Pump Losing Prime Quickly

Discussion in 'Pumps and Tanks Well Forum & Blog' started by xenon, Nov 27, 2012.

  1. xenon

    xenon New Member

    Messages:
    4
    Location:
    Florida
    I have a 120' well used for irrigation here in south Florida. Pipe is galvanized 2 & 1/2". Pump is a 1 & 1/2 hp Goulds centrifugal on a concrete slab next to the well pipe.
    After the pump was left unused for 5 months during the rainy season, it is losing prime within minutes after shut off.
    First I replaced the horizontal mounted check valve between well and pump. No change.
    Then I brought pump in and had it rebuilt, as it was probably 12 years old anyway. No change.
    I can get it to prime by attaching a hose to the bib on top of the pump, and running water in while the pump is operating. After 10 or 15 minutes the pump will prime. Once primed the pressure is excellent.
    There is no lack of water as the water table is now about 4' below ground surface.
    Any diagnosis?
    Thanks.
  2. valveman

    valveman Moderator Staff Member

    Messages:
    4,369
    Location:
    Lubbock, Texas
    A good footvalve is the best way to keep from losing prime. You probably have one that is leaking back.
  3. xenon

    xenon New Member

    Messages:
    4
    Location:
    Florida
    Thanks for the response. I took the plug off the top of the well pipe. Turns out there is no drop pipe; just the well casing. Water level is right at six feet down. Took a hose and ran water into the pipe to see if I could fill it. Pulled the hose after about five minutes and the level did not rise much but there was a lot of bubbling. Large bubbles.

    Dug the pipe down to about five feet. Pipe was clean to about four feet down and then had what looked like surface rust. Water started to show at base of the hole. Could be the ground water or could be from a hole in the pipe.

    What to do now?
  4. justwater

    justwater Well Drilling/Service

    Messages:
    324
    Location:
    FL/GA
    toss the above ground check valve and install 30' of 1-1/4" pvc drop pipe into the well with a foot valve on the bottom, then plumb that into the pump.

    ** fyi, i say 1-1/4" to get max volume but be careful because some fittings are tight inside a 2" ID well. i sometimes turn them down a little on a grinder before installing... you'll need to pull it all out again one day.
    Last edited: Nov 30, 2012
  5. xenon

    xenon New Member

    Messages:
    4
    Location:
    Florida

    Thanks, that is a big help and explains about the 1 & 1/4".

    What fittings would I need to plumb the drop pipe to the pump?
    Last edited: Dec 1, 2012
  6. justwater

    justwater Well Drilling/Service

    Messages:
    324
    Location:
    FL/GA
    they make a double tap fitting that screws into a 2" coupling and is tapped 1-1/4" on both sides.

    OR... use a simple 2" pvc threaded cap, drill a hole with a paddle bit that is just large enough that the drop pipe barely slips through.. slip pipe through and glue elbow/coupling onto pipe and let the drop pipe rest on the fitting. this is easier/cheaper and works quite well. you can seal it up with some silicone or something but if you make it a tight fit and being as its irrigation anyway.. its not necessary.
  7. xenon

    xenon New Member

    Messages:
    4
    Location:
    Florida
    Excellent solution and right price, too.
    Thanks for your help. Much appreciated.
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