The NAVIEN 30015307A Circulation Pump, manufactured with Grundfos components, is a replacement circulation pump designed for Navien NCB and NCB-E series condensing combi-boilers. It circulates heated water through the boiler’s hydronic heating system, maintaining consistent water flow and supporting efficient heat distribution. The pump is used with Navien tankless water heaters and c... https://www.partshnc.com/30015307a-navien-tankless-water-heaters-pump-grundfos-ncbncb-e