US 8,204,633 B2 · Water heater demand side management system

Abstract

A system for shifting energy demand from on-peak time windows to off-peak time windows by using hot water heater load shifting, while providing the end user with the level of service (i.e., availability of hot water) according to the user's customary use described by service quality criteria. The shift is accomplished by a controller located at the end user establishment and in communication with a central control server. The controller monitors local water heater upper and/or lower temperature and controls upper and/or lower water heater heating elements in accordance with a demand shift process commanded by the central control server. The controller may determine usage and remaining capacity for reporting back to the central control server. A volumetric capacity and usage determination is disclosed. The control server may select water heaters according to use patterns and/or measured capacity. One embodiment is adapted for use with existing water heaters without disrupting safety features of the existing water heater.

Claims35

Dependent claims

A water heater controller for controlling a water heater to alter electrical demand while providing hot water for normal use, said water heater comprising an upper heater for heating an upper volume of water and a lower heater for heating a lower volume of water;

said water heater controller comprising:
power control means for controlling power supplied to said upper heater and for controlling power supplied to said lower heater;
a processor configured for controlling said power control means, said processor having a memory, said memory storing a load shift algorithm comprising instructions for varying power applied by said power control means, said load shift algorithm specifying a reserve volume capacity of hot water for said water heater, said reserve volume capacity being a minimum volume of hot water reserved for consumer use and not utilized for load shifting;
a lower temperature sensor configured for measuring a temperature of said lower volume of water and providing a resulting lower volume temperature measurement to said processor;
means for determining a remaining volume capacity of hot water in said hot water heater, said remaining volume capacity being a capability to deliver said remaining volume of hot water on immediate demand;
wherein said processor is configured to control said power control means to control a temperature of said lower volume of said water in accordance with said load shift algorithm when said remaining volume capacity exceeds said reserve volume capacity, and said processor is configured to allow recovery when said remaining volume capacity is less than said reserve volume capacity.

3 more elements

A method for controlling a plurality of water heaters to reduce peak loading on a power grid comprising the steps of:

receiving temperature data by a water heater control server from each water heater of a plurality of water heaters, each said water heater of said plurality of water heaters connected to said power grid at separate customer locations;
said water heater control server generating usage pattern information for each said water heater of said plurality of water heaters based on said temperature data;
receiving load demand information by said water heater control server from a power grid monitoring system monitoring said power grid;
said water heater control server commanding said plurality of water heaters in accordance with a control strategy comprising a temperature limit over time for each water heater of said plurality of water heaters based on said received temperature data, said usage pattern information, and said load demand information;
wherein said control strategy is derived by said control server in accordance with at least one hot water delivery quality criterion applied to said usage pattern information specific to each said water heater of said plurality of water heaters;
said at least one hot water delivery quality criterion being a numerical value relating to the availability of hot water when needed and/or the constancy of temperature of the hot water as delivered.

3 more elements

A method for shifting a timing of an application of a load to a power grid to reduce a peak load on said power grid, said method comprising the steps of:

providing a control server in network communication with a plurality of water heater controllers controlling a respective plurality of water heaters connected to said grid;
determining historical water heater usage patterns for each water heater of said plurality of water heaters, said historical usage patterns comprising usage as a function of time over at least one daily interval;
receiving a load shift goal by said control server from a power grid controller controlling said power grid;
selecting a first set of water heaters of said plurality of water heaters based on said historical water heater usage patterns;
receiving contemporaneous hot water remaining capacity measurements by said control server for each water heater of said first set of water heaters;
selecting a second set of water heaters based on said contemporaneous hot water remaining capacity measurements, said second set of water heaters being a subset of said first set of water heaters;
commanding said respective water heater controllers for said second set of water heaters to reduce a temperature associated with a lower heating element of each water heater of said second set of water heaters to delay an electrical demand associated with heating water in said second set of water heaters.

4 more elements

A water heater controller for controlling a water heater to alter electrical demand, said water heater comprising an upper heater for heating an upper volume of water in accordance with an upper thermostat and a lower heater for heating a lower volume of water in accordance with a lower thermostat, said upper thermostat switching from said upper heater to said lower thermostat when said upper volume of water is above an upper thermostat set point;

said water heater controller comprising:
a power input for receiving power from a power source;
a power output for connecting to said water heater and supplying power to said water heater;
a power control device connected between said power input and said power output for varying the power supplied to said water heater;
a processor having a memory, said memory for storing a load shift algorithm for varying power applied to said water heater to alter the electrical demand by said water heater, said processor configured for controlling said water heater by controlling said power control device;
a lower temperature sensor for measuring a temperature of said lower volume of water and for providing a resulting lower volume temperature measurement to said processor;
a thermostat state sensor for determining a switch state of said upper thermostat and communicating said switch state to said processor;
wherein said processor is configured to operate said power control device to control a temperature of said lower volume of water when said upper thermostat is switched to deliver power to said lower thermostat, said temperature of said lower volume of water controlled in accordance with said load shift algorithm, said lower volume temperature measurement, and said switch state of said upper thermostat.

5 more elements

Dependencies are inferred from the claim text.

Water heater demand side management system

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Water heater demand side management system

Life of this patent

Abstract

Claims35