Why do modern dishwashers pause so much during the cycle?

[fisherpaykel]

Panthera-Bierschaum test

First Google hits re Bierschaum test I found were measuring the head on a beer pour-not knowing German I don't know the reason. How does this test relate to inadequate rinsing dishwashers? And yes, I want at least 2 full clean water rinses. Interestingly I have an antique English lead or flint glass which will not overfoam a bottle of beer poured in as fast as you can. I don't know if surface leached lead is the reason or something else.

 

[logixx]

Apparently, residue from detergent or rinse aid causes the head to collapse. Miele residential dishwashers had two cycles for beer glasses (warm and cold) that ran without detergent and rinse aid for that reason.

 

[panthera]

Already explained

It's an effective test. When I was looking for a dishwasher to replace my poor '79 3φ Miele I read about the test - it's been my index of cleanliness ever since.

 

 

[iheartmaytag]

On my Kitchenaid Tall Tub

I always assumed the pauses were due to sensing.  Because, when you choose one of the cycles that are sensor cycles, Normal, Heavy, Light/China.  The Machine will fill pause, until the correct amount of water is obtained.  Then there are several pauses during the cycle, which again I assumed were due to the sensor.

 

If you choose the 1 hr cycle, no sensor.  The machine fills to the maximum amount washes, drains, fills.  No pausing.    Also goes to mention that the 1 hr cycle does not allow options so it doesn't have need to pause to heat water etc.

 

 

[volsboy1]

 Besides the senors and heating .They also pause because the motors a lot of them that I have worked on  Whirlpool and Frigidaire the ones with the Askol pumps say on the side of the motor.

15 mins on then 3 mins off or 15 min on 5 min off..They put such cheap motors in them now compared to the loud continuous duty type of the good days .

 

[johnb300m]

Motor duty cycles

I must partially disagree with the reason machines pause is due to the ON-OFF duty cycle time of the wash pumps.
Granted, on many drain pumps they can overheat and must have rest periods.
But....we have seen several pieces of evidence on modern dishwashers already, that have these "wet rotor" motors with duty cycles stamped on their labels, yet they WILL run nonstop for a whole cycle segment and be perfectly fine.
I cannot explain why they have duty times on them and not abide by them. Yet some do, such as drain pumps.
But the pausing due to the duty cycle? I have to disagree.
Especially since whatever pausing does occur, never seems to be long enough to match the OFF duty time of the motor call-out.

 

[panthera]

Duty times

Assume certain conditions. I'd guess those conditions are considerably less well ventilated/not conduction cooled/hotter/closer to stall than what these motors are doing in modern dishwashers.

It's not as if they were actually moving any great volumes of water or being subject to tremendous thermal load without any cooling.

Be interesting to research the conditions behind those rating tags.

 

Same with the infamous solenoid and GE's pump. I've had some vintage potscrubbers which hold it down for longer than 15 seconds (Twenty-Eight Hundred, Twenty-Five Hundred) and some which do not. Same solenoid. Just, with that humongous fan blowing right on it in the shaded-pole motor version, who'd worry about it getting warm, much less hot?

 

[tomturbomatic]

Jeff told me about servicing a relatively new KA dw. There is a slowly turning motor which turns a disc in a valve body that selects which wash arm is being powered in that as it rotates, water is directed to different arms. When the valve interrupts the flow, there is no sound. Maybe that is what is happening when you hear nothing from the dw. The lovely thing is that the seal or bushing wears out and the pitiful stream of water that is directed through this motorized distribution valve then leaks down the shaft to the motor and takes it out.

 

[gelaundry4ever]

dishwasher pausing

It pauses repeatedly to allow water to soak into the soil of the dishes for better removal.

 

[seedub]

Edit to my earlier post here

I learned later that my unit *IS* equipped with a soil sensor that works on the Normal cycle.