Temperature and Pressure Relief Valve - Self-closing temperature and pressure relief valves. All brass body. Stainless steel spring. Thermostat is positive, accurate and proven. A unique thermostat with special thermo-bonded protective coating to prevent accumulations of mineral deposits. Valves are preset at 150 pounds. The 1/2 inch valve has a 15,000 BTU rating; the 3/4 inch is 80,000 BTU. 3/4 inch Relief Valve, Lead Free.