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    Residual Gas Detection (3 Posts)

  • mmitpw mmitpw @ 10:01 AM
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    Residual Gas Detection

    Residential Gas Forced Air Furnace:
    Detecting gas at first nozzle/orifice after heating cycle, is this normal operation?
    If so, how long after should gas still be/not be detectable?
  • mmitpw mmitpw @ 5:32 PM
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    valve leakage

    ok so I found this explanation from honeywell:

    https://customer.honeywell.com/resources/Techlit/TechLitDocuments/70-0000s/70-2320.pdf

    apparently gas leakage can occur for up to an hour.

    So here's what happened:
    I smell gas while changing filter.
    Call technician to come check.
    Finds small leak in pipe connection - problem fixed.
    Wife still smells gas, calls utility co.
    they find leakage at first burner orifice - get red tagged.
    Call technician again - order new valve.
    New valve installed - problem fixed.
    Wife still smells gas.
    I check with cheapy detector - leakage at first burner orifice
    Call technician - ordering new replacement for bad new valve

    I have a feeling we'll have the same outcome.
    So is it safe?
    How do I convince my wife that it is?

    Any guidance would be appreciated.
  • Tim McElwain Tim McElwain @ 7:36 PM
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    Some detectors are

    too sensitive as I am sure you read in the Honeywell paper you referenced. I have even seen them register on fresh pipe dope.

    Try this mix some soap and water and take a small brush and put some soap at the orifice and see if it bubbles if not then you are safe.

    The tech who keeps changing gas valves should do a pressure test with a manometer ("U" gauge) or a digital manometer. This is fool proof and if he or she is trained on gas systems it is a no brainer.
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