Patent Publication Number: US-8523560-B2

Title: Spark detection in a fuel fired appliance

Description:
FIELD 
     The present disclosure relates generally to fuel fired appliances, and more particularly, to systems and methods for detecting the presence or absence of sparking during ignition trials in a fuel fired appliance. 
     BACKGROUND 
     Numerous fuel fired appliances have an igniter for igniting the fuel upon command. Fuel fired appliances include, for example, heating, ventilation, and air conditioning (HVAC) appliances such as furnaces, boilers, water heaters, as well as other HVAC appliances and non-HVAC appliances. Fuel fired appliances typically have a combustion chamber and a burner. A fuel source, such as a gas or oil, is typically provided to the burner through a valve or the like. In many cases, various electrical and/or electromechanical components are provided to help control and/or otherwise carry out the intended function of the fuel fired appliance. For example, various controllers, motors, igniters, blowers, switches, motorized valves, motorized dampers, and/or others, are often included in, or are used to support, a fuel fired appliance. 
     One particular type of fuel fired appliance is a fuel fired furnace. Fuel fired furnaces are frequently used in homes and office buildings to heat intake air received through return ducts and distribute heated air through warm air supply ducts. Such furnaces typically include a circulation blower or fan that directs cold air from the return ducts across metal surfaces of a heat exchanger to heat the air to an elevated temperature. A burner including an igniter for igniting the fuel is often used to heat the metal surfaces of the heat exchanger. The air heated by the heat exchanger can be discharged into the supply ducts via the circulation blower or fan, which produces a positive airflow within the ducts. 
     In some instances, the igniter of the burner may fail to produce a spark to ignite the fuel during an ignition trial. If a flame is not detected in the burner during and/or after the ignition trial, the control system may shut down the burner, and in some cases, enter a lockout state. Once in a lockout state, in some cases, a service technician must be called to diagnose and correct the problem before the fuel fired appliance can return to an operational state. Under these circumstances, a significant amount of time may be required for the service technician to diagnose the problem of the igniter failing to spark. Therefore, there is a need for new and improved control systems for detecting the presence or absence of a spark during ignition trials in a fuel-fired appliance. 
     SUMMARY 
     The present disclosure relates generally to fuel fired appliances, and more particularly, to systems and methods for detecting the proper operation of a spark igniter during ignition trials in a fuel fired appliance. In one illustrative embodiment, a fuel-fired appliance system is disclosed. The fuel fired appliances may be, for example, a heating, ventilation, and air conditioning (HVAC) appliance such as a furnace, a boiler, a water heater, and/or any other HVAC appliance or non-HVAC appliance. The fuel-fired appliance system may include a controller, as well as an antenna (e.g. antenna element or internal circuitry) and/or an optical detector. The antenna and/or optical detector may be positioned near an igniter of the fuel fired appliance, where the igniter is configured to produce a spark that ignites fuel during an ignition trial when the fuel fired appliance is operating properly. 
     The controller may be connected to the antenna and/or the optical detector and, in some instances, may be configured to receive a first signal from the antenna and/or a second signal from the optical detector. The controller may determine operation of the igniter when it is activated using the first signal and/or the second signal. For example, in some cases, the controller may monitor the first signal (from the antenna), and determine a relative amount of electromagnetic interference (EMI) or electrical noise adjacent the igniter. If the relative amount of electromagnetic interference (EMI) or electrical noise adjacent the igniter increases, sometimes by at least a predetermined amount, when the ignition assembly is activated, the controller may determine the igniter is fully operational during the ignition trial. If the relative amount of electromagnetic interference (EMI) or electrical noise adjacent the igniter does not increase, sometimes by at least a predetermined amount, when the ignition assembly is activated, the controller may determine the igniter is non-operational during the ignition trial. 
