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Don’t Compromise — Get a Low-Level Carbon Monoxide Monitor

CO Experts Low Level Carbon Monoxide Monitor

You know that saying, Don’t judge a book by its cover? That certainly applies to what may be the best protection against carbon monoxide poisoning you can buy. The CO Experts carbon monoxide monitor doesn’t have a flashy website or marketing program. It doesn’t even have the approval from Underwriters Laboratories (UL) that so many products crave. And there’s a good reason for that.  [Update:  The website has been improved greatly since I first wrote this article in 2012.]

The CO Experts monitor is a low-level monitor that tells you what’s going on with the carbon monoxide levels in your home in real time. It cannot get listed by UL because UL has decided that only high levels matter. Here’s a quote from the UL standard, as given on the CO Experts website:

Carbon monoxide alarms covered by this standard are not intended to alarm when exposed to long term, low level carbon monoxide exposures or slightly higher short term transient carbon monoxide exposures, possibly caused by air pollution and/or properly installed/maintained fuel-fired appliances and fireplaces. See Table 38.1, Part B, False alarm resistance specifications.

Is a low level of carbon monoxide safe?

But does that mean low levels of carbon monoxide are safe? Not according to George Kerr, the brains—and the passion—behind CO Experts. He cites numerous studies showing that low levels of CO are harmful. In fact, problems show up even at really low levels. A UCLA study found that CO levels above 5 parts per million (ppm) was associated with pregnant women having underweight babies with smaller heads.

The existence of such studies probably helps to explain the disclaimers that companies making UL listed CO alarms put on their products. Here’s the warning from the Kidde-Nighthawk Model #KN-COPP-3, as given in the user manual I downloaded from the Kidde website:

You should take extra precautions to protect high risk persons from CO exposure because they may experience ill effects from carbon monoxide at levels that would not ordinarily affect a healthy adult. Are there any infants or small children in the home? Be sure to check them for signs of possible CO poisoning because they might have trouble explaining their symptoms. Infants and children are more susceptible to CO poisoning than a healthy adult.

Pregnant women should be aware that their unborn fetus could be harmed by exposure to carbon monoxide, even when the mother suffers no ill effect herself. Any pregnant woman who suspects she may have been exposed to carbon monoxide should immediately contact her physician.

Is there anyone in the household who is elderly, or who has anemia, heart disease or respiratory problems, emphysema or chronic bronchitis? These individuals are at higher risk for CO poisoning and for health problems from exposure to low levels of carbon monoxide.

Basically, the problem with UL listed alarms is that they’re meant to offer protection to healthy adults during very high levels of CO in a home’s air. So how much CO does a UL listed alarm allow you to breathe? Here’s what UL standard 2034 allows:

  • 30 ppm for up to 30 days
  • 70 ppm for up to 4 hours
  • 150 ppm for up to 50 minutes
  • 400 ppm for up to 15 minutes

If you think about what those numbers mean, it’s actually worse than it looks. For example, as Kerr points out on the CO Experts site, a UL listed CO alarm would allow you to breathe air with 358 ppm for 45 minutes—with NO alarm at all. I don’t know about you, but I’d rather have more protection than that.

The CO Experts low level CO monitor starts giving you warnings when the CO levels it detects are above 6 ppm. As the CO levels rise, the warnings go from visual to auditory and increase in frequency. The highest level of alarm occurs when it reaches 70 ppm, when it gives you a series of beeps every 6 seconds.

Don’t judge a book by its cover

Back to that old aphorism I opened the article with, there are two reasons you might rush to judgment about the CO Experts monitor. I’ve already mentioned one: No UL listing. I hope I’ve convinced you already that that’s not a valid reason. The problem isn’t that this low level monitor isn’t UL listed. The problem is with the requirements for the UL listing.

The second may already be apparent to you if you clicked any of the links above: The CO Experts website is a complete mess. George Kerr is knowledgeable and passionate, and if you spend any time talking with him about this issue, you’ll be convinced that you and everyone you know needs a low level CO monitor. I met him in 2005 at the Affordable Comfort conference (now called the Building Performance Association conference). The problem is that Kerr is also an engineer, and his website shows that. It’s full of great information presented poorly. It’s one of those ’90s websites that somehow has survived 12 years into the new millenium.

Don’t be put off by the website appearance, though. This CO monitor is the real deal. Pretty much everyone I know in the home performance industry swears by these CO monitors. If you want to breathe easy, get yourself one today.


2021 Update:  George Kerr died a few years ago and the website is much more approachable now.  And the CO Experts low level carbon monoxide monitor lives on.  You can buy it at TruTech Tools.*

Click the image to buy the CO Experts low level monitor at TruTech Tools*

CO Experts low level carbon monoxide monitor


Related Articles

Don’t Let the Turkey Get You Down! Carbon Monoxide Alert

3 Problems with Atmospheric Combustion Inside the Building Envelope

Combustion Safety Rule #1: Remove Exhaust Gases from House


* This is a TruTech Tools affiliate link. You pay the same price you would pay normally, but Energy Vanguard may make a small commission if you buy after using the link.

