How is foaming defined in steam heating systems?

Foaming in steam heating systems is defined as the presence of surface impurities that lead to an uneven water line in the boiler. When water contains foreign substances, such as oils or other impurities, they can decrease the water's surface tension and cause bubbles to form. These bubbles can prevent steam from rising properly, disrupting the formation of steam and leading to fluctuations in the water level. This uneven water line can result in operational issues within the steam heating system, such as inefficient heating or even damage to the boiler if not managed properly. Understanding this definition is crucial for maintaining the efficiency and safety of steam heating systems.