Best advice from TC: verify the water is hot before starting the dishwasher. Especially if your water heater is located a ways from your kitchen and the pipes aren't well insulated.
Best advice from TC: verify the water is hot before starting the dishwasher. Especially if your water heater is located a ways from your kitchen and the pipes aren't well insulated.
Cold water only connection for all dishwashers I've seen in New Zealand. Dishwashers have an internal heating element.
Are modern US dishwashers plumbed into hot water?
NZ has 240 Volts (10 Amp 2400 Watt appliances are normal - anything above that needs special wiring). And NZ environmental regulations might be involved too (modern washing machines can be crappy because they try to skimp on water usage - our regulations can be overkill).
> Are modern US dishwashers plumbed into hot water?
Yes.
It is unsurprising that it varies by country, etc. Below is pure speculation while eating a snack:
Likely dishwashers for the NZ market are designed to actually spend sufficient time heating the water.
My impression from watching the TC videos a while ago is that at least in the US, (many) dishwashers probably only do a insufficient time interval of adding more heat to the water.
It makes sense that different markets developed different ways; the brands that optimize for the local trends (cold vs hot water) can skimp on some features and have lower costs.
The plumber recommended not using hot water from the boiler, since it takes so long for the hot water to start coming through it wasn’t worth it.
I have a hot water recirculator for this. The price I pay is that instead of waiting for hot water at the kitchen sink I've to wait for cold water, as the hot water is recirculated through the cold water pipes.
I have seen a return loop on the hot side, but not returning through the cold side. Do you have more info on this? (I do wonder if recirculating hot through a pipe next to a cold pipe would result in heating the cold)
The thing consists of a) a pump that goes on the output of the water heater, and b) wax-based valves that go between the hot and the cold under each sink where you want hot water without having to wait a long time. The valves turn on when the water on the hot side cools, and they close when it gets hot. The pump stops when the valves and hot faucets are all closed, and it has a timer for scheduling hours of operation. I believe it's this:
So you’re always pumping hot water through your pipes? Does that not end up wasting quite a bit of energy? I guess in winter it’s not a big problem since you’re heating your house anyway, but presumably in summer it is just adding unwanted heat?
In the winter, as you note, it's not much of a waste, and it helps keep the pipes from freezing.
In the summer... this is central Texas, so the sun helps keep the water in the pipes hot, so I imagine that the pump is on less often than in the winter. I've not checked though. My gas bills are not out of the ordinary, so I think it's not a ridiculous waste.
That sounds like a great way to get Legionnaire's, unless I'm missing something.
actually its quite the opposite. because the hot water is constantly recirculating its hard for the bacteria to grow. Kind of like why they say never drink from stagnant water but water that is flowing is safer (not neccessarily safe to be clear)
I think all apartment buildings have recirculators so somehow it works.
I've been doing it for 15 years. No legionella here.
I have to ask, showers?
Yes - over the last decade or so they removed the heating element in most US dishwashers. So they either are connected to the hot water line, or have a mechanism to heat the water (or both).
I could be wrong but I'm pretty sure that even today almost all US dishwashers have some mechanism to heat the water, just maybe not the giant exposed element in the bottom like older ones. Water out of the tap is going to be on the low end of usable dish-washing temps at the very beginning of a cycle, let alone 45+ minutes later.
The reason cold or luke-warm water is a problem is that the programs are extremely simple and just assume the input is 110-120f and won't stall the cycle for waiting for the target temp.
I forgot about the exposed element. These days most plastic spatulas withstand high temperature. Back in the day I think every North American family had at least one yellow spatula destroyed by the element.
My dishwasher doesn't have a big exposed heating element in the pan but it still has a water heater to it. It still gets the water very hot even if I start it without getting the hot water flowing first.
Is it still possible to plumb hot water into such dishwashers? Then the heating element have less work...
I bet some manufacturers don't even use temperature sensors in many models, and just assume an approximate incoming water temperature, and heat for a fixed time period according to calculations on amount of water in the system. This guess comes from the impression that cheap temperature sensing circuitry isn't the most reliable long-term.
I bet you're wrong. Is there a website where we can make an adjudicated bet JUST against each other. How many dishwashers come without a hot-wash option? Any dishwasher that didn't heat water enough would struggle with hard fats.
