BACKGROUND OF THE INVENTION 
   The present invention relates generally to a heating system and, more particularly, to a control, powered by a storage device and a thermoelectric assembly, to ensure operation of the heating system whenever the storage device is compromised, i.e., a self-sustaining control, and to enhance efficiency. 
   Gas-powered heating systems are well known. (As used herein, the term “gas-powered” refers to use of natural gas, propane or any other fossil fuel as the fuel source.) Such heating systems are operable in three conventional modes—the stand-by or “OFF” mode, the heating or “ON” mode and the intermediate or “PILOT-ON” mode. 
   For areas where electricity is unavailable, the heating system lacks an energy source for ignition of the pilot burner assembly whenever there is a demand for heating. As such, the heating system is designed to operate in the “PILOT-ON” mode in the absence of a heating demand and in the “ON” mode in the presence of a heating demand. That is, once the pilot burner assembly is manually lit as a part of the start-up procedure, the pilot burner assembly burns continuously, significantly diminishing system efficiency. 
   SUMMARY OF THE INVENTION 
   In a principal aspect, the present invention is a control for a heating system, operable in the three conventional modes—the “OFF” mode, the “ON” mode and the “PILOT-ON” mode. As is well known in the art, such a heating system includes a pilot burner assembly. 
   The control includes a controller, directing the operational mode of the heating system in accordance with a need-based protocol, a storage device and a thermo-electric assembly. In the absence of a heating demand, the controller places the heating in the “OFF” mode. In response to a heating demand, the controller interconnects the pilot burner assembly and storage device to initiate the PILOT-ON mode, and the storage device powers ignition of the pilot burner assembly. The thermo-electric assembly responsively provides a potential that powers the heating system and controller during operation in the PILOT-ON and ON modes. 
   The controller monitors the condition of the storage device. When that condition is compromised, the controller maintains the PILOT-ON mode, in lieu of the OFF mode, such that the heating system remains operational despite the compromised state of the storage device. 
   It is thus an object of the present invention to provide an efficient, self-sustaining heating system. Another object is gas-powered heating system with a self-sustaining control. Still another object of the present invention is a self-sustaining control for a heating system, whereby the overall efficiency of the heating system is improved. It is yet another object to provide a heating system, powered by a storage device, wherein operation is ensured regardless of the temporary expiration of the storage device. 
   These and other features, objects and advantages of the present invention are described or apparent in the following detailed description. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention are described herein with reference to the drawings wherein: 
       FIG. 1  is a schematic illustration of a water heater and a first preferred embodiment of the present invention; and 
       FIG. 2  is a functional block diagram of the various embodiments of the present invention. 
   


   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   A first preferred embodiment of the present invention is shown in  FIGS. 1 and 2  as a self-sustaining control, generally designated  10 , for a gas-powered water heater  12 . It is to be understood, however, that the control  10  is equally adaptable to other heating systems, such as a furnace or fireplace insert. (As used herein, the term “heating system” includes all such heating systems.) 
   The water heater  12  is conventional and includes a tank  14 , water inlet  16  and outlet  18 . Conventional sensors  20 A,  20 B and adjustable temperature selector  22  monitor water temperature in the tank  14  and cooperate in a conventional manner to define a demand recognition assembly  24  for providing a demand signal whenever that temperature falls below the set point, established by the selector  22 . The water heater  12  further includes a pilot burner assembly  26 , having a pilot valve  26 A and a sparker  26 B, and a main burner assembly  28 , having main valve  28 A. The valves  26 A,  28 A provide conventional communication with a gas supply  30 . 
   The water heater  12  is sequenced through its operational modes in response to a demand signal. When heating is required, the OFF mode is terminated with opening of the pilot valve  26 A and ignition of the pilot burner assembly  26  via the sparker  26 B; such ignition begins the PILOT-ON mode. After a time, the presence of the pilot flame enables the main valve  28 A to be opened and the main burner assembly  28  to be ignited; that ignition marks initiation of the ON mode. Upon satisfaction, both valves  26 A,  28 A are closed, returning the water heater  12  to the OFF mode, such that fuel is no longer consumed. 
   The control  10  includes a storage device  32 , a controller or microcontroller  34  and a thermo-electric assembly  36 , interconnected as shown in FIG.  2 . In this preferred embodiment, the storage device  32  is a conventional battery or an equivalent thereof. The control  10  and water heater  12  are powered only by a storage device  32  during the OFF mode. That is, the storage device  32  powers the demand recognition assembly  24 , pilot valve  26 A and sparker  26 B. It is to be understood, however, that the present invention is equally applicable to a heating system powered by conventional electricity when available and powered by the storage device  32  during an interruption. 
