At what temperature should combination temperature and pressure relief valves open to release water out of the tank?

Combination temperature and pressure relief valves are essential safety devices used in water heaters to prevent excessive pressure and temperature build-up. These valves are designed to open and relieve water from the tank to ensure that the internal conditions remain within safe limits. In practice, the opening temperature for these valves is typically set around 210 degrees Fahrenheit. This temperature is carefully chosen because it is near the boiling point of water at standard atmospheric pressure.

When the temperature reaches this threshold, the valve opens to prevent the risk of overheating, which could lead to a potential explosion if the pressure builds too high. The valve's primary purpose is to protect the system by releasing the excess pressure and steam in a controlled manner, ensuring safe operation of the water heater.

The other choices represent temperatures that are either below or above the standard operating threshold for these valves, which would not effectively provide the necessary protection in the event of overheating. The specific setting of 210 degrees Fahrenheit aligns with industry standards and safety guidelines, highlighting its importance in maintaining optimal functioning of water heaters.