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CO2 Detector Location?

Rockford | Posted in General Discussion on January 20, 2007 04:45am

I’ve just hard-wired all the smoke detectors in our new house and I want to add a CO2 detector as well and was wondering where the ideal location should be.

Here are some particulars on the house:

  • 3,000 sf new construction, 2-story
  • Natural gas FAU in attic
  • 3 bedrooms upstairs, 1 down
  • Fireplace downstairs.  Wood burning w/ gas log lighter.

Does it make sense to put it in the attic and wire it in with the smokes?  Or outside the 3 major bedrooms in the hall?  One upstairs, one down?

Thanks!

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  1. DanH | Jan 20, 2007 05:13am | #1

    Note that it's not "CO2" -- carbon dioxide. It's "CO" -- carbon monoxide.

    Carbon monoxide is about equally as dense as regular air, and so there's no strong preference for having a detector high on a wall or on the ceiling, vs lower.

    If the furnace is a sealed combustion unit, the likely failure mode would not be pouring out of the combustion air intake, but rather seeping through a cracked heat exchanger and into the forced air flow. Or some sort of draft drawing combustion products in from outside. Or charcoal smoldering in the fireplace. Only if the furnace is an old style open combustion unit would it really be important to have a detector near it.

    So you may want one detector near the fireplace (though not too close, to avoid false alarms), also covering the rest of downstairs, and another near the upstairs sleeping quarters. Also one in any attached garage. (It's especially good if the garage one is tied into the fire alarms, since otherwise it might not be heard in the house.) Try to position them away from corners, etc, where air might stratify.

    Keep in mind that, while a smoke alarm should ideally alert you within seconds of the fire breaking out, carbon monoxide is generally much slower acting, taking tens of minutes (in the case of a car running in a closed garage, eg) and more often hours or even days to work its effects. Usually the detector will take several minutes to alarm, even at moderately high CO levels. (This avoids certain false alarm conditions.) So you don't need to have the detector right on top of the potential source -- you just want to assure that the house has full coverage based on air circulation patterns.

    Half of the harm that is done in this world is due to people who want to feel important. They don't mean to do harm but the harm does not interest them. --T.S. Eliot
  2. User avater
    rjw | Jan 20, 2007 05:27am | #2

    On locations, I disagree with Dan a bit:

    Mount them at about eye level or slightly above: in most (all?) cases, CO will show up higher sooner because it's in hot gases.

    Get one with a digital readout, get a low level detector if there are any sensitive people in the house (pregnant woman, infant, elderly, heart conditions, anemia, immune system issues)

    One each living level.

    First one: protect the bedroom of the most vulnerable person living in the house.

    Second one: if there are any bedrooms above a garage, one in that/those bedrooms

    And/Or: if there are any unvented gas logs or space heaters - one in that room (better - get rid of THE UNVENTED HEATER)

    Third: In the utility room - in this case, where the water heater is. AND one in the attic - if there's CO in the attic and the returns aren't well sealed, they can pull that CO into the house air.

    In my experience, water heaters and gas stoves are about tied for causing excessive CO

    Fourth, on whatever floor is left.

    Have your gas appliances serviced yearly by a qualified heating contractor. (in my area, maybe 1/10)

    NEVER ignore a CO detector.

    Everyone knows high levels can kill - be aware long term exposure to lower levels can cause permanent, serious health problems: Just because you aren't dead doesn't mean you don't have CO problem.


    What made the teaching of Jesus different and apparently so hard to accept then as now, was that it required a critical reassessment of the structures and values and attitudes of human society as his listeners and followers shared in it.

    - Monika K. Hellwig

    from Jesus: The Compassion of God (The Liturgical Press, 1983)

  3. junkhound | Jan 20, 2007 05:32am | #3

    After the golbal warning thread, dont put a CO2 detector anywhere near Dan or Bob <G>

     

    FWIW,in the house the CO detector  is 15 feet from the fireplace at chest height (special outlet).  Inthe workshop (also used for car repair with engine running, one 5 ft from where the car exhaust gets hooked to the external exhaust hose, the other 5 ft from the wood stove.

    The one in the workshop HAS gone off! - time to open the door. Workshop one also has digital readout to asess when door can be closed again.



    Edited 1/19/2007 9:36 pm ET by junkhound

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