Flow switches are designed to control pump operation or min. flow through a device in sealed heating/cooling circuits. They are not intended for DHW and drinking water. They permit an automatic shut-off of an appliance if its operation is undesirable or dangerous under low flow. When the nominal flow rate is reached, the appliance is switched on again. Flow switches shall be installed directly before or after a pump using 1” union nuts or on a 3/4“ M threaded pipe.