1. Missed the live Ask the Expert event?
    Catch up on the conversation about fertilization strategies for success with the experts at Koch Turf & Ornamental in the Fertilizer Application forum .

    Dismiss Notice

Irrigation Mystery

Discussion in 'Homeowner Assistance Forum' started by Pete215, Dec 13, 2013.

  1. Pete215

    Pete215 LawnSite Member
    Messages: 6

    As an avid 'Do It Yourselfer' I love solving a good home maintenance mystery, usually with the help of the Internet. But I have an irrigation issue that absolutely defies any explanation. Just one zone of the ten in my yard's system will turn on normally and run for as long as 1 minute 15 seconds, and then pressure dies while the Pressure Vacuum Breaker pulses large gushes of water from just under the cap onto the ground. This happens whether I open the valve manually or with the controller. Adjusting the flow rate up or down also makes no difference. The remaining nine zones work normally.
    So far everyone I've talked to maintains that it is not the PVB because the other nine zones work normally, and it is not the zone valve diaphragm, because it works normally initially. It must be a leak they say, but I have searched extensively any kind of leak or wet spots and cannot find any. Plus I've had several leaks before and the PVB did not gush water nor did the zone operate normally for any length of time before malfunctioning.
    The system is 23 years old, I built it myself, and has the following components: Rainbird PVB 150 (1.5") and Randel 216PR zone valves.
    The three issues that I feel make this problem different are:
    #1: The PVB gushes water during the malfunction.
    #2: Manually opening the valve makes no difference.
    #3: The system operates normally for up to 1 1/4 minutes before failing.
    I'd welcome any opinions or ideas that might solve this mystery but so far I can find no one on the Internet that has had an identical experience.
  2. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    The PVB requires a minimum operating pressure to function properly, otherwise it will "gush". Find the leak. First try capping all your sprinklers on that zone and then run it. This will sometimes bring a hidden leak to the surface. If that doesn't work you will need to get into more involved leak detection.

    I suggest/request the mods move this thread to the irrigation forum where this thread is more likely to be seen by people who deal with this kind of stuff on a daily basis, homeowner or not.
  3. Pete215

    Pete215 LawnSite Member
    Messages: 6

    Thank you Kiril, I will do exactly as you say and let you know the results!!
  4. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,316

    The PVB is doing it's job. You have an ongoing upstream negative pressure event occurring.

    If I were onsite I would plug off all of the heads on that zone and turn the zone manually. Using a 18 " long 1" or 1-1/4" piece of pipe I'd listen to the valve and each head for water movement noise. The noise will be the loudest nearest to the compromise.

    It's a pretty basic concept.

    I'm wondering if you are on a well, the zone run/drawdown time is about right for a well.
    Posted via Mobile Device
  5. Pete215

    Pete215 LawnSite Member
    Messages: 6

    Thank you 1idejim! I am in the process of plugging all the heads. This zone has about 15 small emitters, so takes a while and I'll report what happens when I follow your directions. Yes it is on a well.
  6. Sprinkler Buddy

    Sprinkler Buddy LawnSite Bronze Member
    from Florida
    Messages: 1,185

    Want to hear the coming results. Weird it worked for 23yrs and now it doesn't.
  7. Pete215

    Pete215 LawnSite Member
    Messages: 6

    Well, good news. I found the leak. I did exactly what Kiril and 1idejim recommended, and blocked all 25 (low volume) emitters in zone one, and did a walk through after turning the zone on. But the mystery continues. Initially the entire zone was bone dry, so I went back to the source, the PVB. And water was bubbling out of the ground about 2 feet from the PVB. The reason I missed it before, is that the PVB was pulsating large amounts of water and covering the area where the leak was. The PVB is not pulsing water now, even after several minutes. The 'Mystery' as I see it, is that the leak is long before the zone one valve. And the remaining nine zones still operate normally, with absolutely no water at all leaking out of area I found severely leaking when zone one is on. Could be that only zone one builds up enough pressure to separate a crack in the PVC underground. Give me a few days to repair the leak and recheck everything, and I'll let everyone know what I found and if everything is back to normal. Thank you so much for your help.
    Last edited: Dec 16, 2013
  8. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,316

    As Kiril suggested, I would move this to the irrigation forum.

    I would love to see the leak that you have found, a few pics please.
    Posted via Mobile Device
  9. Pete215

    Pete215 LawnSite Member
    Messages: 6

    Well, it looks like we now have all the answers. I was wrong about the leak being outside zone one. I had forgotten this particular nozzle (So far from the zone valve) was part of the pack.
    The stump you see next to the break was some kind of attractive weed I guess, as I never planted it. It was over 8' tall, and looked like some kind of palm tree, so I mistakenly let it grow, as it clearly caused the break.
    I've attached 3 pictures as requested. You can see how close it was to the PVB and the air conditioner
    When everything is back together and checked out I'll submit a final report to this thread. With Christmas so close it may be a week or two. Thank goodness things are cool here in Florida and the lawn needs far less water than normal. Thanks again for all the help.






  10. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,316

    Leaks in automated irrigation systems fall into one of two categories. (1) pre-zone or (2) post zone.
    Pre-zone leaks occur whether the system is running or not.
    They include:
    1) wells and pressure tanks
    2) meters
    3) back flow assemblies
    4) mainlines
    5) isolation valves
    6) master valves
    7) garden valves
    8) zone valve

    A failure or compromise at or before any of the above will create a constantly leaking situation.

    Post zone leaks leak only when the zone is active, whether or not the controller is on.

    Post zone leaks include:
    1) zone valves
    2) lateral lines
    3) swing joints, tees and sprinkler bodies, wipers, stems etc.
    4) auto drains
    5) drip lines, fittings, sprays and emitters

    Note: master valves tend to mask leaks and should be turned on manually when looking for leaks.
    Back flow assemblies are often used to shut systems down in emergency situations. Always check to make sure they are in the on position when looking for leaks and once repairs are made.
    Posted via Mobile Device

Share This Page