If the chimney temperature is 250 degrees Fahrenheit higher than the steam and water temperature, the boiler is ______.

When the chimney temperature is significantly higher than the steam and water temperature, it indicates that the boiler is losing a considerable amount of heat through the flue gases. Ideally, the chimney temperature should be only slightly above the temperature of the steam and water, as this reflects efficient heat transfer from the combustion process to the water in the boiler. Excessively high chimney temperatures suggest that not all of the energy produced by burning fuel is being used effectively to generate steam; instead, a portion of it is being wasted by escaping through the chimney.

This loss of heat can lead to increased fuel consumption and higher operational costs, as the boiler has to work harder to maintain steam production. Furthermore, it can potentially lead to issues such as incomplete combustion, increased emissions, or the formation of soot, all of which signify inefficiency in the system. Therefore, a chimney temperature that is 250 degrees Fahrenheit above the steam and water temperature is a clear indicator that the boiler is not operating as efficiently as it should.