Watts Fill Valve and Backflow Preventer
Provide make-up water to the boiler, and prevent backflow
Bronze Combination Fill Valve and Backflow Preventers are for use in commercial and residential hydronic heating systems to provide make-up water to the boiler and prevent backflow when supply pressure falls below system pressure. Part consists of a bronze Watts Model 9D backflow preventer and a high-capacity bronze Watts Model 1156F feed water pressure regulator in one pre-assembled unit.
Documentation: Watts-911.pdf