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Horn sound on low fire on TT 110

wrxz24
wrxz24 Member Posts: 301
in Gas Heating
So, I had my gas valve replaced after the tech detected gas during a cleaning. However, the smell is still there and now I am getting this low fire horn sound. It goes away as soon as the burner ramps up. I am assuming it's a combustion issue since the valve has been replaced. Any thoughts? I have reached out to the tech and am awaiting his response. I have video of the sound, the horn sound starts at around the 35 second mark. Thanks in advance.

Comments

  • wrxz24
    wrxz24 Member Posts: 301
    Oops. Forgot to post a link
    https://m.youtube.com/watch?v=h5_pIZ9j0Ws
  • Leon82
    Leon82 Member Posts: 684
    It can be the combustion mixture. And since it appeared after a gas valve change it makes sense.

    See if they will cone out and adjust it
  • Tim McElwain
    Tim McElwain Member Posts: 4,642
    What did you have for combustion readings after the valve change and adjustment of the throttling screw?

    What is you inlet gas pressure?

    Is this LP or natural gas?

    Has anyone taken a Combustible Gas Detector and determined exactly what is givng off the odor of gas.
  • wrxz24
    wrxz24 Member Posts: 301
    null
    From tech email "Supply pressure and 2nd stage reg supply pressure is 11 to 14"wc, manifold pressure on unit down stream of gas valve is 10"wc."
    As far as the horn sound, he called tech support and was able to make an adjustment on the gas valve and the sound went away.
    Hi fire numbers are co2 10.9%, 95.3% eff, 78
    Ppm Co, oxygen 4.4 %, 103.1 temp stack, 24.3% oxygen
    Low fire Co2 8.4%, 97.6 eff, 7ppm CO, oxygen 8.2%, 58.7% excess air

    As far as gas smell detection, it was on and off when he placed
    It near the Venturi, as soon as the wind picked up, the detector beeped, and when it didn't, the detector stopped. possible that wind works its way up
    The exhaust and out through the intake??

    thanks in advance
  • wrxz24
    wrxz24 Member Posts: 301
    And it's LP
  • Zman
    Zman Member Posts: 7,611
    Ignore everything but the O2 and CO numbers (and the stack temp if it is really weird).
    The rest of it is calculated by the analyzer and of little real value.
    Your low fire O2 is way out of spec. I have found this to be the culprit of many trombone solos.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • wrxz24
    wrxz24 Member Posts: 301
    null
    Thanks zman. What should the O2 be? I can't find the specs for low fire.
  • Zman
    Zman Member Posts: 7,611
    It will vary a bit by manufacture. I believe triangle tube wants it within 10% of the high fire numbers.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • wrxz24
    wrxz24 Member Posts: 301
    null
    So my o2 is about 50% higher than the number at high fire. So if it gets adjusted at low firing rate, wouldn't that change the combustion numbers at high fire? And now, those numbers are within spec. What about the efficiency ratings? Do they not mean anything or just not accurate? Thanks in advance
  • Tim McElwain
    Tim McElwain Member Posts: 4,642
    These are the readings required according to the I and O manual from Triangle Tube.

    On Propane the readings should be O2 min 2.7%, O2 max 4.7%, CO2 min 10.7%, CO2 max 12% and CO 100 PPM

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