Carbon Monoxide and Heating Systems

* According to the U.S. Consumer Product Safety Commission, in 2002, heating systems contributed to 55 percent of the 188 reported (non-fire) carbon monoxide deaths. * Carbon monoxide is estimated to be the number one cause of poisoning deaths in the U.S.

* Between 1995 and 1999, it is estimated that 10,200 more than 7,800 non-fatal cases of CO poisoning (associated with consumer products) were reported in U.S. hospitals.

* Many CO poisoning cases are misdiagnosed as flu or cold symptoms.

Reduce the CO risk, Install a Flexible Chimney Liner

Where does CO come from?

Carbon monoxide is a colorless, odorless gas produced as a result of incomplete combustion of appliances such as boilers, furnaces, wood-burning stoves, water-heaters and gas cooking stoves (especially when used as a space heater), as well as automobiles. CO presents a direct danger when, under certain circumstances, the toxic gas no longer flows freely out a flue-vent or chimney and begins back-drafting into your home. Who’s most at risk of CO poisoning?

It is estimated that 1 in 20 homes in cold-weather climates are capable of producing the conditions that result in CO poisoning. These conditions can range from a broken or obstructed flue to less obvious situations, such as an overly tight home, inadequate combustion air or extra-powerful exhaust vents.

Automobiles idling in an attached garage – even with the garage door wide open – can raise CO to dangerous levels inside the home if there is not a completely sealed air barrier between the garage and the inside of the house. Children, the elderly, individuals with respiratory problems and pets are at risk for CO poisoning at levels as low as 30 parts per million (ppm), however most commercially available CO detectors will not alarm until levels reach 70 ppm.

Reduce the CO risk, Install a Flexible Chimney Liner

How do you know if your home has the potential for CO?

The surest way to test your home is to have a thorough building performance audit performed, which includes a procedure called a combustion appliance zone (CAZ) worst-case depressurization test. The procedure tests your combustion appliances while the home is placed under severe, worst-case conditions. The test is relatively inexpensive.

How do you prevent CO?

Carbon monoxide can be kept out of a home by maintaining proper draft of your combustion appliances. Basic maintenance activities that include a regular visual inspection of your flue pipe for signs of aging and keeping the flue clear and unobstructed are helpful. More importantly, any time you change the pressure or air-flow characteristics of a house (i.e. adding ventilation, strengthening air-sealing or insulation properties), worst-case testing should be performed to ensure that the upgrades have not compromised the draft of the combustion appliances.

Reduce the CO risk, Install a Flexible Chimney Liner

Will a CO detector protect my family?

Every house should be equipped with a working CO detector, however it should be used as the last line of defense and not the sole means to protect your family. A New York state Health Department bulletin advises, “a carbon monoxide detector is not a substitute for regular maintenance of CO sources.” Most detectors available at local home centers will not alarm until CO levels reach as high as 70 ppm. The state Health Department considers a home dangerous if CO levels of 35 ppm persist for up to one hour, and only 9 ppm for levels sustained over an eight-hour period.

A professional-grade, low-level monitor is highly recommended for homes where children, the elderly, people with respiratory ailments or pets live.
About the Author

The author, John Bishop, is vice president and co-founder of Enhanced Living, Inc. ( a building science consultancy and contracting firm based in Troy, NY. John is the former state marketing coordinator for the award-winning Home Performance with ENERGY STAR and New York ENERGY STAR Labeled Homes program.