My dishwasher has a scalding 75°C option.
How did you conclude that they aren't the most reliable long-term?
Temperature sensing is extremely simple and cheap. Bi-metal contacts have been used since the dawn of electronics, and the solid state versions are also really simple. (Making components that are temperature invariant is the hard task.)
If true, that is a recipe for a lawsuit if it went wrong.
For me, moving away from pods to a dishwasher liquid (cascade 3x from Costco) made the most difference. I add some liquid in the prewash and some in the main compartment. I had to figure out the right amount to add in each via trial and error. I don't pre rinse or run the hot water beforehand, my dishes come out clean.
We had to switch from pods to liquid because the pods make way too many suds, so the emergency float shut off was getting stuck.
Source; that time I replaced my fucking dishwasher because I couldn't figure out why it kept leaking so much everywhere.
I had the opposite problem. I used the gel and the dishwasher wouldn’t completely drain. I had someone out to look at it and they couldn’t figure out what was wrong. I tried a pod as a last ditch effort and it worked.
I’ve since moved and use the powder with my current one, as recommended by Technology Connections, and have had good luck.
I'm surprised you made the switch to liquid and not to powder. It's so much cheaper and not as fussy as liquid. That plus a tiny bottle of rinse aid that lasts forever winds up giving me the cleanest dishes.
I tried using powder as well, but the dishes weren't coming out as clean. I will give powder another shot when my current liquid runs out
We use pods, don’t mess with pre-rinse, dishes come out clean. Don’t worry about water temp. We do use jet dry otherwise the dishes come out wet.
I wonder how much this really matters. For me my dishwasher is far enough from the hot water heater that it generally takes several gallons for the water to run hot. But the wash cycle is 2+ hours long and uses very minimal water (~3 gallons/cycle). Even if I preheated the lines using the tap near the washer, it wouldnt even be lukewarm by the end of the wash cycle.
I recently moved into a home where the previous tenants told us they didn't use the dishwasher because it didn't actually clean the dishes. Having seen TC, I checked the kitchen tap and sure enough it behaved like yours: it took a good 60 seconds to get hot.
We started using the dishwasher on day 1 with TC's pre-heated water tip and have yet to have a single problem with the dishwasher.
I think the most crucial factor is that the initial pre-rinse cycle is usually relatively short, so pre-heating the water means that cycle is done with hot water. My dishwasher at least starts out rinsing for maybe 15-20 minutes before draining and refilling the tub. I also think there is likely some effect in that the main cleaning cycle will at least start out with hot tap water.
My dishes have gotten a lot cleaner since I started running the tap.
Trying this tonight.
How'd it go?
It worked much better. The silverware were perfect. Usually there are a few that need to be hand-washed.
Awesome, spread the word!
The first cycle in the wash is where the hot water makes the biggest difference.
2+ hours long??? Surely you're exaggerating
A lot of newer dishwashers have longer cycles to reduce water usage (and I presume get government environmental certifications like EPA Energy Star?). More soak time means less water needed.
My dishwasher's "normal" cycle is 3 hours, but it has a quick cycle that runs in an hour and does about as good of a job with marginally higher water and energy use. We mostly use the quick cycle.
Mine (Bosch 500 series) has a super long drying cycle, what feels like 30+ minutes after it's done washing.
My generic GE dishwasher defaults to a few hours, it feels closer to 4h than 2h. There is also an overnight mode that seems to take almost 8h. And then a quick wash mode that takes 1h.
2.5h here.
> I wonder how much this really matters. For me my dishwasher is far enough from the hot water heater that it generally takes several gallons for the water to run hot.
(I'll preface this with: If your dishes are coming out clean and you're happy with them, then keep on keeping on. The reason there's a lot of discussion around this is because there are a lot of people who _aren't_ getting clean dishes out of their dishwasher.)
If you listen to your dishwasher's cycles, you'll probably hear it do a relatively short initial rinse to get off the bulk of the gunk, then the main wash, then another rinse. (Maybe multiple washes/rinses, but that's the general pattern.)