     Alternatively, or in addition, the controller may monitor an electrical characteristic of the second signal when the igniter is in a deactivated state and when the igniter is in an activated state. The controller may determine that a spark is present during the ignition trial when the electrical characteristic changes, sometimes by more than a predetermined amount, between the activated state and the deactivated state. Likewise, the controller may determine that the spark is absent during the ignition trial when the electrical characteristic does not change, sometimes by more than a predetermined amount, between the activated state and the deactivated state. 
     The preceding summary is provided to facilitate an understanding of some of the innovative features unique to the present disclosure and is not intended to be a full description. A full appreciation of the disclosure can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
    
    
     
       BRIEF DESCRIPTION 
       The invention may be more completely understood in consideration of the following detailed description of various illustrative embodiments of the disclosure in connection with the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of an illustrative embodiment of an oil-fired HVAC system for a building or other structure; 
         FIG. 2  is a partial cut-away top view of an illustrative oil-fired burner assembly of the HVAC system of  FIG. 1 ; 
         FIG. 3  is a partial cross-sectional view of the illustrative oil-fired burner assembly of  FIG. 2 ; 
         FIG. 4  is a block diagram of an illustrative controller that may be used in conjunction with the oil-fired HVAC system of  FIGS. 1-3 ; 
         FIG. 5  is a schematic diagram of an illustrative antenna that may be used with the controller of  FIG. 4 ; 
         FIG. 6  is a flow diagram of an illustrative method of detecting electromagnetic noise emitted by a spark using an illustrative antenna; 
         FIG. 7  is a flow diagram of an illustrative method of determining if a spark is present or absent during an ignition trial using an illustrative antenna; and 
         FIG. 8  is a flow diagram of an illustrative method of determining if a spark is present or absent during an ignition trial using a detector. 
     
    
    
     DETAILED DESCRIPTION 
     The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings show several embodiments which are meant to be illustrative of the claimed invention. 
     For illustrative purposes only, much of the present disclosure has been described with reference to an oil-fired furnace. However, this description is not meant to be so limited, and it is to be understood that the features of the present disclosure may be used in conjunction with any suitable fuel-fired system utilizing a flame detector or flame detection system. For example, it is contemplated that the features of the present disclosure may be incorporated into an oil-fired furnace, an oil-fired water heater, an oil-fired boiler, a gas-fired furnace, a gas-fired boiler, a gas-fired water heater, and/or other suitable fuel-fired system, as desired. 
       FIG. 1  is a schematic diagram of an illustrative embodiment of an oil-fired HVAC system  10  for a building or other structure. As illustrated, the HVAC system  10  includes a storage tank  32  and an oil fired appliance  12  including a burner  14 . Oil can be stored in storage tank  32  and fed to the burner  14  of the fuel fired appliance  12  via a supply line  30 . As illustrated, storage tank  32  may include an air vent  36  and a fill line  34  for filling the storage tank  32  with oil, but these are not required. For mere exemplary purposes, the storage tank  32  is illustrated as an above-ground storage tank, but may be implemented as a below ground storage tank or any other suitable oil storage tank, as desired. Alternatively, oil or another fuel may be provided directly to the oil fired appliance  12  via a pipe from a utility or the like, depending on the circumstances. 
     A valve  28  is shown situated in the supply line  30 . The valve  28  can provide and/or regulate the flow of oil from the storage tank  32  (or utility) to the burner  14 . In some embodiments, valve  28  may regulate the oil pressure supplied to the burner  14  at specific limits established by the manufacturer and/or by an industry standard. Such a valve  28  can be used, for example, to establish an upper limit to prevent over-combustion within the appliance  12 , or to establish a lower limit to prevent combustion when the supply of oil is insufficient to permit proper operation of the appliance  12 . 
     In some cases, a filter  26  may be situated in the supply line  30 . The filter  26  may be configured to filter out contaminants and/or other particulate matter from the oil before the oil reaches the burner assembly  14  of the oil-fired appliance  12 . 
