1, the water is constantly heated, evaporated, concentrated, resulting in water calcium, magnesium, salt concentration increased, when exceeded their concentration, they precipitate out of water sediment;
2. The water is heated and the bicarbonate is heated down to produce insoluble deposits;
3, with the increase of temperature, the solubility of some salts gradually decreased and precipitated. Impurities in tap water and the fouling of the long - standing microorganisms used by solar energy. These sediments, impurities, dirt stuck to the vacuum tube wall, the formation of insoluble scale.