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PVB installation height?

Discussion in 'Irrigation' started by jcom, Apr 7, 2005.

  1. jcom

    jcom LawnSite Senior Member
    Posts: 791

    I am designing a system with the stub out in the back yard. The stub out is several feet lower than the front yard. If it is necessary to have the PVB higher than the lowest head and the homeowner does not want several feet of pipe in the air by his deck, what are my options? ;)

    I am planning on using a Febco 765 1" backflow device.

    Also, does anyone have any experience with the rotary RBird nozzles for their spray heads. With the GPM of the rotarys, I could put many more on a zone and just regulate the time. Any ideas?

    Thanks in advance for all the info.

    John :waving:

    CAL-LANDSCAPER LawnSite Member
    Posts: 48

    PVB and any anti-syphon devise should be 6 to 12 inches above the highest sprinkler head.
    Check your local building codes for requirements.
    If your stub out to the back yard is 2 feet lower than the system,
    You might need to start the system from the front mainline and come around the house to stay at a more level elevation.
    Then you only need to have one pvb at the start of ALL systems.
  3. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Posts: 2,697

    You won't be able to use the PVB. You'll have to use a RPB. They can be used for systems where the heads are located higher than the backflow preventer. Check with local bldg. dept. Also, let the homeowner know that this is a much more expensive option, then he may not mind the height of a PVB. :D
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,673

    The rotor mist-head-nozzle replacements should be saved for system renovations. It will be years before their long-term reliability will be known.

    As for a PVB installation that needs to be at an unbeautiful height, you might be able to exit the house at the point where you already have the electric meter, gas meter, air conditioning, and so on. One more device won't be as much of an eyesore as it would be on its own.
  5. Broker

    Broker LawnSite Senior Member
    Posts: 382

    Already good advice on the backflow relating to 12" higher then any head or pipe. Let me know how you like the MPR rotor nozzles for spray bodies concerning zoning with MPR 5000series rotors.
  6. Mdirrigation

    Mdirrigation LawnSite Silver Member
    Posts: 2,630

    A rpz backflow can be used in this event . Or come out of the house at the rear , install a blow out point , then run pipe to the front where the evevation is higher and use a PVB.
  7. Broker

    Broker LawnSite Senior Member
    Posts: 382

    When we run into homes like that we also would just install a rpz
  8. Broker

    Broker LawnSite Senior Member
    Posts: 382

    Is it mostly code in your different area's to have the rpz outside or inside. Around here every area is different for residentials. I prefer an outside installation due to the fact of possible discharge.
  9. MOlawnman

    MOlawnman LawnSite Member
    Posts: 161

    In Missouri there is no code regulating where the RPZ should be installed, it just has to be at least 18" above ground. It doesn't have to be above the highest head, it just has to be elevated. Also we are not allowed to install PVB's period. They must be RPZ's or double checks. I personally prefer the4 double check because they can be installed in a pit which makes for a much cleaner installation.

    As far as the MPRotator nozzles, we use them all the time, retrofits and new systems. I love them and I think they are a great invention!!!!
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,673

    Inside installation of an RPZ, unless it's in a utility room with a floor drain, is taking a big chance. One dilemma that faces installers that have a choice between a DCA (double check valve assembly) and a RPZ (reduced pressure zone device) is that the future could bring a change in the plumbing code that would no longer allow the DCA, on account of that device not being rated to protect against toxic backflow. Some locales, that once had requirements for DCA's, tightened their codes, and switched to devices rated for toxic backflow (RPZ and PVB) - none of the older installations were 'grandfathered' and they all had to be upgraded to comply with the new rules. Don't make the mistake of assuming your present plumbing will always pass muster in the future, unless you are already using RPZ's and, where permitted, PVB's.

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