The Taco SmartPlug is designed to upgrade any hot water recirculation system. SmartPlug replaces inefficient timers and aquastats typically used in recirculation systems. It adds intelligence to your system by learning when hot water is used in the home. The pipe- mounted temperature sensor records daily hot water usage patterns during the course of a week. Recorded data is used to automatically run the circulator at the same times the following week. So hot water is always available when it's needed. If usage pattern changes, the SmartPlug adjusts automatically.