Reheat scheduling for water heaters

Abstract

A method for controlling reheating of a tank-style water heater having an upper heating element and a lower heating element is described. The method identifies whether the upper heating element, and optionally whether the lower heating element, or neither of the upper heating element and the lower heating element, is energized when electrical power is supplied to the water heater. The method determines whether to continue supply of electrical power to the water heater based on which of the upper heating element, or optionally the lower heating element, or neither of the upper heating element and the lower heating element is energized when electrical power is supplied to the water heater. The method may be implemented by a controller adapted to selectively permit and deny supply of electrical power to the water heater, where the controller executes program logic for implementing the method.

What is claimed is: 
     
         1 . A controller for controlling reheating of a tank-style water heater having at least an upper heating element and a lower heating element, wherein:
 the controller is adapted to selectively permit and deny supply of electrical power to the water heater;   the controller is adapted to detect an upper heating element activation signal indicating activation of the upper heating element; and   the controller executes program logic for:
 monitoring the water heater for presence or absence of the upper heating element activation signal; 
 responsive to detecting the presence of the upper heating element activation signal, permitting the supply of electrical power to the water heater; and 
 responsive to detecting the absence of the upper heating element activation signal, denying the supply of electrical power to the water heater outside of a scheduled time. 
   
     
     
         2 . The controller of  claim 1 , wherein the upper heating element activation signal is a current in a circuit of the upper heating element when electrical power is supplied to the water heater. 
     
     
         3 . The controller of  claim 1 , wherein the upper heating element activation signal is an electrical characteristic of the water heater when electrical power is supplied to the water heater. 
     
     
         4 . The controller of  claim 3 , wherein the electrical characteristic is a current at an electrical input of the water heater. 
     
     
         5 . The controller of  claim 3 , wherein the electrical characteristic is a resistance at an electrical input of the water heater. 
     
     
         6 . The controller of  claim 1 , wherein the upper heating element activation signal is a sensor signal. 
     
     
         7 . A controller for controlling reheating of a tank-style water heater having at least an upper heating element and a lower heating element, wherein:
 the controller is adapted to selectively permit and deny supply of electrical power to the water heater; and   the controller executes program logic for:
 identifying whether the upper heating element, the lower heating element, or neither of the upper heating element and the lower heating element is energized when electrical power is supplied to the water heater; and 
 determining whether to continue supply of electrical power to the water heater based on which of the upper heating element, the lower heating element or neither of the upper heating element and the lower heating element is energized when electrical power is supplied to the water heater. 
   
     
     
         8 . The controller of  claim 7 , wherein the controller is adapted to detect an upper heating element activation signal indicating activation of the upper heating element. 
     
     
         9 . The controller of  claim 8 , wherein the upper heating element activation signal is a current in a circuit of the upper heating element when electrical power is supplied to the water heater. 
     
     
         10 . The controller of  claim 8 , wherein the upper heating element activation signal is an electrical characteristic of the water heater when electrical power is supplied to the water heater. 
     
     
         11 . The controller of  claim 10 , wherein the electrical characteristic is a current at an electrical input of the water heater. 
     
     
         12 . The controller of  claim 10 , wherein the electrical characteristic is a resistance at an electrical input of the water heater. 
     
     
         13 . The controller of  claim 8 , wherein the upper heating element activation signal is at least one sensor signal identifying whether the upper heating element, the lower heating element, or neither of the upper heating element and the lower heating element is energized when electrical power is supplied to the water heater. 
     
     
         14 . A controller for controlling reheating of a tank-style water heater having at least an upper heating element and a lower heating element, wherein:
 the controller is adapted to selectively permit and deny supply of electrical power to the water heater; and   the controller executes program logic for:
 identifying whether the upper heating element will be energized when electrical power is supplied to the water heater; and 
 supplying the electrical power to the water heater only when the upper heating element will be energized thereby. 
   
     
     
         15 . The controller of  claim 14 , wherein the controller is adapted to detect an upper heating element activation signal indicating activation of the upper heating element. 
     
     
         16 . The controller of  claim 15 , wherein the upper heating element activation signal is a current in a circuit of the upper heating element when electrical power is supplied to the water heater. 
     
     
         17 . The controller of  claim 15 , wherein the upper heating element activation signal is an electrical characteristic of the water heater when electrical power is supplied to the water heater. 
     
     
         18 . The controller of  claim 17 , wherein the electrical characteristic is a current at an electrical input of the water heater. 
     
     
         19 . The controller of  claim 17 , wherein the electrical characteristic is a resistance at an electrical input of the water heater. 
     
     
         20 . The controller of  claim 15 , wherein the upper heating element activation signal is at least one sensor signal identifying whether the upper heating element, the lower heating element, or neither of the upper heating element and the lower heating element is energized when electrical power is supplied to the water heater.