verizonbear
Well-known member
So how can the turbidity sensor distinguish between foil soil turbidity and detergent turbidity? Do'nt most models sense on the first fill? What if you use detergent in the open cup? Just curious.
turbidity sensors in dishwashers, this has been perplexing me ???
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jerrod6
Well-known member
Not sure If I am correct about this, but I think in my DW a 2006 Miele the soil sensor is in the upper right side of a feed pipe to the upper wash arms. The chamber is a shape such that the detergent suds float to the top while the sensor is at the bottom.
There is soil sensing in the first fill which is a pre wash, which is how the machine determines if it is going to change the water between the pre wash/pre rinse and the main wash. There is also load size sensing that lets the machine determine if the pre wash lasts 6 minutes or 13.
In the main wash there is soil sensing also so that the machine will determine the lenght of the main wash after minutes 12 to 18 of the wash. The sensor is also active throughout the entire main wash because I have seen my Dw add time near the end of the wash also. In the first rinse there is sensing so that the machine can determine if it is going to add an additional rinse so that you get 3 rinses instead of 2.
There is no way to tell the sensing is happening. It occurs as the machine is running and there is no specific thing to let you know it is happening, except if you happen to be in the area and notice that the time left increases or decreases(longer wash time, additional rinse added- time will increase near the end of the first rinse, or the pre wash or wash times decrease meaning shorter wash times). If your machine does not have a display that shows the time remaining and the cycle step, then there is no way to tell it is happening at all.
I think this is how my 2006 Miele G2830 operates, other machines might do it differently
[this post was last edited: 9/17/2014-23:00]
There is soil sensing in the first fill which is a pre wash, which is how the machine determines if it is going to change the water between the pre wash/pre rinse and the main wash. There is also load size sensing that lets the machine determine if the pre wash lasts 6 minutes or 13.
In the main wash there is soil sensing also so that the machine will determine the lenght of the main wash after minutes 12 to 18 of the wash. The sensor is also active throughout the entire main wash because I have seen my Dw add time near the end of the wash also. In the first rinse there is sensing so that the machine can determine if it is going to add an additional rinse so that you get 3 rinses instead of 2.
There is no way to tell the sensing is happening. It occurs as the machine is running and there is no specific thing to let you know it is happening, except if you happen to be in the area and notice that the time left increases or decreases(longer wash time, additional rinse added- time will increase near the end of the first rinse, or the pre wash or wash times decrease meaning shorter wash times). If your machine does not have a display that shows the time remaining and the cycle step, then there is no way to tell it is happening at all.
I think this is how my 2006 Miele G2830 operates, other machines might do it differently
[this post was last edited: 9/17/2014-23:00]
I suppose manufacturers have programmed these sensors so that they can somewhat compensate for turbidity due to powders. There are also some more advanced sensors that use two beams of light or are able to assess the number and size of soil particles in the wash water, such as Miele's AutoSensor.
I believe that detergent would technically count as "soil" if used in the prewash cup, which would prompt the dishwasher to treat the first fill as a prewash so that it drains and refills before opening the main cup, preventing an overdose of detergent.
The 2013 Maytag I have is a slightly updated and improved Whirlpool tall-tub, and the soil sensor is right under the sump grate just out of view. The machine pauses a few times throughout the first water charge, and it is then that the sensor activates. If the water is dirty enough, it will do an active purge, simultaneously draining and filling for about 6-7 seconds, cleaning out the filter accumulator in the process. If the water is still dirty enough after 2 or 3 purges, it decides to fully drain and refill for the main wash. There are pauses throughout the main wash and rinses for the exact reason jerrod6 pointed out, which simply decide if the water is clear enough for shorter washes and rinses, and whether or not an extra rinse is needed.
I only use Normal wash for the most part, yet every cycle seems to be slightly different from what I've noticed. Sometimes it would prewash before the main wash, and sometimes you'd hear the detergent cup pop open after about 10 minutes of just the first water fill. When I had a box of Cascade and poured a little into the prewash cup just as a boost along with the tablet, the machine would always execute a water change before the main wash.
The 2013 Maytag I have is a slightly updated and improved Whirlpool tall-tub, and the soil sensor is right under the sump grate just out of view. The machine pauses a few times throughout the first water charge, and it is then that the sensor activates. If the water is dirty enough, it will do an active purge, simultaneously draining and filling for about 6-7 seconds, cleaning out the filter accumulator in the process. If the water is still dirty enough after 2 or 3 purges, it decides to fully drain and refill for the main wash. There are pauses throughout the main wash and rinses for the exact reason jerrod6 pointed out, which simply decide if the water is clear enough for shorter washes and rinses, and whether or not an extra rinse is needed.
I only use Normal wash for the most part, yet every cycle seems to be slightly different from what I've noticed. Sometimes it would prewash before the main wash, and sometimes you'd hear the detergent cup pop open after about 10 minutes of just the first water fill. When I had a box of Cascade and poured a little into the prewash cup just as a boost along with the tablet, the machine would always execute a water change before the main wash.
