Which of the following is NOT a typical indicator of combustion efficiency?

Combustion efficiency is typically assessed through various measurable indicators that reflect how effectively fuel is being converted into energy and how well the combustion process is occurring. The key indicators generally include flue gas temperature, stack oxygen levels, and fuel consumption rates.

Flue gas temperature provides insights into how much heat is being wasted and can indicate whether the combustion process is operating effectively. Lower flue gas temperatures usually suggest more effective heat transfer and higher efficiency.

Stack oxygen levels are crucial because they indicate how well the fuel is being mixed with air during combustion. High oxygen levels often suggest incomplete combustion, which can lower efficiency, while appropriately balanced levels can signify effective combustion.

Fuel consumption rates are directly related to efficiency as they measure the amount of fuel used to generate a certain amount of energy. Higher efficiency will generally result in lower fuel consumption rates for the same energy output.

Water softness level, however, does not directly pertain to the efficiency of the combustion process or the combustion reaction itself. While maintaining proper water chemistry is important for the overall operation of a steam system and can prevent issues like scaling or corrosion, it does not serve as an indicator of how well fuel is being burned or how effectively heat is being utilized in the combustion process. Therefore, it is not