Worcester Bosch flow switch sensor for i Junior Series, Si/C1 Series and RD Series boilers. The flow switch, or flow meter, has an inbuilt sensor that sits inside the heating or hot water system pipework as an important safety mechanism. Designed to sense water flow, the switch feeds information to the boiler's printed circuit board (PCB) to ensure that the burner is not activated when the system is low on water or dry.

• Comes with clips and O-rings