     In the illustrative embodiment, the oil-fired appliance, illustratively an oil-fired furnace  12 , includes a circulation fan or blower  20 , a combustion chamber/primary heat exchanger  18 , a secondary heat exchanger  16 , and an exhaust system (not shown), each of which can be housed within furnace housing  21 . In some cases, the circulation fan  20  can be configured to receive cold air via a cold air return duct  24  (and/or an outside vent) of a building or structure, circulate the cold air upwards through the furnace housing  21  and across the combustion chamber/primary heat exchanger  18  and the secondary heat exchangers  16  to heat the air, and then distribute the heated air through the building or structure via one or more supply air ducts  22 . In some cases, circulation fan  20  can include a multi-speed or variable speed fan or blower capable of adjusting the air flow between either a number of discrete airflow positions or variably within a range of airflow positions, as desired. In other cases, the circulation fan  20  may be a single speed blower having an “on” state and an “off” state. 
     Burner assembly  14  can be configured to heat one or more walls of the combustion chamber/primary heat exchanger  18  and one or more walls of the secondary heat exchanger  16  to heat the cold air circulated through the furnace  12 . At times when heating is called for, the burner assembly  14  is configured to ignite the oil supplied to the burner assembly  14  via supply line  30  and valve  28 , producing a heated combustion product. The heated combustion product of the burner assembly  14  may pass through the combustion chamber/primary heat exchanger  18  and secondary heat exchanger  16  and then be exhausted to the exterior of the building or structure through an exhaust system (not shown). In some embodiment, an inducer and/or exhaust fan (not shown) may be provided to help establish the flow of the heated combustion product to the exterior of the building. 
     In the illustrative embodiment, an electrical power source, such as a line voltage supply  38  (e.g. 120 volts, 60 Hz AC), may provide electrical power to at least some of the components of the oil-fired HVAC system  10 , such as the oil-fired furnace  12  and/or more specifically the burner assembly  14 . The line voltage supply  38  in the United States typically has three lines, L1, neutral, and earth ground, and is often used to power higher power electrical and/or electromechanical components of the oil-fired HVAC system  10 , such as circulation fan or blower  20 , an ignition system of the burner assembly  14 , and/or other higher power components. In some cases, a step down transformer can be provided to step down the incoming line voltage supply  38  to a lower voltage supply that is useful in powering lower voltage electrical and/or electromechanical components if present, such as controllers, motorized valves or dampers, thermostats, and/or other lower voltage components. In one illustrative embodiment, the transformer may have a primary winding connected to terminals L1 and neutral of the line voltage supply  38 , and a secondary winding connected to the power input terminals of controller to provide a lower voltage source, such as 24 volt 60 Hz AC voltage, but this is not required. 
     Although not specifically shown in  FIG. 1 , it is contemplated that the oil-fired HVAC systems may include other typical HVAC components including, for example, thermostats, sensors, switches, motorized valves, non-motorized valves, motorized dampers, non-motorized dampers, and/or others HVAC components, as desired. 
       FIG. 2  is partial cut-away top view and  FIG. 3  is a partial cross-sectional view of an illustrative burner assembly  14  of the oil-fired HVAC system  10  of  FIG. 1 . In the illustrative embodiment, the burner assembly  14  is configured to atomize the oil (i.e. break the oil into small droplets) and mix the atomized oil with air to form a combustible mixture. The combustible mixture is sprayed into the combustion chamber/primary heat exchanger  18  of the oil-fired furnace  12  (shown in  FIG. 1 ) and ignited with a spark from an ignition system of the burner assembly  14 . 
     In the illustrative embodiment, the burner assembly  14  may include a pump  42 , a nozzle  60 , a motor  50 , a blower  66 , an air tube  68 , an ignition transformer  44 , and the ignition system. The pump  42  may have an inlet connected to the oil supply line  30  and an outlet connected to the nozzle  60  via a nozzle line  46 . The pump  42  may deliver oil under pressure to the nozzle  60 . At the nozzle  60 , the oil may be broken into droplets forming a mist that is sprayed into combustion chamber/primary heat exchanger  18 . In some situations, the nozzle  60  may break the oil into a relatively fine, cone-shaped mist cloud. 
