Pump has me stumped

Discussion in 'Irrigation' started by ErikWP, Apr 20, 2005.

  1. ErikWP

    ErikWP LawnSite Member
    Posts: 14

    I have a 1hp pump for a res. irrigation system. Shallow well 26 ft. I have replaced everything from the pump intake to the check-valve. Pump is a little hard to prime, and once it does prime it will run for 3 or more hours fine. Once the pump is off for a while, the preasure drops a bit and it will not self-prime. Need Help.
     
  2. greenworldh20

    greenworldh20 LawnSite Senior Member
    Posts: 659

    buy a new pump.

    problem solved.

    brian
     
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,014

    to check the suction side of the pump while it's operating. If you are drawing water from a well point, its openings, or intake screen, may be getting clogged up. 26 feet of lift is near the practical limit of a shallow well pump's capabilities.
     
  4. ErikWP

    ErikWP LawnSite Member
    Posts: 14

    Is the intake screen on the well point or the pump?
     
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,014

    A PVC point will have slots cut into the material. A galvanized steel well point will have a screen. Doesn't really matter which. If the intake gets clogged up, the pump has to work harder to lift the water, and can overreach its lifting capability, and lose prime. <a href=http://www.extension.umn.edu/distribution/naturalresources/DD0951.html>More about well points</a>
     
  6. ErikWP

    ErikWP LawnSite Member
    Posts: 14

    Wet Boots,
    I want to thank you for your input, it has been helpful.

    Is there any way to clean the PVC well point without pulling it up?
    Any way to force water down to flush out the debris?
     
  7. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    Your original post stated the pump runs fine and only loses prime when it is off for a period of time. This means you have a vacumn leak on the intake side somewhere. It can be in the pump itself or in the joints anywhere from the intake to the check valve. Even if you have replaced everything, if you didn't get it tight/sealed, you didn't fix it. And no, a new pump won't fix it unless the leak is in the pump. The suggestion to try a vacumn guage was a good one. I can't remember the exact figure, but it seems that 29' is correct. 29' is the absolute maximum you can siphon a column of water. Anything taller than that and you can't "pull" water, you must push it instead. The fact that you are drawing from a point very near that absoulte number means that any vacumn leak at all is going to "steal" your prime. Is a submersible pump totally out of the question? The pump would require less maint. and most of them run much more efficiently even though they are more expensive equipment.

    Good luck and post what actually ends up working.
     
  8. ErikWP

    ErikWP LawnSite Member
    Posts: 14

    I have triple checked all connections from the pump to the check-valve, and they all seem to be sealed up.
    How can I determine if the leak is inside the pump? What would I look for?

    Thanks for all the help.
     
  9. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    Your wording implies a visual inspection and I promise that won't allow you to "see" this problem. If you had a big enough leak w/ 26' of lift that you could "see" it, your pump wouldn't pump. As to a leak within the pump..........housing seal, shaft seal, drain plug not sealed and tight, etc. Any place the pump isn't solid cast and was put together would be suspect at this point, but I still think you will find your problem in your intake plumbing.

    One other shot in the dark. How deep is your intake tube? You are "pulling" water 26', but how far below surface is your intake? You haven't droped the shaft say another 6-10'? Water cannot sustain a vertical column more than 29'. With 26' to surface, but drawing from 36' could cause you a problem. Especially if there is flow in and out of the well.
     
  10. ErikWP

    ErikWP LawnSite Member
    Posts: 14

    The distance from the check-valve to the end of the well point is about 20-25' so I should be ok. Plus everything worked good last year.

    This weekend, I am going to replace everything again to make sure.

    Thanks again for your help.
     

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