Patent Application
20070292810
1. Field of the Invention
The present invention generally relates to control systems for heating appliances, and more specifically relates to systems and methods for monitoring and controlling burners and ignition systems in a decorative heating appliance such as a fireplace, stove or fireplace insert.
2. Related Art
Gas, electric, and wood burning heating appliances such as fireplaces, stoves and fireplace inserts are an efficient method for providing warmth and creating the appeal of a fire within a room. Fireplaces have become commonplace in today's building trades for both residential and commercial applications. Most new home construction designs include at least one, and often several fireplaces. Further, a significant number of remodeling projects are focused on fireplaces.
Most known heating appliances include some type of heat control system that facilitates ON/OFF control, the level of heat output, and possibly thermostatic control. In the case of a gas powered heating appliance such as a gas fireplace or stove, heat generation is controlled by igniting a main burner flame and altering the flow of gas to the burner via a gas valve.
Decorative heating appliances such as fireplaces and stoves typically include a combustion chamber wherein heat is generated or simulated in the form of a flame, and the flame is viewable for aesthetic purposes. Many fireplaces and stoves that burn a gaseous substance rather than a solid fuel such as wood attempt to produce a flame or flame effect that simulates burning of a solid fuel. Providing a flame generated from gas can involve ignition, draft, safety and maintenance issues different from burning solid fuel. A heating device that provides improved monitoring and control of a gas flame in a decorative heating appliance would be an advance in the art.
The present invention generally relates to systems and methods for monitoring and controlling heating appliances such as fireplaces, stove, and fireplace inserts. The disclosed embodiments illustrate example systems and methods for monitoring and controlling the burner and other features of a heating appliance, and communicating the status and conditions
One aspect of the invention relates to a heating appliance control system that includes a pilot flame assembly, a main burner assembly, a gas valve, and a controller. The pilot flame assembly includes a pilot flame burner and at least one pilot flame sensor. The main burner assembly includes a main burner. The gas valve is coupled to the pilot flame and main flame burners. The controller is configured to control the variable gas valve in response to signals received from the pilot and main burner sensors. The controller is also configured to monitor a pilot flame at the pilot flame burner with the pilot flame sensor to confirm stabilization of the pilot flame or a pilot flame signal indicative of the pilot flame before activating the variable gas valve to supply gas to the main burner.
Another aspect of the invention relates to a method of generating a decorative flame in a heating appliance. The heating appliance includes a pilot flame assembly, a main burner assembly, a gas valve, and a controller. The method includes activating the gas valve to supply gas to the pilot flame assembly, igniting the pilot flame with an ignition source of the pilot flame assembly, monitoring the pilot flame to ensure stabilization of the pilot flame, and activating the gas valve to supply gas to the main burner assembly for generation of the decorative flame if the pilot flame is present.
A further aspect of the invention relates to a fireplace that includes a combustion chamber enclosure, a main burner assembly, a pilot flame assembly, a gas valve, and a controller. The combustion chamber enclosure includes a plurality of panels that define a combustion chamber wherein a decorative flame is generated. The main burner assembly includes a main burner and a main flame sensor. The pilot flame assembly includes a pilot flame burner, an ignition source, and a pilot flame sensor. The main burner assembly and the pilot flame assembly are exposed within the combustion chamber. The controller is configured to activate the gas valve to provide a supply of gas to the pilot flame burner for generation of a pilot flame, and is configured to activate the gas valve to provide a supply of gas to the main burner for generation of a main flame. The controller is further configured to monitor the pilot flame for a first predetermined time period prior to activating the gas valve to provide the supply of gas to the main burner.
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures and the detailed description that follow more particularly exemplify certain embodiments of the invention. While certain embodiments will be illustrated and describe embodiments of the invention, the invention is not limited to use in such embodiments.
