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 lbs. The 1/2" valve has a 15,000 BTU rating the 3/4" is 80,000 BTU. 63871, 1/2" Relief Valve, Lead Free.