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Good Morning, Valve Closing Question

Discussion in 'Professional Discussions' started by RhettMan, Feb 27, 2019.

  1. RhettMan

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,963

    Iv been having an issue and im probably doing something entirely wrong here.


    Iv been having some some residential systems with newly REPLACED (cut out and replumbed) Master Valves allow water to leak past/thru the MV and then leak 24/7 out of either a mainline compromise or another slowing leaking-thru valve.

    I suppose I have for a very long time been in a complete misunderstanding of the purpose and reason for a MV (on small resi systems).

    Its goes without saying with me of course that the other compromises down the line need to be addressed each and every time as well , HOWEVER, my question and focus remains for this question on the MV.

    Why arent these new 1" slip PGVs (my current go to valve) not closing when in a Master valve arrangement?

    Are the zone valves closing too soon? : not allowing the Master valve the minimum flow rate required to fully close the diaphragm?
    Pressedun likes this.
  2. ArTurf

    ArTurf LawnSite Fanatic
    Male, from Ark
    Messages: 6,360

    Have you verified leak by meter readings or just going by a wet spot?

    Is is possible the MV is closing and the downstream leak simply continues to drain out?
    hort101 likes this.
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 52,631

    If a property is not flat, a system with a master valve will allow uphill water to drain backwards through a zone valve, because diaphragm valves are not capable of preventing reverse flow.
    townfarm, Outlawn and hort101 like this.
  4. OP

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,963

    Your something else, thats exactly whats happening, his curb side meter is the highest elevation.

    What would shoes do?

    Edit. wait.... this slow leak emission is constant, its never depleted. (so it would leak for weeks on end with the iso on and controller off. but ceases with the system iso in the offpostion (12gpm 8 zoner round-about

    The leak is slow, causing a green mold growth on the concrete on the lowest elevation on the property where it meets the curb of an intersection street with that of the curb side meter. (ignore this but if it doesnt make any sense)

    The meter is equiped with one of those iperl meters with digital leak indicators and the leak flow rate must be below the threshold to trigger the leak indicator, as there is not one.

    I have not let dont a pressure hold test, but it seems like a waste of time other than to use the air induction to find the downstream compromise/leak.

    however, im not concerned with the downstream leak at the moment, i cant sleep that water is getting through that M.V.

    I think i understand a bit of what yyour saying about the reversal of flow from a lateral --->thru a valve---> and back into a mainline wioth a compromise, but it would eventually stop leaking, the amount of water in the lateral being the maximum that could flow out..

    I might not be understanding your correctly, or perhaps i had not first provided enough information, im thinking it was my fault on the latter.

    before someone else suggests it, and it ends up being the problem, i better check the new valve could instalation debris, that would be embarrasing.
    Last edited: Feb 27, 2019
  5. OP

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,963

    An Isolation valve and several weeks observation confirms OP.

    I like to hear those wheels grinding art. Keep it up.
  6. OP

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,963

    oopss, pocket post.
    Last edited: Feb 27, 2019
  7. mitchgo

    mitchgo LawnSite Gold Member
    Messages: 3,515

    So you are saying when you shut the water source off - eventually that area drys up . When the source is back on there is a constant wet area and the meters leak detector doesn’t register the leak .

    It’s possible your new Mv isn’t holding tight - it’s obviously the same principle asthe other valves, try not to over think it . If water is passing through this valve non intentional then there is a issue with this valve .

    Along with the other valve seeping .

    Install Sams and be done with it :)

    How often does the system run ? Daily? You could just be draining the ML . Especially if you have 1 1/4++ ML and a few hundred feet . A slow leak like that would take half a day!!
    Outlawn and hort101 like this.
  8. OP

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,963

    The thing is, this has happened to me like 3 or 4 times now.

    What do I end up doing each time?
    I check the new MV for debris, there never is any, of course.

    I then either replace or rebuild the leaking zone valve, should that be the cause of the leak,
    I repair a comprised mainline.

    Of course that method of repair fixes this issue that was called in.


    There sits Rhett, unable to sleep, tossing and turning, knowing that the system appears to have a M.V. but in reality does not.
    Last edited: Feb 27, 2019
  9. Ron Wolfarth

    Ron Wolfarth Sponsor
    Messages: 1,524

    Next time, manually bleed a zone valve and see how much water you get. If none or none after a while, you have a working master valve. You likely have mainline drainage like a previous poster said. I think you said the meter was at the high end of the system. Depending on the amount of grade change, you may have enough pressure to continue a leak just from the mainline drainage.

    *Newcomers/novices* (not you, Rhett)
    Remember that each foot of elevation equals 0.433 psi change. 4.33 psi in 10 feet; 43.33 psi in 100 feet. So a pressure gauge will read 43.3 psi which is installed 100 feet lower than the top end of a water filled pipe which is open to atmosphere. (Static, meaning the water is not moving.)
    hort101 likes this.
  10. OP

    RhettMan LawnSite Silver Member
    from Texas
    Messages: 2,963


    Moving forward, my suspicion is that the zone valve closes first, it having the lesser outlet side pressure (vs. the master valve) while both try to close simultaneously.

    The zone valve having closed, the master valve seems to be weeping instead of closing.

    is it possible? i mean, perhaps a very slow mainline leak is not enough of a inlet outlet pressure difference to close the MV.

    This current issue, I have not yet visited, so i am not sure if it is a mainline compromise, or a ZONE-valve leaking through.

    If it is a valve leaking thru I am going to cut it out, and replace it with a valve that is known to close slower than the PGV master valve, and then I will make it the last zone in sequence and then see if the MV is now closing after a system operation.

    Will think more on this later.

    Edit: Damn! at there is the frustration, by replacing the valve i will not know if the result is due to a "properly closing master valve" or a "now properly closing zone valve".


    Im praying for a mainline compromise instead of a valve flow thru..

    hopeing we can get a shovel on it thisweek. so much rain.
    Last edited: Feb 27, 2019

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