What is the main purpose of using a vent in a heating system?

The main purpose of using a vent in a heating system is to allow air to escape from the system. In hydronic heating systems, trapped air can hinder the flow of water and reduce the system’s efficiency. When air is allowed to escape through the vent, it ensures that the water can circulate properly, allowing for effective heating throughout the system. This is critical for maintaining system performance, as air pockets can create cold spots in radiators or limit the heat transfer from the hot water to the surrounding areas.

Additionally, while increasing pressure, releasing excess water, and circulating hot water are important concepts in heating systems, they do not directly relate to the specific function of a vent. The vent's role is fundamentally tied to managing air—ensuring that the system remains free of air pockets for optimal operation.