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    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #1

    Aug 15, 2010, 03:58 PM
    Static vs Dynamic Water Pressure
    Hi all,
    Our water bill has been a bit high, so I'm trying to understand the cause of it. This led me to testing our water pressure. I went out and bought a water pressure gauge, to test with. Here's where I'm thoroughly confused...

    I hooked up the gauge on a hose bib, next to the water pressure regulator. My static water pressure is 110psi. When I turn a sink faucet on in the house, my water pressure is at 55psi. I believe this is my dynamic water pressure (? ).

    I've been told that my water pressure should be between 40-80psi. So, here's my question:

    Is that 40-80psi the STATIC or DYNAMIC water pressure reading? I tried adjusting the pressure regulator when no water was turned on (static), but my reading never dropped below 110psi. Could this mean my pressure regulator is bad?

    Thanks in advance,
    Gary
    hkstroud's Avatar
    hkstroud Posts: 11,929, Reputation: 899
    Home Improvement & Construction Expert
     
    #2

    Aug 15, 2010, 04:19 PM

    Static pressure should be 50-60 range.
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #3

    Aug 15, 2010, 04:31 PM

    Thank you very much for the quick reply! I called the water dept, and they said my static pressure at the street is 130psi. My gauge is reading the static pressure at 110psi on all of my hose bibs. So, my pressure is obviously way too high.

    I tried adjusting the pressure valve (turned the screw counter-clockwise), but it never drops below 110psi. Could my pressure valve be bad? If so, is it difficult to replace... or would I need to contact a plumber? It looks like it's just held on with a nut on both sides. I'm not sure if I could simply turn off the main water, unbolt the old pressure valve, and replace it with a new. Wishful thinking, I'm sure... but thought I'd ask.

    Thanks again,
    Gary
    hkstroud's Avatar
    hkstroud Posts: 11,929, Reputation: 899
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    #4

    Aug 15, 2010, 04:40 PM

    After making adjustments open a faucet to release pressure, then take another static reading. Yes, the last one I replace was just as easy a you describe. Available at Home Depot and the cheap ones are in the $30 range. A couple of pipe wrenches and some pipe thread sealer.
    ma0641's Avatar
    ma0641 Posts: 15,675, Reputation: 1012
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    #5

    Aug 15, 2010, 04:50 PM

    Many hose bibs are connected BEFORE the pressure regulator so static pressure there may not be too high with 130# at the street. With no water turned on, you won't see any change in the static pressure. Adjust pressure with water running, or adjust PR and flow the water to see if it changed. 110 is static, 55 is dynamic. 55 # drop off seems a bit high with only 1 faucet flowing. You cannot relate static pressure and dynamic pressure without knowing pipe size. For example, you could have a load of pressure on a very small pipe and get hardly any flow because the pipe becomes a critical orifice.
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #6

    Aug 15, 2010, 05:16 PM

    Thanks again for the replies. I tested the static pressure from within the house (at the washer line). The static pressure (with all the water off) is 110psi at the washer inside my house. Once I turned on the sink faucet, it dropped to 55psi.

    I'm not sure which pipe size you're talking about. I have a shutoff valve connected to the pipe coming into the house. Shortly after that, is the pressure valve. Shortly after the pressure valve, I have a hose bib. The piping there appears to be about 3/4", but I could be wrong.

    I also tried adjusting the valve with the water running, but it didn't help any. I'm still at 110psi when I turn off my faucet.

    Sounds like I may need a new pressure valve? My PRV says it's a Watts STD 50, range 25-75.

    Thoughts? Time to replace it possibly?

    Thanks!
    Gary
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #7

    Aug 15, 2010, 05:18 PM

    Pressure regulators cannot reduce a pressure downward UNLESS there is flow.

    Backflow preventers (check valves) do not work with pressure regulators without an expansion tank.

    It does SEEM that your PRV is faulty.
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #8

    Aug 15, 2010, 05:23 PM

    Thanks KISS. I'm going to run down to Ace, Home Depot or Lowe's and see if I can find the same size PRV.

    Gary
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #9

    Aug 15, 2010, 06:05 PM

    Sorry guys... one more question.

    My static reading (from every hose bib, and from within the house) is showing 110psi.

    When I turn on the water, it dropped to 55psi. I turned the valve counter-clockwise while the water was on and I can see the pressure drop. I went down to 10-20psi, and water was slowly flowing from the faucet. The second I turn the water off, the gauge jumps back to 110psi.

    There obviously should be close to 100psi discrepancy between my static and dynamic numbers. Would a faulty PRV do this? I thought it may be faulty, but I'm definitely able to slow down the flow while the water is running.

    Any ideas?

    Thanks,
    Gary


    Oops, meant to say:

    "There obviously should NOT be a 100psi discrepancy between my static and dynamic numbers".
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #10

    Aug 15, 2010, 06:10 PM

    Pressure should not change much.
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #11

    Aug 15, 2010, 06:11 PM

    So what would cause it to change this much? The PRV?

