Radio Linked Tank Float Switches?

mcnutt13579mcnutt13579 Registered Users Posts: 107 ✭✭✭
Customer has 4000 gallon water tank on hill. Well is right next to house. System is pure gravity, no pressure tank at all.

Well pump runs whenever generator runs. Generator runs only when commanded by inverter. Water tank runs dry if there is too much sun, and overflows down the ditch if the generator runs a lot.

I would like to install some sort of tri-level float system in these tanks. One float near the bottom that starts the generator whenever the tank gets too low. Another float near the middle that stops the generator if the bottom float is the one that started it. One float at the top that lets the well pump run and fill the tanks completely whenever it was the inverter that commanded it on.

The catch is that there is no easy possibility of installing a wire to these tanks. They are very far away and the pipe without wire was installed many decades ago through some rough country. Automation was not thought of back then. I want to do it by some radio link but it has to be reliable. I realize I will need a small panel and battery at the tank. The radio path should be pretty much line of sight so at least that should be no problem.

Is there such an animal ready-made?


  • jonrjonr Solar Expert Posts: 1,384 ✭✭✭✭
    Re: Radio Linked Tank Float Switches?

    How about this for a rather wild possibility: turn the pump and any usage off and then measure the pressure. If you can measure it accurately enough, you can determine the height in the tank.

    I am available for custom hardware/firmware development

  • kilewilliskilewillis Registered Users Posts: 4
    did you ever come up with a radio/ wireless control ?
  • mcnutt13579mcnutt13579 Registered Users Posts: 107 ✭✭✭
    We did a lot of research and never really found something industrial-grade enough that we thought it could be trusted.

    Have done several jobs with lots of sweat and difficulty that involved pulling new wires to tanks, etc. but once that is done you know no radio will ever lose its link or have another battery and solar panel to maintain.

    Still on the hunt for the right solution but it also takes the right customer and the right job.  ($$$$)

  • Marc KurthMarc Kurth Solar Expert Posts: 836 ✭✭✭✭
    it has been many years since I was involved with this, but yes, remote RF based pump/tank controls are common. We did several systems with 50,000 to 100,000 gallon tanks located remote from the pumps. These were large ranches and small municipal water systems where reliability and repeatability were critical. Some were better than others when you exceeded 1/2 mile. Even the lower cost systems worked well for shorter hauls. The longest range we did was 4.5 miles and we had to use Yagi's at both ends for the UHF link.

    Ours were set up with a standard two float, High/Low control. A quick Google check found several companies offering RF based remote control for pump/tank/irrigation system links.

    Jonr made a good suggestion, if you have a decent vertical differential at the tank. It would be easy to layout some relay/timer logic to sample the head pressure to accurately determine water column height. Highly accurate transducers don't cost as much as they used to, but if the tank is low will likely get very expensive for the transducer.


    I always have more questions than answers. That's the nature of life.
  • mcnutt13579mcnutt13579 Registered Users Posts: 107 ✭✭✭
    Can you specify a couple of float switch state transmitters you would recommend? 

    There is no shortage of people that say they make what we want, but experience has taught me what to think of that....
  • kilewilliskilewillis Registered Users Posts: 4
    edited March 2019 #7
    I am looking into possible using this controller

    and looks like you have to buy the monitor/ lcd screen

    looks like it runs about $541 usd. only problem is I have to put a battery at the pump controller so it stays in contact with the lcd screen thingamajig
  • mcnutt13579mcnutt13579 Registered Users Posts: 107 ✭✭✭
    Doesn't meet the requirements I laid out, no dual level switching.

    We have been installing these to take advantage of opportunity loads.

    Also being from NZ, the frequency band will probably be wrong here in the US.
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    edited March 2019 #9

    Its doable, I have built several RF Lora stations to wifi station to monitor tank levels, temp etc... They run on a small LiPo battery and a small solar 5.5V panel. Cost is minimal if you build it and write the code yourself. If you dont need constant data then you can put the boards to sleep for determined intervals then wake up and transmit to save power. I have some a mile away no issue. You can code them to talk to each other also like turn off pump or tank full, whatever is needed.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • mike95490mike95490 Solar Expert Posts: 9,199 ✭✭✭✭✭

    That sounds really interesting. I could use something like that, reporting every 4 hours on tank levels

    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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    gen: ,

  • VicVic Solar Expert Posts: 3,069 ✭✭✭✭

    BB Bill posted the following,   also a Lora  devices,  perhaps one of the four sets might be frequency-compatible with the target country:

    FWIW,   we know nothing of the details.  Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • NikiNiki Registered Users Posts: 21 ✭✭
    Re auto wireless pump operation I’ve had good results using a very small bladder tank in parallel with the fill line including a high quality pressure switch and a float valve located at the tank top.  When the tank has filled the float valve pinches off the fill line causing the bladder tank to go up in pressure until it reaches the pressure switch cut-off set point at which time it either interrupts the power to the pump or with Grundfos sqflex can just short the float connections stopping the pump.  When water is used from the remote tank the float valve will open allowing the bladder tank to empty causing a pressure drop on the switch thus changing its state and signaling the pump to start immediately if power is available or later when pumping power is available.  Of course the bladder tank must be adiquatly recharged to push the water up to the storage tank from the bladder tank and a safety pressure relief valve should also be in place just in case the pump fails to shut off when it should due to pressure switch maloperation.
  • jonrjonr Solar Expert Posts: 1,384 ✭✭✭✭
    So basically use over-pressure as a tank full signal.  Nice idea Niki.   

    Most centrifugal pumps won't produce pressure greater than what the pipes can handle, so no need for a safety pressure relief.

    I am available for custom hardware/firmware development

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