CO detector layouts

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mshields

Senior Member
Location
Boston, MA
I have always been told that CO detectors should be placed in accordance with the same rules that govern smoke and heat detectors; e.g. 30 feet on center, no more than 23 feet to the corner of a room, etc..

a) is that correct?
b) where is this defined in any of the applicable codes?

Thanks,

Mike
 

mgookin

Senior Member
Location
Fort Myers, FL
Massachusetts
Mass. Gen. Laws Ann. ch. 148, ? 26f1/2
Requires that every dwelling, building or structure occupied in whole or in part for residential purposes that contains fossil-fuel burning equipment or incorporates enclosed parking within its structure shall be equipped by the owner with working, approved carbon monoxide alarms.
Mass. Gen. Laws Ann. ch. 148 ? 27A
No person shall shut off, disconnect, obstruct, remove or destroy, or cause or permit to be shut off, disconnected, obstructed, removed or destroyed, any part of any sprinkler system, water main, hydrant or other device used for fire protection or carbon monoxide detection and alarm in any building owned, leased or occupied by such person or under his control or supervision, without first procuring a written permit so to do from the head of the fire department of the city or town wherein such building is situated, which permit such head is hereby authorized to issue subject to such terms and conditions as, in his judgment, protection against fire and the preservation of the public safety may require.
 

mshields

Senior Member
Location
Boston, MA
527 CMR 31

527 CMR 31

I'm familiar with the rules governing where CO detection is required. We also have a technical option in our CO code allowing, with approval of the AHJ, that detection be only at the fossil burning equipment (or in those rooms) itself. My question is what are the rules governing their layout in say a boiler room where they are in fact required.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I'm familiar with the rules governing where CO detection is required. We also have a technical option in our CO code allowing, with approval of the AHJ, that detection be only at the fossil burning equipment (or in those rooms) itself. My question is what are the rules governing their layout in say a boiler room where they are in fact required.
I would look first at the location guidelines provided by the manufacturer of the CO detector. Those are then mandated by the NEC if the positioning rules are part of the listing information.
 

nhfire77

Senior Member
Location
NH
I have always been told that CO detectors should be placed in accordance with the same rules that govern smoke and heat detectors; e.g. 30 feet on center, no more than 23 feet to the corner of a room, etc..

a) is that correct?
b) where is this defined in any of the applicable codes?

Thanks,

Mike

a- it depends

b- NFPA 720 for placement and 72 does mention them a bit


What is the specific application? A commercial kitchen perhaps?
 

JDB3

Senior Member
A lot depends upon what the AHJ guidelines follow.

I think that it was in the International Building Code (or something like that) that called for the CO detectors to be outside of the bedrooms (in a common area), if fossil fuels are used or attached garage.
 

E16

Member
Location
Iowa
Occupation
Electrical Contractor
A lot depends upon what the AHJ guidelines follow.

I think that it was in the International Building Code (or something like that) that called for the CO detectors to be outside of the bedrooms (in a common area), if fossil fuels are used or attached garage.

International Residential code states (2009)
315.1
Carbon Monoxide alarms. For new construction, an approved carbon monoxide alarm shall be installed outside of each separate sleeping area in the immediate vicinity of the bedrooms in dwelling units within which fuel-fired appliances are installed and in dwelling units that have attached garages.

315.2 Where required in existing dwellings.
Where work requiring a permit occurs in existing dwellings that have attached garages or in existing dwellings within which fuel-fired appliances exist, carbon monoxide alarms shall be provided in accordance with Section R315.1
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
It's late, and I don't have all my references handy, but IIRC it doesn't matter whether the detector is on the ceiling, on the wall, or down by the floor. The molecular weight of CO is 28, which is the same as nitrogen (N2; composing ~78% of the earth's atmosphere) and within spitting distance of oxygen (O2; MW=32, ~21% of the earth's atmosphere), unlike CO2 which has a MW of 44 and a density therefore of 1.51 versus 0.967 for CO. CO mixes freely with room temperature air, and since it isn't generated (usually) by an open air fire, it isn't driven as a plume to the ceiling as smoke would be. Therefore, for a constant but relatively small volume of generation per unit time, the CO concentration will be the same throughout the enclosed space. For low voltage combination smoke/CO detectors, no closer spacing than that required for smokes alone is called for, so I carefully assume that the standard 30 foot spacing is acceptable. I'd call the manufacturer before committing a design to paper however. Silent Knight says use 30 foot spacing for their IDP-FIRE-CO product.
 
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