Another Sandpoint conundrum

Discussion in 'Irrigation / Sprinkler Forum' started by Armstrr, Aug 5, 2014.

  1. Armstrr

    Armstrr New Member

    Messages:
    7
    Ok. So I built a shop with a basement... Hit the water table... And I mean... I'm right in it. I have a 2/3 acre lot and I put my own system in. When I did the piping I figured I needed about 30 heads or so... As I was mid way through I realized I did not design the sprinkler system with head to head coverage, so I ended up adding lots more heads... Long story short I have some zones with up to 13 heads... I put low gpm tips (Hunter pgp ultras). I installed a flow meter and have measured some zones that take up to 15gpm.

    I have run this system with a little bit of managing for about 3 years... OUT OF THE SUMP PIT. like I said... I'm right in the water table (and yes I can keep the building dry... But that's another story.

    From April to the middle of June I can run the system pretty much indefinitely. The weeping tile around the shop supplies enough water. Once summer and early fall come I need to adjust the run times and set pump delay for recovery.

    I want to be able to run the system when I need to for as long as needed so I have driven 3 sandpoints. They are 36"x2" and have one 5' length of 2" galvanized attached (I had them at 10', but struggled to get good flow... So I pulled them up 5'

    I installed a vacuum guage and ran out of one point only and the system ran much better and the vacuum guage ran much higher indicating I had a leak on the suction side during my earlier attempt.

    I believe fixing that leak will help, but I believe I need a more capable pump.

    Currently I have a 1hp goulds irrigator pump. It worked well when it was only required to pull freely from the sump pit 30" or so.

    I installed 3 Sandpoints believing it would help achieve my goal of being able to output approx 20gpm. I am unsure how pulling on 3 riser pipes affects the pump. I thought it would allow 3 times the capacity, but I'm guessing the suction required is beyond the pumps ability. I wondered if using the 2" risers as casings would work and I tried 1" dip tubes down to the bottom of the Sandpoint. It would run and then loose prime as it was drawn down... So my latest attempt is to seal the risers so it applies a negative pressure to the casing, but still using the 1" dip tubes.

    My first attempt failed and as I said, using just 1 of the sandpoints yielded surprisingly good results... Discharge pressure was a little over 20psi...and the flow was too low for the guage to measure bit I'm guessing 8 or 9gpm.

    So I have just finished reassembling the suction plumbing and used some silicone at the top of the risers to block the suction leak. I'll try it out this aft. In the mean time... I'm thinking the 1.5 or 2 HP irrigator will be adequate, but if there are those who know more about these pumps and can recommend a more suitable yet reasonably priced alternative, I'm all ears.

    I'll try to post a few pics
  2. Armstrr

    Armstrr New Member

    Messages:
    7
  3. Armstrr

    Armstrr New Member

    Messages:
    7
    See the water table level?

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  4. Armstrr

    Armstrr New Member

    Messages:
    7
    The pump

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  5. Armstrr

    Armstrr New Member

    Messages:
    7
    Another angle

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  6. Armstrr

    Armstrr New Member

    Messages:
    7
    This post maybe should be in the pump/wells section? Should I delete and repost there? Or?
  7. Reach4

    Reach4 Well-Known Member

    Messages:
    2,626
    Location:
    IL
    I suggest that you clarify briefly what you are asking.

    Search this page for question marks. Before your latest post, the only one was a the end of "See the water table level?"
  8. Armstrr

    Armstrr New Member

    Messages:
    7
    Last paragraph sums up my question...

    If there are those who know more about these pumps and can recommend a more suitable yet reasonably priced alternative, I'm all ears.

    I gave all the commentary just in case I made a fundamental mistake... Ie multiple well points etc.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,026
    Location:
    Cave Creek, Arizona
    1 point, 3 points, or 100 points, it makes no difference to the pump. It will pull as much water as its capacity, BUT, if any ONE of the points "runs dry" and sucks air, it will shut down the other ones also. I get the impression that you diagnosis may be faulty.
  10. LLigetfa

    LLigetfa DIYer, not in the trades

    Messages:
    4,133
    Location:
    NW Ontario, Canada
    One way to prevent that is to set them deeper than the pump can lift so that the pump just slows down to match the recovery rate rather than suck air.

    Alternately the OP could put down a larger slotted casing and use a submersible. They are not only a lot more efficient, they also never need priming.
    Reach4 likes this.
  11. Mitchgo

    Mitchgo New Member

    Messages:
    8
    Location:
    Seattle

    Interesting setup. I have a huge feeling there are a lot of code violations here.

    The pump is fine it's the setup that's not. These pumps CANT have air .

    Your plumbing - PVC to canoflex with rubber couplers with silicone onto galvi. Any suction of air from those fittings will cause the pump to loose full prime

    I suggest to redo the whole thing and simplify your plumbing.
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