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  1. #1

    Gas Valve-Potential Damage during pressure testing

    Just installed a new Luxaire LP9C, fully modulating, 80K BTU gas furnace. Unit started fine and operated as specified for several days. Then went back to site to change some upstream gas piping. During pressure testing of the upstream gas piping the shut off valve at the furnace accidentailly got bumped and cracked open for less then a second. This exposed the gas valve to potentially as high as 15 psi pressure (but likely more down around 5 psi or so). Subseqent to this occurance no gas leaks are detectable around the units gas valve (White Rodgers 36J27-508 gas valve), and the furnace itself seems to be operating fine and is ramping up and down as usual. Anybody out there make this similar dumb mistake that might have some feedback related to the potential for damage to the gas valve itself? Manufactures recommendaiton is to not expose the valve to more than a 1/2 psi.

  2. #2
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    4,975
    If it works great, pressure normal, flames look good:
    Then I'd leave it.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  3. #3
    Join Date
    Jan 2010
    Location
    Athens GA
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    1,234
    Less than a second is super human speed so I doubt that .It was probably more like 5 seconds.
    That being said if its working ok then its probably fine.
    Of course you could get the manometer out and check.

  4. #4
    Join Date
    Oct 2005
    Location
    Pacific Northwest
    Posts
    2,266
    Quote Originally Posted by Mike Johnson View Post
    Just installed a new Luxaire LP9C, fully modulating, 80K BTU gas furnace. Unit started fine and operated as specified for several days. Then went back to site to change some upstream gas piping. During pressure testing of the upstream gas piping the shut off valve at the furnace accidentailly got bumped and cracked open for less then a second. This exposed the gas valve to potentially as high as 15 psi pressure (but likely more down around 5 psi or so). Subseqent to this occurance no gas leaks are detectable around the units gas valve (White Rodgers 36J27-508 gas valve), and the furnace itself seems to be operating fine and is ramping up and down as usual. Anybody out there make this similar dumb mistake that might have some feedback related to the potential for damage to the gas valve itself? Manufactures recommendaiton is to not expose the valve to more than a 1/2 psi.

    Any time you pressure test like that, loosen the flex connector or union downstream of the gas cock. I'd be Leary of that valve with life and limb at stake and all....

  5. #5
    Join Date
    May 2007
    Location
    Dry as a bone Tucson
    Posts
    4,280

    dumbasszzz mistake

    sign me up on that one.........all it did for me was lockup the valave and make it completely in-operative. Re purged, installed regulator and bingo gazingo......valve worked like new! On re-tests and branch re-routes or extensions that need a new test...every flex gets disconnected and capped regardless of circumstances.
    Some Talk, Some Do
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  6. #6
    Join Date
    Mar 2001
    Posts
    1,213
    As said, the responsibility is yours. That valve could work OK for 10 yrs, or fail tonite. Your call, but you know it could be damaged. ALWAYS open the union fitting after the gas cock, prior to pressure test!)

  7. #7
    Join Date
    May 2008
    Location
    Myrtle Creek. Oregon
    Posts
    182
    Quote Originally Posted by Moose View Post
    As said, the responsibility is yours. That valve could work OK for 10 yrs, or fail tonite. Your call, but you know it could be damaged. ALWAYS open the union fitting after the gas cock, prior to pressure test!)
    I take the union and gas cock valve off, and cap the gas line, then do the pressure test. even with the gas cock still in the line 15psi could push the cock greas out. it does happen.
    a stupid question is a question you wont to ask, but don't

  8. #8
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,164

    Exclamation you blew it

    this is why the gas codes REQUIRE you to disconnect and cap off all appliances. Those gas cocks are rated for 3-5 psi depending upon mfr. but that's only when closed. Yes, some are tested to 100psi but they are rated to about 5 so don't over pressurize them.

    Now that you know this valve has probably suffered an overpressure event, you are liable if something goes wrong and possibly guilty of gross negligence if someone injured because you knew about the potential yet failed to replace it.

    I'd replace the valve and write it off on experience. What's your customer worth?

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