# Carbon Monoxide heavier than air?



## DLN

With the new addition to the 2009 IRC, section 315.1, requiring carbon monoxide alarms outside of sleeping areas in the immediate vicinity of the bedrooms, where fuel fired appliances and attached garages exist, raises an interesting question. I've had many electrical contractors ask me where to put the CO detectors, up high, or down low? We've been allowing the combo CO/smoke detector units to be installed on the ceiling in the hallway, or up high on the wall in the hallway, where smoke detectors are already required. Is carbon monoxide heavier than air, and if so, what good is it to put a combo CO/smoke detector up on the ceiling? I've read that CO is slightly lighter than air, but have also had many people tell me it's heavier than air. Any thoughts??...


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## klarenbeek

CO is just slightly lighter than air, but the difference is so small that it readily mixes with air.The thought for those who say they should be placed high is that when it is generated from a fuel gas appliance is that it is warm and will rise to the ceiling, but, particularly if there are forced air appliances, it should mix fairly evenly throughout the space, so the detector should be effective most anywhere it is placed.


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## rshuey

Years ago the CO detectors were always near the appliance or basement area here. It was explanied to me that in a large 2 story home, the CO detector could go off in the basement while you are sleeping and you would never hear it.

I think that is the reason for placing them outside the sleeping areas.


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## tmurray

Carbon monoxide has roughly the same specific gravity as air, so they weigh about the same. Your carbon monoxide alarm (I'm assuming you meant alarm and not detector) should be installed as per the manufacturer's instructions.


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## Francis Vineyard

Carbon Monoxide is similar to the characteristic of air; manufacturer's recommendations should be followed; if it's a combination it will be the same as for smoke detectors outside the bedrooms. Stand-alone CO detectors location example below required in the immediate vicinity outside the bedrooms;


​

*"IMPORTANT: *
​• When wall mounting, place out of reach of children. Under no circumstances

should children be allowed to handle the CO alarm.

• Placing the alarm at eye level allows for optimum monitoring of the

digital display.

*Locations To Avoid*

*IMPORTANT: *Improper location can affect the sensitive electronic components

in this alarm. To avoid causing damage to the unit, to provide

optimum performance, and to prevent unnecessary nuisance alarms:

• Do not install in kitchens, garages or furnace rooms that may expose

the sensor to substances that could damage or contaminate it.

• Do not install in areas where the temperature is colder than 40°F

(4.4°C) or hotter than 100°F (37.8°C) such as crawl spaces, attics,

porches and garages.

• Do not install within 5 ft. of heating or cooking appliances. (Kxxxx

recommends 15 ft. to prevent nuisance alarms).

• Do not install near vents, flues, chimneys or any forced/unforced air

ventilation openings.

• Do not install near ceiling fans, doors, windows or areas directly

exposed to the weather.

• Do not install in dead air spaces, such as peaks of vaulted ceilings or

gabled roofs, where CO may not reach the sensor in time to provide

early warning.

• Do not install on a switched or dimmer-controlled outlet.

• Do not install this unit near deep-cell large batteries. Large batteries

have emissions that can cause the alarm to perform at less than optimum

performance."

Francis


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## DLN

Thanks Everyone for your helpful input...


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## mark handler

http://www.inspectpa.com/forum/showthread.php?3695-Carbon-Monoxide-detector-locations&highlight=DETECTOR


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