What does thermal efficiency measure in a boiler?

Thermal efficiency in a boiler measures the effectiveness of the boiler in converting energy input into useful energy output, specifically in the form of steam or hot water for heating purposes. The thermal efficiency is calculated as the ratio of the useful energy that can be utilized for work or heating to the total energy input into the system, typically expressed as a percentage.

A boiler with a high thermal efficiency indicates that it is effectively utilizing the energy supplied to it, minimizing waste and maximizing performance. Understanding thermal efficiency is crucial for evaluating the performance of a boiler system, allowing operators to make informed decisions about efficiency improvements, operational costs, and energy management strategies.

The other options, while related to energy and boiler operation, do not directly pertain to the measurement of thermal efficiency. Concepts like energy cost, maintenance frequency, and water volume pertain to different aspects of boiler operation and performance, but they do not capture the essential relationship defined by thermal efficiency, which is focused solely on the output-to-input energy ratio.