What are the operational requirements for a boiler to be considered "in service"?

For a boiler to be considered "in service," it must be properly fueled, manned, and operating within prescribed safety limits. This implies that the boiler is not only functional but also safe and compliant with operational standards. Proper fueling ensures that the boiler has the necessary energy source to operate efficiently. Being manned indicates that there are trained personnel available to monitor the boiler's operation, addressing any issues that may arise. Operating within prescribed safety limits is crucial to preventing accidents, ensuring that pressures, temperatures, and other operational parameters are kept within established guidelines to protect both the equipment and personnel.

In contrast, the other options do not encompass all necessary conditions for a boiler to be deemed "in service." An automatic shut-off feature is beneficial for safety but does not fully define whether a boiler is operational. Monitoring remotely can be part of a modern boiler management system, but being remotely monitored alone does not satisfy the requirement of having the boiler actively manned. Lastly, the notion that a boiler must operate continuously without maintenance undermines the importance of regular maintenance checks, which are fundamental for ensuring long-term safe operation and reliability. Thus, the correct answer encapsulates the essential criteria for a boiler's operational status.