Diagnostic methods and systems are used to determine operating condition and performance of a cooling element in a metallurgical reactor during operation of the reactor. The system can include sensing means, processing means and display means. The sensing means is located in or approximate the cooling element for sensing operating conditions of the cooling element. The processing means is in communication with the sensing means for receiving data corresponding to the sensed operating conditions and for processing the data to determine a relative condition indicator of the cooling element. The display means is in communication with the processing means and displays the relative condition indicator to a user of the diagnostic system. The display means can display a first, second or third state representative of the relative health indicator.