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Comment by eetus | Hacker News Reader

I'm sure that some restaurants could use a faster dishwasher.

Having washed dishes for a while, actually no. A commercial dishwasher only takes ~2 minutes to cycle and dry. They run hot as all fuck. It's the people like me you wanted to be faster.

Commercial dishwashers are not as good at getting food off plates. Any crap left on the plate will get spread on everything else, so you have to pre-wash everything first. You should really do it at home too, but most of the reason a home dishwasher is slow is because it is actually trying to spray every dish, knock stuff off, and then grind it up enough to go through the exit filter. Also, you should clean your filter.

> Any crap left on the plate will get spread on everything else, so you have to pre-wash everything first. You should really do it at home too, [...]

Why? If I have to wash my own dishes, that would defeat the point of a dishwasher..

You'll have to clean that stuff out of your dish washer otherwise.

That's less work than pre-washing all the dishes.

Not really. It’s ground up and goes down the drain with the waste water.

The Technology Connections YouTube channel has some nice, in-depth looks at dishwashers and soap.

> Not really. It’s ground up and goes down the drain with the waste water.

It depends. What you describe is common with American dishwashers. European dishwashers typically don't grind anything up, they just collect it in a sieve.

If you buy a dishwasher with that feature. It's not standard. I know because my parents went cheap on their last dishwasher purchase because "they're all the same." About two years later I got to help troubleshoot why their dishwasher wouldn't get anything clean... the bottom of it was basically a solid layer of rotten food particles.

You don't have to wash the dishes first. Just rinse them under the tap before you put them into the dishwasher. I'm assuming you don't let the dishes pile up before you do that - if you do, you'll get dry dirty plates and 'ware and then yes you would essentially need to wash them by hand. I always rinsed my plates before putting them into the dishwasher (when I had one), it took all of a few seconds. I hate the gunk piling up in the filter, and I definitely felt that the dishes didn't come out as clean as I wanted either, unless I hand-rinsed first.

Compare https://www.youtube.com/watch?v=_rBO8neWw04

My dishwasher manual specifically tells me not to pre-rinse.

Commercial dishwashers sterilize dishes with high heat and steam. It's expected for dishes to be sprayed first by the person doing dishes with a high pressure hose to rid solid food before wash cycle.

Consumer dishwashers instead let enzymes do the work.

So, different applications.

Sure, but I was responding to the commenter saying you really should pre-wash at home too.

As others have mention, commercial dishwashers are faster. With cycle times well under 2 minutes.

The primary purpose of a commercial unit is to sterilize. Cleaning off stuck food is secondary for the machines, as a by hand pre-wash is assumed.

There are two main styles to achieve sterilization:

1) chemical systems. These need a water source of around 130F, use a series of harsh chemicals for cleaning, sterilization and speeding drying. While a home water heater is usually set to a high enough temperature, the commercial dishwasher requires its compartment water to be at this temperature. This usually requires a near by instant water heater.

2) hot water systems. These rely on a water source that is around 180F and do not typically rely on additional chemicals. To get water hot enough requires an attached heater. In North America, this often requires a Three Phase electrical connection.

All of the commercial systems use vastly more energy and water. They produce huge amounts of noise. And far more steam than a home owner would want, they often require ventilation systems to deal with the steam.

This covers the basic styles of dishwashers that would be somewhat recognizable to a homeowner. In fact there are a vast number of specialized systems, depending on specific task and operational scale.

Source: I own a coffee house/bar/bakery

More info

https://www.webstaurantstore.com/guide/620/types-of-commerci...

Back in college i spent a year working part-time as a dishwasher for the school cafeteria. That amounted to me using a high-pressure sprayer to pre-clean some of the dishes and utensils (watch out spraying those ladles though!), and then putting them on a conveyor belt that would wash and dry them very quickly. Much like this one:

https://www.youtube.com/watch?v=HCM13eOWVgY

Same idea as every restaurant I've worked at, though some were smaller.

But yeah basically high pressure hose + conveyor belt.

The dishwasher's job was mostly to scrape and spray everything beforehand, pull forks out of the trash, etc. Some glassware had to be done by hand, too.

You're supposed to let the dishes cool before using, but in practice they went out almost immediately. Could cause problems if they were chilled rapidly, hot glasses used for sodas with ice, etc.

Restaurant dishwashers are a different beast to what you have in your kitchen. Gets the job done in seconds. Of course, they are also very expensive, really loud, uses very hot water, are really large, and probably use harsher chemicals.

I worked in a hotel kitchen as a teenager in the early 70s. I don't think we used any chemicals at all in the dishwasher. But we did rinse the dishes first. They were so hot when they came out of the washer that they dried instantly and were too hot to handle with bare hands.

> . They were so hot when they came out of the washer that they dried instantly and were too hot to handle with bare hands.

This is not far off how your dishwasher at home works either - open it when it switches to "dry" mode and you'll notice that everything is hot as hell. The "dry" time is relaly "cooling down" time.

Oooh, yes. Though the "done in seconds" commercial dishwashers are a good number of model & feature upsells above the most basic ones. Might need 240V and serious amps, too.

I think they already use professional dishwashers that blast the dishes clean in about a minute.

This guy has one at home: https://www.youtube.com/watch?v=lnKAVFBIH1c

This french company sells 'Bob', a miniature restaurant-like dishwasher: https://daan.tech/ch/discover-bob-mini-dishwasher/

There's an interesting project about refilling their proprietary detergent cartridges here:

https://github.com/dekuNukem/bob_cassette_rewinder

Thanks for sharing that, it's super cool ! Loving to see that there is this effort done. I will definitely try it out.

“Robust, designed to last 10 years”

Wow we are setting the goals low these days.

It's depressing to see how society accepts such low standards.

They do which is why they have special industrial dishwashers. I worked in a restaurant many, many years (decades?) ago. There was a room dedicated to dishwashing. There was a manual pre-rinse area and the washer itself would blaze through a rack of dishes in minutes. A guy manned it full time during the busy hours.

This wouldn’t be practical in a home.

Restaurant dish washers are already extremely fast and efficient. They wash dishes in a couple of minutes. They also consume a lot of power and water, and take some time to heat up in the morning when starting work.

Restaurants use faster dishwashers. Those things are a sight to be seen

yup! i used one once in my life and the amount of pressure they create is absolutely crazy. the one i used could clean + pre-dry everything in like, 90s.

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