What is the function of a pressure relief valve on a boiler?

• A. To relieve excessive pressure to prevent boiler failure or explosion
• B. To regulate thermostat setpoint
• C. To filter the combustion gases
• D. To cool the boiler during startup

Answer: (A)

A pressure relief valve is a safety device that opens when the boiler system pressure rises above its designed limit, venting steam or hot water to reduce pressure and prevent boiler failure or explosion. Once the pressure falls back below the reset point, it reseals and continues protecting the system. It’s not responsible for thermostat control, filtering combustion gases, or cooling the boiler during startup—those tasks are handled by other components. Regular testing and maintenance ensure it will operate correctly when needed.