What is a common method of controlling boiler temperature?

A thermostat is indeed a common method of controlling boiler temperature. It functions by sensing the temperature of the water or steam within the boiler system. When the temperature reaches a predetermined level, the thermostat sends a signal to the burner to either reduce the fuel supply or shut it off entirely, maintaining a stable temperature. This automatic regulation helps prevent overheating and ensures that the boiler operates efficiently and safely.

Other methods mentioned, while they play roles in boiler operation, do not primarily serve to control temperature. For instance, adjusting the water level is crucial for maintaining proper operation and avoiding overheating, but it directly influences pressure rather than temperature alone. Increasing the fuel supply affects temperature but does not involve a feedback mechanism to maintain a specific temperature setting. Opening the safety relief valve is a safety measure to prevent excessive pressure, not a temperature control method.