     At the same time as the oil mist is being sprayed into the combustion chamber/primary heat exchanger  18 , the blower  66 , which is driven by motor  50 , may be configured to provide an airstream, which in some cases, may be a relatively turbulent airstream, through air tube  68  to mix with the oil mist sprayed into the combustion chamber/primary heat exchanger  18  by the nozzle  60  to form a good combustible mixture. In some cases, a static pressure disc  52  or other restrictor can be positioned in the air tube  68  to create the relatively turbulent airstream or air swirls to mix the airstream and oil mist. 
     In the illustrative embodiment, the ignition system of the burner assembly  14  may include one or more electrodes, such as electrodes  62  and  64 , having one end electrically connected to the ignition transformer  44  and another end extending adjacent to the nozzle  60  and into the oil mist provided by the nozzle  60 . When an electrical current is provided to electrodes  62  and/or  64  from the ignition transformer  44 , the electrical current may create a “spark” that can ignite the combustible mixture and produce a flame. In some embodiments, the electrodes  62  and  64  may be secured and/or mounted relative to the nozzle  60  in the flow tube  68  with a mounting bracket  54 . To electrically insulate the electrodes  62  and  64  from the mounting bracket  54 , an insulated material or covering, shown as  56  and  58 , may be provided over a portion of the electrodes  62  and  64 . As shown in  FIG. 3 , one end of the electrodes  62  and  64  can be electrically connected to the ignition transformer  44  via one or more springs  70 . However, it is contemplated that other suitable connectors may be used to electrically connect electrodes  62  and  64  to ignition transformer  44 , as desired. 
     In the illustrative embodiment, a controller  48  may be included or electrically connected to the burner assembly  14 . The controller  48 , which may be an oil primary control, may be electrically connected to and/or control the operation of motor  50  for driving blower  66 , ignition transformer  44 , pump  42 , and/or oil valve  28  in response to signals received from one or more thermostats or other controllers (not shown). Although not shown, the controller  48  may be linked to the one or more thermostats and/or other controllers directly (wired or wireless) or via a communications bus (wired or wireless) upon which heat demand calls may be communicated to the furnace  12 . The controller  48  may also be used to control various components of the furnace  12  including the speed and/or operation of the circulation fan  20 , as well as any airflow dampers (not shown), sensors (not shown), or other suitable component, as desired. 
     In the illustrative embodiment, the controller  48  may be configured to control the burner assembly  14  between a burner ON cycle and a burner OFF cycle according to one or more heat demand calls received from the thermostat. When a burner ON cycle is called for, the controller  48  may initiate an ignition trial of the burner assembly  14  by providing oil to the burner assembly by actuating valve  28 , activating the pump  42  to provide pressurized fuel to nozzle  60 , and activating motor  50  to drive blower  66  to provide air for mixing with the oil mist to form a good combustible mixture. The controller  48  may also be configured to selectively energize electrodes  62  and  64  using ignition transformer  44  to ignite the combustible mixture. The energized electrodes  62  and  64  may create a “spark” to ignite the combustible mixture and produce a flame. When a burner OFF cycle is called for, the controller  48  may be configured to actuate valve  28  to cease providing oil to the burner assembly  14  and shut off motor  50  and pump  42 . 
     As shown in  FIG. 3 , a detector  72  can be provided in or adjacent to the burner assembly  14  in some embodiments. The detector  72  may be configured to detect the presence of a spark and/or a flame during an ignition trial and/or the burner ON cycle. In some cases, the detector  72  may include a light sensitive detector, such as a light sensitive cadmium sulfide (CAD) cell  72 . However, it is contemplated that any suitable light detector may be used including, for example, a photo-diode or any other suitable light sensitive device. The use of a light sensitive detector may be particularly suited to a burner, such as, for example, an oil-fired burner, that is configured to optically sense the presence or absence of a flame as a single sensor may be used to sense both the flame and the spark. However, it is not required that a single sensor be used to sense both the flame and the spark in the burner and it is contemplated that a separate spark sensing detector and a flame sensing detector may used, if desired. 
