Carbon Monoxide Detector Mounting

Carbon monoxide alarms and detection systems now have more direction on mounting and alerting thanks to NFPA 72 2022

NFPA 720: Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment (2015) currently does not have any requirements for the mounting height/location of a carbon monoxide detector.  However, NFPA 720 does specify that is a carbon monoxide detector is installed in a room with a fire fueled appliance such as a generator, hot water heater, furnace, etc., it is to be mounted on the ceiling.

The reason behind the NFPA 720 placement of carbon monoxide detectors on the ceiling in these areas is makes perfect sense. Continue below:  

Carbon monoxide has a molar mass of 28.0, which makes it slightly lighter than air, whose average molar mass is 28.8. According to the ideal gas law, CO is therefore less dense than air.  With that said, the heat generated by these appliances will make the carbon monoxide (CO) more buoyant and present it to the carbon monoxide detector on the ceiling.

Another source for the mounting and installation of carbon monoxide detectors is found in NFPA 72 2019 section 17.12 "Carbon Monoxide Detectors"

NFPA 72 Carbon Monoxide Requirements per Chapter 17

NFPA 72 2022 Section 17.12.1 

Where required by other governing laws, codes, or standards, carbon monoxide defectors shall be installed in accordance with the following:

    1) On the ceiling in the same room as permanently installed fuel-burning appliances, and

    2) Centrally located on every habitable level and in every HVAC zone of the building, and

    3) Outside of each separate dwelling unit, guest rom, and guest suite sleeping area within 21 feet (6.4 m) of any door to a sleeping room, with the distance measured along the path of trave, and

    4) Other locations where required by appliance laws, codes, or standards or

    

NFPA 72 2022 Section 12.12.2 

Carbon monoxide detectors shall meet the following requirements:

    1) Carbon monoxide detectors shall be listed in accordance with applicable standards, such as ANSI/UL 2075, Gas and Vapor Detectors and Sensors.

    2) Carbon monoxide detectors shall be set to respond to the sensitivity limits specified in ANSI/UL 2034, Standard for Single and Multiple Stations Carbon Monoxide Alarms.

NFPA 72 2022 Section 17.12.4 

All carbon monoxide detectors shall be located and mounted so that accidental operation will not be caused by jarring or vibration. 

NFPA 72 2022 Section 17.12.5 

The location of carbon monoxide detectors shall be based on an evaluation of potential ambient sources and flows of carbon monoxide, moisture, temperature, dust, or fumes and of electrical or mechanical influences to minimize nuisance alarms. 

NFPA 72 Carbon Monoxide Requirements per Chapter 18

NFPA 72 2022 Section 18.4.3.1 

Where a carbon monoxide detector or alarm is required by other codes or standards or by the authority having jurisdiction and where an audible signal is required, a distinctive signal patter shall be required that is different from a fire evacuation signal.

We know this as Temporal Code 4. 

NFPA 72 2022 Section 18.4.3.2 

Where an audible signal is required, the carbon monoxide signal shall be four-pulse temporal pattern and comply with the following:

    1) Signals shall be a pattern consisting of four cycles of 100 milliseconds +/- 10 percent "on" and 100 milliseconds +/- percent "off" followed by 5 seconds +/- 10 percent "off" as demonstrated in figure 18.4.3.2

    2) After the initial 4 minutes of the carbon monoxide signal, the 5-second "off" time shall be permitted to be changed to 60 seconds +/- 10 percent.

    3) The alarm signal shall be repeated in compliance with 18.4.3.2(1) and 18.4.3.2 (2) until the alarm resets or the alarm signal is manually silenced.

NFPA 72 2022 Section 18.4.3.3

The signal shall be synchronized within a notification zone of a protected premises. 

NFPA 72 2019 Section 18.4.3.4 

The audible signal of carbon monoxide alarms and systems installed to meet the requirements of NFPA 72 chapter 29 shall NOT be required to be synchronized.

NFPA 72 2022 Section 23.8.4.9

Unless otherwise permitted by 23.8.4.9.1 signals form carbon monoxide detectors and carbon monoxide detection systems transmitted to a fire alarm system shall be indicated as a carbon monoxide alarm signal. No more general supervisory signals for carbon monoxide alarms or detection system. 

NFPA 72 2022 Section 23.8.6.1.2

Except as permitted in 23.8.61.3 occupant notification of carbon monoxide systems shall be throughout the protected premises. 

NFPA 72 2022 Section 23,8.6.1.3

Where carbon monoxide alarm signals are transmitted to a constantly attended on-site location or off-premises location in accordance with this chapter, selective public mode occupant notification zone encompassing the area where the carbon monoxide alarm signal was initiated. 

NFPA 72 2022 Section 23.8.6.3.3

The boundaries of carbon monoxide alarm notification zones shall be coincident with the area where the alarm initiation originated and other signaling zones in accordance with the building's emergency response plan. 

On another note, make sure that when you place your carbon monoxide detector outside of the sleeping area you still achieve a sound level of 75dB at the pillow with the door closed.

Read more hear about the new laws and state legislation for carbon monoxide detection in California.

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