What type of efficiency test must be conducted during an annual tune-up?

During an annual tune-up, the combustion efficiency test is necessary to ensure that appliances and systems are operating as intended. This test evaluates how effectively fuel is being converted into usable energy and how efficiently the combustion process occurs. It measures parameters such as flue gas composition, stack temperature, and overall combustion characteristics.

This is critical in maintaining safety and performance, as it can help identify any issues with the combustion process that could lead to inefficient operation, increased emissions, and potentially hazardous conditions such as carbon monoxide production. Regular combustion efficiency testing can also pinpoint the need for adjustments or repairs, ensuring that systems continue to function optimally and safely throughout the year.

The other types of efficiency tests, while valuable in different contexts, do not focus specifically on the combustion process, which is why they are not the correct answer in this situation.