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Residual Gas Detection

mmitpw Member Posts: 2
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 Member Posts: 2
    valve leakage

    ok so I found this explanation from honeywell:


    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 Member Posts: 4,588
    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.