Good general overview?

Discussion in 'Irrigation / Sprinkler Forum' started by ToolsRMe, Oct 24, 2006.

  1. ToolsRMe

    ToolsRMe New Member

    Messages:
    145
    Location:
    CO
    Good general overview of backflow preventer, etc.

    I've read *sprinkler system project* and the good comments there. My question is about a different part of the system.


    My landscape architect has installed three drip lines. We're waiting until spring to install the plumbing.



    The previous owner had a sprinkler system that was not maintained for several years. We decided to destroy his hoses, etc., because he did not blow out the lines and they were leaking badly.

    We still have the 3/4" copper coming out of the city supply but I have not been able to trace where the 3/4" for the previous sprinkler system goes. I don't know what I'm looking for in terms of the plumbing.

    I know I need some kind of back flow preventer but I'm clueless as to what it looks like. I presume that the previous owner had a backflow preventer but given the crappy plumbing and electrical that I found while doing the remodel, I'm not sure if he had one.

    Is there some general overview where I can read up on drip systems and back flow preventers and manifolds and timers and god-knows-what else?
    Last edited: Oct 24, 2006
  2. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    The backflow preventer goes in the sprinkler mainline after it has branched from the domestic supply. That prevents contaminated water from the irrigation side from getting into the domestic supply. There may be different configurations than mine, but I would assume they are all somewhat the same. Mine is a brass fitting about 16" long. Water comes in on one end and out the other. It has a springloaded device on the inside that makes it function. My city requires annual certification to make certain it is functioning properly. You can get one at a box store or irrigation supply house. It's been several years since I bought mine and I don't recall what I paid for it, but sinces it's brass (copper) it's undoubtly ten times more anyway. From the backflow, you run your pipe to the manifold which is just the valves for each zone. Mine are installed in a control box just outside my basement. The controller is in the basement, and the wires run out into the valve box. You can use PVC for all of the irrigation lines. You must make certain the backflow preventor doesn't freeze. It can be blow out with air, but I remove mine in the fall just to be sure. Then I blow out the system, one zone at a time, with my air compressor. If you don't have a decent compressor, hire it done by a yard service. They use big units that can blow the whole system at once. I'm not sure what you have to do about a drip system, I suppose the end of each zone would have to be opened or you'd blow the nozzles apart.
  3. jimbo

    jimbo Plumber

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    8,997
    Location:
    San Diego
    Toro, Rainbird, Orbit, Hunter, Irritrol all have loads of information on their websites. Your local home store usually has tons of free brochures.
  4. ToolsRMe

    ToolsRMe New Member

    Messages:
    145
    Location:
    CO
    Anyone have a picture of a typical back flow preventer?

    In terms of drip systems, I've heard from several sources that the drip part of the system does not have to be blown out because the pipe expands to accomodate ice. Plus, since it is a drip system, it sorta evacuates itself, anyway.

    What, apparently, needs to be blown out are the valves and the lines leading to the valves. I am clueless as to what the valves or manifold look like.

    I've heard nothing about inspection of the backflow in my city. I'm guessing that a majority of the sprinkler systems in this city don't have a permit (geez, I wonder if I need one?) and I suspect that the backflow is not inspected.

    Is there a quick disconnect on the backflow or are we talking sweating copper?

    I've found a box (see pictures) [​IMG][​IMG]that I think is the electronics for the valves.

    I also have these two green boxes [​IMG]that appear to be buried in the ground. My general rule is don't mess with things that you don't understand ... so what should I expect (other than dead animals) in these green boxes?


    P.S. How does one insert pictures into the body of the message?

    Attached Files:

    Last edited: Oct 25, 2006
  5. Rancher

    Rancher Guest

    You'll find the 24 VDC electric valves in those boxes. All in all your system looks operational, I would just manually turn the valves on and see what works, you can either do that at the valve, or from the control box on the wall.

    Rancher
    Last edited by a moderator: Oct 25, 2006
  6. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    Make a quick trip to a box store and take a look at the various components. Having no experience with drip irrigation, I can't say for sure about draining the lines in the winter, but I'd be a bit concerned about water in my lines. Backflow preventers are connected with unions in my system so it can be easily removed and replaced. A manifold is something you manufacture to accomodate your valves. The main water line comes in and is divided with tees into the individual zone valves, each of which has a line coming out. The valves will usually be in a line and live an a control box. Mine are under the surface of the ground, but they wouldn't have to be. The control box for the valves can be located most anywhere, it is just a timer device that sends low voltage power to the solonids on the valves at and for the prescribed time. I plugs into a standard AC outlet and has a 9VDC battery to keep the programs if the AC fails. (Not to operate the system) Mine is in the basement just inside of the valve box location. The wires go through a conduit which is sealed against water leak. There is a hot wire for each zone in the system plus a single ground common to all zones. I can't speak for your city, but I'd be surprised if they don't require preventors and inspections. If I don't comply with the inspection, my water service is terminated. At least in theory, a system that had no backflow prevention could contaminate the city water main.
  7. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    Do a Google on "backflow preventer" and you can get some good explanations and illustrations of these devices.
  8. Rancher

    Rancher Guest

    Acutally the 9 VDC battery runs the program all the time, the AC transformer supplies the 24 VAC to operate the valves.

    Rancher
  9. ToolsRMe

    ToolsRMe New Member

    Messages:
    145
    Location:
    CO
    So my next question is: How do I open those boxes. I haven't tried yet.

    There's a depression on the cover that looks like I could get a pinky in there. Do I use a screwdriver? If I open it will I be breaking a watertight seal?

    Also, any recommendations for a good backflow preventer? The last thing I need is for dirty water to get back into my house or back to the mains.
  10. Rancher

    Rancher Guest

    They are valve boxes, go to the orange box store and look in the plumbing department. I use a screw driver between the green lid and the black box on the end where there is a depression and hole, it is not watertight, and definately not gopher proof.

    While you are at the home depot store, look in the irrigation area, they have them.

    Rancher
  11. SteveW

    SteveW DIY Senior Member

    Messages:
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    Location:
    Omaha, NE
    Maybe that depends on the brand - I know that on my Toro controller, the 9V battery is purely for preserving the memory of the stored programs.
  12. SteveW

    SteveW DIY Senior Member

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    Location:
    Omaha, NE
  13. Rancher

    Rancher Guest

    Depends on where you live, what State, what City.

    I live in the County and they don't want to issue permits for any improvement under $1,000 (was $500 last year), the City is the same way.

    Rancher
  14. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    That's a surprise to me - seems any jurisdiction would want to know if you were doing something which could potentially contaminate the water supply.
  15. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,358
    Location:
    Yakima WA
    I use a Watts backflow on my system, but I'm sure there are others that will preform well, too.
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