Carbon Monoxide in the Home
By: New Jersey Home Inspector Michael Del Greco
Carbon Monoxide in the Home
Submitted by: Michael Del Greco, New Jersey Home Inspector Lic GI 0121, President of Accurate Inspections, Inc, a New Jersey home inspection company
This silent killer claims about 1,500 lives each year in the U.S.
Carbon monoxide (CO) is one of the toxins that remains from incomplete combustion of fossil fuels. Fossil fuels include oil, gas, and coal. Small amounts of CO, such as those emitted from the kitchen range, will usually be found in the air in the home. These amounts pose no health concerns for the occupants.
However, health problems can develop if one is exposed to CO in large amounts, such as those emitted for many hours from a blocked chimney. In extreme cases, the presence of CO can be lethal.
BLOCKED CHIMNEYS, NOT HEAT EXCHANGERS, ARE THE REAL CULPRIT
Much has been written about heating systems causing dangerous levels of CO gas in homes. The heating furnace itself will not cause CO amounts of any concern to be emitted into the home.
If the heat exchanger fails (the heat exchanger is the part of the furnace that keeps burned fuels separate from the air in the living space) CO is rarely emitted in the air. If CO is emitted, the amount released is not significant. Here\'s why:
The typical furnace has a fan that circulates the indoor house air to and from the heating system and living space. This fan creates approximately 18 times more pressure on the house side air than the typical pressure created by atmospheric burners. In the event of a failure, this pressure causes the air from the living space to pass to the exhaust side of the unit and up the chimney.
This is not to say that a failed heat exchanger is acceptable. It is not. However, the likelihood of significant CO gas being delivered to the living space has been grossly overstated. A chimney that is blocked for many hours or days is the only item that would deliver dangerous amounts of CO gas to a dwelling.
THE REASONS WHY CO LEVELS VARY IN DIFFERENT HOMES
Carbon monoxide in homes is difficult to research due to numerous variables, including:
1) The size and air volume of a home. The more air in the home, the easier gases will dissipate.
2) The number of air changes per hour in modern homes that have thick insulation, etc.
3) The type of construction. Various types of frame and masonry construction will have an effect on the air changes and air infiltration.
4) The type of heating system. Combustion air requirements and efficiencies have some effect on air movement and changes.
5) Operating fans and exhaust systems. When on, these systems dissipate all the air in the house in minutes. The size of the systems and of the house will determine how effectively this is done.
According to an American National Standard\'s study on heat exchangers, leakage of waste gases is acceptable as long as the combustion chamber and vent do not leak more than 2% of flue gases. (Testing parameters are .1\" water column static pressure on the interior of the heat exchanger.)
HOW CO KILLS
CO reduces the ability of the hemoglobin in the blood to carry oxygen to the brain and body. This is akin to not breathing. The blood recovers quickly if the exposure is not continuous. Typical symptoms include headaches, fatigue, insomnia, nausea, and heart palpitations. The most desirable condition would be a zero level of CO.
Information provided by Michael Del Greco, New Jersey Home Inspector Lic. GI 0121, American Society of Home Inspectors Member 102273, Pesident of Accurate Inspections, Inc. A West Paterson New Jersey Home Inspection firm.