Zone Struggles To Come Up, But Then....

Discussion in 'Irrigation' started by MEXANDME, Jul 25, 2011.


    MEXANDME LawnSite Senior Member
    Messages: 396

    I have a customer with a zone (7 rotors / 1 PGP and 6 RB 5004's) that struggles to come up (sometimes you have to pull up one or two rotors by hand to get the zone to come up) but once it is up; there is really good pressure. In Fact, it is hard to push one of the rotors down with your foot.

    (1 HP pump/shallow well with no hose bib or pressure gauge. 2-gallon bladder tank and pressure switch.)

    Since the zone has such good pressure after it is finally up, could this be a valve problem as opposed to a water volume / pressure problem?

    All other zones with 7 rotors are OK. I moved this zone from 3 to 1 at the clock in hopes that the bladder tank would give it an initial boost but it did not seem to help.

    The problem zone does have a lot of lateral pipe associated with it; probably about 300 feet.

    Thanks for any feedback!


    Messages: 18,668

    Have you inspected the valve? What make is it? Richdel 205 valves tend to go bad by slowly losing flow through the valve.

    MEXANDME LawnSite Senior Member
    Messages: 396


    It is a RB 1" DVF.

    I have opened and closed the flow control and bleeder screw but I have not taken the valve apart. (I will have to dig up a large valve box to get to it.
    4 valves in a 12x18 box.)


  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,764

    try some check valve heads

    Messages: 18,668

    You could have a kink or rock somewhere restricting the flow enough to keep it from pushing all the heads up. Once you get them up and sealed it has enough pressure to make the rotors work. If you had a meter this would be an easy troubleshoot. I guess you could try smaller rotor nozzles and see if that works if not then you have a bottleneck somewhere.
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,764

    I saw a low-pressure zone (system with a PRV upstream of the meter) with one of the heads a Hunter I-20SS ~ all the other heads were up and spraying about full force before even a drop of water escaped the I-20 Whether this was an intentional arrangement, I don't know, but it had the effect of taking one head out of the loop while the others popped up.
  7. DanaMac

    DanaMac LawnSite Fanatic
    Messages: 13,226

    Restricted flow by roots or rocks as Fimco stated. or leaking wiper seals at the heads. Or the zone is stretched on GPM. Or combination of all of it. Try nozzling down to start, and do the check valve heads that WB mentioned, at least on the lowest one or two heads.
  8. Lite Headed

    Lite Headed LawnSite Member
    Messages: 160

    I'm going with leaking wiper seals. I've seen it many times, when a loaded GPM zone will operate "properly" once the heads are manually pulled up to make the seals seat.
  9. S.O.Contracting

    S.O.Contracting LawnSite Member
    Messages: 186

    I've had DV's where the diapraghm had swollen over time and was restricting the flow through it. Kinda like Peter said the Irritrol 205 will.
  10. WalkGood

    WalkGood LawnSite Bronze Member
    Messages: 1,910

    Thanks for typing what I was thinking.

    To the OP:

    Just worked on a similar situation. 5 PGP's on this one zone that *use* to perform much better. Has a booster pump on 5/8" meter with 3/4" Cu main. Heads slow to rise, don't spray very well. Sunk below turf, dated from 1999, leaky at the seals and shafts all scratched up.

    Started at the furthest head. Each head I replaced, the pressure would increase 4 psi to 7 psi. They would all spray a little better/further too. Started at just about 23 psi measured at the manifold hose bibb, pump running, before I started replacing. Pressure now at almost 50 psi. More importantly they are all pumping much more water from the nozzles.

    Leaky seals - a little at each head and the whole zone suffers if the volume isn't available to make up for the loss.

    Now, I've seen a zone with 7 or 8 PGP's w/#7 nozzles on a 1.5" line with over 120 psi static pressure. Leaky seals on all yet they all also pump out a lot of water and each looks like normal volume. Commercial customer doesn't care about the water waste since the heads "are all working fine". I've also seen a broken head on a zone, water shooting straight up. Yet all the other heads pumping out water like nuthins wrong.

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