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Carbon Monoxide Detector Placement

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

www.jaymarinspect.com


Comment balloon 53 commentsJay Markanich • October 08 2018 11:06AM

Comments

Good morning, Jay Markanich I have a plug in detector on each floor of my home including the basement....

Posted by Barbara Todaro, "Franklin MA Homes" (RE/MAX Executive Realty ) about 1 month ago

Good morning Jay. Thanks for the suggestion and guidance. Certainly the plug in ones are easier to instal

Posted by Lise Howe, Assoc. Broker and Attorney Licensed in DC, MD, VA, (Keller Williams Capital Properties) about 1 month ago

Good morning James,

I knew we needed one but now know there should be a couple more, Thank you.

Make yourself an astonishing day.

Posted by Raymond E. Camp, Licensed Real Estate Salesperson Greater Rochester (Howard Hanna Real Estate Services) about 1 month ago

And you do good good, Barbara!

Lise - the combo smoke/carbon detectors should not be used.  Many have been recalled - they cause fires!

Hey, Raymond!  I have Kidde detectors, but Nighthawk makes a good one too.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Good morning Jay. The right time of year for this important reminder. Enjoy your day!

Posted by Wayne Martin, Real Estate Broker - Retired (Wayne M Martin) about 1 month ago

Hence the post, Wayne!  The time is now!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Good morning Jay Markanich,

Such an important post! The plug in ones are certainly easier to install..thanks for the guidance and excellent advice.

Posted by Dorie Dillard CRS GRI ABR, Serving Buyers & Sellers in NW Austin Real Estate (Coldwell Banker United Realtors® ~ 512.346.1799) about 1 month ago

Good morning Jay. This is sooooo very important. Great and specific.

Posted by Sheila Anderson, The Real Estate Whisperer Who Listens 732-715-1133 (Referral Group Incorporated) about 1 month ago

They are Dorie, and work very well.

Sheila - it is, and thanks for your kind words!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Hi Jay Markanich - This can be deadly to anyone but the risks go up with homes that are heated with natural fuels. 

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.

Posted by Sheri Sperry - MCNE®, (928) 274-7355 ~ YOUR Solutions REALTOR® (Coldwell Banker Residential Brokerage) about 1 month ago

Thank you very much, Jay, for sharing your experience and your advice.

Posted by Roy Kelley, Roy and Dolores Kelley Photographs (Realty Group Referrals) about 1 month ago

That's a lot of interesting information about carbon monoxide, combustion and gasses, Jay.  

Posted by Myrl Jeffcoat, Greater Sacramento Real Estate Agent (GreatWest Realty) about 1 month ago

Sheri - natural fuels are what combust and cause CO, especially when done inefficiently.  As to that unfortunate family, there are about 1000 CO deaths every year, usually due to ignorance and a lack of detectors.

Anytime Roy!

I'm glad you were educated Myrl!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Lots of people do job one: buy a CO detector. Job two on placement is just as important. You did a great job explaining what carbon monoxide is, how it works and where to place your detector. This article will save lives.

Posted by Debe Maxwell, CRS, Charlotte Homes for Sale - Charlotte Neighborhoods (www.iCharlotteHomes.com | The Maxwell House Group | RE/MAX Executive | (704) 491-3310) about 1 month ago

Thank you Debe!  Those are very kind words.  Now, if only more people would read this post!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

To much math for me Jay Markanich . How about Radon = Bad

Detector = Good

Posted by Bob "RealMan" Timm, Bob Timm, Project Coordinator for Tivoli Homes (Tivoli Custom Homes) about 1 month ago

Attention AR folks. Whatever Jay says, just do it, You'll be glad you did.

Posted by Jon Quist, Tucson's BUYERS ONLY Realtor since 1996 (REALTY EXECUTIVES TUCSON ELITE) about 1 month ago

We have a gas furnance and a fireplacce and we have three.  One near the furnace, one near the fireplace and a third in our bedroom.  I used to have one in each of the kids bedroms, but they are long gone from living here and I simply have not replaced the older units since those rooms are empty.

