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High outdoor CO readings....

NY_Rob Member Posts: 1,370
Early Sunday morning my Sensorcon Inspector displayed 14ppm CO inside the house.
Very odd since we're normally at 0ppm, no one was up except me and I hadn't used the stove or any other combustion based appliance. The boiler (sealed combustion mod-con) had not fired since Sat evening, etc... there was literally no source that I could think of that would produce that high level of CO indoors.
Anyway, being stumped as to the source of the CO... I opened a couple of windows and the sliding back patio door. Even more surprisingly... within a couple of min when circling back to check the Sensorcon I noticed it had now climbed to 16ppm! I then took it outside to "clear it" with fresh air... and it kept climbing... and climbing, eventually stopping at 29ppm outdoors!

Within 20min or so of that high 29ppm CO reading a light wind came in from the west and the CO level started dropping quickly and hung in at about 15ppm for a good part of the afternoon. By 7pm the outdoor (and indoor) reading was back down to 0ppm again.

So much for stepping outdoors for some fresh morning air.... :o


  • Jamie Hall
    Jamie Hall Member Posts: 22,941
    Indeed. There are many places, sadly, where the "fresh morning air" is somewhat dubious. There are advantages to living in the country...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • RomanP
    RomanP Member Posts: 102
    That is interesting, Rob. Wonder where it came from. Nice yard by the way
  • NY_Rob
    NY_Rob Member Posts: 1,370
    RomanP said:

    That is interesting, Rob. Wonder where it came from. Nice yard by the way


    We've been in a low atmospheric pressure situation for about a week now, it rains almost every day and it's been foggy at night. Sunday morning there just wasn't even a breath of air to move anything so everything was just hanging in the air. As soon as the morning fog lifted and a slight breeze blew through the CO started dropping.

    If I had low level Co detectors in the house they probably would have been alerting with LED's and chirps.

  • Zman
    Zman Member Posts: 7,549
    I have the same sensor. Occasionally I get a reading around 8 if I warm up the truck with the sensor in the cab. Otherwise it reads close to zero all the time.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Tinman
    Tinman Member Posts: 2,808
    I was in a mechanical room yesterday for an indoor swimming pool. Two 400k modcons feeding an AHU and a large HX for the pool. My new Sensorcon read 0-1 the entire time in the room. While doing a combustion analysis, the CO for each boiler was always under 20 until the probe accidentally fell out of the flue and then it shot up to over 8000 before going into sensor protection.

    I have a second Sensorcon that also read consistently below 3 ppm. Chlorine has to be the culprit. Agree?
    Steve Minnich
  • Sal Santamaura
    Sal Santamaura Member Posts: 526
    NY_Rob said:

    ...So much for stepping outdoors for some fresh morning air...

    It's been many years since ASHRAE stopped using the term "fresh air" and replaced it with "outdoor air." :)
  • NY_Rob
    NY_Rob Member Posts: 1,370
    I wish I had thought of it at the time... it would have been interesting to bring my recently factory calibrated & certified combustion analyzer outdoors Sunday morning when the Sensorcon was reading 29ppm.... :(