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Newly installed irrigation system troubleshooting

Discussion in 'Irrigation' started by Hissing Cobra, Sep 5, 2011.

  1. Hissing Cobra

    Hissing Cobra LawnSite Senior Member
    Messages: 705

    Hey guys, I'm usually on the Fertilizer lawn end of things but I'm trying to learn a lot about the Irrigation aspect of things. I just had an irrigation system installed at my house and I'm having some issues with it that I will need some advice on. If any of you can offer any, I'd greatly appreciate it.

    First off, I'll give you the basics.

    3/4" line coming from town water supply, going into an older 3/4" spigot, into a 5/8" town supplied water meter, going into another older 3/4" spigot, out to 3/4" line, into 3/4" Febco backflow, and into 1" mainline to the first valve box.

    I have 90 psi at the backflow and a 6 zone system.

    Zone 1 - 3 Hunter Pros 04's (left side front bed)
    Zone 2 - 3 Hunter Pros 04's (left side front bed)
    Zone 3 - 4 Hunter PGP's (front circle)
    Zone 4 - 4 Hunter PGP's (back lawn)
    Zone 5 - 4 Hunter PGP's (back lawn)
    Zone 6 - 3 Hunter Pros 04's (back strip of lawn)

    Problem # 1 - When system turns on (doesn't matter which zone it is), the backflow leaks water everywhere (luckily it's mounted outside the house). To rectify this, I need to turn one of the ball valves to the closed position and slowly open it, then that zone will work fine. Because of this, I cannot trust the system to run when I'm not home or when I'm asleep.

    Problem # 2 - Area in center of backyard is not getting hit with the PGP's. I've changed out nozzles and have gotten it to hit those areas but I'm still not too happy with the way it's done and I feel as though this may be a band aid fix.

    I've had the irrigation contractor back 3 different times to address these issues and he's at a loss. I've decided to try and rectify these issues but I may need your help in steering me into the right direction.

    So far, I've done a couple of things in regards to the backflow. I've talked to my local plumber (the person who installed the backflow) and he came out with a gauge to check things out. He showed me that I'm getting 90 psi at the backflow but when the zones kick on, the pressure drops to 20 psi before rapidly increasing. He thinks my problem may be twofold. He's proposing to change the old style 3/4" spigots on the main line before and after the water meter, to new 3/4" full flow ball valves. He thinks that this may reduce that rapid pressure drop. If that doesn't work, he suggested changing the 5/8" water meter to 3/4". My question to you all is this, "Are we on the right track?"

    As for the area in the center of my yard that's not getting "hit" by the irrigation heads, I've changed out a bunch of nozzles in the PGP's. Prior to my changing them, I noted that the irrigation contractor had the Red # 3's in all heads. I did some research on matching precipitation rates and changed out the corners to # 2's and the 180 degree units, I changed them out to # 4's. This helped a lot but I feel as though this is a band aid fix and I think I may have to have another zone put in where there's a head directly in the center of the yard. Anyone have any thoughts on this?

    If anyone can offer some advice, I'd greatly appreciate it.


  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,259

    tell us about your location
  3. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,095

    Why the hell was not a 1" mainline and backflow installed to the valve manifold from the meter is beyond me. Is the backflow assembly a DCVA or a RP? Having x amount of static pressure means nothing after figuring friction loss to the head. What's the deal with the "spigots", is it not a automatic system? My head hurts. :dizzy:
  4. GreenI.A.

    GreenI.A. LawnSite Silver Member
    Messages: 2,131

    Pete -
    do you know what you are getting for gallon per min at the backflow? Having spiggots at the meter is deffinetly a big choking point, swap those for ball valves. One of the biggest thing i'm thinking is your supply is 3/4" but you are upping that to 1" irrigation line, you're losing alot of presure there. How long are he runs from the house to the v.box, and from the v.box to the heads? What about elevation change, is your yard flat or are there heads that are higher than the febco.

    You don't have any guys that come in that can swing buy your house and figure it out? John M. should be able to point you in the right dirrection.
  5. Hissing Cobra

    Hissing Cobra LawnSite Senior Member
    Messages: 705

    I'm in Wareham, Massachusetts.
  6. GreenI.A.

    GreenI.A. LawnSite Silver Member
    Messages: 2,131

    realized I accidentaly deleated a sentence, that 5/8" meter is a big issue.
  7. Hissing Cobra

    Hissing Cobra LawnSite Senior Member
    Messages: 705

    I do not know why a 1" mainline and backflow weren't installed. I have 3/4" line coming in from the town's water supply, through the foundation of my house to a 3/4" old style "needle and seat" spigot. From there, it goes into a 5/8" water meter that's been supplied by the town. From there, it goes into another 3/4" old style "needle and seat" spigot. From there, the main water supply line inside my house is 3/4", thus, the 3/4" line to the 3/4" backflow, to a 1" line to the valve box. The spigots are there so that the water can be shut off and the meter changed or serviced by the town. It's "code" in my town for this setup.
  8. mitchgo

    mitchgo LawnSite Silver Member
    Messages: 2,922

    no it's not it's the 3/4 city supply upstream of the meter is the bigger issue.. Many people use this line all at once.

    Having a massive pressure drop like that indicates a severe flow restriction.. More then likely it's your service line that supplies your house ( probably galvi).. Tapping the back flow assembly at the water meter's point of connection would help reduce this.. However more investigation is needed . Make sure all your valves are open fully including your water meter
  9. DanaMac

    DanaMac LawnSite Fanatic
    Messages: 13,185

    It's a matter of available water volume. You have high pressure, but weak volume availability. It may be in the spigot that you mentioned. Something is blocking the water.
    1. the contractor did a poor upfront job of designing the system to the available water volume provided
    2. you/he/plumber may be able to help correct it by, like you said, replacing the inline components to allow better water flow - spigot, meter, etc.
    3. reducing the nozzle sizes may help prevent the water from dumping, but performance of the heads and coverage will be weak
    4. pressure regulator may be faulty, giving high pressure, but low water volume output
    5. if that contractor could not troubleshoot this, then he doesn't know what he is doing and you may be in for a lot more problems if the rest of his install follows his troubleshooting skills
  10. Hissing Cobra

    Hissing Cobra LawnSite Senior Member
    Messages: 705

    I don't know what we're getting for gallons per minute at the backflow. My plumber said that the spigots and meter are definitely a problem and he proposes the changing of the spigots to 3/4" full flow ball valves. If that doesn't work, he said that the meter will have to be changed to a 3/4" unit by the town water department. I'm waiting for them to come and change the ball valves and this will definitely get done. If it doesn't fix the backflow flooding problem, I'll get the meter changed as well, then everything will be 3/4" up to the backflow and 1" from that point on.

    My ground is relatively flat and none of the heads are above the backflow in terms of elevation. The backflow is on the side of the house, directly above the first valve box and there's a 1" supply line from the backflow to that valve box. I then have a 25' one inch line that goes out to my backyard to valve box number two.

    I don't have any guys that can swing by and check it out, that's why I'm asking for help here. Also, it helps me to understand things better. I have talked to John M and he's also on board with the meter being a bottleneck to the system.

    On a side note, I have other questions in regards to the Red PGP nozzles. How do you know which ones to put in the heads as a base starting point? I've been reading up on matched precipitation rates and I understand how they work but don't understand what a starting point should be. Is it based on pressure, volume, or both?

    I will get this system working 100%, it's just a matter of time!:drinkup:
    Last edited: Sep 5, 2011

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