The Washing Machine Man

Appliance Specialist.

How does the Auto cycle on my dishwasher work?

Manufacturers attempt to lure us consumers to their product by building in features that attract us and make the function of devices require less intervention.

The dishwasher AUTO cycle is an example of this. The idea is to select, on the control panel, AUTO, and let the dishwasher decide how it will set the cycle.

Here's how it works.

There is a device inside the dishwasher like a camera called a turbidity sensor. This device takes a picture of the wash water after the cycle has started and so allows the controlling computer to decide how to set the cycle. If the wash water is really dirty then the dishwasher will heat the water more as compared to a load that isn't so dirty. Water quantity and cycle times are adjusted too, depending on the information from the turbidity sensor. The auto cycle works within a range of temperatures.  The base temperature of some models for a load of dishes like, say, just coffee cups can be around 45 degrees. The high end of the auto setting can be around 60 degrees for greasy dishes. Some makers have increased the base temperasture to 55 degrees because they have discovered that 45 degrees is not quite enough even for cleaner dishes. Lipstick on coffee cups for example needs that bit more sometimes. 

Makers suggest that dishes are left greasy when the machine is loaded, to give the turbidity sensor something to work on with dirty water. That is, if the water in not really dirty then the load will be set to a lighter duty cycle and therefore may not remove all of the food particles from the dishes. Putting greasy dishes in the machine will therefore 'crank up' the cycle to a heavier duty cycle.

I have discovered that placing really dirty dishes in the machine consistently does make the machine smelly and grease can build up in some areas of the machine. Sometimes dishes remain in the machine for a day or so before the dishwasher is ready to be used. The appliance can become an unhygeinic device quite quickly. Areas around the door hinge and under the lower door are places where the dishwasher doesn't get to, so splashing grease around off of dirty plates soon makes the machine grotty.

An opinion shared by many is to rinse the dishes first. Just a quick whizz under the tap, so removing most grease. But what will this do to the AUTO cycle? It will cause the turbidity sensor not to adjust the cycle to a hot temperature and to set it to a shorter time, so producing a poorer result. We don't want that , do we?    Consider this.

Heat and hygeine go hand in hand !

A fixed cycle without using the AUTO feature at all is a consideration. If the cycle was set to say 60 or even 70 degrees fixed, then you would know exactly what  temperature will be reached.  A sixty or 70  degree wash connects to a 70 degree rinse in most machines. So using a fixed cycle can have advantages. The cleanliness of the dishes is more of a guarantee knowing an adequate temperature will be reached. A hotter rinse will produce better drying too.

I'ts up to you to experiment, but now you have the information which hopefully will clarify the setting of the cycles.

N.B. Concerns about the use of extra water to give the dishes a rinse under the tap first are valid, but remember, the modern dishwasher uses somewhere around 15 litres of water per cycle, so a bit of a rinse first is still no big deal.  

N.B. If rinsing dishes first just leave a bit of grease on them to give the detergent something to 'attack' otherwise there is a risk of having etched glassware. This etching usually only happens in soft water areas. If you have rain water or a water softener then you are at more risk of etching. I have not experienced etching problems in our mains water areas as there are sufficient minerals in the water to prevent this. Etching    ....click here

 

©Copyright Tony Pike 1/1/2011

 

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