What device in a hot water heating system allows trapped air to escape from the system?

In a hot water heating system, an air vent plays a crucial role in maintaining system efficiency and safety. When water is heated, it expands, and any air trapped in the pipes can prevent the system from functioning properly. An air vent allows this trapped air to escape, ensuring that the system can operate at optimal levels. If air is allowed to accumulate, it can create air pockets that reduce heating efficiency, lead to uneven heating, or cause noise and hammering in the pipes.

The proper functioning of an air vent is vital because it helps maintain the right pressure and circulation of water throughout the heating system, preventing potential damage and maximizing performance. By removing trapped air, the air vent contributes to a more efficient and reliable system overall.