An ultra-violet (UV) assembly for treating a fluid with UV light has a housing. A mounting bracket defines a slot and a hollow. A UV source includes: a tab that twist-locks in the slot a connector that aligns with the hollow and an RFID tag. An RFID antenna interacts with the RFID tag to emit a RFID tag position signal. A flow switch sends a flow signal. The flow switch includes: a guide a shaft slidably mounted to the guide a disc on the shaft a magnet coupled to the shaft and a sensor for generating a magnet position signal. During no flow, a spring biases the shaft so that the magnet is positioned to be detected by the sensor. During flow, the flow applies pressure to move the disc and, in turn, the magnet moves to be positioned to not be detected by the sensor.