This Post Has 24 Comments

  1. Co experts unit is an
    Co experts unit is an excellent monitor. Also the NSI3000 Low level monitor from National comfort institute.  
    Low level monitors are a must.

  2. Interesting. I just installed
    Interesting. I just installed several First alert wireless interconnected combined smoke+CO detectors yesterday. One of the caveats on the product literature (which I actually read from end-to-end, believe it or not) stated that (my paraphrasing): for environments with small children or individuals with breathing problems (I don’t recall if it mentioned pregnant women), a CO detector with an alarm threshold lower than 30 ppm should be considered.  
    My first reaction was: Now where on earth would I go to find a commercially available home CO detector if I really needed one??? So maybe our psychic link was what inspired you to write this post! 
    Anyway, I’m in the habit of every so often spot checking my home environment, especially around my combustion areas with my Testo CO stick, but what normal (or even no so normal, in my case) home owner even think of do that? 
    Thanks for posting this. 

  3. Sorry, I meant to say &quot
    Sorry, I meant to say “where would I go to find a commercially available home CO detector with an alarm threshold lower than 30 ppm” in my comment above…

  4. Didn’t see anything on CO
    Didn’t see anything on CO Experts website on how to order one. Are they available in any retail stores?

  5. I loves me some 90s website
    I loves me some 90s website style, flash tags and all. 
    But as with the commenter above I see no “where to buy” link … it would be great if you could update the article with a link to a few reputable stores/sites that carry these.

  6. How interesting that on this
    How interesting that on this day a school in Georgia has a major, significant CO event. Levels apparently as high as 1700ppm. 
    A 100% preventable (and detectable) problem. 

  7. The CO regs (UL 2034) are the
    The CO regs (UL 2034) are the result of pressure from cities who’ve had to deal with the cost of nuisance alarms. This is why low-level alarms like the one from CO Experts can never be UL listed.  
    In 2010, a bill was proposed in Congress that would require all homes with combustion appliances or attached garage to have UL 2034 compliant CO detectors. As I understand it, low-level CO monitors would not only not satisfy the law, but would be prohibited.  
    I just checked and the 2010 bill referenced in the above links didn’t pass, but was reintroduced this year as H.R.4326 in the House, and as S.3343 in the Senate.

  8. Sorry, I removed the links in
    Sorry, I removed the links in my previous comment, as they were pointing to discussions in a closed group on LinkedIn, and I failed to edit the last sentence. 
    @James, the CO Experts monitor is available from InspectorTools ( Two other low-level monitors are available: National Comfort Institute sells one through its affiliates (, and Pro-Tech out of Canada makes one (

  9. For those looking, the link
    For those looking, the link to order on the CO experts page is at the top of the left column. Titled “All questions and orders.” 
    Like John Poole I regularly test my home, and others, for CO with a combustion analyzer. It isn’t uncommon to find low levels in homes with gas ranges or other unvented appliances. What really got me down on commercial CO detectors was an incident while visiting a friend one cold day. He mentioned that his neighbors were without heat and their service company wasn’t going to be there for several hours. Would I look at it? I’m not a heating tech but I figured I’d try the reset switch and it would work or not. 
    We walked in the door and I nearly screamed. In the middle of the room was a propane “pot” heater, no windows were open and the flame was not the nice steady color the directions talk about. 
    I asked everybody to leave, got my analyzer from my truck and measured about 350 PPM in the house. They had a nice new(er) CO detector in the next room, plugged in and totally silent. 
    My blower door fan cleared the building nicely, the neighbors stayed with my friend ’til the service guy arrived and I encouraged them to get the CO experts unit. I don’t know if they did but I decided to practice what I preach.

  10. Great information, I never
    Great information, I never considered this before. It is actually great timing as I am thinking about getting a CO detector for my mother’s new home.  
    The only drawback is the price and availability. From what I can tell these things are around $200+. Are there any budget oriented models that work similar?

  11. @Brad, as per my previous
    @Brad, as per my previous comment, the CO Experts monitor is sold by Their current price is $179. ProTech’s low-level monitor (model 8505) is available for $100 to $110. Just follow the “Where to buy” link on the page linked in my previous comment.

  12. I bought the exact monitor
    I bought the exact monitor pictured in your article, but with a Pro Tech brand on Amazon for $84.99 with free shipping, and it is UL approved.It is the “ProTech 7035-SL Sealed Lithium Powered Carbon Monoxide Alarm with Display” Note it is the Model7035, not the cheaper model 7030 without the led display. The direct link on Amazon is:;=1355076237&sr;=8-1&keywords;=ProTech+7035-SL+Sealed+Lithium+Powered+Carbon+Monoxide+Alarm+with+Display

  13. @Bob, the ProTech 7035, even
    @Bob, the ProTech 7035, even though it has same case, is not the same monitor as the CO Experts. In particular, the 7305 will not display less than 40ppm unless the user presses a button, in which case it will display down to 10ppm, according to the specs. This is how it can be UL rated. ProTech’s low-level monitor (not UL rated) is the 8505.

