this post was submitted on 22 Nov 2023
535 points (98.0% liked)
Technology
58070 readers
2799 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
I 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.
Yeah the hot water way seems better.
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?
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.
your energy calculations are forgetting the energy cost of the pre-heated water, it's the appliance equivalent of an offshore tax haven!
Do European homes not have hot water heaters?
They do, they're just not connected to the dishwasher so don't need to be factored into its energy usage.
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.
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.
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
Who is "our"? I don't know where you live dude
everyone, ever. unless you are running some industrial operations that require constant hot water, there is no reason for even a large family to be using water continuously, and hot at that
Heating a volume of water a given number of degrees takes the same amount of energy regardless. Using a lower wattage heater is just going to make it take longer, not save any power.
So if you heat the water in a tank, pump it through a cold pipe to a dishwasher, then reheat it, you're suggesting you're using the same amount of energy as heating cold water directly in the dishwasher?
No idea how Americans can't understand that most of the developed world is decades ahead of them environmentally nowadays 😂
I understand the difference, I was pointing out the wattage thing doesn't really make sense.
Using gas to heat water is considerably cheaper than using resistive electric. Especially when the electric was historically provided by coal or gas anyway.
Burning gas to heat water into steam to turn a turbine to turn a generator to pump electricity to a resistive element inside a dishwasher is not nearly as efficient as just burning the gas inside a water heater and sending it to the dishwasher. The heat losses incurred while passing the water from a gas heater to the dishwasher are a tiny fraction of the losses incurred in the convoluted processes involved in traditional electrical generation.
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.
Ha ha ha that's about 50 years out of date bud 😂
It may be 50 years out of date now. It wasn't 50 years out of date when dishwashers became common and the standards were established.
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…
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.
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.
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)
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.
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?
Speaking for The Netherlands here, but I believe our situation is very similar to the UK in this regard. A lot of houses are equipped with a gas-powered tankless heater which supplies both central heating and hot water. These come in various sizes and output capacities, so you can install one which comfortably suits your needs. Using hot water for multiple things at once shouldn't be an issue if you have the right heater installed.
In the UK your dishwasher is typically connected only to the cold water intake, so that's not a problem unless you have multiple showers in your house... that said, water heaters are often limited to either heating or hot water (not both at the same time), but that's not an issue in practice since you're not going to be using the hot water for long periods of time.
That seems way less efficient and more prone to issue than just having a central appliance that’s responsible for making hot water.
Dump a kettle of boiling water in the dishwasher before you start the cycle.
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.
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.