     In the example shown in  FIG. 3 , the light sensitive CAD cell  72  may be mounted or otherwise secured in the air tube  68  with holder  74  so that it can view the flame when a flame is present and, in some cases, a spark when a spark is present. The CAD cell  72  may be electrically connected to the controller  48  via wires  76  and may send an electrical signal to the controller  48  corresponding to the amount of light detected. For the illustrative CAD cell  72 , the resistance of the CAD cell  72  may be light dependent, with the resistance decreasing with more light (e.g. spark or flame present) and increasing with less light (e.g. no spark or flame). In some instances, the CAD cell  72  may be configured to have a “dark” resistance when no spark or flame are present, a “light” resistance when a flame is present, and a resistance between the “dark” resistance and the “light” resistance when a spark is present without a flame. In some cases, the “dark” resistance may be relatively larger than the “light” resistance. For example, the “dark” resistance may be about 20 kilohms, 50 kilohms, 100 kilohms, 500 kilohms, 1 megohm, or any resistances between, for example, 50 kilohms and 1 megohm. The “light” resistance may be any resistance less than the “dark” resistance. Further, it is contemplated that in some implementations, the light detector may be configured such that the “light” resistance may be greater than the “dark” resistance or, in other words, the resistance of the light detector may increase with more light, if desired. 
     In some embodiments, the CAD cell  72  may “watch” the burner assembly  14  for a spark at startup (i.e. during ignition trial). If the spark is not detected, CAD cell  72  may send an electrical signal to the controller  48  indicating that no spark is present and, in some cases, the controller may shut down the burner assembly  14 . In some embodiments, the controller  48  may enter a lockout state to prevent further operation of the burner assembly  14 , but this is not required. 
     Additionally, in some embodiments, the CAD cell  72  may “watch” the burner assembly  14  for a flame at startup and during a burner ON cycle. If the flame fails for any reason, the CAD cell  72  may send an electrical signal to the controller  48  indicating that no flame is present, and the controller may shut down the burner assembly  14 . In some embodiments, the controller  48  may enter a lockout state to prevent further operation of the burner assembly  14 , but this is not required. 
       FIG. 4  is a block diagram of an illustrative controller  48  that may be used in conjunction with a fuel-fired system, such as, for example, the oil-fired HVAC system of  FIGS. 1-3 . It is contemplated that the illustrative controller  48  may be used with any type of fuel-fired appliance, such as gas-fired appliances (e.g. furnace, water heater, boiler, etc.) or oil-fired appliances (e.g. furnace, water heater, boiler, etc.), as desired. 
     In the illustrative embodiment, the controller  48  includes a control module  80 , an antenna  90 , and an optional spark error notification module  92 . Control module  80  may be configured to control the activation of one or more components of the oil-fired HVAC system  10 , such as the burner assembly  14 , valve  28 , and/or oil-fired furnace  12 , in response to signals received from one or more thermostats (not shown) or other controllers. For example, control module  80  may be configured to control the burner assembly  14  between a burner ON cycle and a burner OFF cycle according to the one or more heat demand calls. In some instances, control module  80  may include a processor  82  and a memory  84 . 
     Memory  84  may be configured to store any desired information, such as programming code for implementing the algorithms set forth herein, one or more settings, parameters, schedules, trend logs, setpoints, and/or other information, as desired. Control module  80  may be configured to store information within memory  84  and may subsequently retrieve the stored information. Memory  84  may include any suitable type of memory, such as, for example, random-access memory (RAM), read-only member (ROM), electrically erasable programmable read-only memory (EEPROM), Flash memory, and/or any other suitable memory, as desired. 