The idea is to make that first rinse most effective. Anything that can be taken off in the pre-wash cycle is something that won't be washed off in the main wash and cycled over the dishes over and over.
As people normally use their dishwasher, that cycle is being done with cold to lukewarm water and no soap. Most people wouldn't see a oily plate with dried-on sauce on it and think to clean it by spraying it in the sink with cold water until it were clean. But that's what the dishwasher's doing to their dishes.
Hence the suggestion of running the hot water tap first. It's a very easy thing to do to ensure the dishwasher's using hot water in that initial rinse and everyone generally accepts that hot water's going to dissolve and rinse off the food and oils better.
Another very easy improvement is adding a bit of soap to the basin. Most dishwashers only have a single compartment for soap and it's released during the main wash. If you throw a squirt/scoop of detergent into the basin before you start it, that will get mixed in to the pre-wash cycle.
The cycle's happening anyway, using hot water and soap is just making the most of it!
Anecdotally (like all these other comments), my wife's approach is definitely the "racoon on meth" archetype--throw the dishes wherever they could fit, throw one of those detergent pods in, hit "start", close it, wait a few hours, then take all the dishes out and dump water out of cups and bowls and handwash them because they're still filthy. When I was building the kitchen, she was questioning the expense and effort of the dishwasher because in her entire life she's never had one that actually cleaned the dishes properly and thought they were kind of pointless.
Since I didn't want to spend the next however many years hearing about how the dishwasher sucks, after we put it in I played dishwasher czar for a month. I loaded the dishes properly, put in the proper amount of soap (and a sprinkle in the basin), made sure the rinse aid wasn't empty, ran the tap first, ran the dishwasher. Every single load came out spotless. She'd often question something I was putting in because "there's no way it's going to get that off". It did. Every time.
Wife satisfied that the dishwasher is good and having had a month of instruction I unleashed the meth-y racoon on it, and we're back to the dishwasher being a really elaborate rinsing machine we use before handwashing the dishes.
Is it just the running the tap? Probably not. Just like it's not _just_ the adding soap to the basin, using the rinse aid, loading them properly, etc. They all contribute to "using the dishwasher most effectively".
There are no dishwashers in Europe that can be connected to hit water. I had no idea that this is a thing somewhere.
Are US washing machines connected to hot water as well?
That's no true - many european dishwashers can be connected to cold or to hot water. I have a Siemens one that has this option.
Oh, really? I cannot say that I've tried them all, but the maybe 6 or 7 I had (mine or part of a rental) had only cold water connections.
Yes! US washing machines have dual water intakes: one for cold and one for hot.
The best way to do that... Pre-rinse!!!
Pre-rinsing uses way more water than is typically necessary just to get the water hot, especially given that to be an effective pre-rinse you're going to want the water to be hot already before you even start.
You don't rinse everything! There's always a few items that need an extra squirt before they go in. (Like pots and pans.) By the time those few items have an extra squirt, the water in the pipes is hot enough to start the dishwasher.
Don't. I used to do it till I read an article telling me not to do that.
Remove solid gunk. Load dishwasher. Make sure you have Rinse-aid in the dishwasher. Run. Done. Comes out clean.
Rinse aids are toxic substances that will harm your stomach.
previous hn article and discussion: “Gut epithelial barrier damage caused by dishwasher detergents and rinse aids (sciencedirect.com)”
https://news.ycombinator.com/item?id=38275060
All restaurants and food service facilities use “rinse agents” or “drying agents”; they simply never have the time or capacity to air-dry dishes and silverware, so eff whatever the training courses tell us to do, from the County Department of Public Health. Just slather everything with chemicals and make sure nobody can smell them from the dining room or taste it on a spoon.
And yes they’re toxic. Of course they are! Next, let us coat all surfaces with antimicrobial toxins, starting with everything in the hospital, and your infant’s diaper-changing stations, and your stapler at work.
It will be just like Nethack, where you open a spellbook to read it, but it is “coated with contact poison!” so I hope your Unicorn Horn is available.
There is no research that states such. Most online articles are referencing a study done on professional dishwashers, in which they complete their task within 2 minutes and some rinse aid was still found on the dishes.
Home dishwashers, the ones that take 4 hours on average, are not going to result in the same thing. Claiming such would be like claiming you won't use dish soap since technically it can still be left on your dishes when quickly washed.
