Thursday, January 21, 2010

Open Mike: dishwasher vs washing machine

This has been bothering me ever since we became homeowners and perhaps you could help me figure it out. Why does it take washing machine 10-15 mins to do the laundry while dishwasher works for an hour? Our dishwasher and washing machines happen to be of the same brand. They both do pretty good job of removing the dirt. In both cases, the dirt mostly comes from the same source - food. You know, kids...
When doing dishes or laundry by hand, it takes approximately the same amount of time. Right?
Why does it take 3-4 times longer for a dishwasher to clean the dishes from the same food, than it does for the washing machine to clean the clothes?

Let's have an "open mike" style conversation here. No answer is wrong, any ideas accepted. Perhaps we could even patent something :)
Enter your ideas Family Puzzle Marathon page.

13 comments:

bobsyouruncle said...

Because the dishwasher includes the drying cycle. In my house, the dishwasher (which I loathe) takes 2 hours, and the clothes washer and dryer take one hour each.

W said...

@Bobs: I think thats a pretty good answer.

Just to throw out other ideas: maybe it takes a longer amount of time for the water to drain out from the dishwasher machine than the washer?

Maria said...

Interesting points.
I am pretty sure I did not count the drying time for the dishwasher. But we will double-check it with a clean experiment tonight and report back.

By the way, our "fast" washing machine is 7 years old, while our "slow" dishwasher is only 2 years old. Both, Kenmore brand. But even fancier and more expensive dishwashers that I saw were all taking at least an hour.

I know it sounds crazy, but I am tempted to try doing some plastic dishes in the washing machine on a gentle cycle and seeing what will be the result....

Joan said...

My Bosch dishwasher has a "quick clean" cycle that is only 36 minutes. i never use the long one because it is 96 minutes. Dishes are fine on the short cycle. both times include drying. my husband thinks the longer cycle machine have lower water pressure.

Anonymous said...

In a washer, the clothes are moving at high speeds, so the centrifugal forces will help pry the dirt loose from the clothes, after the soap did its part.

In the dishwasher, the dishes are stationary and the water jet has to wash down the dirt with no help from any other force. Hence dishwasher will take more time

Anonymous said...

To add/comment to Anonymous above:
Clothes are submerged in water, and rubbing against eachother during the wash cycle, both of these aspects increase the efficiency of the cleaning process.
If a dishwasher were designed like an ultra-sonic cleaner (filled up with water, then vibrated at high frequency), it too coud clean as fast as a washing machine (but the water bill would be horible).

Anonymous said...

This does not hold true for all machines. My mother's German washing machine takes over an hour for a regular wash, and this is longer than our dishwasher. I have always been puzzled by how American washing machines have such short cycles.

Kim said...

and the bill to replace all the dishes and glasses would be pretty bad, too. :-)

Maria said...

Hey, I am not this crazy. Only a little bit, like most of us. I was musing only about plastic dishes in the washing machine, not plates and wine glasses.

We have some great ideas here above:
1) dishwasher takes longer because large part of the cycle devoted to drying or water draining;
2) in the washing machine clothes are moving at a much higher speed that allows them to rub against each other increasing the efficiency and speed of the process;
3) only some washing machines are faster than dishwashers;

according to Wikipedia:
4) top-loaders washing machines are much faster than side-loaders, but usually use much more water and energy. This may explain why the European versions that someone refers above are on average slower.

Feel free to add more ideas below.
And check for a new puzzle tomorrow morning.

Jenny said...

I'd say the most likely reason is the friction we find in our clothes washers but not in our dishwashers. For an example, hand wash a dirty plate as you would normally: with soap and some type of scrubbing device (sponge, brush, etc.). The food comes off quickly. Now try washing a similarly soiled plate using only a spray of soap and the water from the faucet. No outside friction. It will take quite a while and many passes under the faucet to clean the plate. You could try washing your clothes in a similar experiment but anyone who has ever been out in a downpour of rain can tell you that they would not consider their rain-soaked clothing to be clean.

Maria said...

Love Jenny's answer. Think she deserves a puzzle point for it. Anonymous solvers - please feel free to sign your real or fictional name so that we can assign you puzzle point as well.

Jerome said...

Nobody meantioned here that during the wash cycle in a washing machine, the washing machine moves back and forth (top loading). The cloths change direction very suddenly. It's sort of an example of Newton's 3rd law and the same principle used when knocking snow off your feet in winter. The change in direction causes a lot of dirt to separate from the clothing. Soap helps in the process.

Thad said...

Another factor may be that the dishes need to be cleaned to a higher sanitary level. We're going to eat off of them after all. Do clothes need to be that clean?

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