Carbon Monoxide Detector Placement

Reblogger Barbara Todaro
Services for Real Estate Pros with RE/MAX Executive Realty 104763

An important message about CO with a detailed explanation of placement and the reasons why.... thanks, Jay....

Original content by Jay Markanich 3380-000723

Carbon monoxide detector placement.

That title surrounds a question I get a lot during home inspections.  And this one -

Is carbon monoxide lighter or heavier than air?

Of course, any time you have gas appliances or a wood-burning fireplace, you should have at least one carbon monoxide (CO) detector in the home.

CO is odorless, tasteless and DOES NOT GIVE WARNING that it is being produced or building up.

And, is it lighter or heavier than air?  Which means, does it rise or fall when produced?

Since the molecular weights of gases differ, what makes them move is convection.  If a gas is released because of combustion, it would tend to rise due to its heat.

CARBON MONOXIDE HAS NEARLY THE DENSITY OF AIR.  CO is slightly lighter.   You can figure this out.  For example:

O=16   C=12   N=14   H=2

You would add things to get the pure density of gasses.

H2 = 1+1 = 2 (very light)
O2 = 16+16 = 32 (slightly heavy)
N2 = 14+14 = 28 (about neutral)
CO2 = 12+16+16 = 44 (heavy)
CO = 12+16 = 28 (about neutral)
H2O = 1+1+16 = 18 (light) - as in humidity or steam
Radon = 222 (very heavy)

So what is the density of air?  The air we breathe is composed of 80% Nitrogen, 19% Oxygen, .6% inert gases and .4% Carbon Dioxide.

N2 + O2 + CO2 = ?
.8(28) + .196(32) + .004(44) = 28.9 (by definition air is neutral)


So how does CO compare with air?  It is 3% lighter.  So it distributes very easily through a house.


But when CO is produced, it immediately begins mixing, and therefore diluting, with the air around it.  Therefore, it mixes with nitrogen, which doesn't burn, oxygen, which is burned creating the CO, H2O (humidity) and CO2 which are in the air.  So the CO produced is not in pure form in the air.  It is very diluted.  And as CO is produced, it is warmer than the air around it.

So what is the most advantageous place to put a CO detector?  CO moves with the air, so where the air is flowing it will go also.  It is very unpredictable where the air, and therefore CO, will move at any given time.  That is why the instructions with the unit you buy do not say to place it high or low on the wall.

Understanding all that, the National Fire Protection Association (NFPA) suggests in 720, 2-1.1.2* 1998 -

"A carbon monoxide alarm or detector should be centrally located outside of each separated sleeping area in the immediate vicinity of the bedrooms. Where bedrooms are separated and the audibility of the alarm or detector to occupants within the bedroom area could be seriously impaired, more than one unit could be needed. Each alarm or detector should be located on the wall, ceiling, or other location as specified in the installation instructions that accompany the unit."


Which detector should you buy?

The suggestion is one that is plugged in and preferably with a battery back up.  These detectors use electrochemical technology to detect CO gas.  Like smoke detectors, they are effective for 10 years.

A local Fire Marshall, my neighbor, told me that the plug-in detectors seem to have a better record for fewer false positives than do the battery-only detectors.  But that is his experience!  

My recommendation:  buy a good plug-in detector!  If you want, get one with a battery back up.  Put it near any potential CO source and another near your bedroom(s).  Be sure everyone will hear it.


And you will be safe and feel safe. 

Jay Markanich Real Estate Inspections, LLC  

Based in Bristow, serving all of Northern Virginia.

Office (703) 330-6388   Cell (703) 585-7560


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Wayne Martin
Wayne M Martin - Chicago, IL
Real Estate Broker - Retired

Good morning Barbara. As furnaces fire up and fireplaces begin to see use this is an important reblog. Thanks! Enjoy your day!

Oct 08, 2018 05:27 AM #1
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I am pleased that you are pleased, Miss B!  Oh, and thanks for the reblog!  The more the merrier!

Oct 08, 2018 05:39 AM #2
Joan Cox
House to Home, Inc. - Denver Real Estate - 720-231-6373 - Denver, CO
Denver Real Estate - Selling One Home at a Time

Barbara, great choice for a reblog, and amazing how many listing agent don't let the Seller know they need these!  

Oct 08, 2018 06:21 AM #3
Grant Schneider
Performance Development Strategies - Armonk, NY
Your Coach Helping You Create Successful Outcomes

Good morning Barbara - a very important and educational post from Jay Markanich .  We have had all of our replaced.

Oct 08, 2018 06:46 AM #4
Sheila Anderson
Referral Group Incorporated - East Brunswick, NJ
The Real Estate Whisperer Who Listens 732-715-1133

Good morning again Barbara. A terrific choice for a re0blog and it matters.

Oct 08, 2018 07:26 AM #5
Sheri Sperry - MCNE®
Coldwell Banker Residential Brokerage - Sedona, AZ
(928) 274-7355 ~ YOUR Solutions REALTOR®

Hi Barbara Todaro - This can be deadly to anyone but the risks go up with homes that are heated with natural fuels. Great reblog Barbara.  

I remember last Xmas a family went to a cabin in a mountain community nearby and all 4 of them were lost. It was very sad.

Oct 08, 2018 07:28 AM #6
Roy Kelley
Realty Group Referrals - Gaithersburg, MD

Thank you very much, Barbara, for sharing this excellent reblog selection.

Oct 08, 2018 08:05 AM #7
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I am pleased that you are pleased, Miss B!  Oh, and thanks for the reblog!  The more the merrier!

Since I didn't get credit for posting this the first time I redundanted it.

Cool new word, huh?

Oct 08, 2018 09:00 AM #8
Paul S. Henderson, REALTOR®, CRS
RE/MAX Northwest. - Tacoma, WA
Tacoma Washington Agent/Broker & Market Authority!

 I often get confused when reading the carbon monoxide placement guides because some say to place it high like a smoke detector and others plug in low...

Oct 08, 2018 09:11 AM #9
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