15 minutes for pump to start pumping

Discussion in 'Irrigation' started by Robie, May 14, 2006.

  1. Robie

    Robie LawnSite Member
    Posts: 4

    Hi Folks, 1st post,
    I basically do handyman work for a few folks. One of my clients has had some irrigation problems and I have been going through the system. All is fine now but one area. The sprinkler heads take 15 minutes to start after the pump starts. The water is drawn from a lake. I replaced the check valve, which is partially submerged, and almost at the end of the PVC going into the lake. The supply PVC is probably 12 feet of a 30* uphill run before it gets to the pump. The check valve is also about that far away.
    Should the check valve be closer? Any other hints to get water pumping faster?
    Thanks.
     
  2. Robie

    Robie LawnSite Member
    Posts: 4

    Okay, let me re-phrase that. How far away from a pump should a check valve be?
     
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,021

    I would always have a check valve right at the pump. Depending on how much vertical distance there is between the lake surface and the pump intake, a foot valve, or some other sort of check valve might be needed at the lake end of the suction line. Slow priming can mean a suction line problem. Is there an intake filter to keep debris from fouling things up?
     
  4. Robie

    Robie LawnSite Member
    Posts: 4

    Thanks for the reply. No, there is no filter I can see. The PVC has very tiny "slits" running the length of the piece that is submerged...probably around 3' long. The old check valve showed no signs of debris and truth be told, probably worked okay. Between the check valve and the pump, there is around 12' of PVC leading to the pump at a 30 degree incline. I see no signs of leaking whatsoever.
    Should I possibly install another check valve at the pump?
    What is a foot valve?
     
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,021

    If there's a hairline crack somewhere in the suction line, it could screw things up for you. I always like a check valve right at the pump, because that would help a pump maintain its prime. In some applications, a separate removable-screen suction line strainer might be installed, if the suction line passed too much debris.

    A foot valve is the combination of a check valve and a strainer. Not a fine-mesh strainer, but just enough of a screen to stop pump-killing debris.
     
  6. Rainman7

    Rainman7 LawnSite Senior Member
    from NY
    Posts: 288

     
  7. Robie

    Robie LawnSite Member
    Posts: 4

    Well, went through the entire system that could be seen. Re-programmed the computer, cleaned filters, made sure connections were good etc. The system has 6 stations. The first is timed to go off at 6 AM and run 30 minutes, then on to the next and then, the next, etc.
    All is fine, and the pump comes on at 6 AM, but the first station doesn't actually start spraying water for 15 minutes. Once the pump is pumping, all is good.
     
  8. hosejockey2002

    hosejockey2002 LawnSite Bronze Member
    Posts: 1,195

    Like Wet Boots said, you may have a tiny leak on the suction side of the pump. When you are trying to draft up that far (12 feet), the smallest leak can make priming nearly impossible. Even if the pump is in perfect shape with no leaks, 12 vertical feet is a significant distance to draft.
     
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,021

    I think he meant 12 sloped feet, or maybe 4 or 5 vertical feet. Still, if the water is draining back through the pump, it could easily take those several minutes for the pump to clear the air from the suction line.
     

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