The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:
While the invention is amenable to various modifications and alternate forms, specifics thereof have been shown by way of example and the drawings, and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
The present invention generally relates to systems and methods for controlling features of a heating appliance. The example systems and methods described herein provide improved safety, diagnostics capabilities, and performance for heating appliances, in particular heating appliances such as fireplaces, stoves, and fireplace inserts that generate a decorative flame. One example system includes a controller that monitors the pilot flame of the heating appliance to determine stability of the pilot flame prior to supplying fuel to a main burner of the heating appliance. An accurate understanding of the pilot flame condition can be helpful for reducing incidence of delayed or aggressive ignition of the main burner, which otherwise occasionally can occur if there pilot flame is not in a condition to properly ignite the main burner. A pilot flame can have many undesirable qualities including significant oscillations, diminishing size over time, and nonexistence. The use of sensors and other features can provide the desired understanding of the pilot flame that can in turn be used by the controller to decide among a variety of options including, for example, whether or not to ignite the main burner, to shut OFF and restart the pilot flame, to lock out the system, or to send maintenance reports.
The use of a controller in a heating appliance can provide advantages related to maintenance of the appliance. A controller is defined as any device that controls an operational feature or device of the fireplace. The controller can include memory for storing information related to the performance of the heating appliance. This stored information can be accessed in a variety of ways including, for example, automatic uploads via a network such as the Internet or telephone lines, or wired or wireless communication by a maintenance person using instruments such as a handheld PDA during a maintenance visit. The controller can also be used to access trends in the heating appliance performance or length of use of the heating appliance and provide reports, notices, warnings or the like related to suggested maintenance needs. This type of advance notice related to maintenance issues can help reduce down time for the heating appliance that would otherwise occur if maintenance were delayed.
Another aspect of the example systems and methods disclosed herein relates to automated control of the pilot flame in response to temperature conditions, for example, associated with the heating appliance (e.g., within the combustion chamber or a plenum of the heating appliance) or outside of the building structure within which the heating appliance resides (e.g., outside atmospheric temperatures). Air temperatures can affect such conditions as burning efficiency and draft conditions in the heating appliance. Running the pilot flame for a predetermined time period in advance of igniting the main burner can raise the air temperatures in the heating appliance and reduce the incidence of draft and efficiency problems. The use of one or more thermistors, thermometers, or thermostats to determine temperatures at various locations such as, for example, inside the heating appliance, in the living space in which the heating appliance is exposed, or outside the building structure (i.e., the atmospheric temperature) can be an effective way to assess whether or how long the pilot flame should run before igniting the main burner.
Some example heating appliances with which the disclosed systems and methods could be used include universal vent, horizontal/vertical vent, B-vent, and dual direct vented fireplaces, stoves, and fireplace inserts, as well as multisided heating appliances having two or three glass panels as side panels.
Referring now to
The location of the pilot flame assembly 22, valve 30, controller 36, power supply 38, main burner flame sensors 20, 21, the pilot flame assembly 22, and thermistors 40, 42 can be altered in other embodiments. In some configurations, only a single main burner flame sensor may be provided and a single thermistor provided in the combustion chamber 16, while in other embodiments more than two sensors or thermistors can be provided. Further details related to the purpose and function of the various features of fireplace 10 is described below with reference to
Generation of a decorative flame can involve some unique issues compared to other types of heating appliances wherein a flame or flame display is irrelevant. For example, a fireplace heating appliance such as fireplace 10 shown in
The example control and monitoring systems disclosed herein provide improved safety by reducing the likelihood and incidence of undesired delayed ignitions and aggressive starts. This can be accomplished in several different ways. One way is to perform a status check of system components prior to initiating a start-up sequence for the heating application. This status check may be considered a diagnostic or self-check in which at least some of the system components (e.g., sensors or other hardware) are checked by the system controller/processor to ensure that the component is operating as expected and that signals are properly communicated between the components and the controller/processor. For example, the system self-checks the components to confirm proper voltages, resistance levels, and impedances before proceeding in a start-up sequence of the burner. Another way is to restrict a gas flow to the main burner until the presence of a pilot flame has been confirmed and preferably a confirmation that the pilot flame is stabilized. Further, a main flame can be confirmed at the main burner within a predetermined time from when a gas flow is supplied to the main burner. If the main flame is not detected, the gas flow can be stopped. In some instances of detected system problems (e.g., lack of main flame), the control system is shut down until maintenance can occur. These and other features provide improved safety and functionality in a heating appliance.
Referring now to
In some embodiments, the system 100 may include multiple valves, main burner assemblies, and pilot flame assemblies. These multiple features can be controlled and monitored independently. In some embodiments, these multiple features can be interdependent on each other.
