What can lead to excess soot accumulation in an oil furnace?

Excess soot accumulation in an oil furnace is predominantly caused by insufficient air supply during combustion. For proper combustion to occur, a balanced mixture of fuel and air is required. If the air supply is inadequate, the oil does not burn completely. This incomplete combustion results in unburnt fuel particles that accumulate as soot on the heat exchanger, flue pipes, and other components of the furnace.

When there is not enough oxygen present, the combustion process becomes inefficient, leading to the formation of soot rather than clean gases. This accumulation not only reduces the efficiency of the furnace but can also pose safety hazards and increase maintenance needs.

While factors such as too much fuel and low-quality oil may contribute to combustion issues, the key factor in excess soot production specifically ties back to the air-fuel ratio, underscoring the importance of a sufficient air supply for complete combustion.