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allowable co in flue gas

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rick in Alaska
rick in Alaska Member Posts: 1,458
I am having a problem with co concentrations in flue gas samples recently that I haven't been having this summer. I bought a new Testo this year and have not seen much co in my samples until just about a month ago. now it seems that most of my calls are running about 20 to 30 ppm co.. My question is; what is accepted levels in the flue gas and why is it just showing up? Also, just worked on a wood/oil boiler with a Beckett that is running around 800ppm and doesn't seem to change much no matter what nozzle combination or air mix I use. Flame looks excellent and doesn't appear to be impinging anywhere. Unit is shut down now until I figure it out.
Will be away from the computer for a little while but await responses.. Thanks in advance.
Rick in Alaska

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  • [Deleted User]
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    we use

    the bacharach training seminars and they teach us to use 400 ppm air free as the max limit...
  • Glenn Harrison
    Glenn Harrison Member Posts: 405
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    A.G.A. / G.A.M.A. max limit on a heating appliance is

    400 ppm. However, if you take a class from Jim Davis at N.C.I. (National Comfort Institute) his protocals are for a max of 100 ppm, and quite frankly I'm much more comfortable with 100, 400 is way too high even if it's "legal".

    What are some of the other readings you are getting in conjunction with the 20 to 30, or the lower readings for that matter. If your O2 is too high, this can cause higher CO levels, or can cause really low CO readings too.
  • Steve Ebels
    Steve Ebels Member Posts: 904
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    Readings?

    Are these numbers showing up right after start-up or when the (boiler/furnace ) is hot?
  • rick in Alaska
    rick in Alaska Member Posts: 1,458
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    readings

    The boilers have all been running to steady state. The wood/oil unit is running about 400 degrees exhaust. The best I have been able to get for co2 is 10.5% with a 70 degree nozzle. I even did an overfire reading to make sure it was not infiltration and got the same readings. Am quite baffled about this one as nothing looks wrong with the fire, but I am not able to get the readings where I want them. Also, am having to use more air than I think should be there to get the smoke down.
  • John@Reliable_4
    John@Reliable_4 Member Posts: 101
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    Rick,............

    did you check the end cone ,"z" and the pump psi ?
  • Glen
    Glen Member Posts: 855
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    It is my experience that this is not unusual for a wood/oil combination. Both fuels share a common vent - and the wood smoke affects all interior surfaces - causing the CO values you have measured. I too have tested. tweaked, changed nozzles. played with the air until the wee hours - wood smoke interference was the only conclusion I came too.
  • rudy_2
    rudy_2 Member Posts: 135
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    Slight correction

    While we 'teach' that 400 ppm (air free) is the AGA standard, we maintain that 100 ppm (air free) is a maximum that should be easily attainable.

    My own suggestion is that 0 to 50 (ppm air free) is what you want to shoot for.
  • rick in Alaska
    rick in Alaska Member Posts: 1,458
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    end cone

    Yes, I checked the end cone,"z", and fuel pump pressure. All normal. NOthing looks out of place except the co2 and the co levels.
  • Mark Hunt
    Mark Hunt Member Posts: 4,909
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    It's gotta be


    impinging on something then.

    Look again.

    Mark H

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  • Bob_19
    Bob_19 Member Posts: 94
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    Could Be

    your excess air is running a little high decreasing your Co2 levels. What are your O2 readings? I'll bet it's higher than 3%

    Also your fuel mix could be different from year to year throwing you off.
  • rudy_2
    rudy_2 Member Posts: 135
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    Hadn't considered...

    A buddy of mine has a Yukon wood/oil set up. He'd heated with wood for years and decided to go oil last winter. Took a look at it last fall, got 'most' of the smoke out, but still had 600+ CO readings.

    Hadn't thought about all the creasote, etc., burning off.
    He burned oil all last year, I'll be curious if its running any cleaner now.

    It also fires into a real big, brick lined chamber. I've thought about putting in a cerefelt liner and seeing if that helps. Pretty sure it would.
  • Mad Dog
    Mad Dog Member Posts: 2,595
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    On Long Island, The local gas utilty Giant

    Keyspan allows no more than 50 ppm in the flue. Mad DogI agree with Mark, Someting is impinging or somethin else aint right...too high!!!! Mad Dog

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  • rudy_2
    rudy_2 Member Posts: 135
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    Just wondering

    Is that 50ppm diluted or 50ppm air free?
This discussion has been closed.