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

The role of an air vent in a steam system is crucial during the startup process. Specifically, air vents are designed to remove air from the system. When a steam system is initially filled with water, trapped air can inhibit the flow of steam and reduce the system's efficiency. Air can also cause water hammer and other issues if not adequately vented. By facilitating the removal of air, the air vent ensures that steam can fill the system uninterrupted, allowing for more efficient heating and operation. This process helps maintain the system's efficiency and effectiveness as it starts to generate and distribute heat.