Lynden Home Inspection (King of the House) -- Carbon Monoxide: The Odorless, Silent Killer

By
Home Inspector with King of the House Home Inspection, Inc. Home Inspector Lic #207
You might think, from the title of this blog, that I am planning to write about high blood pressure, diabetes or another one of the well publicized medical conditions that we hear about on a daily basis. However, this article specifically refers to a serious condition that can exist in homes -- homes that you as realtors sell and homes that we home inspectors inspect.  That condition is dangerous levels of carbon monoxide.

Carbon monoxide is a by-product of combustion and can come from defective, improperly installed or worn out appliances or flues. Wood burning devices can be a source of CO; however the most common suspects are oil, propane and natural gas appliances: water heaters, gas dryers, gas and oil furnaces, gas fireplaces. One time I had a fellow call me, panicked that he might have a CO problem. Ends up that he had no wood burning devices and he had an electric hot water heater, an electric range and dryer, electric baseboard heaters. That was one individual who did not have to worry much about CO levels -- unless he was sneaking a barbecue in the house during cold weather.

Personally, and it is beyond the standards of a regular home inspection, I run a carbon monoxide test with a sophisticated meter if I have a concern about an appliance -- usually an older furnace, sometimes a water heater. By the way, most gas ranges, as the burners are being lit, put out CO -- hence the strong recommendation for a range hood over gas ranges. I will hold the CO detector in different locations but I was taught by an HVAC professional that one of the smartest things to do is to put the meter on a heat supply register that is near the furnace. That best simulates CO exposure into the home. For your information here are a few key CO levels, and what to expect from them, listed in parts per million, the measurement that is used:

9ppm..... maximum allowable concentration for short term exposure in a living area

35ppm....maximum allowable concentration for continuous exposure, over 8 hours, in industry

200ppm... maximum concentration allowable in a 15 minute period. Likely to cause headaches, nausea after a couple hours.

400ppm....headaches in a couple hours, life threatening after 3 hours. This is the maximum allowable CO in flue gas, so you can see why you do not want a leaky flue at the furnace or water heater.

12,800ppm...okay, there are lots of numbers from 400ppm up to this point, but they are all really bad for you after about 150 ppm. At 12,800 levels approach instant death -- in 1 to 3 minutes.

Different home inspectors have different ways of looking at this issue. Some do not have a CO detector and some do not want one. Personally, if I have a fear of a furnace or installation, I feel better knowing I put the CO meter on it. Obviously, if readings are high -- such as the furnace in the photo below -- you better believe I warn that an HVAC pro should be called in prior to running the furnace at all. Actually, if I do not like the condition or age of the furnace, even if CO levels are normal, I still recommend that an HVAC technician evaluate and service the furnace and the heat exchanger. I guess that I run the CO test for my own peace of mind. At least I know that, even if the client puts off the HVAC service, he or she will not be exposed to dangerous levels of CO. I do not want a client going into a permanent sleep, the result of logistic issues. Other inspectors, who choose not to use a CO meter,will normally recommend HVAC service, as I described above. They just do not do the test.

Safety: I think that, unless a person lives in a home with all electric heat and the appropriate electric appliances, the new, affordable CO alarms should be installed.  These emergency "dummy alarm" devices for consumers are not at all the same as the meter in the photo. It takes higher levels of CO to alarm them. They really are an emergency device. When they go off, take it seriously, the device has either detected significant levels of CO, or it has gone on the fritz. As an example, a basic CO alarm, unlike an expensive CO meter, has a time function tied to it as it reads the level of the concentration.  Under say 100 ppm the alarm might not alert for several minutes, yet if it detects 400 ppm it will sound more quickly. This gauging of the level of CO vs time is intended to simulate the absorption of CO into the body, without causing false alarms due to smokers, gas burners and that kind of thing. For more detailed information on CO, please visit this site.

SOS --The lights and alarms are sounding. 145ppm, way too high

Charles Buell has written a related article that I think you will find interesting.

Thanks for dropping by.

www.kingofthehouse.com

http://activerain.com/kingofthehouse

Bellingham WA home inspector

Steven L. Smith

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Steven L. Smith

If you enjoy nostalgia and music of yesteryear, click on Elvis' gold record to visit This Day In History. To explore The Stories Behind The Music blog posts click on the electric guitar. 

 

        

 

 

 

 

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Rainer
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Sean Allen
International Financing Solutions - Fort Myers, FL
International Financing Solutions

Great post and very relevant. I once had a tenant complaining of headaches every night and it turned out to be from the water heater flu not venting out correctly and he was getting CO poisoning.

Sean Allen

Feb 08, 2008 10:58 AM #1
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Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector
Good stuff Steve, I think in time we all will be coming around to being more pro-active about testing for Carbon Monoxide---I know I "require" (LOL) testing for it by the HVAC when they are servicing gas appliances---especially the older ones.  I think what makes HIs nervous is that there are so many variables with it was well as the maintenance and cost of testing equipment is a serious commitment.  Then you can have well drafted furnaces that won'd show up a serious carbon monoxide issue---so checking the vent while the appliance is running is a good idea too.
Feb 08, 2008 10:59 AM #2
Rainmaker
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Barbara S. Duncan
RE/MAX Advantage - Searcy, AR
GRI, e-PRO, Executive Broker, Searcy AR
I know of several instances where the carbon monoxide level was so high the heater was turned off.  In one house there were two furnaces and they BOTH were turned off.  The people had no money to replace them so the real estate agent loaned them the money to get two new furnaces.  CO is dangerous!!  Good post.
Feb 08, 2008 11:24 AM #3
Rainmaker
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Steven L. Smith
King of the House Home Inspection, Inc. - Bellingham, WA
Bellingham WA Home Inspector
Big thanks to Charlie for the photo opportunity. He let me come over to his pad after he did some do-it-yourself HVAC work. Big improvement from before.
Feb 08, 2008 11:31 AM #4
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Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

I knew there had to be a carbon monoxide joke in there somewhere:)  Do you know that there are actually industrial uses for the stuff?   Including as a fuel and a reducing agent in chemical manufacture.

Feb 08, 2008 11:40 AM #5
Rainmaker
101,020
Chris Frantz
EDU Real Estate Group - Indianapolis, IN

We had our carbon monoxide detector go off at around 2am one winter night.  Called out the fire department and they said the detector was faulty.  So the next morning I bought several different models.  Better to be safe than sorry.

Feb 08, 2008 12:08 PM #6
Rainmaker
1,243,432
Steven L. Smith
King of the House Home Inspection, Inc. - Bellingham, WA
Bellingham WA Home Inspector
Thanks for the comments all.
Feb 08, 2008 01:39 PM #7
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Steven L. Smith

Bellingham WA Home Inspector
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