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Thread: Detecting Water system problems before...

  1. #11

    Re: Detecting Water system problems before...

    Thanks Slugman,

    Low tech can be good. I have seen a few examples, like this. My problem is that I don't typically look at the pump house these days as the trees are really growing up around it. Most of the examples I have seen with the pulley setup are for large outside tanks. Our tank is built into a pump/tank building. Another option inside the tank room, would be a clear level tube like are often put on boats.

    I probably have quite a few options to play with here. Probably the simplest would be, that I could try to connect up a light to the outside of the building, that turns on when there is power available to the pumps. There is a circuit breaker, that runs power through a float valve near the top of the tank, that is on when the tank is not full. It then gives power to the Contactor (sp) which is more or less 4 relays that gives power to the two different Well pumps. So can probably hook up to that circuit with a bright light...

    Right now I am playing around with the radios. In addition to the two Feather M0 radio boards, I purchased a couple of the RFM95 LoRa breakout boards which I am experimenting using Teensy 3.2 (and a 3.6 beta) boards. Will be interesting to see in the next few days if I can talk directly from my office to the pump house. If not may have to try building a repeater...

    I am currently starting off by measuring currents. I will probably monitor the power going out of 4 circuit breakers.
    Well 1, Well 2, Pressure Pump, Heater. Note the three pumps are 220V, so will only monitor one leg of each. So far I have three of the Sparkfun current sensors, which have small headphone jacks at the end. I did a quick and dirty very small circuit board with a connector, plus load resistor and resistor divider and a 3 pin connector, which I ordered a set of 4 of these for $2.34 from digistump. Should ship in the next couple of days.

    Once I know these are working, I will either use one of my existing Teensy boards, or may make a new custom one, that has breakouts for the Radio, connections for current sensors, probably a direct connection to use Teensy 2.8" color touch screen, and a few extra connections for maybe things like temp... Then probably do a quick and dirty case design to 3d print...

    With the above, I will not be able to detect how full the tank is, but hopefully can detect that the tank is full or not.

    I should be able to detect this two different ways.

    1) If both wells come on at the same time, it is most likely because the float valve turned on the circuit to both pumps, so tank WAS full before this.

    2) If both turn off at same time, most likely because of float valve.

    2.1) Could not count above If they shut off or start at different times, then at least one of the pumps have pumped their reserve dry and the pump saver turned the pump off. We can hopefully detect this the same way the pump saver does. When well is out of water, the pump starts to use less current as there is nothing to pump. So the pump circuitry detects this and shuts off power to keep the pump from burning out. It then starts a timer which allows the well to recharge and after so much time it turn back on. I am assuming I will also see this current drop.

    Some of the monitoring of other circuits is for detecting other problems or the like.

    Example: if the pressure pump keeps going on all day and all night, then maybe there is a leak somewhere.

    Also if the pump cycles on and off too often, maybe I should add a 2nd pressure thank.

    If it is cold outside and the heater never turns on, maybe I forgot to turn on the circuit.... Maybe I should also monitor pump house temp.

    And most specific to this last problem. If I see that only one well turns on, it lets me know that there is probably a problem with one of the wells, and hopefully I can have someone take care of it before I run out of water.


    Anyway it gives me some good excuses to try out some different things and who knows maybe I will actually complete it and maybe detect the next problem before it is a real problem.


  2. #12
    Join Date
    Jun 2010
    Rep Power

    Re: Detecting Water system problems before...

    Hmmmm. Measuring the water height directly bypasses the complexity of multiple wells, but doesn't tell you if one well has an issue.
    Where I used to work we used a float on a beaded line/pully system attached to a shaft encoder, which counted every millimetre of change in water level in an observation bore (No pump installed) or stilling-well on a river bank. Encoder, line & pulley were all matched. The encoder was attached to a simple logger to count the pulses & convert it to height vs time, which was downloaded every few months. These days they are more complicated loggers that are on telemetry, sat phone etc, but the system is basically the same. Not sure what they cost, but it would be a couple of hundred dollars. Ours were supplied by "Hydrological Services" which were more recently bought out by "Kisters". Dunno if there is a US company that would supply similar systems that you could connect to something.
    The other version we used was a calibrated gas back-pressure reading system, but that required gas to be slowly pumped through to keep the lines full. Bit too complicated for what you want.

  3. #13

    Re: Detecting Water system problems before...


    Sounds like interesting setups. Sounds like some of them were setup to keep track of maybe the ground water and river/stream levels.

    Which also could be interesting here as well. For example to see how much the static water level is dropping during the drier seasons. But probably beyond what I am probably going to do for now.

    Assuming I actually follow through this time and assemble everything, and the current information still does not give me enough info, I may then actually add measuring the actual water level in the tank. Probably the easiest thing would treat this like a big boat and use some marine products, like:

    There are a few other things with our well setup, I may wish to change (although have not yet in 10 years).

    Example: The two wells are hooked up, with the float valve going to the "Contactor" which when the tank needs water, it applies power to both wells at the same time. I wish at times it would alternate them, with typically only one on at a time.