Load Sensing
2 ways:
1. Amount of water needed to wet the load (water that pools on top of cups and water captured on surfaces), measured either by variance in pump amperage or by the water level sensor.
2. Rise of temperature per time. More dishes equal more energy needed to heat up.
2 ways:
1. Amount of water needed to wet the load (water that pools on top of cups and water captured on surfaces), measured either by variance in pump amperage or by the water level sensor.
2. Rise of temperature per time. More dishes equal more energy needed to heat up.
rolls_rapide
Well-known member
"There is no way to tell the sensing is happening."
Er, yes there is - on some machines.
My 2004 Bosch Logixx with the alternating spray arms, slows the circulation pump for about 20 seconds or more, then it picks up speed to normal again. A few seconds later, the display shows "Recalculating Time", and the time changes accordingly from say, "1.35" to "1.25".
When I first got the machine, I tested an automatic sensor cycle by putting a teaspoonful of instant coffee powder into the machine. The pre-rinse water was pumped out. I quickly opened the door and dropped another spoonful of coffee powder inside. A second pre-rinse was automatically added before the main wash.
Er, yes there is - on some machines.
My 2004 Bosch Logixx with the alternating spray arms, slows the circulation pump for about 20 seconds or more, then it picks up speed to normal again. A few seconds later, the display shows "Recalculating Time", and the time changes accordingly from say, "1.35" to "1.25".
When I first got the machine, I tested an automatic sensor cycle by putting a teaspoonful of instant coffee powder into the machine. The pre-rinse water was pumped out. I quickly opened the door and dropped another spoonful of coffee powder inside. A second pre-rinse was automatically added before the main wash.
richnz
Well-known member
We have an older Miele. Regardless of the degree of dirt, I am yet to notice it repeat a prewash cycle.
The Sensor Wash cycle seems a closed process in that there are no options for one to adjust (I was expecting some sensitivity adjustment). Nope, just magic.
Not even feedback from the turbidity sensor.
The Sensor Wash cycle seems a closed process in that there are no options for one to adjust (I was expecting some sensitivity adjustment). Nope, just magic.
Not even feedback from the turbidity sensor.
jerrod6
Well-known member
Richnz
Not sure how old your Miele is but mine from 2006 does a decent job of sensing the soil and load size. I use detergent in the prewash even if I use a tab(bit of powder in prewash) and the soil sensor does not care about suds in the prewash. It does care about excess suds in the first rinse because when this condition exists or if there is a lot of oil or cheese left over in this rinse at around the 6 minute mark the time left will increase to a time above where the first rinse began. It will rinse two more minutes, drain, then do a second rinse for about 8 minutes. After that it will continue and do a Final rinse. So for this machine suds don't matter in the washes but they do matter in the rinses. There are also times when the time in the first rinse is increased by about 10 minutes but there is no water change so in this case it is just extending the time of the first rinse and not adding a third.
If I have a small load but still a bit dirty the prewash will last 7 minutes instead of 13. If the load is light soil the prewash lasts 13 minutes, the water change is skipped the cycle display changes to say Main Wash and the detergent cup opens.
During the wash between minutes 12 and 18 if required the machine will increase or decrease the time of the wash. Near the end of the wash there may be another adjustment but so far the only thing I have seen is an increase in the time not a decrease.
Over all the soil and load sensor seems to do a decent job in my conditions, but I am sure newer models may be better at it.
Not sure how old your Miele is but mine from 2006 does a decent job of sensing the soil and load size. I use detergent in the prewash even if I use a tab(bit of powder in prewash) and the soil sensor does not care about suds in the prewash. It does care about excess suds in the first rinse because when this condition exists or if there is a lot of oil or cheese left over in this rinse at around the 6 minute mark the time left will increase to a time above where the first rinse began. It will rinse two more minutes, drain, then do a second rinse for about 8 minutes. After that it will continue and do a Final rinse. So for this machine suds don't matter in the washes but they do matter in the rinses. There are also times when the time in the first rinse is increased by about 10 minutes but there is no water change so in this case it is just extending the time of the first rinse and not adding a third.
If I have a small load but still a bit dirty the prewash will last 7 minutes instead of 13. If the load is light soil the prewash lasts 13 minutes, the water change is skipped the cycle display changes to say Main Wash and the detergent cup opens.
During the wash between minutes 12 and 18 if required the machine will increase or decrease the time of the wash. Near the end of the wash there may be another adjustment but so far the only thing I have seen is an increase in the time not a decrease.
Over all the soil and load sensor seems to do a decent job in my conditions, but I am sure newer models may be better at it.
Load sensing, I am guessing thats why my Maytag starts and stops so many times during the first fill. It fills a bit, pumping the water and monitors the pump to see how much air is pumped through with the water (pump cavitation)... When the pump just stops pumping air through it stops filling. I've timed this between times I've had both racks full, either rack full, both racks full of plates and bowls or the top rack full of cookware and the bottom rack with containers.. All of the times are different from each other and the times with just one rack full or big bulky items are in the dishwasher the fill times are shorter than full loads or loads with lots of little items.
