Water heater stacking detection and control

A controller for operating a water heater to limit water stacking in a water heater tank, comprising:

• a sensor input configured to receive a signal from a temperature sensor corresponding to the temperature of the water in the water heater tank;
• a memory for storing a user-defined temperature set point;
• an output for providing a control signal to control a heater of the water heater;
• and
• a processing block coupled to the sensor input, the memory and the output, the processing block configured to provide the control signal via the output to control the temperature of the water in the water heater tank based on the user-defined temperature set point by selectively operating the heater in a sequence of heating cycles, the processing block determining 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 processing block determines that stacking is likely occurring in the water heater tank, and if the processing block determines that stacking is likely occurring in the water heater tank, the processing block is configured to control the temperature of the water in water heater tank based on a second temperature set point, wherein the second temperature set point is lower than the user-defined temperature set point.

A method of operating a water heater to limit the effects of stacking in the water heater, the method comprising:

• sensing the temperature of the water in the water heater;
• controlling the temperature of the water in the water heater based on the sensed water temperature and a first temperature set point;
• determining if stacking is likely occurring in the water heater using the sensed water temperature;
• and
• if it is determined that stacking is likely occurring in the water heater, controlling the temperature of the water in the water heater based on the sensed water temperature and a second temperature set point, wherein the second temperature set point is lower than the first temperature set point.