Patent ID: 8875664

Claim:
A water heater comprising: a tank; a heater for heating water in the tank; a sensor provided a signal corresponding to the temperature of water in the tank; a controller coupled to the sensor for receiving the signal corresponding to the temperature of the water in the tank, the controller storing a normal user-defined temperature set point for the water in the tank; the controller is configured to control the temperature of the water in the tank based on the normal user-defined temperature set point by selectively operating the heater in a sequence of heating cycles, wherein the controller determines a measure related to a length of time of at least some of the heating cycles, and if the measure falls below a threshold value, the controller determines that stacking is likely occurring in the tank; if the controller determines that stacking is likely occurring in the tank, the controller is configured to control the temperature of the water in the tank based on a second temperature set point, wherein the second temperature set point is lower than the normal user-defined temperature set point; and wherein if the measure falls below the threshold value for one or more heating cycles, and then during a subsequent heating cycle the measure rises above the threshold value, the controller is configured to increase the second temperature set point toward the normal user-defined temperature set point.