What is the main function of an air vent in a steam system?

The main function of an air vent in a steam system is to remove air from the boiler. When a steam system is first filled with water, air can become trapped in the system. If this air is not expelled, it can create pockets of air that interfere with the proper circulation of steam. The presence of air can hinder the system's efficiency, as it takes up space that should be occupied by steam, which is more effective for heating.

Air vents are designed to allow this trapped air to escape, ensuring that the system is filled with steam, which then can effectively transfer heat to the intended areas. This helps in maintaining the system's efficiency and functionality. Keeping the system free of air ensures that the steam produced can deliver the intended thermal energy without obstruction or decreased performance.