Temperature algorithm for water heater

A method of operating a water heater, the water heater including a storage tank including a water inlet and a water outlet, a circulation pump configured to deliver water to an external heater of the water heater, an upper temperature sensor configured to sense an upper temperature related to an upper area of the tank and output an upper temperature signal corresponding to the upper temperature, and a lower temperature sensor configured to sense a lower temperature related to a lower area of the tank and output a lower temperature signal corresponding to the lower temperature, the method comprising:

• receiving a first upper temperature signal and a first lower temperature signal;
• comparing the first upper temperature signal to a sum of a setpoint temperature threshold minus a preset temperature differential value;
• comparing the first lower temperature signal to a high limit temperature threshold;
• and
• activating the circulation pump in response to the first upper temperature signal being less than the sum of the setpoint temperature threshold minus the temperature differential value and the first lower temperature signal being less than the predetermined high limit temperature threshold.

A water heater comprising:

• a storage tank including a water inlet and a water outlet;
• a circulation pump configured to deliver water to an external heater of the water heater;
• a first temperature sensor configured to sense a first area temperature related to a first area of the tank and output a temperature signal corresponding to the first area;
• a second temperature sensor configured to sense a second area temperature related to a second area of the tank and output a temperature signal corresponding to the second area;
• an electronic processor configured to:
• receive a first temperature signal corresponding to the first area and a first temperature signal corresponding to the second area;
• compare the first temperature signal corresponding to the first area to a sum of a setpoint temperature threshold minus a preset temperature differential value;
• compare the first temperature signal corresponding to the second area to a high limit temperature threshold;
• and
• activate the circulation pump in response to the first temperature signal corresponding to the first area being less than the sum of the setpoint temperature threshold minus the temperature differential value and the first temperature signal corresponding to the second area being less than the predetermined high limit temperature threshold.