Automatic set point detection for water heaters operating in a demand response

• Main Authors: Black, Jason W, Thornton, Douglas, Adams, Lauren
• Format: Patent
• Language: English
• Published: 05.06.2018
• Subjects: BLASTING; CALCULATING; COMPUTER SYSTEMS BASED ON SPECIFIC COMPUTATIONAL MODELS; COMPUTING; CONTROL OR REGULATING SYSTEMS IN GENERAL; CONTROLLING; COUNTING; DOMESTIC HOT-WATER SUPPLY SYSTEMS; DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATINGSYSTEMS; ELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; ELEMENTS OR COMPONENTS THEREFOR; FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEATGENERATING MEANS, IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; HEATING; LIGHTING; MECHANICAL ENGINEERING; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS ORELEMENTS; PHYSICS; RANGES; REGULATING; SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES; SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES; VENTILATING; WEAPONS

An electric water heater that includes a thermostat is retrofitted for remote control as follows. A relay is installed on an electrical feed to the electric water heater. Water temperature and electric current or power through the electrical feed are measured over time with the relay closed, and the thermostat deadband maximum and minimum are detected as the water temperature at which the thermostat turns the heating element off, and the water temperature at which the thermostat turns the heating element on, respectively. The detected thermostat deadband maximum and minimum are stored as load controller deadband maximum and minimum, respectively. The thermostat set point is raised, and the electric water heater is thereafter controlled using the load controller by operations including closing the relay when the water temperature falls below the load controller deadband minimum and opening the relay when the water temperature rises above the load controller deadband maximum.