What device is used to protect hot water boilers?

The use of a safety relief valve is essential in protecting hot water boilers from excessive pressure scenarios. This device serves a critical function by automatically discharging water when the internal pressure reaches a predetermined limit, thereby preventing potential damage or catastrophic failure of the boiler system.

Boilers operate under high-pressure conditions, and as heat is added, the pressure can increase significantly. If this pressure exceeds the safe operating limits, the safety relief valve activates to release steam or water, ensuring that the system remains within safe parameters. This safeguard is crucial for maintaining the integrity of the boiler and ensuring safe operation.

In contrast, other devices have different roles in boiler operation and safety. A pressure regulator is designed to maintain a specific pressure within the system but does not release excess pressure like a safety relief valve. Temperature control devices manage the temperature of the water in the boiler but do not directly address pressure concerns. Flow control valves regulate the water flow but do not provide relief from elevated pressures. Hence, the safety relief valve is specifically tailored for protecting hot water boilers, making it the correct answer.