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Comment by superseeplus | Hacker News Reader

Also worth checking your dishwasher manual to see if it has a minimum temperature requirement for the incoming water. If it does, run the kitchen faucet till the water gets as hot as it can before starting the dishwasher. Many cheap dishwashers have a heating element which cannot heat the water to the required cycle temperature unless the incoming water is hotter than a certain temperature. More expensive dishwashers can work with cold or hot water.

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My belief is that manufacturers use the same heating elements between europe (240V, but often piped to the cold water line) and North America (120V, but usually piped to the hot water line).

No matter what, North American dishwashers will only be able to draw 1500w, and probably less because they're not always on a dedicated circuit, and have other power needs than just heat. So it's probably not a "cheap diswasher" vs expensive one issue.

I’ve seen no models that are the same across the US and EU market, do you have any evidence for this?

The amount of water heated up in each cycle is small enough that 1500W is not the limiting factor. Maytag recommends connecting to the hot water outlet and recommends a minimum temperature of 120F [1].

The Miele user manual for their USA models recommends connecting to the cold water inlet unless the hot water is known to be heated by a very efficient source [2].

[1] https://producthelp.maytag.com/Dishwashers/Product_Info/Dish...

[2] https://media.miele.com/downloads/05/c4/00_96106053F20B1EDDB...

> recommends connecting to the cold water inlet unless the hot water is known to be heated by a very efficient source

Huh? How does it matter to the dishwasher?

It doesn’t. They just assume that the user is looking for the most efficient solution. There are pros and cons though. The delicate crystal cycle uses a very low temperature and will only work with cold water. Some of the faster cycles will only be as fast as claimed if the supplier water is already hot.

I haven't checked code - but since my wiring had the dishwasher and garbage disposal shared on a single 20A, I would expect that each now have a requirement to not consume more than 1200W.

At 1200W and a 2.5 gallon wash cycle, I'd expect heating from 70 to 130F would take about 20 minutes. Unless the pre-rinse cycle was extended, I would expect this would mean the soap was released at the start of the wash cycle before the water was to temperature.

... And don't forget to check that your dishwasher actually is hooked up to hot water, not cold.

I don't think many people outside of the US actually hook their dishwasher up to hot water? And dishwashers work just fine in eg Germany.

(Though they might have different dishwashers in Europe with better heating?)

I'm rather confused about that as well. My dishwasher is hooked up to cold water because that's the only option.

Why would it be the only option? It seems to be the standard in Europe, but not sure why you couldn’t connect it to the hot water line instead. This is especially true if you have an efficient hot water source like solar or a heat pump water heater.

You have to hire (or be) a plumber to make the change. Often getting access to the pipes can be tricky. Depends on how your house is though. Sometimes this is as simple as connecting the hose to the other valve already in place, sometimes this means opening up the wall to get access to the pipes.

Normally the only pipe that's available to dishwashers is the cold water pipe.

However, even if you had hot water available, it would actually be to hot. The hot water entering can be much hotter than the required 30C for the lowest setting, so the dishwasher would need to cool the water.

In the U.S. dishwashers are almost always installed directly next to the kitchen sink, where either the cold or hot line can be easily tapped with a tee valve. I guess plumbing/kitchen layout is done differently in Europe.

As for heat setting, what’s the reason to be concerned with tap water being too hot? I don’t think plumbing code would allow water to be available at the tap that was hot enough to actually damage any type of utensil/drinkware/etc? I presume the only reason there might be a lower heat setting is simply for energy savings, which is kind of moot if you’re instead pulling hot water from the efficiently heated water supply.

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