Patent Publication Number: US-2011073101-A1

Title: Control system for heating systems

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Utility patent application Ser. No. 12/047,055, filed Mar. 12, 2008, entitled “CLOSED-LOOP CONTROL SYSTEM FOR HEATING SYSTEMS”, now U.S. Pat. No. ______, issued on ______ which claims priority to U.S. Provisional Application No. 60/894,411, filed Mar. 12, 2007, entitled “CLOSED-LOOP CONTROL SYSTEM FOR HEATING STOVES.” 
    
    
     TECHNICAL FIELD 
     The present disclosure relates, generally, to heating systems and, in particular, to a closed-loop controller for providing control of various aspects of a heating system. 
     BACKGROUND 
     Various heating systems, including fireplaces and furnaces for home installations, may have been made available to consumers in recent years with improved control systems. Despite improvements, such heating systems may be limited in the ability to control the heat distribution from the heating system to the area to be heated. 
     For example, while current heating systems have frequently utilized various techniques to separate the combustion air from the room air, such as direct air venting systems, very little has been done to improve heat transfer and distribution. Furthermore, feedback from the heating system may aid in increasing efficiency of the system. This efficiency may include decreasing the amount of spent, unused fuel, maintaining a generally optimum temperature and determining if various augers are jammed or not working properly, among other variables. 
     SUMMARY 
     In accordance with various aspects of exemplary embodiments, a heating system transfer controller may be configured to control variables of the heating system, such that the heating system may operate more efficiently. In accordance with an exemplary embodiment, an exemplary heating system may include a feed auger, air intake, an exhaust vent, a combustion chamber and a controller. The heating system may include various types of heating configurations, such as fireplaces, stoves, furnaces or other like heating systems. The air intake is configured to receive external air into the heating system, while the exhaust vent is configured to remove exhaust from within the heating system. Both the air intake and exhaust vent can be configured in various manners, shapes and sizes for providing the respected air intake and heat exhaust functions. 
     In accordance with one aspect of exemplary embodiments, the heating system controller may be configured to control various portions of the heating system based, at least in part, upon the pressure within the combustion chamber. In accordance with another exemplary embodiment, the heating system controller may determine a portion of the heating system is not operating properly, based at least in part upon feedback from sensors of the system. 
     In an embodiment, various portions of a fireplace system may be manipulated to reduce inefficiencies of the system. These inefficiencies may include, but are not limited to, inadequate burning of the fuel, inadequate amount of fuel, different types of renewable fuel such as wood pellets, wheat, and/or corn, and/or other fuel, and/or combinations thereof, and different fuel grades, inefficient heat transfer from the combustion chamber, non-optimal pressure in the combustion chamber, inefficient temperature in the combustion chamber, and/or inefficient amount of ash within the combustion chamber, and/or other inefficiencies, and/or combinations thereof. 
     Other inefficiencies may also include inefficiencies due to different types of fuels, variations in size of fuels, moisture content, and/or different atmospheric conditions, and/or combinations thereof. 
     In accordance with other aspects, the heating system controller may be capable of controlling variables of the heating system based at least in part upon signals and/or information received from sensor of the heating system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The exemplary embodiments may be described in conjunction with the appended drawing figures in which like numerals denote like elements and: 
         FIG. 1A  is a block diagram of an exemplary heating system in accordance with an exemplary embodiment; 
         FIG. 1B  is a cross-sectional view of a heating system in accordance with an exemplary heating system according to an exemplary embodiment; 
         FIG. 2  is a block diagram of an exemplary control system in accordance with an exemplary embodiment; and 
         FIG. 3  illustrates a user interface in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure may describe various functional components. It should be appreciated that such functional components may be realized by any number of hardware components, electrical and mechanical, configured to perform the specified functions. In addition, exemplary embodiments may be practiced in any number of heating system contexts, and the fireplace systems described herein are merely one exemplary application. 
     Referring now to  FIG. 1 , in accordance with an exemplary embodiment, a solid fuel heating device  10  having a combustion chamber  12  is illustrated. In an embodiment, a heat exchange arrangement in the form of hollow pipes  19  can be disposed towards the top end of combustion chamber  12  and may be heated hot air from combustion chamber  12 . Ambient air, as indicated by arrows  22 , may be circulated through hollow pipes  19  by a fan  21  mounted in a side wall of the heating device, or any other convenient location, such as proximate the hot air exhaust area, to exhaust heated air from pipes  19  into the ambient air, in a direction indicated by arrows  22 . This may be accomplished to heat the surrounding area of heating device  10 . Fan  21  may be configured in various locations for circulating ambient air through pipes  19 , with such pipes  19  being arranged in various manners for discharging heat to the surrounding area. 
