Which component is essential for controlling the flow of water into a boiler?

The feedwater pump is essential for controlling the flow of water into a boiler because it is responsible for delivering the necessary amount of water into the system to replace what is converted to steam and ensure the boiler operates efficiently. The pump maintains the required pressure and flow rate of feedwater, which directly affects the boiler's performance and safety. Proper feedwater supply is crucial since inadequate water levels can lead to overheating and potential damage to the boiler.

The other components have distinct roles that do not directly control the flow of water into the boiler. The pressure valve regulates pressure within the system but does not actively manage water flow. The safety valve functions to release excess pressure, preventing boiler explosions, rather than controlling the influx of water. The drain valve allows for the removal of water or sludge from the boiler but is not involved in feeding water into the system. Thus, the feedwater pump is uniquely positioned as the component that directly facilitates the flow of water necessary for boiler operation.