What device is used to eliminate air at the boiler in a steam system?

The correct answer is the air eliminator. In a steam system, particularly at the boiler, it is crucial to remove any trapped air that can prevent efficient steam generation and distribution. The air eliminator functions by allowing air to escape from the system, thus promoting the proper circulation of steam and ensuring that the boiler operates effectively.

When air is present in the system, it can lead to reduced efficiency and even damage if not properly managed. The air eliminator typically uses gravity and differences in density between steam and air to facilitate this process, ensuring that the steam system remains operational and efficient.

While air vents also serve a similar purpose of releasing trapped air, the term "air eliminator" specifically refers to devices designed for this duty in steam systems. Other options like air compressors and pressure relief valves have entirely different functions, such as maintaining system pressure or providing safety by relieving excess pressure, and are not used for air removal in steam systems.