     A detector  88  may be coupled to or in electrical communication with the control module  80 . In some cases, the detector  88  may be a light sensitive detector, including for example, a CAD cell, such as CAD cell  72  shown in  FIG. 3 , a photodiode, and/or other suitable optical detection device or system capable of detecting the presence or absence of a spark, as desired. The detector  88  may be configured to provide an electrical signal to the control module  80  having an electrical characteristic (e.g. resistance, current, voltage, etc.) indicating the presence or absence of a spark during an ignition trial. For example, in the illustrative embodiment of the detector  88  including CAD cell  72 , as discussed above, the resistance of CAD cell  72  may be light sensitive, and may vary according to the presence or absence of light. In some cases, the resistance of the CAD cell  72  may decrease with more light (e.g. spark and/or flame present). For example, the CAD cell  72  may have a “dark” resistance in the range of 50 kilohms to 1 megohm and a “light” resistance that is less than the “dark” resistance. If the spark is not detected during startup, the control module  80  may receive a signal from the detector  88  indicating that no spark is detected and, in some embodiments, the control module  80  may shut down the burner assembly  14  and/or valve  28 . 
     In some embodiments, a threshold level may be stored in memory  84  of the control module  80 . The threshold level may be a level at which, under normal operating conditions, the electrical characteristic (e.g. resistance, current, voltage, etc.) of the flame detector  88  is expected to change by an amount that reliably indicates a spark is present. When the electrical characteristic of the signal received from the flame detector  88  changes by more than the threshold level during an ignition trial, the control module  80  may determine that a spark was successfully produced by the ignition assembly (e.g. electrodes  62  and  64 ). When the electrical characteristic of the signal received from the flame detector  88  does not change or changes less than the threshold level during an ignition trial, the control module  80  may determine that a spark was not successfully produced by the ignition assembly (e.g. electrodes  62  and  64 ). In the example case of a CAD cell  72 , the control module  80  may determine that the ignition assembly produced a spark when the CAD cell  72  has a resistance that decreases by the threshold level, and did not produce a spark when the CAD cell  72  has a resistance that did not decrease by the threshold level. In some cases, the threshold level may be a percentage based level, such as, for example, a 5 percent change, a 6 percent change, a 7.5 percent change, a 10 percent change, a 15 percent change, or any suitable percentage change, as desired. In other embodiments, the threshold change level may be a predetermined change in the electrical characteristic of the detector  88 , such as, for example, 5 ohms, 10 ohms, 20 ohms, 50 ohms, or any other resistance or electrical characteristic, as desired. It is further contemplated that, in some embodiments, the threshold may be a learned value based on past history of igniting the burner. For example, if it is determined that a signal received from the detector  88  routinely shifts or changes by a relatively consistent amount, such as 10 percent, on successful ignition attempts, the threshold level may be set at that amount, for example, 10 percent change. In some embodiments, as the burner ages and characteristics of the burner change (due to wear out, soot build up, etc.), the threshold level may be adjusted (e.g. increased or decreased) to maintain reliable performance of the burner. At some point it may be determined that the detector  88  is no longer capable of sensing spark. In this case the control module  80  may activate an alarm indicating that the detector  88  cannot sense spark and/or the control module  80  may abort the optical manner of sensing the spark. 
     Antenna  90  may also be configured to detect operation of the igniter during an ignition trial of the fuel-fired appliance. While the antenna  90  is shown as part of the controller  48 , it is contemplated that the antenna  90  could be located remotely from the controller  90  but in communication with the controller  90 . In some cases, the antenna  90  may detect electromagnetic interference (EMI) or electrical noise produced by the ignition assembly when it is operational (e.g. spark is present and/or current passing through electrodes). In some instances, the control module  80  is electrically connected to the antenna  90  to receive the detected signal from the antenna  90 . The control module  80  may be configured to determine operation of the ignition assembly during an ignition trial. In some embodiments, the antenna  90  can include one or more antenna elements and/or internal circuitry, such as a metal trace on a printed circuit board, acting as an antenna. However, it is contemplated that antenna  90  may be any suitable antenna that may detect EMI or electrical noise produced by the ignition assembly. If igniter operation is not detected during an ignition trial, the control module  80  may receive a signal from the antenna  90  indicating that no spark is present and, in some embodiments, the control module  80  may shut down the burner assembly  14  and/or valve  28 . 