Referring now to
The control panel 210 may be mounted on a wall or other location that is remote from a heating appliance in which other components of the system 200 are positioned. The remote control unit 214 can communicate directly with the wall unit 210 or may be able to communicate with the controller 202. The remote control unit 214 provides for control of the system 200 by a user from a variety of locations without restriction by a wired system. The system 200 can include other forms of communication such as those described below with reference to
The battery backup 212 provides a unique DC power backup system that is described in further detail below in connection with
The controller 202 is capable of bi-directional communication with most if not all of the features 218, 220, 222, 224, 230, 234, and 204. In one example, the controller 202 includes a variety of components as shown in
The memory 242 can be volatile or non-volatile memory for the storage of various types of information necessary to operate the controller 202 and other features of the system 200. The communications connection 244 can be a serial bus connection or other type of connection that provides flexibility in the types of components that operate using controller 202. The removable and non-removable storage 248, 256 can be used to store different types of information that may or may not be overwritten, downloaded, or uploaded as desired. The input and output devices 250, 258 can include, for example, features of a communication system for transmitting and receiving signals via, for example, the communications connection 244. The bi-directional serial databus 262 may be a communications device separate from the input and output devices 250, 258, or may integrated into one or more of the devices 250, 258.
The databus 262 can provide plug-and-play capabilities for the system 200. Various components of the system 200 can be given identification or data labels that are identifiable by the controller 202. When a component is plugged in or otherwise added to the system 200 or the heating appliance, two-way communication occurs between the added component and the controller 202. The controller is can be preprogrammed to perform certain functions and operate in a predetermined way upon receipt of the data label for that added component or some combination of components coupled to the system. Similarly, components already operable on the system can function or operate in a predetermined way upon adding a new component that has been identified via the data label and databus by the controller. The software or firmware that is run by the CPU 240 of the controller can be updated as needed. For example, the software/firmware of the controller 202 can be updated in view of new components that are to be added to the system 200.
In one example application of the databus 262 function and the plug-and-play functionality of the system 200, a user interface panel (available, for example, via the input devices 250) can provide options for control of an ember bed of the fireplace when the ember bed has been coupled to the controller 202, but the control options of the user interface panel are removed when the ember bed has been removed/decoupled from the controller 202. The databus 262 provides communication from the user interface panel to the ember bed, and information concerning the ember bed (e.g., whether is activated and functioning properly) is communicated from the ember bed back to the user interface panel via the databus.
The D/A and A/D converters 252, 260 in the system 200 or other features of the heating appliance. The D/A and A/D converters can also be used to convert different types of signals incoming via and outgoing via the input and output devices 250, 258. The power supply can be, for example, coupled to the AC power supply 216 in the form of, for example, a 3 volt AC power supply. The power supply can also be coupled to the battery backup 212, wherein the battery backup provides, for example, a DC power supply using a standard sized battery (e.g., D battery) that is rechargeable or non-chargeable.
The controller 202 can run according to a software code that is loaded into the controller memory 242 and operated with the CPU 240. The software code preferably provides for monitoring and control of various components of the system 200 such as, for example, the ignition source 222, pilot and main flame sensors 222, 224, thermistor 218, control panel 210, blower 230 and lights 234. The code preferably also provides for storage of performance information such as pilot flame and main burner flamer ignition history, hours of operation, flame sense signals, lock out history or other maintenance-related information.
The controller 202 and system 200 generally can have additional functions and features for monitoring and control of a heating appliance as shown and described in U.S. patent application Ser. No. 11/238,640, filed on Sep. 28, 2005 and titled GAS FIREPLACE MONITORING AND CONTROL SYSTEM, and U.S. Published Patent Application No. 2005/0208443A1, which patent applications are incorporated herein by reference.
The lights 234 can be used for a variety of purposes including, for example, backlighting in a heating appliance as shown and described in U.S. Published Patent Application No. 2004/0173202A1, or for providing a simulated electric glowing ember in a heating appliance as shown and described in U.S. Pat. No. 6,053,165, which patent application and patent are incorporated herein by reference. Control of the lights 234 by the controller 202 can be correlated with other functions of a heating appliance and the system 200. For example, modulating the lights 234 can be synchronized with modulation of a main burner flame with a modulator 230, or with modulation of a speed of the blower 230.
