5HP pump too small?

Discussion in 'Irrigation' started by IrriMaster, Aug 17, 2007.

  1. IrriMaster

    IrriMaster LawnSite Member
    from FL
    Messages: 2

    Hi guys,

    I just finished installing a community system for a condo association. Roughly 2 miles of 2" pipe main, and a uncountable amount of 1" zone pipe, around 750 Rotors.

    We are pulling water from a lake with a 5 HP pump, but the heads are performing badly.

    Do I need to get a bigger pump? What about getting a booster?
  2. jerryrwm

    jerryrwm LawnSite Bronze Member
    Messages: 1,274

    What are the specs on the pump? And why was it selected? Who spec'd it?
    How big are the zones you are trying to run?

    One problem I see is the 'two miles of 2" main line'. Why so small? Is the mai looped?

    Get us a little more information.
  3. Bigred350

    Bigred350 LawnSite Senior Member
    Messages: 808

    Sounds like a lack of planning to me. You better go back to the drawing board and figure your gpm and pressure loss per zone. And then pick your pump out.

    What type of pump is it. Centrifical,well pump???

    Messages: 18,668

    Irrimaster I think you are going to get toasted but hang in their and you'll learn something. By the way what is your experience level and is this your first pump job? Also look up the word kludge before you proceed on solving your problems.
  5. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Man... not enough info. I'm still stuck on watering 750 rotors with a 2" main line.
  6. IrriMaster

    IrriMaster LawnSite Member
    from FL
    Messages: 2

    The main line is 2", it is not looped.

    I figured a 5HP pump could easily produce 100 GPM, so I used #10 nozzles in the PGP, 10 heads per zone.

    1.5" inch zone valve and then 1" for the zone lines.

    I think I need more GPM.
  7. bobw

    bobw LawnSite Senior Member
    Messages: 807

    Well... a PGP with a #10 nozzle uses 6-8 Gallons per MINUTE (as per Hunter's site). So, 10 of them on a 1" line is 60-80 gallons per MINUTE. Doesn't really matter much that your pump can push 100 gpm... the restriction is how much can you push through a 1" line. A 1" line might be good for about 15 gpm....
  8. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    Given what little info you have provided, I would consider reducing your nozzle size before increasing your GPM.
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,400

    Also, see if the main can be looped, to reduce the pressure losses at the greatest distance from the pump.

    In general, for a (unlooped) 500 foot run of 2-inch, think of 30 gpm flows, or even less, if you're feeding it with a single-stage centrifugal pump. For 10,000 feet.....

    Messages: 18,668

    This isn't NASCAR in which you can say I think I need more HP. It's a math formula and clearly you did not do any math and now you are still thinking?:hammerhead:

Share This Page