Long distance well control dilemma

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New Member
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Port Angeles WA
I am designing a single family house water system and need some advise on the best way to control the pump.
275' head between pump and cistern. 245' well depth. 20gpm well
2000 gal cistern 700' away
Power is located at well site,
3/4hp grundfos 3wire pump with a grundfos 3/4hp control box will deliver 6.69 gpm according to grundfos.
I would like to turn pump on when cistern is 1/2 empty keeping cycles on pump to maybe 1 or 2 times a day. Long life I hope.
I don't want to get involved in a wireless controller, costly and impossible for a guy like me to fix.
Don't like the idea of a float valve and pressurizing the line and a pressure switch at pump, more things to go wrong.
I'm hoping there is solid state switch that only needs maybe 1/10 of a amp to switch the 240 volts on at the well using float switches in the cistern and use maybe a 14-2 uf, direct bury wire that should hold up for the long term between the cistern and the pump control box.
Is there anything like this or a better solution?


Cary Austin
Staff member
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Lubbock, Texas
Long distance control lines will cause more problems than a pressurized system. Impedance between the two long wires is a problem, as they sometimes will not disconnect the pump when the switch opens. Voltage spikes, gophers, and soil movement also give long wires many problems.

Besides not requiring any wires, there are many other reasons a pressurized system is better. Pump starts easier with the correct head on it. Demand valve opening and water flowing from a small pressure tank eliminates water hammer that happens when the pump starts into a line that is not pressurized.

But if you want to use the long wires, try DC voltage to the relay because of the impedance problem.

LOW YIELD WELL_and storage with two PK1A.jpg


In the Trades
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A 240 volt 2HP Orbit pump start relay is approx 1/10 amp at 24 volts AC
18 gauge wire should be good for at least 750 feet at 24 volts and 1/3 amp.
Use a basic float switch and plan for eventual failure of that float switch. Where does the extra water go if the cistern overflows? Use a cycle sensor to protect the pump from running in a dry well.

Hey, wait a minute.

This is awkward, but...

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