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PVBs on a system with a grade

Discussion in 'Irrigation' started by ReboundMan, Aug 14, 2006.

  1. ReboundMan

    ReboundMan LawnSite Member
    Messages: 2

    New guy post, please be kind. I've been reading through the archives and have found some great information but haven't come across my particular situation. I have a nice clean run from the water supply a central point where I would like to locate all my valves. But two of the zones go up a slight grade, for a total of about 10' of elevation. I really don't want to run my main all the way out to the high point and locate all my valves out there - and I can feasibly come off the water supply, and run 12' up the wall of a shed and anchor a PVB up there, then come right back down, giving me the required hight above the highest point in the system (and no visual problems because it's behind the shed, but still open for servicing).

    Does that make more sense than running the main a-way out back and then coming back in for the lower zones? Or am I missing something simple....always an option.

  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,582

    An RPZ backflow preventer is elevation-indifferent. Locate it at any place you wish, as long as it's a foot above grade.
  3. JeffY

    JeffY LawnSite Senior Member
    Messages: 324

    I would go with the RPZ as well. Plumbing codes in certain states\cities require the PVB to be no higher than 6 feet as they do not want the inspectors to have to carry around ladders for safety reasons.
  4. Hank Reardon

    Hank Reardon LawnSite Senior Member
    Messages: 599

    Are PVB's allowed in Bothell? I thought you'd need a double check there.
  5. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    WA is doublecheck land.
  6. indysoccer16

    indysoccer16 LawnSite Member
    Messages: 24

    If I am pulling out of a lake that is the neighbor hood retention pond that is located in my back yard, do I need a backflow preventor. I mean I would not be putting any contaminents into the water that wouldnt already be there. I am located in illinois also. Btw, I am new to this, this will be my second install and it is my own house. My first was my bosses office and everything turned out great, but that was 4 years ago.
  7. NNL&LS

    NNL&LS Banned
    from zone 5
    Messages: 88

    You might want to check with the local codes on that. I would say that you don't need one, but some areas are picky about water of any type.
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,582

    Surface water isn't considered potable, so it wouldn't be needing protection.
  9. ReboundMan

    ReboundMan LawnSite Member
    Messages: 2

    You're spot on - thanks. In reviewing the code for them, it appears that I do need to have them availble for inspection....now all I have to count on is an 11' tall inspector :)
  10. jerryrwm

    jerryrwm LawnSite Bronze Member
    Messages: 1,274

    Don't confuse the two devices. The PVB or Pressure Vacuum Breaker must be a minimum of 12" above the highest outlet. This prevents backpressure keeping the device open (more or less) The DCA is designed to work against backpressure so elevation is not a factor so the device can be lower than the heads and in some municipalities be below grade.

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