PVB question

Discussion in 'Irrigation' started by Dirt Boy, Aug 29, 2011.

  1. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,235

    RPZ,s suck, thats why I didnt recomend it.
     
  2. Dirt Boy

    Dirt Boy LawnSite Senior Member
    Posts: 487

    The flo sensor would probably be the answer, at least according to my thinking.
    Yes Boots, there is the "standard" what are they 1/2 - 1 gal tank.
    Kiril, I fail to see how adding a master valve or delay in will do anything.
    If the controller tells the zone valve to turn on, and it delays 1 sec. or 60 sec. the pressure in the system is going to be the same. Same think with a master valve. The VSP is not going to turn on until the pressure drops, and when the pressure drops, due to the small pressure tank, there is always going to be a "lag" of a second or three before the pressure builds back up in the line.
    Perhaps I'm blind to your reasoning, but again, there is no pump start per se, IOW's the sprinkler controller is not kicking on a relay, the relay is being turned on by pressure drop at the very small pressure tank.
    Hope that makes sense!
    What there needs to be is a flo sensor to activate the pump relay, instead of relying on the pressure switch.
     
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,007

    If there is a pressure switch and a pressure tank of sufficient size, then the PVB should be staying closed. Of course you would have a master valve, so the tank and switch can function properly.
     
  4. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,235

    He already said its not a pressure switch but a constant pressure flow senser if Im not mistaken.
     
  5. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,235

  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,007

    It might be cheaper to let it continue to burp water, than to mess around with it.
     
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,007

    If it's a constant pressure system, then it isn't doing a heck of a job. Maybe a bigger tank near the PVB would help.
     
  8. Dirt Boy

    Dirt Boy LawnSite Senior Member
    Posts: 487

    Correct AI,
    And yes Boots, it really isn't hurting anything, homeowner just asked about it, and if it had to be that way.
    Yes a bigger tank would help, but that ain't going to happen.
     
  9. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,298

    A slow opening master valve may allow the system to lose enough pressure to kick the pump on but not cause the backflow to dump.

    I thought you said there was no pump relay? :dizzy:
     
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,007

    some PVBs will not take to the continual re-pressurizing - the poppet washer will wear out prematurely
     

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