🔥 Elevate Your Heating Game with Watts! Experience rapid system filling and purging. Combines pressure regulation and backflow prevention. Durable construction for long-lasting performance. Compatible with 1/2" union solder inlet and NPT threaded outlet. Streamline your boiler feed lines with ease. Quick fill & purge 1/2" inlet Backflow preventor The Watts Automatic Fill Valve B911S-M3 is designed for hydronic heating systems, providing a combination of feed water pressure regulation and backflow prevention. Its all-bronze construction ensures durability, while the 1/2 inch union solder inlet and NPT threaded outlet make installation a breeze. Enjoy quick system filling and purging for optimal performance.