The integral design of the Taco 3450 Combination Boiler Feed & Backflow Valve combines a Cartridge style backflow preventer with a pressure regulating Cartridge style boiler feed valve into a unique one piece body configuration. Taco’s 3450 combination dual check backflow with atmospheric vent and boiler feed valve with purge auto-reset, dial in pressure setting and adjustable indicator sets a new standard for performance and serviceability.