1.5" well pump to 1" feed for irrigation

Discussion in 'Irrigation' started by Ramairfreak98ss, Jan 15, 2013.

  1. Ramairfreak98ss

    Ramairfreak98ss LawnSite Silver Member
    Messages: 2,210

    A commercial site has a 2yr old well system with 1.5 pipe coming into the building. I turned on a faucet, that was flowing about 4gpm, and it took just over 3 minutes to get the well pump to turn on.

    Pressure starting was 38psi.
    minus ~12 gallons of water displacement in two 40-50 gallon ballast tanks and pump kicked on at 32psi.

    Pump turns off at 58psi within about 60-70 seconds.

    I know we'd have to set the water pressure turn on point higher than 32, at least 40psi, 58psi is plenty for even the farthest runs in 1" PVC.

    The system would need 16-18 zones from one 1" line branched off the 1.5" main line from the building. Run times may be a bit long with so many zones, but all the 1" pipe is already stubbed out under the curbs, sidewalks and brand new paved parking lots, so we have a maximum of one 1" line from the building to the first box.

    We can use water from 5pm - 8am free will. They're not cheap, and willing to pay for a top notch system to some extent. If the 1" line is flowing ~20gpm to each zone, will it cause the pump to cycle on and off the entire time?

    Should each zone be designed to start at 40-58psi, but assume you'll only have 40psi, and pull enough water for each 1" line zone to keep the pump maxed and not able to reach 58psi to shut back off?

    No major areas here, all will be spray zones and probably rain bird 5000 series rotors. 1" line wouldn't power the larger ones with the distance even if we had the space to utilize them.

    Looking to use a Rainbird esp-smt controller with ET manager and wireless controller... more for our use than theirs.

    They currently have a 2yr old Hunter controller "the $85 homeowner one" on 4 zones for spray heads by the building... just to keep things from dying when the building was built.
  2. djagusch

    djagusch LawnSite Platinum Member
    from MN
    Messages: 4,358

    You have a flow of 4 gpm? Good luck with that.
    Posted via Mobile Device
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,750

    None of the posted numbers are giving the steady-state performance of the water supply.
  4. AI Inc

    AI Inc LawnSite Fanatic
    Messages: 27,061

    As boots said you need to do a real flow test and see what the well is actualy producing.
  5. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,170

    I'm staying out of this mess, I've been enough trouble on other threads.
  6. Ramairfreak98ss

    Ramairfreak98ss LawnSite Silver Member
    Messages: 2,210

    No, yeah i would need some luck with that! The faucet was only located fairly close to the main line, but 1/2" line, so its limited to about 1/4 of what the full 1" line should provide wide open.

    Al Inc. , We're going to T off the main line this week to bring 1" outside, sine right now the 1" line we'll be using is connected to a 1/2" hose bib... obviously not the way to do it,but the construction firm did it temporarily until they had full irrigation installed. Once i get the backflow installed outside, i'll see exactly how much flow they'll have at starting pressure and ending when the pump turns off at 58psi.

    We will be running the 1" from the building, ending with heads over 400' away near the street for probably 5-7 of the zones. We've run 3/4" and 1" previously on runs 200-250' , so we'll have water out that far, just concerned about how long everything will need to run, and moreso, that the pump isnt turning on/off constantly since i'm sure the pump will flow for the capability of a 1.5" line, not the 1" line for the irrigation.

    It wouldn't kill the job to just run all 1.5" to the valves and everything, but would be considerable work since its all new parking lot and we'd be cutting through new 6" thick pavement in a few places. Rather make it work with the existing 1" they installed underground last year than have the customer incur that expense.
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,750

    A 400 foot run can be a problem, because of the pressure losses in the pipe. If you have to leave the pressure switch alone, you might have to 'supersize' the mainline to make its pressure loss close to zero.
  8. AI Inc

    AI Inc LawnSite Fanatic
    Messages: 27,061

    Dont go with starting pressure and end when the pump turns off. Thats not a flow test. You need to empty the storage and see what the well is actualy producing.
  9. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,358

    Agreed, begin with a 2hr pumpdown test. Take gpm tests every 30 mins.

    Determine the working pressure and demand requirements after the pumpdown test.
    Posted via Mobile Device
  10. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,170

    Yup, it's the recharge rate you're going to pass or fail with, which is no big deal if one has a clock that has a delay between zones/programs feature.

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