FIELD OF INVENTION

Embodiments relate to water heaters.

SUMMARY

Electric and heat pump operated water heaters use electrical energy to heat the water located inside a water tank to maintain the water within a temperature range. The electrical energy may come from a power source such as a grid, or a power grid, for example but not limited to, an energy company power grid or a home power grid including solar panels, windmills, or other energy sources. The power grid distributes electrical energy to balance supply and demand at any specific time within a specific area. The demand for electrical energy from the power grid varies with, for example, time of day, seasons, geographical area, usage, and other factors. The price for the electricity delivered by the power grid varies according to the overall demand on the power grid at a particular time and area. For example, the price of electricity increases during peak hours, and decreases during off-peak hours.

Some water heaters may include control units that control the heating elements based on the electrical energy demand, while other control units control the heating elements based on the temperature of the water with respect to a water temperature range. Furthermore, participating in programs that control the heating elements based on the electrical energy demand may, in some instances, reduce the amount of hot water that is available to the user (e.g., to conserve energy). In such instances, the user may not have sufficient hot water available for comfortable use. While some users may be able to tolerate these instances, other users may find the occasional lack of hot water unacceptable.

One embodiment provides a water heater system receiving electrical power from an electrical grid. The system includes a water tank having a vertical axis, an upper portion, and a lower portion. The system further includes an upper heating element, a lower heating element, an upper temperature sensor, a lower temperature sensor, and a control circuit. The lower heating element is disposed below the upper heating element with respect to the vertical axis. The upper heating element and the lower heating element are configured to heat water within the water tank. The upper temperature sensor is configured to produce a first signal having a relation to a water temperature within the upper portion and the lower temperature sensor is configured to produce a second signal having a relation to a water temperature within the lower portion. The control circuit includes a transceiver communicatively coupled to a grid controller and an electronic processor. The electronic processor is configured to monitor an average water temperature of the water within the water tank based on the first and second signal, operate the upper heating element and lower heating element in a first operation mode, and receive, via the transceiver, either an add load command or a shed load command. The electronic processor is further configured to operate the upper heating element and lower heating element in a second mode in response to receiving the add load command and operate the upper heating element and lower heating element in a third mode in response to receiving the shed load command.

Another embodiment provides method of operating a water heater system configured to receive electrical power from an electrical grid. The water heater system includes a water tank having a vertical axis, an upper portion and a lower portion; an upper heating element; a lower heating element disposed below the upper heating element with respect to the vertical axis, the upper heating element and the lower heating element for heating water within the water tank, an upper temperature sensor configured to produce a first signal having a relation to a water temperature within the upper portion; a lower temperature sensor configured to produce a second signal having a relation to a water temperature within the lower portion, a control circuit including a transceiver communicatively coupled to a grid controller, and an electronic processor. The method includes monitoring an average water temperature of the water within the water tank based on the first and second signal, operating the upper heating element and lower heating element in a first operation mode, receiving, via the transceiver, either an add load command or a shed load command, operating the upper heating element and lower heating element in a second mode in response to receiving the add load command, and operating the upper heating element and lower heating element in a third mode in response to receiving the shed load command.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