Posted by Tammy Lankford,, Broker GA Lake Sinclair/Eatonton/Milledgeville (Lane Realty Eatonton, GA Lake Sinclair, Milledgeville, 706-485-9668) about 1 month ago

Hi Jay

Thanks for some great education! CO detectors are required by law here in CA (as our smoke detectors) but I occasionally find them lacking, or find only 1 in a 2-story home. It can become a potential issue with our appraisers here if they don't see one to photograph for their reports. I always point out to the listing agent when one is missing (and it's usually on the main floor) to avoid problems.

Jeff

Posted by Jeff Dowler, CRS, The Southern California Relocation Dude (Solutions Real Estate ) about 1 month ago

Great post and very good information on an important lifesaving topic!

It is state law in Alaska too.  

You are so right about not placing them too high or too low.

Posted by Debra Leisek ( Bay Realty,Inc Homer Alaska) about 1 month ago

Great to know!

Posted by Steven Pomeroy, Your Dream is my Passion. Poconos PA Realtor. (Better Homes and Gardens Wilkins) about 1 month ago

Thanks Bob.  CO detectors do work, but I'm not sure about radon detectors.  is a concentration of 4 parts in a trillion detectable?

And thank you, Jon.  My legal name is Jon as well, spelled the right way.

Tammy - I would say you are protected!  Replace them every 10 years.

Jeff - I didn't know that.  What if the house is all electric?  And a photo from an appraiser can't tell how old a unit is.  But having them is better than not!

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Debra - if you place them in a wall receptacle that pretty much defines the height!

Glad you found it useful, Steven.  Thanks for stopping by.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

 

Congratulations on your featured blog.  Well deserved and keep them coming.

 

Posted by Richard Weeks, REALTOR®, Broker about 1 month ago

Jay, thanks for sharing the great information about carbon monoxide! Have a great day.

Posted by Matthew Klinowski, PA, Golf Community Real Estate Specialist (Downing-Frye) about 1 month ago

This reminds me of why they add sulphur to gas. It alerts you! without it bye-bye

Posted by Richie Alan Naggar, agent & author (people first...then business Ran Right Realty ) about 1 month ago

I have always questioned this!  (especially since the instructions are about as clear as mud on the packaging)  I have been replacing my smoke detectors with combo units - figuring it is better to have more  around the house... and of course they are all on the ceiling.

Posted by Robert Rauf (HomeBridge Financial Services (NJ)) about 1 month ago

A well deserved feature Jay! Excellent information!

Posted by Sharon Tara, New Hampshire Home Stager (Sharon Tara Transformations) about 1 month ago

Thank you Richard.

Glad you enjoyed it, Matthew.

Richie - unfortunately that cannot be added to CO!  Bummer is...

Robert - they recommend against using the combo units as so many have been recalled.  They cause fires!

 

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Thank  you Sharon.  Glad you found the post!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Jay- well deserved feature for this one. We all buy these detectors but you are the first explanation I've seen about where to place it and whether to buy a plug-in or battery operated one. With all of these available to us, we need to take advantage and prevent any more needless deaths from carbon monoxide poisoning. 

Posted by Kathy Streib, Home Stager - Palm Beach County,FL -561-914-6224 (Room Service Home Staging) about 1 month ago

Hi Jay Markanich   Thank you for bringing this subject back to light at this time of the year. We have gas everything...(even myself on occassion).  We have numerous detectors throughout our home as the furnace and water heater are in the basement and the gas stove and garage are on the main floor.  

I talk frequently with clients and others about detectors and am amazed at how many do NOT have them.

Are they fail safe?   No...but just like with smoke detectors, they are a heckuva a lot better than not having one at all.

I just had clients buy 2 apartment complexes and strongly suggested they put carbon monoxide detectors in each unit and the hallways since the furnaces of one of the units are located in the hallways.

