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Thread: Wet round spots around sprinklers problem + Backflow device Q

  1. #1

    Unhappy Wet round spots around sprinklers problem + Backflow device Q

    We recently had our backyard sprinklers installed. There is one problem though: after only 5-10 minutes of being on, wet round spot appear around all 32 sprinklers and stay there for more than 6-8 hours (Arizona, 106F!).

    What can be a problem?
    Is it possible that all 4 new valves got clogged during the installation and don't shut off completely? (I think highly unlikely)

    Our backyard set up is:
    Hunter Pro C controller
    Hunter PGV-101G valves (x4)
    Hunter SRS04 pop up spray bodies w
    Hunter MP Rotators 2000 90-210 & I just noticed that 360s are from MP Rotators 3000 series (don't understand the reason, all sprinklers are placed pretty equally)
    x2 PCM-300 3 Sta module F/pro C controllers were added to our Hunter controller


    I opened one of the sprinklers after they were running for 5 minutes and I saw water slowly but constantly flowing from the pipe, (valves looked dry, I assumed they were not leaking)...

    Also, we have a 765 Pressure Vacuum Breaker installed.


    I wanted to know if its valves can be turned off safely during emergencies. For example, can I turn left side valve during any irrigation problems and right-side if the water supply to the house needs to be shut off. I apologize, but I'm complete newbie at these things and have no idea how to operate a backflow valve.

    Thank you!

  2. #2
    Plumber jimbo's Avatar
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    What are we watering here! Concrete?


    Anyway, in the lower picture, that is a pressure vacuum breaker, backflow preventer. The valve on the left is the outlet, and the valve on the right is the inlet. I can't see anything in the picture that would involve the water to the house. Perhaps some more pics will clear that up.


    If the sprinklers in question are at the bottom of any slope, then they will drain all the residual water in the pipes after each cycle. The solution....install the rainbird antidrainback heads.

    6 hours seems like a lot, so don't rule out leaky valves
    Last edited by jimbo; 05-22-2009 at 06:50 AM. Reason: add

  3. #3

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    Quote Originally Posted by jimbo View Post
    What are we watering here! Concrete?
    Well, we will be watering grass - I don't want to buy sod before I know for sure that the irrigation system works without any problems.

    Quote Originally Posted by jimbo View Post
    Anyway, in the lower picture, that is a pressure vacuum breaker, backflow preventer. The valve on the left is the outlet, and the valve on the right is the inlet. I can't see anything in the picture that would involve the water to the house. Perhaps some more pics will clear that up.
    I apologize for not being clear. I found the description of this device online: Febco 765 PVB. Pressure Vacuum Breaker provides protection against water back-siphonage and contamination. Used for irrigation and commercial applications, but I couldn't figure out if it can be used to stop the flow of the water to your irrigation system or your house in case of emergencies by turninng these blue handles (vertical & horizontal) or I should never turn/touch them? What are these handles for? I think our main emergency shut off valve should be located near the water meater, in a box close to the road, but is it the only way to stop water flow in case of a major disaster?

    additional photos:

    side view:


    Quote Originally Posted by jimbo View Post
    If the sprinklers in question are at the bottom of any slope, then they will drain all the residual water in the pipes after each cycle. The solution....install the rainbird antidrainback heads.

    6 hours seems like a lot, so don't rule out leaky valves
    I read about a "slope problem", but we have round wet spots around all sprinklers in our backyard. We have a small slope away from the house for water flow, but otherwise it seems pretty even.

    Also, why would all 4 brand new valves leak? (poor installation?)

  4. #4
    Sprinkler Guy Wet_Boots's Avatar
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    Check your water meter to see if there's a slow leak through the valves. What's the supply pressure?

  5. #5
    Plumber jimbo's Avatar
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    The two handles you are referring to can be used to shut off water to the garden, or for testing and maintenance of the valve itself. Those two small ports you see are gauge connections for a tester.

    The lever just above the ground level is your main water shut off for everything.

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