The Principle Operation of a Dual Check Valve Backflow Prevention Device – Typical Installations
The DuCV is typically installed on residential water service lines after the water meter to prevent pollutants generated within the residential water piping system from entering the public water system distribution system. It does not protect the consumers of water within the premises from the hazardous of cross-connections. It is not a testable backflow prevention device so there is no way of knowing if the DuCV is operating properly. Also, the installation of a DuCV on the service line will prevent the expansion of water when heated. Therefore, a thermal expansion tank shall be installed on the hot water heater when a DuCV is installed on the service line. The DuCV is not equipped with a vent or relief port, therefore, drainage is not a concern.