     In some embodiments, the control module  80  may be configured to optically (using detector  88 ) and electrically (using antenna  90 ) detect operation of the ignition assembly. In other words, the control module  80  may be configured to utilize both the detector  88  and the antenna  90  in an attempt to detect the operation of the ignition module during an ignition trial. In some cases, this may provide for redundant detection, which in some cases, can be more accurate, more reliable, and more versatile. The control module  80  may be configured to determine the ignition module is non-operational when, for example, both the detector  88  and the antenna  90  indicate the ignition module is non-operational, or, in other cases, the control module may determine the ignition module is non-operational when either of the detector  88  or the antenna indicates the ignition module is non-operational. 
     Further, it is contemplated that the control module  80  may be configured to utilize only one of the detector  88  and the antenna  90  to detect operation of the ignition module, depending on the determined reliability of the detector  88  and antenna  90  for the specific installation. For example, if the ignition assembly or electrodes  62  and  64  are shielded in a particular installation, so that a sufficient amount of EMI or electrical noise may not be picked-up by the antenna, the control module  80  may be configured to operate using the detector  88  to optically detect the presence or absence of a spark. In other cases, if the detector  88 , such as CAD cell  72 , is not properly optically aligned with the spark, the control module  80  may operate using the antenna  90  to detect operation of the ignition module. In these situations, the control module  80  may be configured to determine the reliability of the detector  88  and antenna  90  for detecting operation of the ignition module, and may subsequently operate with the more reliable of the antenna  90  and detector  88 . In other cases, the control module  80  may operate using both the detector  88  and antenna  90 , such as described above. 
     Further, it is contemplated that in any of the embodiments mentioned previously, the control module  80  may be configured automatically select the more reliable of the detector  88  and antenna  90  for detecting operation of the ignition module, but this is not required. The control module  80  may determine, for example, that a particular component (e.g. detector  88  or antenna  90 ) is capable of detecting operation of the ignition module while the other component (e.g. detector  88  or antenna  90 ) is not capable of detecting operation of the ignition module. In some cases, this may be based, at least in part, on past performance of the burner. For example, if the burner repeatedly lights with the detector  88  indicating a spark is present and the antenna  90  indicating the ignition module is non-operational, the control module  80  may determine the detector  88  is reliable and the antenna  90  is unreliable. Similarly, if the burner repeatedly lights with the antenna  90  indicating operation of the ignition module and the detector  88  indicating that the spark is absent, the control module  80  may determine the antenna  90  is reliable and the detector  88  is unreliable. In other cases, the controller module  80  may determine that the detector  88  and/or antenna  90  is unreliable if a signal received from the detector  88  and/or antenna  90  indicates the ignition module is operational all the time. In any of these situations, the control module  80  may be configured to disregard the unreliable component, if desired. In some embodiments, the control module  80  may also issue an alarm (visual or audible) indicating that the detector  88  and/or antenna  90  is unreliable in determining operation of the ignition module. 
     In some embodiments, an optional spark error notification module  92  may be provided. The optional spark error notification module  92  may be configured to issue a notification or other indication to an operator or service technician if the control module  80  determines that the igniter is not operational during ignition trial. In some embodiments, the spark error notification module  92  may include an audible notification and/or a visual notification. Examples of audible notifications may include, for example, an alarm, siren, audible message, and/or other audible notification, as desired. Examples of visual notifications may include, for example, a flashing light, a constant light, a textual message displayed on a display or sent via email, and/or other visual notification, as desired. The spark error notification module  92  may alert an operator or service technician that the igniter is not providing sufficient sparking to ignite the combustible fuel during the ignition trial. 
     Although not shown in  FIG. 4 , it is contemplated that the controller  48  may include a user interface that is configured to display and/or solicit information as well as permit a user to enter data and/or other settings, as desired. In some instances, the user interface may include a touch screen, a liquid crystal display (LCD) panel and keypad, a dot matrix display, a computer, buttons and/or any other suitable interface, as desired. 