   The storage device  32  has at least a first measurable, monitorial status parameter, indicative of the condition thereof. In this preferred embodiment, the status parameter is current output voltage. 
   A suitable controller  34  is the MSP430 product family, available from Texas Instruments, Inc., 12500 TI Boulevard, Dallas, Tex. 75243. The controller  34  is programmed with a need-based protocol for proper sequencing of the water heater  12 , as discussed above. 
   The thermo-electric assembly  36  includes a conventional thermopile  38 , or an equivalent thereof, in thermal communication with the pilot and main burner assemblies  26 ,  28 . The thermopile  38  converts heat, generated by the burner assemblies  26 ,  28  during the PILOT-ON and ON modes, to an electric potential or voltage. In this preferred embodiment, the thermo-electric assembly  36  furthers includes a DC-to-DC converter  40 , interposed the microcontroller  34  and thermopile  38 , to enhance the produced potential. The converter  40 , functionally coupled to the thermopile  38 , is thermally isolated from the burner assemblies  26 ,  28 . 
   As a part of sequencing the water heater  12 , the controller  34  is interconnected to and powered by the storage device  32 . In response to a heating demand from the demand recognition assembly  24 , the controller  34  interconnects, either conventionally through the controller  34  itself or through conventional gate circuitry (not shown), the pilot burner assembly  26 , including the pilot valve  26 A and sparker  26 B, and storage device  32 , which powers ignition to begin the PILOT-ON mode. Thereafter the controller  34  isolates the storage device  32  to preserve its life, and the potential provided by the thermo-electric assembly  36  is appropriately coupled to power the water heater  12  and the controller  34 . 
   In addition to sequencing of the water heater  12  through the OFF mode (which begins with closure of the pilot and main burner assemblies  26 ,  28  and ends upon ignition of the pilot burner assembly  26 ), the PILOT-ON mode (which begins with ignition of the pilot burner assembly  26  and ends with ignition of the main burner assembly  28 ), and the ON mode (which begins with ignition of the main burner assembly  28  and terminates with closure of the pilot and main burner assemblies  26 ,  28 ), the controller  34  monitors the status parameter of the storage device  32 . The controller  34  is programmed with a status threshold, related to the storage device  32  and representative of a compromised state. 
   The controller  34  periodically receives the status parameter, in a conventional manner, and compares the received status parameter with the status threshold. Whenever a predetermined relationship exists, indicative of a compromised storage device  32 , the controller  34  initiates and maintains the PILOT-ON mode in lieu of the OFF mode, i.e., in the absence of a heating demand. That is, whenever the comparison reveals that the storage device  32  is failing and may not be capable of firing the sparker  26 B, the controller  34  alters the sequencing of the water heater  12  to ensure continuous, uninterrupted operation. The water heater  12  is therefore operational, despite a failed or compromised storage device  32 , so long as the pilot burner assembly  26  and thermo-electric device  36  are functional. In this regard, any conventional technique for monitoring the status of the storage device  32  may be utilized. 
   In this preferred embodiment, the control  10  also includes a display  42 , coupled to the controller  32 . Whenever the predetermined relationship between the status parameter and threshold exists, the controller  32  activates or illuminates the display  42 , signaling the need for battery replacement. 
   In a second preferred embodiment, the storage device  32  is rechargeable, such as a rechargeable battery, capacitor, super-capacitor or an equivalent thereof. (Again, any conventional technique for monitoring the status of the storage device  32  may be utilized.) Here the controller  34  additionally interconnects the storage device  32  and thermo-electric device  36  during the PILOT-ON and ON modes of operation. This allows the potential generated by the thermo-electric device  36  to recharge the storage device  32 . This recharging interconnection may be limited to those periods of time when the predetermined relationship between the status parameter and threshold exists. 
   A similar heating system, utilizing the less efficient PILOT-ON approach discussed above, is described, in detail, in commonly owned patent applications, Ser. Nos. 10/382,303 and 10/382,050, both filed Mar. 5, 2003, and entitled “Method and Apparatus For Power Management” and “Method and Apparatus For Thermal Powered Control” respectively. The teachings thereof are incorporated herein by reference. 
   While various preferred embodiments have been described herein, it is to be understood that modifications and changes can be made without departing from the true scope and spirit of the present invention, as defined by the following claims, which are to be interpreted in view of the foregoing detailed description.
A self-sustaining control for a heating system, having conventional operational modes and pilot burner assembly, is disclosed. A controller directs operation in accordance with a need-based protocol and monitors the condition of a storage device, which provides system power during the stand-by or off mode under normal conditions. A thermo-electric device is in thermal communication with the pilot burner assembly and powers the system whenever the pilot is lit. Regardless of heat need, the controller directs operation in a pilot-on mode, in lieu of an off mode, whenever the storage device is compromised.