    Thanks
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #12

    Aug 15, 2010, 06:31 PM

    A very small water line would have a large pressure drop which I doubt you have or the PRV.
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #13

    Aug 15, 2010, 06:37 PM

    Awesome - thanks for your input. I'll move forward replacing the PRV.
    speedball1's Avatar
    speedball1 Posts: 29,301, Reputation: 1939
    Eternal Plumber
     
    #14

    Aug 16, 2010, 05:37 AM

    How old is your house? What kind of pipes? Copper. Plastic or galvanized? The pressure loss, after you open up faucets,
    May be a volume problem because of mineral buildup in your pipes. 110 PSI is too high. It puts a strain on joints and valves. The average house pressure is 45 PSI, ( that's why water towers are 100 feet high).
    Before you replace the PRV try this;
    1. Close the gate valves before and after the PRV. Open
    The bypass valve slowly in the bypass line and blow
    The system down. Care should be taken not to open
    The bypass completely to prevent the safety relief
    Valve (if installed) from popping off. After blowing down
    The system, close the bypass valve.
    2. Loosen the lock nut on the adjusting screw to allow
    Adjustment. Relieve the adjusting spring. See Figure
    2-1.
    3. Slowly open the inlet side gate valve to the fully open
    Position, and partially open the outlet valve so only a
    Small amount of fluid can pass.
    This bulletin should be used by experienced personnel as a guide to the installation of the Model GD-24 Pressure
    Reducing Valve. Selection or installation of equipment should always be accompanied by competent technical
    Assistance. You are encouraged to contact Armstrong International, Inc. or its local sales representative for additional
    Information.
    1. An Armstrong ìYî strainer (20 ñ 100 mesh, depending
    On liquid quality) should be installed before the PRV
    To reduce the chance of dirt fouling.
    2. Pressure gauges should be installed before and after
    The PRV.
    3. Piping a bypass line with a globe valve around the
    PRV will allow system operation while the PRV is
    Being serviced. Install only if fluid cannot be shut-off
    To service PRV.
    4. Do not install quick opening or closing valves
    Downstream of PRV.
    5. Install the PRV with the flow in the direction of the
    Arrow on the body.
    Improper adjustment of the pressure reducing valve may cause hunting, improper control, and possible damage to the
    Valve itself. Adjust the valve as follows:
    4. Slowly turn the adjusting screw clockwise until the
    Desired pressure is obtained on the downstream
    Pressure gauge.
    5. Slowly open the outlet valve to the fully open position.
    6. Adjust pressure again after system stabilizes.
    Turning the adjusting screw; Clockwise increases
    Pressure and Counterclockwise decreases pressure.
    7. Tighten the adjusting screw lock nut after adjustme
    Good luck, Tom
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    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #15

    Aug 16, 2010, 03:44 PM

    Tom,
    Great information - thanks! My home is 5yrs old and has copper pipes. I'll give this a try, before I go through replacing the PRV.

    Thanks,
    Gary
    ma0641's Avatar
    ma0641 Posts: 15,675, Reputation: 1012
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    #16

    Aug 16, 2010, 07:03 PM

    I believe you need a PRV. Look to see how it is connected, some are pipe thread, some are sweat-Hope for pipe thread.
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #17

    Aug 17, 2010, 06:31 PM

    Status update, and another question :)

    I'm pretty confident that my PRV is in fact faulty. I ran to home depot, and picked up a 1" PRV. Unfortunately, the one I bought has larger gaskets... so the nut will not thread onto the PRV. So, I'm just going to purchase the same one I currently have.

    Here's where I need your help. There are about 10 different connection options to choose from. I want to make 100% sure I get the right one.

    This is EXACTLY what my existing PRV looks like:
    http://www.westsidewholesale.com/med...7/575017-1.jpg

    When I go to Watt's website, here are the available connections:
    Threaded, solder, PEX, quick-connect and CPVC with both union and double union connections.

    So, which one do I need? Mine has threads on the OUTSIDE, so I know they're not female threads. I also know they're not solder connections. Would mine be considered union connections?

    Thanks in advance,
    Gary


    So, it looks like I need an NPT threaded double union. Does this sound correct?

    Thanks!
    hkstroud's Avatar
    hkstroud Posts: 11,929, Reputation: 899
    Home Improvement & Construction Expert
     
    #18

    Aug 17, 2010, 07:07 PM

    Show us a picture of your existing PRV
    Attached Images
     
    shacall's Avatar
    shacall Posts: 14, Reputation: 1
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    #19

    Aug 17, 2010, 07:35 PM

    Thank you very much Harold! It looks like I need a double union connection, since the nut will thread onto these exterior threads.

    Thanks again,
    Gary
    hkstroud's Avatar
    hkstroud Posts: 11,929, Reputation: 899
    Home Improvement & Construction Expert
     
    #20

    Aug 17, 2010, 07:43 PM

    Repeat, one end should screw on to a threaded male adapter, the other end would be a union connection.

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