there a heating element in a US dishwasher regardless? Otherwise, it feels like it has got to continually add more hot water to keep the temperature up…
Rivalarrival@lemmy.today 7 months ago
That is the real reason why UK / EU dishwashers use the cold water supply. They don’t consider a building’s hot water supply to be potable water. Their hot water was once held in atmospheric pressure, gravity-fed tanks, exposed to environmental contamination. Brits treated central hot water as unclean. This is also why they often used separate taps for hot and cold water. If they need clean, hot water, they heat cold water at the point of use.
The US never allowed atmospheric pressure hot water tanks. Our hot water is not exposed to environmental contaminants, and is presumed potable.
sunbeam60@lemmy.one 7 months ago
As a Dane living in the U.K., I agree. I’d never seen an atmospheric pressure water system growing up but coming here, that seemed the norm. Now, 20 years after, the norm in U.K. new installation is high pressure water systems (so called “system boilers”) so it is changing slowly. But in the U.K. they have an almost mortal fear for high pressure systems, thinking they’ll explode at any moment.
Taringano@lemm.ee 7 months ago
I believe it’s mostly due to not having always hot water hookups available where laundry would be or not consistently having hot water always available. (as in on demand, from a large boiler that wouldn’t impact the remain of the hot water uses)
sunbeam60@lemmy.one 7 months ago
Yes in many places, hot water is produced on demand in smaller residences. This means your dishwasher relying on hot water would kill your shower.
I know this seems odd probably to Americans … but many houses in the U.K. doesn’t have the space for a hot water tank.
Nollij@sopuli.xyz 7 months ago
I’m intrigued- does that mean the UK uses “tankless” water heaters, at least in smaller residences? Are they underspecced that they can’t handle a shower at the same time as a (typically) 3.5 gallon dishwasher?