Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

What are your policies regarding High CO?......Boilerpro

Boilerpro_3 Member Posts: 1,231
I find about a third of older cast iron burner atmospheric draft hood equipped gas fired boilers have high CO (700 to 2400PPM) Most can be brought down to about 225PPM with just a slight change in input. However, on those units that won't clean up, what do you do, assuming all else is OK? Under what circumstances do you "pull the plug"?



  • Timco
    Timco Member Posts: 3,040

    Laars was kind enough to put me in touch with techs of theirs as well as engineers to give the OK to adjust the manifold offset pressure just below their usual standards to achieve 50ppm or less. Had to twist WM's arm to get a typical CO output #. Also based on O2 and CO2 readings. Correct orifice helps...derated for your altitude / caloric gas value. Check vent for proper / too much / too little draft. Combustion air is important. I've needed to drop the manifold pressure just below spec a couple times with mfg approval.


    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
    Just a guy running some pipes.
  • Jim Davis_3
    Jim Davis_3 Member Posts: 578

    The ANSI Z21 Standard for CO in a boiler in 400ppm(Air Free.) This would be the CO reading times the O2 dilution facter. This means the equipment is operating outside it's approved safety certification and according the AGA and now CSA it should be turned off, disable and a written warning must be given to the customer which they should sign. The more important question is were these readings stable or where they jumping up and down or rising. If so they are the most dangerous of all conditions and should also be disabled. I am familiar with many court cases where this was not done and it has cost contractors tens of thousands of dollers in law suits. When it was done the contractor walk away scott free. Lowering gas pressure does not fix the problem it only allows it to continue to run longer and cost the customer more fuel.

    Anytime the CO readings are rising or in excess of 400ppm equipment must be disabled by industry standards.
This discussion has been closed.