What primarily causes scaling in a boiler?

Scaling in a boiler is primarily caused by high mineral content in water. When water is heated in a boiler, various dissolved minerals, such as calcium and magnesium, can precipitate out of the water as scale, especially when the water temperature rises. This process occurs because hot water has a reduced ability to hold certain minerals in solution. As these minerals crystallize, they form deposits on the internal surfaces of the boiler, which can lead to reduced efficiency, increased fuel consumption, and potential damage to the boiler over time.

In contrast, high temperatures can enhance the scaling process, but they are not the fundamental cause; rather, it is the minerals present in the water that lead to the formation of scale. Aged boiler components may have their own set of challenges but are not a main contributor to the initial scaling problem. Excessive water pressure can lead to other types of issues within a boiler system but does not directly cause scaling. The presence of minerals in water remains the primary factor in the development of scale in a boiler system.