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Comment by oh_sigh | Hacker News Reader

On the topic of dishwashers, can anyone tell me why no dishwasher let's me fill it with, say, 20 loads worth of detergent and then it just dispenses it as needed? My dishwasher can do that with "rinse aid"(which I don't use), but I've never seen one that can do it with regular detergent.

Another "hack" is that the tray you're supposed to fill with detergent is almost always way too big. People think "more soap -> more clean", but that is only true to an extent. You will be just fine filling it only halfway up, even if you have a full load in there. The same goes with laundry detergent.

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My dishwasher can't do that, but my clothes washer can. The limitation is space inside of the device for the reservoir. In a clothes washer there's plenty of space between the cylindrical wash basin and the square housing, but in a dishwasher there is much less available space between the square dish cavity and the housing, and that space is generally filled with sound deadening and thermal insulation.

Great observation on space utilization!

GE makes dishwashers that do exactly this. You look up your water hardness in a table, push some magic buttons as described in the manual to tell the dishwasher how hard your water is, and you pour detergent into the reservoir. Interestingly, you are strongly advised not to mix chlorine-based detergent with enzyme-based detergent at risk of turning the mixture into hard-to-remove goo.

Are you sure you're not thinking of dishwasher salt? https://fredsappliance.com/service/dishwasher-salt-use/

Yes.

https://products.geappliances.com/appliance/gea-support-sear...

Sadly this seems to have been discontinued.

Seems like determining water hardness would be something the dishwasher could do.

Have you ever taken a dishwasher apart? I have and it's an unbelievably simple machine that they charge you big bucks for. There's a lot it could do but manufacturers are in the business of making money, not selling complex, hard to maintain machines.

They are very simply constructed - and I think that's for two reasons: 1, it's cheaper, and 2 - My experience with dishwashers is that they are sort of intended to be disposable. They're relatively cheap, and replacement parts for the things that can fail regularly are very nearly as expensive as the actual machine.

The control board is the thing most likely to go (electronics and water); everything else is floats and switches. It's also 7/8ths the price of an entirely new machine.

This is one conspiracy theory I whole-heartedly subscribe to.

My experience (and this may be brand or price-point dependent) is the opposite. My Bosch had a couple of failures (that ideally would never happen, of course), but because the parts are fairly standardized and the design is very elegant, I feel like it's one of the last few "owner-repairable" items in the house.

The replacement parts were very reasonable (a fraction of the original cost of the dishwasher), easy and quick to obtain (from a particular retailer which also does very informative non-pushy YouTube videos for reparing/diagnosing problems), the diagnosing was straightforward (like debugging code), and the replacement was manageable (if a little cramped).

There may be a price cut-off where this starts being true, and where it stops being true. My particular dishwasher was ~$1k 10 years ago, has had ~$120 of parts replaced over that period, one of which was cosmetic, and has otherwise worked flawlessly. All in all, I'm very happy with that trade-off.

I just checked, and there are two control boards that could be replaced - each $150.

I'm pretty enamored with the engineering elegance of the dishwasher. Until I opened one up and had to fix something I always thought it would be a lot more complicated than it really is.

I've had the same experience with our Bosch dishwasher.

It may depend on the manufacturer, but my impression was they were usually about the simplest white goods to repair. You can buy the pumps, valves etc cheaply, and they’re quite accessible.

This is like Apple charging half the phone to fix a cracked screen.

Half a phone? The screen repairs are like $100-200 depending on your model, while the new phone is over $1000. It's also not just the glass, when you get your iPhone screen replaced, they replace the entire front half of your phone, basically everything involved with the display, and put a new front on. So I think you are pretty wrong here, I think they charge less than half the phone, and you actually get half of a new phone.

They can be well over $200 for some phones:

https://support.apple.com/iphone/repair/service/screen-repla...

I get that it's a lot of parts, but this is the most fragile piece of the phone and Apple would be wise to take a note here from their competitors and explore other options. There is no reason why it needs to be a lot of parts replace to fix your cracked screen, or even have a screen that cracks at all, other than a lack of imagination in the engineering department.

The inexpensive ways to measure hardness are colorimetric: you add some reagents to the water and look at the color. Electronic colorimeters exist but are not particularly cheap. Electronic colorimeters with automatic reagent dispensing also exist and are quite expensive. And you need reagents.

I’d rather save $500 or more on my dishwasher and type in the hardness. Even without my utility report, hardness tests are cheap if a human operates them.

The main annoyance is the fact that there are a couple different units for hardness.

Probably not worth it, since your hardness doesn't change, and is a number that you can get from the water utility.

You're not buying expensive enough dishwashers - Miele have recently launched machines which do just that:

https://www.youtube.com/watch?v=tQPmumBcAF4

They use a proprietary disposable reservoir, so there's an opportunity to get hacker points by working out how to refill it yourself!

One design issue would be keeping the reservoir and chute dry enough that the detergent supply doesn't cake up. Another is that dishwashers are designed to fit into a very specific space in a typical kitchen, and any extra gadget takes away from the capacity of the tub.

Or even easier, just create a hockey puck of detergent that dissolves a certain amount each time you run it. Kind of like those toilet pucks.

Once it disappears, drop a new one in.

Some users might get annoyed if it isn't compatible with whatever type of dishwasher detergent they want to use. And there are at least 4 types: liquid, powder, gelpacs/pods, and tablets.

It's easy to solve that with a compartment and a door that flips open. I don't know of an easy way to solve it for 20 loads.

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