> Home dishwashers, the ones that take 4 hours on average
I've never had one that took 4 hours. The most is about 2.5 hours.
There is absolutely no need for rinse aids if you already wash the utensils with water before putting the in the dishwasher. This is good practice.
I guess we have wildly different levels of risk tolerance. I even use an extra rinse cycle. You will understand only after have gastrointestinal trouble. Speaking of which, have you had a colonoscopy lately?
If you're going to spend time doing that, why not just wash the dishes by hand anyway?
That takes significantly longer and uses significantly more water.
I can't recall ever using a dishwasher that had a connection to the hot water line.
I've never had one that wasn't connected to the hot water line.
If you've got both available, I can't see any reason why you'd choose to hook it up to cold. That just means it takes longer for your dishwasher to heat up.
Well both are not always available. In many countries, there is no hot water tank/line. There are only inline heaters or very small tanks locally where needed (each bathroom and kitchen sink). Then, you buy appliances such as dishwashers and clothes washers that also have inline heaters built-in (and you don't need to think about this, in such a region, this is the default thing that is sold).
It doesn't necessarily take longer to heat up, they are pretty much instant since they are designed to heat as needed locally as needed (don't need to heat a large volume of water) and they are at least as fast to provide hot water as a central hot water tank. They can be gas or electric powered depending on what is available/cheaper in the region and you never run out of hot water with an inline heater.
Even if you do have a central hot water tank, it's possible that heating water locally at the dishwasher is faster depending on distance to the tank. Anecdotally, I used to wait for hot water in the kitchen when I lived in Canada and I no longer do in Europe where I have no central hot water tank. In North America, recent high end home kitchens feature a local inline heater for hot water at the kitchen sink even though a central hot water tank exists.
Everyone in the uk has a central hot water heater, and nobody has a hot-water plumbed dishwasher. Presumably the 230V supply is enough to heat the water up quickly.
Do you also have hot water plumbed washing machines?
In the US, yes washing machines are generally connected to both hot and cold water. Unlike dishwashers which need to get even hotter than hot water, washing machines generally don't have any internal heating element at all.
If it takes x gallons for your hot water to run through, and your dishwasher only consumes <x gallons before stopping long enough for your hot water line to cool again, then connecting your dishwasher to your hot water line would both waste hot water and never get any.
Our dishwashers in Europe must be connected to cold water (I just checked a manual)
Not sure why you were downvoted. This sounds like absolutely crucial advice for people in countries where dishwashers don't heat the water on their own. I've never seen one like that in my life, but yeah, sounds important.
When the dishwasher has to heat the water, it's slower than from the water heater.
That's because heating water from the 120 volt circuit that the dishwasher runs on is slow. (At least in North America, 240 volt countries might not have this issue.)
I know this is common knowledge now, but just for people who might not realize it: a typical North American NEMA 5-15R receptacle will indeed deliver 120V 15A electricity, but the electrical grid is split-phase 240V. Right across from my dish washer is an electric range; most of these require 240V 30A or 50A receptacles (I think mine is 30A, but I could be mis-remembering.) So it's not like we couldn't have higher power dishwasher, but if you already have central water heating it's kind of senseless to heat the water at the dishwasher.
Ah, I forgot about North America being 120 V, that would indeed explain it. IIRC that's also why electric kettles are not really a thing there while being ubiquitous where I live.
Most people I know have an electric kettle here in the US. Every office I've been to has had one in the break room. Anyone who drinks tea or eats a lot of ramen or drinks anything but drip coffee will have a kettle.
It's really more that historically Americans have been fine with drip style coffee makers instead of drinking pour overs or tea.
I think that has more to do with Americans not drinking a lot of hot tea.
I had an instant 195 F (90.5 C) faucet in my previous kitchen which worked well for the rare times I made tea. Worked fine with a 120V circuit.
This is popular in the Netherlands (the only country in Europe where I saw this)
(At least in North America, 240 volt countries might not have this issue.)
Central America, parts of South America, Japan, and Taiwan are also ~110 volt.
https://en.wikipedia.org/wiki/Mains_electricity_by_country#/...