Dishwashers Alternating Wash

[countryguy]

I know that modern dishwashers are all about energy conservation but why do they alternative the water to the bottom and middle spray arms? Are the pumps so weak that they can't put out enough water to both arms at the same time? I had a '91 Maytag with a full sized wash arm on top along with the spray tower in the middle and it sent the water to all 3 levels. Other than being noisy, that machine could clean anything. Except for a select few, why don't modern dishwashers have a full sized wash arm on top instead of that small constant rinse arm?

Gary

 

[dj-gabriele]

It's not the weak pump but the reduced water usage.
There actually isn't enough water to run both showers at the same time!
Go figure that an "older" machine (say 1999) used 20-22 litres per water each cycle and had enough to pump in both arms at the same time.

A current machine uses half that much and physically can't pump in both wash arms with the same pressure or the pump cavitating, so it was solved using a wash arm at a time. Same result, less noisy machine, halved water use and same cleaning power at the expense of longer cycle times.

Some high end machines can be set in "quick" mode (varioperfect in Bosch, "forte e veloce" in SMEG, etc...) they use more water and run the pump in a more powerful fashion to complete the cycle faster at the expense of energy and water consumption.

As far as the third top arm I find it almost useless, I have a machine with bottom and middle only and cleans well, and another with the third shower arm and orbital cleaning and it cleans perfectly all the time (but we're comparing two different market segments, very bol and very tol!)

 

[cycla-fabric]

I will guess to say that there is not enough water in the tub to be diverted to all spray levels at one time. A cup of water can only go so far in cleaning a load of dishes.

Doug

 

[countryguy]

On my Maytag the normal wash/rinse cycle was 45 minutes with an additional 30 minutes for a heated dry. My current K/A (about 5 yrs old) runs for over 2 hours on the normal cycle (I'm guessing about 90 minutes wash/rinse). So running an electric motor for twice as long but using less hot water is that big of an energy savings?

Gary

 

[re563]

Actually.......

there is energy savings. Even though the machine is running longer, the motors suck up less energy than say your 1990"s model. I believe your maytag has a 1/3 horse power moter. Today most manufactures are using 1/5 horsepower. This along with turning down your hot water heater to 115 - 130 and letting the dishwasher heat the water own it's own works very well. Also, since the removal of phosphates from dishwasher detergents, they work best with a cooler, longer wash. The final rinse is heated to 140-155 degrees depending on what options are selected.

 

[petek]

On our KA when it's running on the one hour wash cycle you can hear that it's running pretty much full blast throughout. However on the sensor cycles which take up to 3 hrs, after the intial full blast washing it sounds like it winds down, the detergent dispenses and is basically just giving the dishes 90+ minutes of a gentle soaking. Keep anything wet that long (incl the kitchen sink) and of course it's not going to take much physical force to remove the remains .

 

[logixx]

Yes, lower water intake results in only one or two spray arm working (two if you count ceiling wash arms or nozzles).

My Bosch will use 10 liters (2.6 gal) for a three-hour Eco wash or, on the same cycle with the speed mode activated, 13 liters (3.4 gal.) while reducing the time down to one hour. It'll still alternate between lower wash arm + ceiling shower OR middle arm, though.

This load took 95 minutes to complete: a warm prewash, 70C (158F) wash, two hot rinses, a 73C (163F) final rinse and drying.

 

[yogitunes]

my brother has a Bosch that I installed....one advantage to the selected zone wash, is he can wash "top rack only" for say, glassware or smaller loads....or "bottom rack only" where the top rack comes out, and you can wash tall pots/pan and/or cookie sheets.....

somewhat of an advantage...

 

[washer111]

Hmmm.

If our Dishdrawer were a full sized dishwasher, I doubt it would be very be very frugal. The spray force and water sloshing has to be seen to be believed. Its rather amazing people get poor washing performance. It uses 6.7L for the Normal cycles (Wash (50ºC), ONe Rinse then Final RInse at 60º to improve drying). 

 

Here is my "proof" (thanks to Dadoes for this video)

 

[jerrod6]

would have loved to see that video but with dishes inside the machine.