The Watts F383800 740 1-1/2" Pressure Relief Valve is a safety component designed to protect compatible plumbing, hydronic heating, and HVAC water systems from excessive pressure. It automatically opens when system pressure exceeds its specified limit, releasing excess pressure to help prevent equipment damage and maintain safe operation. This valve is suitable for compatible boilers,... https://www.partshnc.com/f383800-watts-740-1-1-2-pressure-relief-valve-2-60-psi-4-907-000-btu