    Also think I should add a backup pressure pump, that I can switch on if/when the main pump fails. Probably not powerful as the main one, that was sized up to handle house/garden/shop, plus fire system (at least two sprinklers...). Maybe nice if secondary pump could run off of battery, so it could also handle power outages. Main house has automatic generator, but pump house on different meter...

    But again probably out of the scope of this project.

    Thanks again

  4. #14
    Join Date
    Sep 2010
    Rep Power

    Re: Detecting Water system problems before...

    That first link is just three cheap float switches on three lengths of rods with a giant price tag. I rather want to make a joke about it being cheaper to just use the level sensing method used in Waterworld, but nothing humorous is coming to me at the moment. Which reminded me of a project at the UGA college of engineering several years ago that involved a small autonomous air boat (fan boat?) to map out lagoon depths using GPS and some sort of sonar instead of having humans go around in boats with long graduated poles to manually measure depth all around the lagoons.
    Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
    "You have failed me, Brain!"
    gives free advice only on public threads

  5. #15

    Re: Detecting Water system problems before...

    Yep the first one is the Cheap 3 float switches, plus rods, plus electrical circuit which lights up some LEDS or the like. However the main thing is it is approved for potable water systems.

    Another system, I was looking at, looked more interesting, but when I asked if it was approved they said no, they have not gone through the process, and it was made of PVC pipe and speaker wire (whatever that may happen to contain).

    As I mentioned, currently going to play with simply monitoring how the different pumps are running and deduce if the tank is full or has been full recently, which for my case should be sufficient (I hope).

  6. #16

    Re: Detecting Water system problems before...

    I was thinking about trying to add the current sensors to my simple board, but I think I would be better off with a simple board, that just does that and then connections to my simple board. May order simple board soon, to start playing with it, but may try to do initial layout of the sensor board, such that maybe it can just plug into other board...

    Again I am using some of the Current Sensors from Sparkfun

    I screwed up my first mini board, so I want to breadboard some of it. The schematic for reading one, currently looks like:
    Click image for larger version. 

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    Things I need to verify, include what is the proper load resistor (R1) for this sensor with a 3.3v system. I currently have it here showing 18...

    Resistors 2 and 3 (resister divider) and the 10uf Cap are setup that you pass half system voltage to one side of the sensor to scale the voltage up such that you don't go negative.

    With my desired setup, I would like to have probably 4 of these sensors (Well 1, Well 2, Pressure Pump, Heater). So should I duplicate R2/R3/C1 for each of these sensors, or is it sufficient to pass the 1.67v signal to all 4 of the sensors? My first inclination is to duplicate them as maybe it would maybe reduce the output of one from maybe influencing an other? And should not hurt anything except space, a little extra cost, ...


  7. #17

    Re: Detecting Water system problems before...

    What are the interface specs for that sensor? I don't understand how the sensor changes the voltage going to the board at all.
    Does the sensor have a separate power supply? Or does the board in turn have an input-impedance load, matched to the sensor, and in the same ballpark as the 470k source impedance?

  8. #18

    Re: Detecting Water system problems before...

    Hi Jwatte,

    My guess is you know more of the electrical stuff than I do, but my basic understand is:

    The Current Sensor,, basically is a bunch of wires that more or less wrap around the wire you are measuring and uses induction to form a current on that wire. The load resistor then converts the current into a voltage. As your AC power goes plus and minus, you use the 1/2 voltage to pass in the sensor to offset it, so the voltages stays positive.

    The datasheet from the sparkfun page is:

    More interesting is the page, talking about project using these form of sensors:

    Probably the most interesting link is from the project page I mention:


  9. #19

    Re: Detecting Water system problems before...

    I see! Inductively coupled. (I'm more used to Hall Effect sensors like ACS715 with separate supply, but those are better for non-mains-power voltages.)

    At 15 mA per 30A, a load resistor of 1 kOhm would generate 15V differential, and 100 Ohm would generate 1.5V differential. Assuming you're plugging into a 3.3V sensor, 47 to 100 Ohm seems about right, assuming you're measuring currents up to 30A and there's no bigger inrush current to fry your input port. (Or you can use a TVS/Zener to help protect against overvoltage.)

    The 470 kOhm resistors seem somewhat soft to me, even with a high input impedance (such as the 1 MOhm of a cheap oscilloscope.)
    The input impedance of an ADC on an AVR microcontroller is low enough that they recommend < 10 kOhm source impedance, so I'd try maybe 4.7 kOhm for each of the resistor divider, instead of 470 kOhm.

    So, that concludes what I know about impedance matching; someone who does this for a living should probably correct whatever I got wrong :-)

  10. #20

    Re: Detecting Water system problems before...

    Thanks for the hints. My quick calculations yesterday from the one site looks like the load should maybe be something like 80+, which looks like it is in range of what you mentioned.

    Sounds reasonable on your idea of 4.7K to be safe and I am reading from this probably better to have separate ones for each sensor.

    Thanks again

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