Leaking Febco backflow valve, only when 1 specific zone starts?

Discussion in 'Irrigation / Sprinkler Forum' started by Big Chicken, May 13, 2012.

  1. Big Chicken

    Big Chicken New Member

    Messages:
    7
    Location:
    Nebraska
    Hello all,

    I have a Febco backflow valve that has started leaking under the bonnet, only when zone 4 of my 7 zone sprinkler system starts. The whole valve is only 2 years old and the rest of the system is 5. The leak will only last a couple seconds, but dumps quite a bit of water before it reseals itself. I have not taken apart the Febco yet to see if the pieces are cracking or the o-ring is cracked. I would think those should be fine if it is only leaking on one particular zone. Any ideas what could cause this issue?

    I should note that contacting the installing company is not possible because they went out of business right after finishing my system.
  2. mike1059

    mike1059 irrigation tech.

    Messages:
    56
    Location:
    Portland, OR
    I have to ask if your water source is a well feeding a tank. The only way I know to get that effect from a pvb is if the main line pressure drops below a certain level till the pump catches up. Try programing a delay between stations 3-4 and 6-7 and that should stop the leak.
  3. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,332
    Location:
    Yakima WA
    It sounds like your local area ignores the requirement that backflow preventers on sprinkler lines be inspected and certified each year by a licensed inspector. This inspector will make the necessary repairs to the BFP as needed. Where I live, if this inspection is not done and the report filed with the city, the city will discontinue water service until the inspections is made. Years ago, the city made all of the inspections, but this became too big of a job for them, so they send out a list of qualified inspectors each year for users to choose from. Cost will vary from inspector to inspector, but typically is $35 plus repairs. Repairs are not need too often, but when they are it is usually a simple O ring or similar part and not at all expensive. I suggest you contact your city to see what you local requirements are and if they can provide at least a list of qualified inspectors. This is not a DIY job, it requires test instruments and training.
  4. Big Chicken

    Big Chicken New Member

    Messages:
    7
    Location:
    Nebraska
    Sorry it took so long to reply. I'm on a city water source in a town of 1800 people. I am on the far edge of town on a hill, so there may be a drop in pressure at times. I should also note that after further investigation, the backflow valve will only allow water out when I run zones individually. When I have the program run, there is no leak. It seems that when manually switching zones pressure will drop for a second or two. With the program running, there is an immediate supply of water to the next zone and no water leaks from under the bonnet.
  5. Big Chicken

    Big Chicken New Member

    Messages:
    7
    Location:
    Nebraska
    Yeah, this is small town Nebraska. No inspections yearly, just a post card mailed out asking if we have them in place. The house is fully up to county code with all plumbing. It was built 5 years ago and inspections were done then. We never get any type of follow up inspections unless a building permit is needed for some type of addition or remodel.
  6. mike1059

    mike1059 irrigation tech.

    Messages:
    56
    Location:
    Portland, OR
    The next thing to check is if there is a master valve installed before the pvb. If there is then the pvb is acting normaly. Also the master valve should have been installed after the pvb just to prevent your current trouble.
  7. Big Chicken

    Big Chicken New Member

    Messages:
    7
    Location:
    Nebraska
    No master valves on either side.

    I could have really used one 2 years ago when the PVB I had blew up one day that temps dipped below 32. Luckily I was home to hear the water gushing out 5 foot in the air and could turn off the water supply. That bad weather forecast cost me a new PVB.
  8. mike1059

    mike1059 irrigation tech.

    Messages:
    56
    Location:
    Portland, OR
    I'm going to guess that station 4 is your largest zone, probably with rotor or impact heads and the sudden loss of pressure when the zone activates is what is causing the backflow to open. Installing a pressure regulator after the pvb should stop the discharge. Other then that the system seems to function normally.
  9. Big Chicken

    Big Chicken New Member

    Messages:
    7
    Location:
    Nebraska
    Zone 4 is the farthest from the water source. It hasn't gotten any worse, so I believe you're correct in that it is working fine. I will look at installing a pressure regulator. I appreciate the help.
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