The dangers of gas heaters

Written by catalina bixler
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The dangers of gas heaters
Gas fireplaces require pose unique safety considerations.. (Image by, courtesy of David Shand)

Whether gas heating comes from a furnace, a space heater or a gas-log fireplace, there are many dangers that can result from improper installation, operation and maintenance. Both Canada and the United States maintain up-to-date standards for the safe manufacturing and use of gas heaters. A gas heater requires owners to regularly follow manufacturers' cleaning guidelines or to have the units serviced by professionals.


More common in rural areas where natural gas service is unavailable, using bottled propane for heating has avoidable dangers. Propane is heavier than air, so any tank or line leaks collect and travel along floors, which can expose it to such dangers as the pilot lights of gas water heater or ovens; as such, propane tanks are always installed outside the building. Even unused tanks need to be stored outside and 30 to 40 feet from the house to avoid fire risks.

Health Issues

A lack of ventilation and unidentified leaks can cause indoor air pollution and resultant health and safety risks. Unvented gas heaters (against the law in some states) in small, tightly sealed spaces can use up all the oxygen in the room, causing health dangers or death. In such installations, only use units that have oxygen-depletion sensors that shut off the heaters when oxygen levels reach unsafe low levels. The two prevalent health threats of using gas heaters in poorly ventilated rooms are carbon monoxide and nitrogen oxide gases resulting from leaks, blocked ventilation and equipment failure. Moderate exposure to carbon monoxide can induce flu-like symptoms. People prone to heart and respiratory ailments may experience chest pains. Carbon monoxide and nitrogen oxide from an unvented gas heater can induce colds and asthma among children. The ultimate danger of prolonged exposure to either of those noxious gases is death.

Gas Log Heaters

Increasing in popularity, the gas log heater dangers arise from flammable or combustible materials being used near the flames, including liquid fuels such as lamp oil, spray paints, solvents, insecticides, and all pressurised containers (such as furniture spray or air freshener) located closer than 3 feet to the heater. Dust, pet hair, paper, and other flammable substances must be kept from the heater. Leaving a gas log heater burning when away from home invites fire danger from airborne debris.


Have gas heaters serviced by a professional at least every two years, and well before the onset of the heating season. In general, danger arises when yellow or sooty flames appear with blue-flame heaters. Loud noises when lighting the pilot on a gas heater indicates possible safety risks from faulty equipment or problems in the gas line. Discolouration from heat on the appliance housing or when the heater walls are too hot to touch also indicates that servicing may be necessary. Only use gas heaters equipped with basic safety features such as thermocouples (which cut off the flow of gas when the flames blow out) and oxygen-depletion sensors.

Other Dangers

Other hazards from fire and carbon monoxide poisoning arise when using patio gas heaters inside a building. Fire risk occurs with forced-air gas heaters that have grills that have not been first cleaned of lint or dust. Blocking the airflow of a gas heater causes gas build up, leading to fires or health risks. Not replacing the front panels as needed on wall-mounted gas heaters increases the menace of fire. Sealing doors and windows while using gas heaters risks occupant health from lack of oxygen or from the build up of noxious gases; drafts from doors and windows may actually be a benefit when using gas heaters.

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