The Watts 0121627 LF5300A 1/2" Lead Free Bypass Control Relief Valve is a pressure management component designed to regulate excess pressure in compatible plumbing and hydronic heating systems. It operates by opening a bypass or relief pathway when pressure reaches its designated setting, helping maintain stable system conditions and protect equipment from excessive pressure buildup. ... https://www.partshnc.com/0121627-watts-lf5300a-1-2-lead-free-bypass-control-relief-valve-0-250-psi