Taco Flo-Cheks open automatically when the circulator starts running. When the room thermostat is satisfied and the circulator is stopped, the Flo-Cheks close immediately, preventing gravity circulation. Gravity circulation of water is induced by the difference in specific weight or density of the hot water in the vertical supply pipe and the cold water in the vertical return pipe. The lighter hot supply side water, which naturally wants to rise, is drawn up and around the system by the "pulling down" effect of the heavier cold water in the vertical return pipe. The amount of gravity circulation is dependent on the height of the system and the differential between the hot and cold temperatures. In systems with multiple zones, "ghost flow" may occur if a Flo-Chek is not installed on each zone. Ghost flow is induced when a circulator on one zone is running but is still able to bypass water through a zone that is not calling, due to a differential in piping resistance between the two zones.
Source: Taco Flow Control Submittal Data
Taco products such as flow controls can be found at www.supplyhouse.com