     In an embodiment, the convection and combustion flow system may also be used in other manners by utilizing heat transfer devices to extract heat, including flat and/or accordion plate heat exchangers, air flow passages for exhaust and/or convection air, casting, hot air intake, and/or other methods and systems for discharging heat to the surrounding area. The utilization of heat exchangers with a stove may increase the efficiency of the system, increase the convection temperature, and/or lower the exhaust temperature, and/or combinations thereof. 
     Furthermore, combustion and convection air flow may be configured to be parallel, counter, and/or cross flow, and/or combinations thereof to further increase efficiency. In an embodiment, heat exchange between the convection and combustion air, heat exchange between the air intake and the exhaust air, mixing the exhaust air with the air intake, etc. may make the system more efficient. 
     Many different types and configurations of heat exchangers may be utilized with the system. A corrugated surface plate, or a casting made from copper or other high heat transfer coefficient material may be positioned between different air flows to enhance heat transfer. Utilizing finned tubes may further increase the surface area and increase the heat transfer characteristics of the system. Furthermore, the alteration of the air flow devices to create turbulence or other disruption may further increase efficiency. 
     Other types of heat exchangers, such as heat pipes, or condensers may also be utilized to enhance heat transfer, as they may utilize the phase shifts of fluids to release heat at a much higher rate. Furthermore, there may be other heat exchangers that enhance heat transfer such as coaxial venting, radiator, spiral plated exchangers, and/or any other heat exchanger that may enhance heat transfer. 
     Heating system  10 , as herein illustrated in the exemplary embodiment, may be a biomass pellet, fuel, and/or grain-fed, and/or other fuel, and/or combinations thereof, space heating stove. The system may include a “key,” which may allow the system to utilize different fuels. The key may be added to allow the use of various type of fuel. The system may allow a user to switch fuel type without shutting down the system. 
     In an embodiment, system  10  may include a hopper  23 . Hopper  23  may be configured for storage of fuel sources, such as solid fuel pellets  24 , for example. Hopper  23  may be various sizes, shapes, and configurations for storage of fuel. In an exemplary embodiment, fuel pellets  24  may be fed into a fuel bed  25  of combustion chamber  12  by an auger  26  feeding a chute  27 . 
     In the exemplary embodiment, solid fuel pellets  24  entering combustion chamber  12  may be projected into fuel bed  25  by gravity and supported by a support mechanism in the form of a support tray  28 . Support tray  28  may be fixedly secured under the bottom, open end of the inner wall  16 . An ash collecting tray  29  may be removably secured under this support tray  28  and accessible through a door  30 . A sensor may be included, which may alert a user that the ash pan is full. This may indicate that the pan should be emptied. If the pan is not emptied, the system may shut down, or other sequence, to protect the system. 
     Solid fuel pellets and grains (fuel)  24  may also be fed from the bottom or the side of the unit, or any other configuration for providing fuel, and the like, onto fuel bed  25 . For example, rather than hopper  23  and/or auger  26 , many other mechanisms or systems for conveying materials may be suitably implemented. 
     The system may be capable of operating a high-efficiency burn mode, or a clean burn mode, which may be user selectable. 
     Shown in  FIG. 2  is a block diagram of an exemplary heating system  200 . In an embodiment, system  200  may be connected to a user interface  61 , which may be provided with an internal memory  62 . User interface  61  may allow a user to input information to controller  60 . Furthermore, user interface may allow a user to control certain aspects of the heating system  200 . In an embodiment, user interface  61  may also be capable of transmitting user input, which may condition the controller to operate within a stored programmed mode of operation, depending on the type of fuel being fed to the burner. Variables such as temperature, type of fuel, and many other variables may be controlled by controller  60  via user interface  61 . 
     In an embodiment, system  200  my include software, hardware, and/or firmware, and/or combinations thereof to control the various aspects of the system. The software/hardware/firmware may be capable of being upgraded to allow for improved, and/or different modes of operation. 
