Pressure Reducing Valve Sweating?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by prashster, Oct 31, 2009.

  1. prashster

    prashster New Member

    Messages:
    941
    I have a PRV just inside the main water shutoff of my house.
    I do not have an expansion tank.

    Recently, the PRV has started 'sweating' and driping. I took it apart and cleaned the gaskets, thinking it was that. But it's actually oozing out of the brass itself.

    How can this happen? Am I just seeing things?
  2. msgale

    msgale New Member

    Messages:
    90
    Location:
    Ohio
    are you sure it's oozing out of the brass (which means porous, and need to replace)
    as opposed to condensation( bcs. valve is colder than the air in the room)?

    Could tape on some alum. foil ove the leak, and see where the water is> that will answer the above question,if you aren't sure
  3. It's the time of the year where the temperature of the air against the temperature of the water causing it to sweat.

    Fall and Spring are the most common times for condensation to occur.
  4. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    If it is the whole valve Dunbar is right if it is just 1 part of the valve then it needs to be replaced...
  5. prashster

    prashster New Member

    Messages:
    941
    Thanks, All. This has been happening over the span of several seasons at least. I only discovered the problem this Spring. But it's leaked about a gallon since then (I'm catching everything in a bucket). I was hesitant to fix bkz I figured it was condensation. But nothing else is condensing, and the volume of water loss seems too high to be condensation.

    It's sweating right THROUGH the brass. Where it happens, the brass appears slightly off color.

    I'm pretty sure it needs to be replaced, but I'm baffled as to WHY this would happen.
  6. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    I have seen this before...just have it replaced and all will be well...
  7. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    I think it's working too hard. It must be reducing a lot of pressure! In it's old age it's getting tired and probably a little nervous, thus sweating the bullets! Put the old timer out of its misery... :D
  8. Runs with bison

    Runs with bison Member

    Messages:
    897
    Location:
    Midwest
    I assume that it is dezincification that is making the metal porous. I've never come across it, but am aware of it being a common problem in some applications. We were always careful about our material specs and that is probably why I was not seeing it. The following link might prove helpful.
    http://www.hghouston.com/coppers/brass75.htm I have had other unrelated materials fail in this same way (porous leakage rather than obvious pitting, cracks, erosion, etc.)

    In your case it makes you wonder if the original alloy was not properly made, or if the valve was overheated during installation.
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    Prv

    If it is a poor grade of brass, it will develop leaks through the metal. Condensation only occurs when the water is below the dew point of the air, and seldom occurs unless there is a constant water flow to keep the pipe chilled.
  10. prashster

    prashster New Member

    Messages:
    941
    Thanks for all those responses. I really appreciate it. I've ordered a new valve. It's a threaded union on both sides, so I doubt it was heated during installation...
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