Causes of a heating oil odor coming from a chimney

Written by jessica kolifrath
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Causes of a heating oil odor coming from a chimney
Your chimney should be cleaned at least once a year to prevent fires. (chimney image by hazel proudlove from

Pre-existing chimneys are often used to vent oil fuelled appliances, such as water heaters and furnaces. If heating oil odours or fumes can be smelled in the home or around the chimney, this indicates a serious problem. Other potentially dangerous fumes are vented along with the oil odour, and they are likely leaking into the home as well.

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Chimney Leaks

Cracks and leaks in the chimney allow the fumes and odours that are supposed to be vented out of the home to enter your living space. Some of these odours may be benign, but other fumes such as carbon monoxide are very hazardous to your health. The experts at the say that soot from an oil burning appliance builds up in a chimney, deteriorating the liner. Having your chimney cleaned and inspected will prevent future damage. If the chimney cleaner detects damage or leaks in the chimney, you should have it repaired before using the oil burning appliance again to prevent the risk of carbon monoxide poisoning.

Oil Furnace Puff Back

A puff back or back fire occurs when oil accumulates in a furnace or burner. When the flames in the appliance light up, this excess oil explodes, according to Inspectapedia. A loud bang is accompanied by the smell of oil emanating through the chimney and vents of the house. These occurrences blow soot and the odour of heating oil throughout the house. The pressure of this explosion damages the vents and ducts of the home, and can also damage the interior of the appliance. If your oil burning appliance is experiencing back fire, shut if off until a technician can determine the cause.

Cracked Hot Air Exchanger

Peter Hutton writes in his column for Boston Globe that a cracked heat exchanger, a part of a oil furnace that releases heat into circulating air, can release the smell of burning oil into the chimney. A damaged heat exchanger is a fire hazard and should be replaced promptly. If enough oil is being released into the air, it can build up in the chimney or other places around the house. This also poses a fire risk, as a stray spark or ignition on another appliance could ignite accumulated oil. Call a service technician and have your heat exchanger examined if you use an oil furnace.

Insufficient Air Intake

Oil will vaporise and travel through the exhaust vents on an oil burning appliance if it is not being fully combusted. High efficiency oil furnaces and water heaters often struggle to draw enough fresh air for full combustion, according to Small chimneys or vents, excessive insulation around the appliance or blocked air intake vents all lead to this problem. While vaporised oil is not necessarily a health hazard, poor combustion creates other hazardous fumes that may cause health problems in the home's inhabitants.

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