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Thread: Irrigation pump and cistern question

  1. #1

    Default Irrigation pump and cistern question

    Hi everyone. I learn a lot by reading your posts and appreciate your knowledge and willingness to share it. I am working on a residential irrigation system that has a large cistern, a 1hp jet pump, 7 zones with aerial risers and popups. The problem I have is that I want to convert the aerial system to drip emitters and am not sure if the pump will overdrive them and cause component failure or I should downsize the pump and motor. I am in south florida so there is no danger of freezing.

    There is no valve on the discharge side of the pump to regulate output. The cistern is approx 1000 gallons and is fed by city water and has rainwater gutter collectors. Since the pump has a 2" suction line it drains the cistern faster than the 3/4" city water can refill it. Sophisticated float switching (4 wires) for which I have no schematic was previously used to regulate city water filling but disabled by prior repairmen. The irrigation controller actuates a solenoid valve that allows city water to fill the cistern but there is no shutoff it will continue overfilling the cistern without connecting the 4 wires previsouly mentioned to some contactor device.

    What pieces oif information should I begin accumulating in order to make this system work properly? I have an volt/ohmeter and can check the 4 wires I believe come from the cistern to determine if there are open or closed dry contacts connected to them. The pump motor needs servicing anyway as the bearings are starting to whine.

    Thanks for your help!

  2. #2
    Sprinkler Guy Wet_Boots's Avatar
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    Default

    If you have no brand name for the float switch, you might post a photo, and use your multimeter to explore what the contact arrangement is.

  3. #3

    Default No float switch name or photo available

    Thanks for your reply. The problem is that I cannot dig down (2') to the top of the cistern and float switch without uprooting lots of established shrubs on top of the cistern. I guess I am going do as you suggest and try to determine the contact arrangement with an ohm meter.

    Would it be safe to say there should be an upper limit contact to prevent overflow and a lower limit contact to prevent running the pump dry? I am thinking there should be a contact that would allow for some city water to come into the cistern, but not fill to the top in order to leave room for rainwater to finish filling it. Does that sound probable?

  4. #4
    Sprinkler Guy Wet_Boots's Avatar
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    Assume nothing - measure everything

  5. #5

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    Do you have backflow protection between cistern and city water?

  6. #6
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    You said you have a jet pump with a two inch suction. That would be a centrifugal not a jet. They can't make much pressure, so I wouldn't worry about the drips.

    All you need to turn off the city water is one float switch which could be a piggy back used with 24 volts to close/open a solonoid valve.

    For dry run protection, the same system could be installed backwards from above. Or you could use a hot stop thermostat on the pump to detect higher than normal water temperature.

    bob...

  7. #7

    Default Brass air fittings

    Now that is a lot of brass air fittings http://www.***********.com/subpages/airfitting_1.htm there is just about every type
    of air fitting that you could want. Wholesale prices too. I guess these could be used as small water pipe fitting also. I
    used some of the parts to make my babington wvo burner.

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