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

carbon monoxide from steam rad vents?

CHRISBPS Member Posts: 3
I work in a plumbing supply house and recently sold a small peerless gas steam boiler to a contractor. For whatever reason pseg came to the house and found

carbon monoxide coming out of the vents on the rads! Has anyone ever heard of this?


  • Hitzkup
    Hitzkup Member Posts: 63

    How did they determine that the air vent is the source?
  • Someone has alot to learn,,,,

    If that were true,,, our morning coffeemaker would have killed us all long ago!  :-)
  • Tim McElwain
    Tim McElwain Member Posts: 4,444
    Yes I had this happen

    many years ago on an old steam boiler which had a crack in the top of the boiler above the water line. The air shutter on the burner was closed and the burner was burning yellow making CO it got through the crack and up into two radiators and vented into the room.

    I also had this happen on a brand new steam boiler install several years ago replacing an old steam system and it somehow got in to the piping through a crack in a fitting. The cause was a plugged chimney that the installer failed to find which eventually caused the new boiler to soot up and CO to come out the vent on the radiator on a one pipe system. 
  • "got in to the piping through a crack in a fitting"

    C`mon Tim,, arent you reaching just a bit??

    Anyone with steam will be scared silly!

    I`m curious to know the detector used.
  • Steamhead
    Steamhead Member Posts: 14,330
    If Tim says it can happen

    I believe him.

    I think it could also happen if the main vent was in the boiler room and the CO in the boiler room was high (blocked chimney and no blocked-flue switch, anyone?). When the system cooled and the main vent opened, the vacuum would draw CO into the system.

    This is yet another reason to test everything you work on. We do.

    Any home or building owners reading this, no matter what type of system you have- if someone comes to work on your system, ask if they use a digital combustion analyzer. If they don't- throw them out immediately and get someone in there who does!
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
    CHRISBPS Member Posts: 3

    Thank you for your replies!

    The contractor went back to the job with a digital CO meter and did the following.

    1- Went into boiler room and fired up all units (a small packaged hw boiler and a water heater, along with the steam boiler in question) and got a clean reading in the boiler room.

    2- Removed the releif valve from the steam boiler and took a reading near the opening, readings climbed to 250 ppm and stopped as soon as the boiler started to steam.

    3-Checked general area and around the 2 end of main vents(at ends of building) to see if near garage, drier vent, or anything maybe producing CO.Nothing found

    4- next step trying to set up appt with rep and contractor to repeat tests and hopefully find something overlooked
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    What gets out, must go in....

    Try flooding the boiler and near boiler piping and see if you have a leak in the vessel. If you do, you should replace the boiler any way.

    Are any carbon based water treatments being used on the boiler that might have high VOC capabilities?

    Interesting in deed.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
    CHRISBPS Member Posts: 3
    Good suggestion

    great idea-- common sense(now that you said it)  as far as treatment/additives the only thing put in the boiler as far as we know was some steam clean, done after the problem was discovered.

    made appt with rep, contractor,to meet on job thurs 5/13

  • Tim McElwain
    Tim McElwain Member Posts: 4,444
    Monoxer CO

    tester was initially used then a commercial tester by the local Fire Department. I retested with a Testo Combustion Analyzer.

    I have also had a case that gasoline fumes came out of the vent on a radiator.

    When you work for a gas utility you get many strange and unusual foreign odor complaints.
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!