What should be done if a boiler shows signs of excessive pressure?

The correct response emphasizes the importance of safety and immediate corrective action when a boiler exhibits signs of excessive pressure. A boiler is a pressurized vessel, and if it shows signs of excessive pressure, it poses a significant risk for failure or explosion. Therefore, it's crucial to take immediate action to address the situation.

Checking safety systems, such as pressure relief valves and gauges, ensures that any malfunctioning parts can be identified and rectified before they lead to a hazardous situation. This proactive approach minimizes the risk of accidents and helps in maintaining the safe operation of the boiler. Monitoring and addressing pressure levels is a critical aspect of boiler maintenance and operation, ensuring compliance with safety standards and regulations.

In contrast, the other options do not address the immediate need for safety. Checking humidity levels does not relate to pressure management, increasing heat would only exacerbate the situation, and ignoring the issue poses significant dangers. Thus, the correct course of action aligns with established safety protocols in boiler operation.