Venting: What you don’t know can kill you

Johnny Morgan, Bankston, Jr., Joseph D.  |  10/13/2009 10:52:32 PM

News Release Distributed 10/13/09

Many household appliances such as gas heaters and dryers, fireplaces, furnaces and gas ranges operate by burning a combustible fuel such as natural gas, propane, wood or other fossil fuel. Appliances of this type (combustion appliances) need proper venting to operate safely.

Dr. David Bankston, LSU AgCenter agricultural engineering specialist, said venting, as used here, includes routing combustion gases to the outdoors and the equipment used to do the job.

“Anything that burns produces combustion gases. Combustion gases contain large amounts of carbon dioxide and water vapor and, with incomplete combustion, carbon monoxide,” Bankston said. “Although carbon dioxide and water vapor are not toxic, they can produce harmful effects if their concentration is allowed to build up.”

Carbon monoxide is extremely dangerous. In fact, it is the leading poison killer in the United States, according to Bankston.

Low-level carbon monoxide exposure can cause headaches, nausea, weakness, dizziness, disorientation, sleepiness and/or breathing difficulties, the engineer said. Many of these symptoms are the same as for common illnesses such as the flu.

Bankston said people should be particularly concerned if other members of the household also have symptoms and everyone feels better when they leave the house.

“Carbon monoxide can be produced any time there is combustion, but it is more likely when you see a yellow or yellow-orange flame. It is very dangerous, particularly since it cannot be seen or smelled,” he said.

To promote health and safety, most appliances, such as water heaters and home heaters that produce large quantities of combustion products and are used for long periods, are vented to the outdoors.

Products such as gas ranges should not be used for heating, Bankston said. They do not burn clean and can produce dangerous fumes because they rely on natural house ventilation – the exchange of indoor and outdoor air through doors, windows and cracks – to prevent buildup of combustion products.

Bankston said many old-style unvented heaters also relied on this in the past. This usually worked well because most old houses were quite drafty.

Today, although they are not allowed in some areas, you can still buy unvented space heaters.

“The instructions included with them say to use them in a well-ventilated area, perhaps with an open window,” Bankston said. “They also stress that the heater should be well-maintained and the flame should be blue.”

He said most unvented space heaters will include an oxygen-depletion sensor to turn the heater off if oxygen levels are low.

Under proper conditions, these unvented appliances can work, but today’s tighter houses reduce the normal ventilation and may cause a device that would be safe in an old, drafty house to be a hazard, Bankston said. Under these conditions, it is imperative that venting be used and be correct.

For more information on how you and your family can be safe with appliances that operate by burning a combustible fuel, contact your local LSU AgCenter extension office or visit the Web site at

Johnny Morgan

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