The system 200 can, in other embodiments, include additional features or multiples of the features illustrated in
The heating appliance can include visual indicators such as, for example, one or more light emitting diodes (LEDs) to convey diagnostic information related to the heating appliance. The visual indicators can use color and sequenced ON/OFF operation to convey information. Example diagnostics definitions or states that can be communicated by the visual indicators include System Abnormal, System Idle, Normal Operation, Cold Climate Mode, System Normal, Low Flame Pilot Sense, Low Main Burner Flame Sense, Failed Pilot Ignition Trial, Failed Main Burner Ignition Trial, and Hard Lock Out.
In one example, the diagnostics definitions provided above are communicated using a green LED and a red LED. The LEDs can be integrated into a housing of the controller or may be positioned at another location independent of the controller. In one example, the LEDs are mounted in a housing of the controller and the controller is positioned within an outer enclosure of a heating appliance. The heating appliance may include removable panels or translucent coverings that provide visualization of the LEDs for purposes of obtaining the diagnostics information represented by the LEDs. In another example, the controller is positioned remotely from the heating appliance such as in a wall structure or combined with a wall-mounted control panel. In a further example, the LEDs can be independently mounted with a wall mounted control panel that is positioned remotely from the heating appliance. In a still further example, the LEDs are exposed at a front panel of the heating appliance that is exposed for viewing at all times.
The LEDs can be flashed ON and OFF in different combinations of number of flashes, duration and color schemes to communicate the diagnostic information. For example, the LED scheme for the OFF mode indicates system idle shown with a continuous LED and no flashing, and the LED scheme indicating system normal is that the red LED is turned OFF without any flash cycles. With this simple LED scheme, a user or maintenance personnel can quickly determine a condition of the system and the heating appliance by merely viewing the LEDs. In other embodiments, more or fewer LEDs can be used with any desired LED flashing and duration schemes to communicate the necessary information.
The controller can provide operation of the heating appliance in a plurality of different modes. Some example modes include Off, Pilot Ignition, Mainer Burner Ignition, Hard Lock Out, Soft Lock Out, and Self Checks. These six modes are independent from each other to the extent that the controller typically operates in only one of the modes at a given time. For example, it is preferred to turn OFF the Pilot Ignition Mode prior to initiating the Main Burner Ignition Mode. When the controller enters the Hard Lock Out Mode, the controller cannot move into another mode until maintenance occurs by a qualified maintenance person. In a soft Lock Out Mode, the controller can move into different modes if certain actions occur such as, for example, pressing a reset button for the controller, turning ON a gas supply to the valve, replacing batteries in the battery backup for the system, or restarting the Pilot Ignition Mode.
Pilot flame sense signals related to monitoring of the pilot flame for purposes of the operational modes described above is described with reference to
An alternative to the first configuration is a configuration in which the pilot flame sense signal is monitored at times t2, t3, t4, or at any other time after t1, in an effort to better understand the state of the pilot flame before attempting to ignite the main burner flame. Such monitoring at additional times can help determine whether the signals A, B, C stabilize and the level at which they stabilize.
Referring now to
Another way of determining whether or not a gas flow should be supplied to the main burner based on the pilot flame sense signal is to allow lapse of a predetermined amount of time regardless of the stabilization state of the pilot flame so long as the flame is above an ON/OFF threshold. In some scenarios, burning the pilot flame for a certain amount of time creates heat and energy within the heating appliance to provide the desired draft and ignition conditions. With these improved conditions, it may be possible to improve the likelihood of proper main burner flame ignition even with a lower quality, less stable pilot flame. Thus, in one configuration the gas flow may be provided to the main burner at time t4 if the time t4 is adequate to create the desired heat and energy conditions even though the flame sense signal may not be fully stabilized.
Referring now to
In another scenario, the stabilized main flame represented by signals K, L, M, N can decrease levels over time, again illustrating possible performance issues and/or a need for maintenance for the main burner. A controller can be configured to perform this type of monitoring and analysis of stored data that has been gathered over time. The controller can also be configured to generate notices, reports, or other signals notifying a user or maintenance personnel of the need for maintenance and/or repair of certain aspects of the main burner, sensors, associated with the burner, etc.