     In an embodiment, an exemplary controller  60  may be provided with input signals from a temperature sensor  64  that senses the temperature of the heating device  10 . In an embodiment, temperature sensor  64  may be located on a wall of the heating device, and/or other suitable location. Controller  60  may also monitor input signals from an operational thermo sensor  65 , which may be capable of indicating that a flame is present in the burner chamber. Temperature sensor  64  may be located on the outside, back wall, and/or other suitable location of combustion chamber  12  to sense the temperature thereof. For example, if temperature sensor  64  detects a predetermined high temperature signal, controller  60  may shut off the fuel feed auger that delivers the fuel to the fuel bed of the fuel burner, thus commencing an orderly automatic shutdown of device  10 . Accordingly, controller  60  may be capable of modulating the operation of the system to maintain a desired temperature output. 
     In an embodiment, heating system  200  may include a hopper sensor. Hopper sensor  40  may be capable of detecting the amount of fuel within the hopper. Hopper sensor  40  may be further capable of indicating various levels of fuel in the hopper to controller  60 , such that the level may be displayed, and/or an alert may be generated indicating various levels of fuel, such as too low and too high, among many others. 
     In an embodiment, heating system  200  may also include a pressure sensor  66 , which may be positioned to be capable of measuring the pressure within combustion chamber  12 . Controller  60  may receive a signal from pressure sensor  66 , which may indicate a pressure level in combustion chamber. There may a particular pressure range, which may generally correspond to a relatively optimal burn conditions for the system. In an embodiment, if the pressure is outside of a range, controller  60  may then control other aspects of the system based at least in part on the pressure. For instance, if the pressure is lower than the optimal range, the controller may increase the combustion fan speed to add more pressure to the combustion chamber, or slow down the feed auger to accommodate pressure drop. 
     System  200  may also include a fuel level sensor  67 , which may be capable of indicating the level of the fuel available to the system. Sensor  67  may be capable of detecting the amount of fuel within the hopper. Sensor  67  may be further capable of indicating various levels of fuel in the hopper to controller  60 , such that the level may be displayed, and/or an alert may be generated indicating various levels of fuel, such as too low and too high, among many others. Controller  60  may receive a signal from fuel level sensor, and indicate via user interface  61 , or other method or system, the fuel level, and/or high or low levels of fuel available. In the embodiment shown in  FIG. 1 , the level, and/or high and low levels of the solid fuel may be measured and indicated. 
     Controller  60  may also be capable of controlling the speed of combustion fan  68 , which may be located within heating device  10  as illustrated in  FIG. 1 , or otherwise outside, or in in-flow communication, to facilitate intake and exhaust air. Controller  60  may also control the speed of convection fan  21 , which may be used to force the air through heat exchangers  19 . 
     Controller  60  may also control ash auger  54 , which may be capable of evacuating the ashes depending on the operating parameters of the system and high or low ash fuel type. In an embodiment, system  200  may include a sensor  254 , which may be capable of measuring the speed of ash auger  54  and/or operation of ash auger  54 . Alternatively, sensor  254  may indicate whether or not ash auger  54  is moving. If controller  60  is sending a signal for ash auger  54  to run, and sensor  254  indicates that ash auger  54  is operating abnormally, or not at all, this may indicate to controller  60  that the ash auger system is not operating properly. Controller  60  may then control system  200  to insure that no damage is done, either to the system or to the surrounding area. The above-mentioned control may include an orderly shutdown of the system, and/or an alarm to alert the user. 
     The system may also include a content sensor  255 , which may be capable of sensing the amount of moisture and/or carbon content within the fuel in the fuel bed to insure the fuel is burnt to a degree to allow the ash auger to remove the fuel. Other sensors may include a sensor capable of detecting and alerting when the system may need to be cleaned and/or serviced. 
     Similarly, system  200  may include a feed auger  26 , which may be controlled by controller  60 . In an embodiment, feed auger  26  may be configured to provide solid fuel to system  200 . In an embodiment, system  200  may include a sensor  226 , which may be capable of measuring the speed of feed auger  26 , and/or the presence of fuel in the auger. Alternatively, sensor  226  may indicate whether or not feed auger  26  is moving. If controller  60  is sending a signal for feed auger  26  to run, and sensor  226  indicates that feed auger  26  is operating abnormally, or not at all, this may indicate to controller  60  that the feed auger system is not operating properly. Controller  60  may then control system  200  to insure that no damage is done, either to the system or to the surrounding area. The above-mentioned control may include an orderly shutdown of the system, and/or an alarm to alert the user. Furthermore, the controller may insure that no backfire may occur. 
