Which of the following is a preventative measure for scaling in boilers?

Using water softeners to reduce mineral content is indeed an effective preventative measure for scaling in boilers. Scaling occurs when dissolved minerals, primarily calcium and magnesium, precipitate out of the water and adhere to the surfaces of the boiler. These scale deposits can severely hinder the efficiency of heat exchange surfaces, leading to increased energy costs and potential damage to the boiler system.

Water softeners address this problem by removing these hard minerals from the water supply, effectively reducing the potential for scale formation. By substituting sodium or potassium ions for calcium and magnesium, the water is conditioned to minimize scaling, thereby improving the operational efficiency and longevity of the boiler.

Other methods mentioned, which could be beneficial for boiler maintenance, do not specifically target the root cause of scaling in the same way that water softeners do. For example, regularly flushing the boiler might help remove existing deposits but does not prevent the initial formation of scale, while ensuring consistent pressure levels and increasing water levels may help in managing overall boiler operation but do not address mineral content specifically.