pump system question

Discussion in 'Irrigation' started by clc19chase, Aug 6, 2008.

  1. clc19chase

    clc19chase LawnSite Member
    Posts: 102

    just added 4 zones to a lake pump system. my problem is while any zone is running the pressure is surging. the system consist of 1 1/2 suction running about 45 feet to pump. when lake is full the elevation change is only like4 feet max. right now the lake is almost 4 feet down. the pump is a 2 horse meyers with a 1 1/2 main running no more than 35 to 40 feet to the furthest valve (1 inch valves and laterals).... zone 1 consist of 13 rainbird 1804's (2 of them have 15' van at 360, and the other 10 are 15 vans at 210 degrees) This is a landscape redesign and the landscaper could have possibly damaged the main today with shovels. I thought it may have been a busted lateral but 2 new zones are performing this way. Is there anything that can happen to a pump to make it perform like this. when this surge is at it best pressure the heads are performing great but the low end of the surge the heads will start going down a little also.
  2. hoskm01

    hoskm01 LawnSite Fanatic
    Posts: 5,690

    Sounds like a pump issue. Has the pump been maintained?
  3. clc19chase

    clc19chase LawnSite Member
    Posts: 102

    probably not. I pulled the pump end down to see if debris might have been in it. but nothing. just brass impeller
  4. clc19chase

    clc19chase LawnSite Member
    Posts: 102

    I must add that when trying to flush the lines before setting heads. the pump would not clear all of the cavitation with 13 funny pipes open. the highest funny pipe never got water but this same zone performed well 2 days ago after setting heads and before the landscaper arrived
  5. Waterit

    Waterit LawnSite Silver Member
    Posts: 2,906

    You have an air leak on the suction side of the pump making it cavitate.
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,712

    Do some of the zones operate correctly? No pump issues? If so, that might suggest a problem with capacity, connected to the lower lake level increasing the suction lift.
  7. clc19chase

    clc19chase LawnSite Member
    Posts: 102

    I will try the zones that were already there to see if they perform right. I guess it is hard to find an air leak on the suction line buried in the ground
  8. Waterit

    Waterit LawnSite Silver Member
    Posts: 2,906

    Yes it is, but it's more likely your leak (if there is one) is at a threaded joint.
  9. h20 guy

    h20 guy LawnSite Member
    Posts: 50

    Agree with Waterit, a suction side leak will get you everytime, sounds like work to dig it up but most likely your problem.
  10. cmrgrounds

    cmrgrounds LawnSite Member
    from augusta
    Posts: 45

    Im not to familar with pump systems but is it possible that you have to much pump or not enough heads on each zone to keep the pump running? I have a property where the homeowner had a 300 ft drilled well to supply water for the irrigation and the system would surge because there were not enough heads on each zone. The pump would cut off and back on at certain pressures and the sprinklers would surge. One minute the sprinklers were spraying good then they would be barely spraying at all. We had to add more heads to each zone to keep the pump from reaching the maximum pressure so it would stay running throughout each cycle.

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