Flow Switches are used to cut off power to the chiller incase the water flow stops (such as a pump failure or during water changes). The Flow Switch prevents the water inside the chiller from become frozen and bursting the pipes: which will damage the chiller and cause leakage. The Flow Switch is installed in the plumbing system before the chiller and the switch is plugged in between the chiller and the controller. In UV sterilizer installations, the Flow Switch can be used to turn off the UV sterilizer and prevent the unit from over-heating. This 230V Flow Switch is rated at 20 amps and can be used with chillers up to 1-1/2 HP.