The Conbraco Industries 10-614-15 Hot Water Relief Valve, 3/4" x 1", 1,977,000 BTU, 75 PSI is a high-capacity safety valve designed to protect HVAC and hydronic systems from excessive pressure. It operates by automatically releasing hot water when system pressure exceeds the 75-psi limit, ensuring safe and consistent operation. https://www.partshnc.com/10-614-15-conbraco-industries-34x1-75-hw-1977000-btu