Which component helps to control the amount of water supplied to the boiler?

The feed water regulator is the component that plays a crucial role in controlling the amount of water supplied to the boiler. Its primary function is to maintain a consistent water level within the boiler, ensuring that it does not run dry or overflow. This regulation is vital for the safe and efficient operation of the boiler, as the correct water level is necessary to generate steam effectively and maintain pressure equilibrium.

By automatically adjusting the flow of water into the boiler based on the current level, the feed water regulator helps to optimize the boiler's performance and efficiency. This ensures that the heating process remains stable, ultimately increasing the longevity of the boiler and preventing potential damage from inadequate or excessive water levels.

In contrast, other components like the expansion tank serve different purposes, such as absorbing excess pressure generated by thermal expansion, while the pressure gauge monitors the pressure inside the boiler, providing information but not controlling water supply. Steam traps are designed to remove condensate and air from a steam system but do not control the water supply to the boiler. Understanding the specific roles of each component helps to clarify why the feed water regulator is the correct answer.