What does the term 'combustion efficiency' refer to?

Combustion efficiency is a critical concept in the context of oil heating systems, where it specifically refers to how effectively a burner converts fuel oil into heat energy. This metric assesses the proportion of energy contained in the fuel that is successfully transformed into usable heat for a space.

When a burner operates, not all the fuel is transformed into heat due to various losses, including unburned fuel and heat escaping in the flue gases. Therefore, a higher combustion efficiency indicates that a greater percentage of the fuel's energy is being utilized for heating, resulting in better performance and reduced fuel costs.

This understanding is vital for maintaining and optimizing heating systems, ensuring they operate efficiently and economically. Other options like the speed of oil burning, heat output per unit of oil, and oil temperature during combustion do not encapsulate the essence of how effectively combustion is achieved in terms of energy conversion.