What is the purpose of a pressure relief valve in a hot water boiler?

The purpose of a pressure relief valve in a hot water boiler is to prevent overpressure conditions. As water is heated, it expands and can create significant pressure within the boiler system. If this pressure exceeds the safety limits, it can lead to dangerous situations, including potential boiler failure or explosions. The pressure relief valve is designed to open at a predetermined pressure, allowing excess steam or water to escape, thereby relieving pressure and maintaining safe operating conditions.

This safety mechanism is critical in ensuring the integrity of the boiler and protecting both the equipment and personnel from harm. The other options do not align with the primary function of a pressure relief valve, as it does not measure temperature, regulate flow, or control system pressure directly; rather, it acts specifically to release pressure when it becomes too high.