Dynamic pressure drop after regulator?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Vitaliy, Sep 10, 2005.

  1. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    Hi,

    About a week ago I installed Conbraco Series-36 pressure regulator.
    City water pressure is 90+psi. Static pressure right after the regulator
    is 50psi (default setting). Whenever water is used City pressure stays
    about the same but pressure after the regulator (pressure gauge is
    about 5†away from the regulator) drops down to 40psi or even 30psi
    (depend on water usage). This is totally unexpected behavior. At the
    far end (next to open faucet) pressure may drop significantly (even
    down to 0psi) but right after the regulator it should be close to the
    whatever it set to (50psi). Am I right? All my plumbing pipes are 1/2â€
    and closest faucet is about 15-20 feet away.
    Something is wrong with this picture but what?
    What should I check and how to correct/fix this problem?
    Is my regulator simply broken and must be replaced?

    Thank you,

    - Vitaliy
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,811
    Location:
    Cave Creek, Arizona
    regulator

    The only way the pressure after the regulator can drop is if the demand is greater than the regulator can deliver. Your 1/2" pipes should not be able to draw that much water, so the assumption is that the regulator, the control valve ahead of it, or the water line to the regulator is deficient.
  3. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    OK,
    pressure right before the regulator is always 90+psi static or dynamic
    regardless of water usage. Pressure right after the regulator is 50psi
    static and drops down to 30-40psi as soon as water is used. Looks like
    the problem is regulator itself.
    Is this correct assumption?
    This is Conbraco, Series-36 regulator and it is only a week old.
    Problem started immediately after I installed this regulator, so it is
    very unlikely that strainer already is clogged.
    Is this just my luck or Conbraco regulators are not good in general?

    Thank you,

    - Vitaliy
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Don't rule out the possibility that the strainer got clogged by debris loosend inside the shutoff valve during install. Check the strainer.
  5. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    Strainer looks nice and clean.
    I tried to setup 50psi dynamic pressure wile water was running and
    noticed strange regulator behavior – it kind of was trying to avoid
    setting between 40 and 50psi. In direction “from low to high†pressure
    was smoothly increasing up to 40psi and then jumped to a bit above 50psi.
    The same story in opposite direction – smoothly goes down to 50psi and
    then jumps to 40psi. As of now I set pressure to 50psi dynamic. Static
    pressure is a bit over 60psi – not too bad. But this does not look right. Should I replace regulator?

    Thank you,

    - Vitaliy
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