The pilot flame sense is monitored from the initiation of the Pilot Ignition Mode through the Main Burner Ignition Mode, in a soft lock out mode, and during soft checks until the OFF mode is again initiated. The pilot flame sense should be above a threshold drop-out level. Preferably, the pilot flame sense is greater than four times nominal drop out threshold. If the flame sense stabilizes less than two times the nominal drop out threshold, operation is continued and a diagnostic signal is generated. When the pilot flame sense stabilizes above two times drop out threshold, the diagnostic signal is terminated.
The pilot flame sense should vary less than 10% for at least two seconds before initiation of the Main Burner Ignition Mode. If the pilot flame sense is above the drop out threshold but varies greater than 10% for ten seconds, operation proceeds and a diagnostic signal is generated. If the pilot flame sense varies less than 10%, for two seconds, the diagnostic signal is terminated. Once the pilot flame sense stabilizes the operation sequence proceeds to the main burner mode. If the pilot flame sense does not stabilize above the drop out threshold after 45 seconds, the pilot ignition sequence is terminated and another diagnostic signal is generated.
With the ignition sequence terminated, the Pilot Ignition Mode can be manually initiated again by changing system state from ON to OFF and back to ON again. The pilot ignition will be automatically initiated again after a 15 minute delay for a total of three ignition tries. After three failed automatic pilot ignition trials the soft lock out mode is initiated. The diagnostic signal terminates only upon a successful pilot ignition.
The main burner flame sense is monitored from the initiation of the main burner ignition through the sequence of modes to either the OFF mode or a Cold Climate Mode if a Cold Climate Mode (see below) is initiated. The main burner flame sense is preferably above a drop out threshold. The main burner flame sense is preferably greater than four times a nominal drop out threshold. The main burner flame sense stabilizes less than two times a normal drop out threshold, operation continues and a diagnostic signal is sent. When the main burner flame sense stabilizes above two times the drop out threshold, the diagnostic signal can be terminated. The main burner flame sense should occur within 10 seconds of opening a main burner valve. If the main burner flame sense does not occur within 10 seconds of opening the main burner valve, the main burner valve is closed and the pilot operation mode continues with another diagnostic signal being sent. After the main valve has been closed, the pilot mode operates continuously and the pilot flame sense is monitored until a successful main burner ignition occurs.
Any time during a main burner ignition time out period (i.e., the main valve closing after 10 seconds of no main burner flame sense) if the pilot flame sense is not stable and greater than two times nominal drop out threshold the system goes into a hard lock out mode and a diagnostic signal is sent. If the pilot flame sense is stable, the Main Burner Ignition Mode can be manually initiated by cycling the control from ON to OFF and ON again. Retries will not be allowed to occur less than 5 minutes apart after the first failed main burner ignition trial.
Normal heating appliance operation is initiated by either a heating appliance ON command being received at the serial bus of the controller or wires of the system are shorted (e.g., 3 volts DC continuous on one of the com ports). An example normal heating appliance operation is defined according to the following steps:
a. Initiate self checks
b. Initiate pilot ignition
c. Monitor pilot flame sense
d. Initiate main burner ignition
e. Monitor main burner flame sense.
Normal operation is terminated by either heating appliance OFF command being received at the serial bus. The normal operation terminates if a Cold Climate Mode is not active and the system returns to OFF mode, or if the Cold Climate Mode is active the main valve is turned OFF and the Cold Climate Mode continues.
A variation of the normal heating appliance operation is illustrated in the flow diagram of
The step 306 of checking the status of the main burner can occur concurrently with other steps 302, 304, 308, 310, 312, 314. For example, the system may continuously check the status of the main burner at all times to ensure that the main burner is either OFF or ON at the proper time or else a lock out of the system can occur.
Another example heating appliance operation is illustrated with reference to
If a pilot flame is present, the controller monitors the pilot flame to determine whether the pilot flame is stabilized in a step 410 and if it is stabilized the controller turns ON the main burn valve in a step 412. The controller then determines the presence of a main flame in step 414 and if a main flame exists, the controller monitors the main flame in a step 418. If the controller does not determine the main flame, the controller turns OFF the main burner valve in a step 416 and there is a repeat of steps 410, 412, 414. In the step 406 wherein the pilot flame is not present, the controller turns OFF the pilot valve in a step 408 and the step 402 is repeated. If the pilot flame is not stabilized in the step 410, the controller again turns OFF the pilot valve and the step 402 is repeated.