     Similar sensors may be provided in other areas of the system including, but not limited to, the combustion and convection fans. A power supply  69  may provide power for the controller and interface, which, in an embodiment, may be 12 VDC. In an embodiment, a system may also include a battery backup. The system may also have the capability to change to battery power during a power outage, indicate the power outage, and that the battery is in use. Furthermore, the charge remaining in the battery may also be indicated. 
     Referring now to  FIGS. 1 ,  2 , and  3  in accordance with exemplary embodiments, there will be described the operation of an exemplary controller  60 . This controller  60  may be coupled to a user interface  61 , which may be provided with an internal memory  62  (see  FIG. 2 ). In the embodiment of  FIG. 3 , user interface  61  includes a keypad-type configuration, with a display  76 . In embodiments, display  76  may be an LED-type display, and/or an LCD-type display. Other display types may be utilized without straying from the concepts disclosed herein. 
     Furthermore, user interface  61  may be configured to allow a user to control and/or manipulate the operation of the solid fuel biomass pellet heating device  10 , such as the system illustrated in  FIG. 1 . 
     Controller  60  may be configured to control the motor(s) and the fans, and inputs and operating parameters utilizing information from the sensors. To start the operation of a biomass pellet device  10 , a user may actuate the button labeled “Start”  78 . This may cause the pellets to be automatically fed to the burner and ignited by an ignition device, to create an initial fuel bed. Other steps may then be accomplished to start the operation of heating system  10 , such as starting the system with a fire starter, and/or starting with one fuel and continuing the burn with another fuel. Other ignition methods may be utilized, including utilization of an air pump and an igniter to assist in creating a torch effect, and/or more than one ignition source. Furthermore, a user may turn off the heating device by depressing the button labeled “Stop”  80 . 
     In an embodiment, the “Service” actuator  82  may activate diagnostics for the system. The diagnostics may include tuning the burn to compensate for atmospheric conditions, and/or variations in fuel, and fuel quality. It will be appreciated that the diagnostics of the system may include many other diagnostics. 
     In an embodiment, the user may select a desired mode of operation of device  10  by inputting desired parameters into the controller by the use of interface pad  61 . Interface pad  61  can also be provided with heat level buttons  73 , which may control the amount of heat produced by the system. This may increase or decrease the temperature in combustion chamber  12 . This increase may cause an increase in the temperature of the heated air released by the biomass pellet device through the heat exchanger located above the flame, which may be regulated by a separate fan. All of these operating parameters may be capable of being stepped up or down, to maintain relatively optimum performance levels and/or to decrease inefficiencies of the system, according to the desired heat performance required of the device. 
     Additionally, the entire system can operate from a remote thermostat to regulate all of these operating parameters based at least in part upon the setting(s) of the thermostat. User interface  61  may also be removed from the system and be used remotely. A “Prime Stove” actuator  72  may be provided, which may be capable of activating a method for manually priming the heating device. This may be due to the various types and/or qualities of the fuel being utilized. Priming may not be necessary for all fuels, types, and/or qualities. 
     Inputs from actuators may be sent to the controller, which may regulate the speed of the motor, which drives the ash auger. Control switches  73  may also be utilized to set a desired BTU output of the pellet stove. Through the software of the controller, the type of fuel and substantially optimal operating conditions of the device may be regulated and maintained. 
     User interface  61  may also include a fuel selection button  70 , which may be configured to indicate to the controller the fuel that will be used. Different choices for fuel may appear within display  64 . The user may then depress “Heat” actuator  74 , which may allow a user to adjust the heat level using buttons  73 . This may allow the controller to control various aspects of the system based at least in part upon the type of fuel being used by the system. In an embodiment, the types of fuel shown are solid fuels. However, other fuels, such as non-solid fuels, may also be utilized. 
     User interface  61  may be attached to the system, or may be a remote control. Furthermore, user interface  61  may also be capable of communicating with other devices within the heating environment to further control the operation of the system. In one embodiment, another device may be a temperature sensor that may interface with the system. 
     The present invention sets forth a heat transfer controller that is applicable to various heating system applications. It will be understood that the foregoing description is of exemplary embodiments of the invention, and that the invention is not limited to the specific forms shown. Various modifications may be made in the design and arrangement of the elements set forth herein without departing from the spirit and scope of this disclosure. For example, the sensors utilized are not limited to those shown herein. Furthermore, other user interfaces may be utilized as well. Many other processors/controllers, as well as sensors may be utilized without straying from the concepts disclosed herein. These and other changes or modifications are intended to be included within the scope of the present invention, as set forth in the following claims.