High CO in stack

[dave24]

Have extremely high carbon monoxide levels in residential stack (2-3,000 parts per million). The boiler was originally coal and converted to natural gas. It is clean, getting good flame, draw is good and is reaching 81 efficiency. Can't figure out what can be contributing to such a high count -- it's surposed to be around 100 ppm.

[what96]

I have seen this exact situation before on two conversion boiler that were oil and converted to natural both units were above 3000ppm and combustion area and heat exchangers were clean. I pulled burners, checked gas pressure, adjusted primary air and shutters all atempts failed to bring co level down. I was told by a tech that was around during the mass conversions that was going on at the time there was so much demand for conversion burners at the time that quality of burner was not a consern because of low gas prices and volume of work being done. Suggest replacing boiler or at least a modern efficent burner. Any one reading this know how high co level would have to be to become combustible?

[pitman22c]

Honestly, if it's a coal to gas conversion this thing needs to be replaced.

If, however, you're dead set on being an enabler the first thing I would do is clock the meter to see if the correct amount of gas is being consumed. It may be this NEVER ran properly. Your responsiblity though is to shut it down. Call the gas company.

[Jim Davis]

It can't be getting a good flame if it is producing 2-3000ppm of CO. Would be helpful to know your O2 and Flue Temperature. What type of burner? If your flue tempeature is less than 400 degrees and your O2 is above 9% you are underfired and the flame is too cold. If your O2 is below 6% or lower and your flue temperature is under 400 degrees, your air is closed too far. Without all the readings diagnostics are difficult.

[gje1]

I agree with pitman. You'll need to clock the meter to find out what it's burning at (BTU). Than you'll need to know the input rating (BTU). Compare the two.
Your local gas company should have a conversion chart and be able to do the calculations for you. Most CO problems are overgassed or undergassed. I'm not saying that's your problem but it's a place to start. You should also have some sort of sticker on the appliance stating when and who did the conversion. Better hurry though, soot is combustable, like black powder, but at what temperature I'm not sure.


[Edited by gje1 on 02-18-2005 at 06:41 PM]

[fat eddy]

That is a very high count by anyones standard, there is something wrong with that unit or the measuring device,There should be visible evidence. It can not possibly be burning clean to the eye and getting those kinds of readings. I think the normal CO that you see in a flue is about 15 PPM not 100 PPM and should be near zero PPM.

[pitman22c]

You can absolutely have a high CO and have a flame that looks normal w/o sooting. We see it several times a year.

[rsmith46]

Its overfired or has a lack of commbustion air. The stack temp will tell you which.