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  1. #1
    Join Date
    Mar 2010
    Location
    Prescott, AZ
    Posts
    91

    Default carbon monoxide from ?????

    todays inspection:

    10 year old 2600sf duplex townhome. A good quality home with 3 gas appliances. The furnace is in the attic (typical here) with combustion air from soffit and roof attic vents. There is a vented gas-only fireplace with auto pilot (pilot is only on when burner is on). And a gas water heater in a lower level closet, combustion air from interior through louvered door. This is open to both levels- a very large downstairs family room, and the kitchen/living/dining above. (The range is electric.)

    The home has been vacant for months. I turned on my monoxor II (calibrated within last year, used daily) in the kitchen and picked up 12 ppm CO. I had not turned on the furnace or fireplace. I took the detector outside and it dropped to 1 ppm. Back inside it was reading 11 to 12 ppm in every room. Took it downstairs to the water heater closet and turned on the wh, a little puff (went to 14 ppm) near the vent pipe which is not unusual for a conventional tank wh. Started the furnace and fireplace and no CO in the supply air or near the fireplace.

    I cannot figure this out. The furnace had not been on, the fireplace had not been on, and the CO by the wh was no more than in the upper level bedrooms. There were no openings between the garage and home, or to the adjacent home, including through the attic. Home is on a dead end road, no traffic or heavy equipment nearby, and all doors and windows were closed when I arrived. Slab floor and a well ventilated attic. Yet there was 12 ppm CO in every room in the home.

    After completing the rest of the inspection I put new batteries in my detector (didn't need them) and repeated the test. The detector went to 1 ppm outside, but 11 to 12 ppm in every room, but no more near the wh or when I started the furnace or fireplace.

    Any ideas?

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  2. #2
    Join Date
    Oct 2010
    Location
    MONTREAL QUEBEC-CANADA
    Posts
    1,851

    Default Re: carbon monoxide from ?????

    Did you try testing the CO device outside?
    CO detectors require calibration. My MTP CO-180 is due shortly.

    Robert Young's Montreal Home Inspection Services Inc.
    Call (514) 489-1887 or (514) 441-3732
    Our Motto; Putting information where you need it most, "In your hands.

  3. #3
    Join Date
    Mar 2010
    Location
    Prescott, AZ
    Posts
    91

    Default Re: carbon monoxide from ?????

    Yes I did check the detector outside. The first time I started in the home with 12 ppm, took the detector outside where it dropped to 1 ppm, then back in where it went back to 12. Second time with new batteries I started outside with 1 ppm, then went inside and found 12 ppm again.

    I have not failed. I've just found 10,000 ways that won't work. (Thomas Edison)

  4. #4
    Join Date
    Oct 2010
    Location
    MONTREAL QUEBEC-CANADA
    Posts
    1,851

    Default Re: carbon monoxide from ?????

    Sorry for the deleted post. I find it hard to post without errors. Likely on my side.

    Likely due to the home being vacant for many months. Mention it in your report.

    Robert Young's Montreal Home Inspection Services Inc.
    Call (514) 489-1887 or (514) 441-3732
    Our Motto; Putting information where you need it most, "In your hands.

  5. #5
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
    Posts
    4,585

    Default Re: carbon monoxide from ?????

    I don't think your detector was lying.
    There is obviously not much air exchange from outside. Maybe good for energy savings, but not healthy when occupied. The water heater is the suspect, maybe a standing pilot light and there's a bit of back drafting?

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  6. #6
    Join Date
    Dec 2008
    Location
    Maryland
    Posts
    2,777

    Default Re: carbon monoxide from ?????

    Brought in from adjacent unit?


  7. #7
    Join Date
    Mar 2010
    Location
    Prescott, AZ
    Posts
    91

    Default Re: carbon monoxide from ?????

    I mentioned that I did not see any openings from the garage or adjacent home. I did not mention that I did not see any problems with the gas appliance vent pipes.



    Thanks, all. I submitted the report this morning (but still welcome any insights). I always recommend a co alarm when there isn't one. I described the co levels, suggested it may be from the home being closed up tight for many months, and recommended a co alarm a second time.

    I have not failed. I've just found 10,000 ways that won't work. (Thomas Edison)

  8. #8
    Join Date
    Oct 2010
    Location
    MONTREAL QUEBEC-CANADA
    Posts
    1,851

    Default Re: carbon monoxide from ?????

    Looks like you covered your bases.

    Been sampling CO on all levels for years.

    I am going back years but, I used a smoke pencil at any gas fired appliances hood vent, to see if backdrafting occured You can do the same with your gas detector. Look for PPM spikes.

    Robert Young's Montreal Home Inspection Services Inc.
    Call (514) 489-1887 or (514) 441-3732
    Our Motto; Putting information where you need it most, "In your hands.

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