A gradual increase in stack temperature could indicate which condition in a boiler?

A gradual increase in stack temperature in a boiler is an indication of heating surface fouling. When the heating surfaces, such as tubes or surfaces that transfer heat, accumulate soot, scale, or other deposits, the efficiency of heat transfer diminishes. As a result, the boiler must work harder to maintain the desired steam output, which can lead to higher stack temperatures. This condition signals that the heat generated by the fuel is not being efficiently transferred to the water, causing more heat to be lost up the stack. Monitoring stack temperature is crucial for maintaining efficient boiler operation, and an increase can prompt further investigation into potential fouling or inefficiencies that require treatment to restore optimal performance.

Low fuel supply, boiler water level drop, and a faulty ignition system typically lead to different operational issues that do not generally manifest as a gradual increase in stack temperature. These scenarios impact boiler function in different ways, so recognizing the symptoms related to heating surface fouling is important for effective troubleshooting and maintenance.