bad pressure loss causes.

Discussion in 'Irrigation' started by Turf Dawg, Jun 3, 2014.

  1. Turf Dawg

    Turf Dawg LawnSite Gold Member
    Messages: 3,719

    Got called to a system that they said had been working but the home inspector said had low pressure and a couple of zones not coming on.

    When I got there all the zone valves showed to be fine just not enough pressure to raise the heads. It has a double check and master valve. The static is 70 psi but activate any valve and it drops to 20 or below. With the main valve open and no section valve open it does not drop. I will check the meter tomorrow and find out the flow with it running. What besides a leak would cause that kind of loss. I am not sure yet where the main ties in at.
    Rookie help needed.
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  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,070

    Use all the test ports on the DCVA to take pressure readings. You may discover a jammed poppet.
  3. Turf Dawg

    Turf Dawg LawnSite Gold Member
    Messages: 3,719

    I do not have any gauges to check the double check with.

    It just seems strange to me (being a rookie) that the dynamic pressure at the house hose bib would drop to less than 20 psi when the irrigation would come on without a major leak. Seems, by what I have seen, to have large enough main and lateral piping for the GPM being used
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  4. 1idejim

    1idejim LawnSite Fanatic
    Messages: 10,915

    time to make an investment I would think.

    If the demand is greater than the supply the psi would/could drop that far.
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  5. DanaMac

    DanaMac LawnSite Fanatic
    Messages: 13,174

    I have one home I'm going to Thursday to replace the PRV. It is reducing flow/volume, but still allows 80 psi. I see it happen quite often.

    The thing that kills me, is I told the homeowner to get a plumber to replace it. It's before the meter and I'd rather not touch it in that placement. I explained to the H/O what was wrong. Plumber comes out and says that I don't know what I'm talking about, pressure is fine at 80 PSI, there are too many heads on the zones, blah blah blah. Charges the H/O $85 and makes me look like a fool. Bullsh!t. I can HEAR the friggin' restriction at the PRV. It's whining loudly directly at the PRV. The H/O is now upset at me. I'm replacing it Thursday, and then telling the H/O to call the plumber to forward me the $85 check. The H/O has been saying all along that they have weak pressure inside the house as well. I want to bury the plumber in a jumbo valve box and move on.
  6. cjohn2000

    cjohn2000 LawnSite Senior Member
    Messages: 570

    Some plumbers wont fit inside a jumbo box maybe an XL Armor box?:laugh:
  7. S.O.Contracting

    S.O.Contracting LawnSite Member
    Messages: 186

  8. mitchgo

    mitchgo LawnSite Silver Member
    Messages: 2,907

    I have lost faith in most plumbers knowledge.

    I had the same story the other week except it was the water district telling the homeowner everything was fine when it wasn't and the issue was on their side.
  9. DanaMac

    DanaMac LawnSite Fanatic
    Messages: 13,174

    I have another neighborhood that has weak volume on about half of the street. The street does gain elevation quite a bit, and the higher up you go, the worse it is. It's been that way for at least 10 years now. Systems installed work very weak when they were built at the far limits of "typical" GPM. Meaning the zones have been designed at 12-15 gpm (higher in some instances), when they may only be getting 6-10. I've had to come in and split zones, do MP or Toro Precision nozzle change outs, or tell the customer to cut out grass and minimize sprinklers. So in the past couple weeks, the water district for that street went to every home and changed out the PRV, and then screwed down the adjusting bolt all the friggin' way down. THIS DID NOT HELP NOR SHOULD IT HAVE. The problem is on the district's side, not the interior plumbing. They have standard static pressure, just no volume. The PRV could be a problem, but on EVERY SINGLE HOME? No, that indicates it's on the supply side leading to the neighborhood.

    Putting a gauge on a testcock will show whatever static pressure is available. I've seen as high as 150 without a PRV. But the hole on a 1/4" thread testcock is minimal, maybe 1/8" diameter at best. This hole will not allow enough water to run a zone. It is a choke point, a restriction. It reduces how much volume can move through it. Why can't a plumber or a water district employee understand this?
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,070

    Spoken very diplomatically.

    Indeed, why be a know-nothing chump for the lack of maybe 20 bucks worth of gauges and adapters?

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