Swap something problematic for something harmless. This is the basic principle of ion exchange by which scaling in pipes and heating coils is prevented. The minerals calcium and magnesium contained in the water are the problem. When heat is applied, these two, combined with hydrogen carbonate, become scale. If calcium and magnesium are removed from the water, in contrast, no scale be formed.
The foregoing is exactly what happens during ion exchange. Calcium and magnesium are removed from the water and harmless sodium is added. This turns hard water into soft water and the risk of scaling is reduced considerably. The ion exchange principle is derived from nature where it can, for instance, be observed in zeolite rock. In water treatment, ion exchange is considered to be a particularly economic process to transform hard water into soft water. Grünbeck uses this process.