Taco's Fast Fill boiler feed reducing valves are the perfect solution to low pressure problems in your hydronic system. The adjustable pressure range of the Fast Fill line makes it easy to optimize your system. Set your desired system pressure, and the 335-3 will maintain that pressure by adding water to your system automatically. An internal check prevents your system from emptying in the event of a pressure failure. Purging a system with Fast Fill valves is a breeze as the Fast Fill lever may be locked in the open position, overriding typical circulation processes. The bronze construction of this valve makes it ideal for applications where corrosion resistance is important.