What is the effect of hardness on boiler water?

Hardness in boiler water primarily refers to the concentration of calcium and magnesium ions. When water with high hardness levels is heated in a boiler, these minerals can precipitate out and form scale on the internal surfaces of the boiler. This scale buildup acts as an insulating layer, which hampers effective heat transfer and can significantly reduce the boiler's efficiency. Over time, it can also lead to overheating of the metal surfaces, potential failure of the boiler, and increased fuel consumption to achieve the desired temperature and pressure.

In contrast, other options either misrepresent the effects of hardness or suggest that it is benign. For example, while rust formation is more closely related to the presence of oxygen and other corrosive agents in the water rather than hardness alone, the idea that hardness has no significant effect overlooks the critical issues it can cause, such as scale buildup. Lastly, the assertion that hardness improves steam quality is inaccurate, as excessive hardness can lead to foaming and carryover of impurities, which would negatively affect steam quality rather than enhance it. Thus, recognizing the correct impact of hardness on boiler water is crucial for maintaining operational efficiency and safety in steam systems.