Disclaimer: This post was originally posted by Hero Member, bdobs. This user is located SF Bay Area 8b. This was originally posted on June 18, 2009.
KH
The AWS system is basic genius. You just need to know where you want the water level, and cut the tubing so that the bottom of the air bell sits at that level, or just a tad deeper.
It works on Bernoulli's Principle to flex a diaphragm closed as the water level (pressure) rises around a sensing cup, and when the pressure rises high enough, the pneumatic diaphragm shuts off.
So once the water level hits the bottom of the air bell and, in essence, seals it off....the diaphram closes and so does the water flow. Once the water in the reservoir drops below the bottom of the air bell, the pressure up top is now enough tp open the valve and let water in. The water will rise and again the pressure below the valve will be greater than above and shut off the flow, and on and on and on.
No, they all don't need to be at the same level. Each box and AWS valve is mutually exclusive of each other. I cant really comment on the needed water pressure to activate the system though.
I am running EB's and non Earthboxes on the same line with no troubles
Brian
Just to clarify things here a bit. This system has nothing to do with Bernoulli's Principle (which relates to pressure differentials between between gasses moving at different speeds. . The water control is a two chamber, diaphragm controlled flow controller. The water level sensor side of the system is open ONLY at the bell end of the clear tube. The bell serves an important role in pneumatic control system. the volume of the bell is pressurized as it is forced into the clear vinyl tube. it is this air pressure which takes the normally OPEN valve and closes it by pushing the diaphragm against a very tiny orifice. If the orifice wasn't there, the pressure side of the two chamber system would require much more pressure to seal the water inlet.
so, while level of the box is important, it isn't critical. For example, if the long axis is tilted such that the sensor is lower than it should be, you will get incomplete filling.... remember, the sensor simply detects and acts on water depth. On the other hand, if the box is tilted back (away from the overflow hole) on the short axis, the system will continuously sense a low water condition and as a result, never shut off.
This isn't complicated. The most common problems that these systems suffer from is 1) debris from an unfiltered water supply that eventually prevents the diaphragm closing the orifice. Remember, the smaller the orifice, the more easily it is blocked.
The patent is well worth reading.
https://patents.google.com/patent/US6848483B1/en
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