  14. Gerald, 

    Good to know. I’ll press that button before going to bed at night. Thanks, 

  15. Ah, sorry David. Don’t know
    Ah, sorry David. Don’t know where I got Gerald from. Thanks again. 

  16. Have had the unit for several
    Have had the unit for several weeks now. Registers 10 ppm when button is pushed. Had it next to our gas range all day. Registered zero. I noticed the comments on ventless fireplaces was closed with the comment that gas industry people were posting propaganda. I kind of resent that. Feels like censorship to me. I don’t see the difference between a gas range & cooktop and a ventless fireplace, even though I don’t have one. I just heat soapstone bricks on my rangetop when the power is off. I do have a few hundered dollars invested in good CO2 and Co detectors. I bristle when people condemn anything, unvented gas ranges, sugar, heavy cream, whiskey, pork fat, etc., without valid scientific proof. Their opinions are no better than mine.

  17. Bob S.: If
    Bob S.: If you ever find yourself in the position of maintaining a blog with a lot of articles and comments, perhaps you’ll understand. It’s easy for people to cry censorship over what I do with my blog when they know nothing about the maintenance, the spam comments that I continually have to delete, and that I do this all by myself. This isn’t a big corporation with lots of staff and money. It’s one person writing about 3 articles a week and trying to respond to as many comments as I can, which is getting to be a smaller and smaller percentage because, with 400+ articles, something’s got to give.  
    It’s not just the ventless gas fireplace article. I’ve decided to keep comments open on articles for only one year, so all articles that I published more than 365 days ago are now closed for comments. If the article’s older than that, I don’t have time to keep deleting spam and responding to people repeating the same thing that’s been said several times before they ever found the article.  
    If your want to comment here in the Energy Vanguard Blog, there’s still plenty of opportunity because I’ve written 135 articles in the past year and will probably write about the same number this year. Combustion safety is a topic I write about fairly often, so you can still speak your mind on the topic here, as you’ve done in this article. I welcome your comments. If this were true censorship, I’d just delete your comment and any other that I didn’t like.  
    Regarding the issue of ventless gas fireplaces, there’s a reason that combustion safety experts don’t recommend them. There’s a reason that green building programs don’t allow them. If you’re willing to take a chance on them in your home, that’s fine. I will stick with the folks who understand the issue and recommend venting exhaust gases to the outside. 

  18. It is amazing that about 75%
    It is amazing that about 75% of the homes we upgrade do not have already have CO alarms installed. To think that local building codes have not mandated them to date is astonishing, given the documented harm that low level CO exposure can do. To see UL only concerned with high levels is disappointing, to say the least.

  19. Defender just released a new
    Defender just released a new Low Level CO Monitor in November. 
    The monitor automatically displays CO levels detected of 5 ppm or more, and provides a visual alert at 10 ppm and an audible alarm at 15 ppm. 
    Two factory installed lithium batteries will power the monitor for up to five years. 
    Visit for more information.

  20. @Don, good to have another
    @Don, good to have another low-level CO monitor. How long does CO have to be above 15 ppm to trigger ann alarm?  
    Also, how can your alarm be UL-2034 listed if it alarms at 15 ppm? UL-2034 prohibits an alarm below 30 ppm continuous for 30 days.

  21. To introduce myself, I am the
    To introduce myself, I am the manufacturer’s representative for the Defender CO monitor and alarms, which are made in Canada. 
    We are an OEM manufacturer, and have been making CO alarms for other manufacturers and under our own brands since the early 90’s. 
    Defender’s UL Listed CO Alarm, model CA6150, will “automatically” display CO levels detected of 30 ppm or more, and is programmed with an initial alarm threshold of 45 ppm within approximately 90 minutes. As CO level increases, alarm time decreases. 
    The CA6150 is a hybrid between a retail type alarm and a low level CO monitor, in that you can, with One Touch of a button, “manually” monitor the current CO level as low as 10 ppm, peak CO level from 10-999 ppm, and peak duration from 0-999 minutes. 
    The Defender LL6070 is a true Low Level CO Monitor, but is necessarily not UL Listed (UL Listed CO Alarms must alarm at or below 70 ppm, but cannot alarm below 30 ppm). 
    These are the alert and alarm thresholds for the LL6070: 
    Displays 5 ppm within 1 minute of detection 
    Within 10 minutes of detecting 10 ppm, red LED flashes 4 times/minute 
    Within 60 minutes of detecting 15 ppm, horn beeps and red LED flashes 4 times/minute 
    Within 30 minutes of detecting 25 ppm, horn beeps and red LED flashes 4 times every 5 seconds 
    Alarm time continues to decrease rapidly as CO level increases 
    The MSRP for the Defender CA6150 CO Alarm is $79.95, and the MSRP for the Defender LL6070 Low Level CO Monitor is $149.95. There are substantial discounts available for licensed contractors.  
    Please feel free to visit, e-mail, or call us at (800) 253-1529 for more information about the Defender LL6070 Low Level CO Monitor.

  22. @Don, thanks for clarifying.
    @Don, thanks for clarifying. I was confused because your link in previous comment was for the UL-2034 listed detector.

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