Yes...they were grandfathered in to the previous owners but now become a requirement...although we all know a requirement does not always mean adherence.

Thanks again!!

Posted by Mike McCann - Nebraska Farm Land Broker, Farm Land For Sale 308-627-3700 or 800-241-3940 (Mike McCann - Broker, Farmland Broker-Auctioneer Serving Rural Nebraska) about 1 month ago

We need a carbon monoxide detector on each level in California. It poses issues with step-down rooms, but I tell sellers just install it anyway. It is only twenty bucks and solves all sorts of issues with appraisers and their opinions.

Posted by Elizabeth Weintraub Sacramento Real Estate Agent, Top 1% of Lyon Agents, Put 40 years of experience to work for you (Lyon Real Estate) about 1 month ago

There are some good ones out there, Kathy.  I use Kidde.

Thank you, Mike.  And adherence to any principle is the basis for the principle's success.

Better safe than sorry, Elizabeth.  If there is one on every level then good - and why not?

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Jay, I live in a condo with no gas or wood burning units. We have parking on the ground floor, but it is open. Is there any real need for a detector?

Posted by Tom Bailey (Margaret Rudd & Associates Inc.) about 1 month ago

I would think not, Tom, but I really don't know!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Thanks for the informative and detailed and timely post on the subject. Think I will add these as Christmas gifts for my kids this year.

Posted by Greg Large, A Tradition of Trust (ERA Real Solutions) about 1 month ago

Anytime Greg.   And that's a good idea too!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

This is great information to share. I like Greg Large 's suggestion to buy these as gifts!

Posted by Kat Palmiotti, The House Kat (Grand Lux Realty, Monroe NY, 914-419-0270, kat@thehousekat.com) about 1 month ago

Thanks for sharing!!!

"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."

Posted by Sham Reddy, CRS (H E R Realty, Dayton, OH) about 1 month ago

Kat - they're selling like pancakes!

Thanks Sham.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

This is a post worth sharing for all of us. The builders I work with install them in every home.

Posted by Joe Pryor, REALTOR® - Oklahoma Investment Properties (The Virtual Real Estate Team) about 1 month ago

Jay, that's a whole lot of valuable information in one post. Thanks for sharing. 

Posted by Mike Cooper, Your Winchester, VA Real Estate Sales Pro (Cornerstone Business Group Inc) about 1 month ago

That would be a solid practice, Joe.  And thanks!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Thanks Mike.  And I showed my work, professor!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Congrats on the feature arcticle and thanks for sharing such important information.  Hoping this helps motivate people to include this item in their home safety features.

Posted by Sajy Mathew, Making your real estate dreams become a reality! (Coldwell Banker Residential Brokerage) about 1 month ago

Thanks Sajy.  Every home with combustible appliances should have CO detectors.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

Hello Jay --- it's good to know what an expert thinks.  Good information. 

Posted by Michael Jacobs, Los Angeles Pasadena Area Real Estate 818.516.4393 (Coldwell Banker Residential Brokerage) about 1 month ago

Thank you, Michael, for that very nice compliment.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

We usually always do hardwired CO units that last 10 years.  This ensures you don't have the CO detector find its way to a drawer the second it won't stop beeping.  

Posted by Kevin Mackessy, Dedicated. Qualified. Local. (Blue Olive Properties, LLC) about 1 month ago

Kevin - a lot of those are the combo smoke and CO detectors which aren't recommended because so many of them have been recalled.  The individual CO detectors are fine.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) about 1 month ago

That reminds me, I have a new one that I bought to plug into the wall with a battery back up, but it's not doing much good still in the packaging on my junk counter.  Better get to unwrapping and plugging that in today.

Posted by Chris Ann Cleland, Associate Broker, Bristow, VA (Long and Foster REALTORS®, Gainesville, VA) 18 days ago

A lot of work to be sure, Chris Ann, but you can do it!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) 18 days ago

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