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co and boilers

ed wallace
ed wallace Member Posts: 1,613
on a natural draft gas boiler what kind of co readind should i be getting at the flue

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  • Steamhead
    Steamhead Member Posts: 16,712
    Maximum allowable

    is 400 PPM. But most of us, including myself, think that's way too high. I'd shoot for a maximum of 50 PPM- lower if possible.

    If you have trouble getting the CO reading down, check with the boiler manufacturer.

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  • ive always followed

    100 ppm co or 400 ppm co air free
  • As much as possible

    I try to get below 50 PPM. This is sometimes not possible on certain boilers. It can also be a problem with some conversion burner jobs that have not had service recently.

    The newer high efficiency systems seem to have their own standards although they do stay below 400 PPM which is the ANSI standard for allowable CO air free.

    I have had some 80 % + warm air systems that I could not get below 100 PPM.

    I would make sure that the manufacturer gives you a figure to shoot for. That would be the standard for that piece of equipment. I have had problems sometimes getting this information from some.

    It is also important to take a full set of readings CO2, O2 etc. It is possible to have a high CO2 reading and be making CO. What is called being on the wrong side of the chart. That is why the O2 reading is important.
  • ed wallace
    ed wallace Member Posts: 1,613
  • That's great

    if you can get it that low and you know your detector is calibrated and working okay.

    I have had that with a Carlin G3A conversion burner on a converted oil boiler a few times. The Carlin burner gives you real good air entrainement on the burner which cuts down potential CO. The oil boiler was a Utica boiler that was in real good shape and had been maintained well when on oil.

    I am assuming your BTU input is correct???
  • Rudy
    Rudy Member Posts: 482
    CO readings

    15 ppm's is OK as long as the O2 reading is within specs, typically 7% to 9% and the draft is between -.02 and -.04 WC" (on atmospheric equipment).
    Remember that when you are measuring flue gases, all you want to pay attention to is the CO air free reading.
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