The by product of incomplete combustion of fuel oil is carbon and sulfur- commonly called oil soot. Oil soot accumulates on the walls and base of the chimney. The accumulation of these soot deposits can fall to the base of a chimney, or directly into the top of the oil fired appliance. This fallen soot build up may restrict the flow of flue gases which consist mostly of nitrogen, carbon dioxide, sulfur dioxide and water vapor. The combustion process also produces carbon monoxide( a tasteless, odorless, poisonous gas). Carbon monoxide may spill back into the house instead of going up the chimney if appliances are not adequately cleaned.
A common misconception is that the oil service company takes care of the chimney. The reality is they don’t. Additionally, many oil burner service techicians may tell the homeowner that the system is okay without even inspecting the entire chimney.
Chimney interiors when not properly maintained, will decay and breakdown. Regular maintenance always pays off in the long run. As stated earlier soot is comprised of carbon, sulfur. This sulfur when mixed with rain water or moisture from the flue gases is absorbed into the flue tiles and starts a deteriorating process called flaking of spalling. As the flue tiles flak, pieces of tile fall to base of chimney and can eventually block the flue gases from exiting the chimney.
The national Fire Protection Association (NFPA 211) states that chimneys shall be “inspected annually and cleaned and repaired if needed”.
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