A Cold Climate Mode can be used to improve draft of the heating appliance and to improve efficiency and startup capabilities. Cold Climate Mode involves running the pilot flame for a predetermined amount of time that is longer than the normal time periods of to the Pilot Ignition Mode in advance of initiating the Main Burner Ignition Mode. Running of the pilot flame heats up the area in the heating appliance and causes a draft out of the heating appliance exhaust pipe so that when the main burner flame is ignited, the exhaust gases automatically flow out of the combustion chamber of a heating appliance. There is typically a balance in efficiencies between running the pilot flame to create the desired draft and ensuring that the heating appliance maintains optimum efficiency. Thus, the Cold Climate Mode is preferably controlled with time restraints that provide the desired draft generating results while burning the pilot flame a minimum amount of time to increase efficiency.
The Cold Climate Mode is initiated by either a “pilot” command received at the serial bus of the controller, a temperature of the system thermistor is below a predetermined amount, or the thermistor is shorted (˜0 ohms detected). The Cold Climate Mode is only active when there is no demand for the main burner. Beginning at the OFF mode, the Cold Climate Mode first initiates self checks, initiates Pilot Ignition Mode and monitors the pilot flame sense. From the normal heating appliance operation, when the normal heating appliance operation is terminated, the pilot operation is maintained. When going from Cold Climate Mode to a normal heating appliance operation, the normal heating appliance operation is initiated and execution of the ignition sequence from the main burner ignition occurs. Cold Climate Mode termination occurs if there is no main burner ignition demand and none of the Cold Climate Mode initiation criteria are valid, thus the pilot operation is terminated.
A Stove Timer Mode can be used in operation of a stove style heating appliance. Stoves sometimes have more common problems with generating a proper draft than other types of heating appliances, such as a fireplace. The stove timer is used to delay the initiation of the main burner ignition after start up of the pilot flame when the stove has not been used for a predetermined time such as, for example, three or more days. The stove timer automatically places the system in Cold Climate Mode for three days after the stove has been used in order to maintain a certain temperature in the stove and to maintain a draft.
The following is an example stove startup sequence using a Stove Timer Mode:
The use of a 5 minute delay between pilot ignition and main burner ignition helps to ensure creation of a draft in the stove. The 3 day operation of the Cold Climate Mode after the stove operation is terminated helps maintain the stove in a ready-to-operate condition during a time period in which it can be more likely that the user will again use the stove. Other time periods for the delay and the cold climate operation time are possible. For example, the delay time can be about 1 to about 30 minutes, more preferably about 1 to about 10, and most preferably about 3 to about 6 minutes. The cold climate operation can be about 0.5 days to about 10 days, more preferably about 1 day to about 5 days, and most preferably about 2 to about 3 days.
Referring not to
Referring now to
The heating appliance control system 902 can include a connector for future add-on sensors that can go to different ports of a microcontroller such as I/O's, A/D or D/A converter lines. The system can also include the capability (e.g., via a serial port) for a service technician to retrieve the history of the heating appliance's actions and/or problems from the microcontroller or communication transmission. Such capability can also include the possibility for future upgrades in code and a possibility of talking with another microcontroller that could be in an add-on device in the future. The system can use LEDs as status indicators on the heating appliance, at other locations in close proximity to the heating appliance, or at the remote computer location. These visual indicators can be turned OFF or removed according to user preferences.
The examples provided above with reference to the attached Figures focus on gas burning decorative heating appliances such as fireplaces, stove, and fireplace inserts. The systems and methods described above could be modified to provide the same or similar functions for other types of decorative heating appliances such as, for example, electric, wood burner, and pellet fireplaces, stove and fireplace inserts. While such alternative heating appliances may not include a valve or the type of ignition system required for ignition of a gaseous fuel, such alternative heating appliances can include different types of ignition systems and heat sources that can be monitored and controlled with the assistance of sensors, as well as blowers, light fixtures, air filters, scent generating devices and other features that can be monitored and controlled. For example, the system can include sensors that monitor the fuel supply associated with the decorative heating appliance. For example, a sensor or other monitoring device can be used to monitor a pellet supply level for a pellet stove or fireplace, or a liquid propane (LP) supply level for a LP gas fireplace.
The present invention should not be considered limited to the particular examples or materials described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the instant specification.