       FIG. 5  is a schematic diagram of an illustrative controller  100  including an illustrative antenna  104 . In some embodiment, antenna  104  may be used in conjunction with the controller  48  shown in  FIG. 4 . As shown in  FIG. 5 , the controller  100  may include a microcontroller  102  mounted on a printed circuit board (PCB)  108 . In some cases, the microcontroller  102  may be implemented as the control module  80  shown in  FIG. 4 , if desired. As illustrated in  FIG. 5 , the antenna  104 , which can be a metal trace  104  on the PCB  108 , may be electrically connected to a pin  109  of the microcontroller  102 . In some cases, the antenna  104  may be configured to provide a logic level low (e.g. logic 0) or a logic level high (e.g. logic 1) input to the microcontroller  102 . In the illustrative embodiments, the antenna  104  is biased to a ground pin of the microcontroller  102  via a resistor  106 . In such a configuration, the antenna  104  may be biased to provide a logic low level input to the microcontroller  102  when no EMI or electrical noise is detected. However, it is contemplated that the antenna  104  may be biased to a logic high level, such as to a supply voltage of the microcontroller  102 , if desired. In the illustrative embodiment, resistor  106  may have a relatively large resistance, such as 1 megaohm. However, this is just one example and it is contemplated that any suitable resistance, or even none at all may be used, as desired. 
     In the illustrative embodiment, EMI or electrical noise produced operation of the ignition module in the burner assembly can produce one or more interrupts in the normal logic level low signal of the antenna  104 . The microcontroller  102  may be configured to determine operation of the ignition module by determining the number of interrupts per unit of time when the ignition assembly should be sparking (e.g. activated state) and when the ignition assembly should not be sparking (e.g. deactivated state). Since a spark should generally create an increased level of EMI or electrical noise, there should be more interrupts per unit of time when the igniter is properly operating. If, however, the igniter is not properly operating, the number of interrupts per unit of time detected by the microcontroller  102  may not increase or be sufficiently high. 
       FIG. 6  is a flow diagram of an illustrative method of detecting the amount of EMI or electrical noise emitted by a spark with a controller  48  having an antenna, such as antenna  90  and antenna  104 . The illustrative method may be employed by controller  48  shown in  FIG. 4 , if desired. As shown in block  110 , the controller  48  may detect a logic level change in the signal received from the antenna  90  and  104 . In block  112 , when a logic level change has been detected (e.g. the voltage crosses a threshold voltage level), the controller  48  may increment a counter. 
     In decision block  114 , the controller  48  may determine if the counter reached a predefined count value. If the counter has not reached the predefined count value, then the controller  48  may return to block  110  and wait for the next logic level change in the signal received from the antenna. If the counter has reached the predefined count value, then in block  116 , the controller  48  may record the amount of time that was needed to reach the predefined count value. If the amount of time that was needed to reach the predefined count value was relatively small, then there may be a relatively high amount of EMI or electrical noise, which may indicate operation of the ignition module. If the amount of time needed to reach the predefined count value was relatively large, then there may be a relatively low amount of EMI or electrical noise, which may indicate the ignition module is not operating. 
       FIG. 7  is a flow diagram of an illustrative method of detecting the presence or absence of a spark during an ignition trial using an illustrative antenna, such as antenna  90  and antenna  104 . The illustrative method may be employed by controller  48  shown in  FIG. 4 , if desired. As shown in block  120 , the controller  48  may determine the time needed to reach the predefined count value when the igniter is deactivated (e.g. not sparking). In some cases, this may be determined using the illustrative method of  FIG. 6 . However, it is contemplated that the controller  48  may instead use a different method to determine the number of interrupts per unit of time, if desired. 
     Then, as shown block  122 , the controller  48  may determine the time needed to reach the predefined count value when the igniter is activated (e.g. should be sparking). In some cases, this may be determined using the illustrative method of  FIG. 6 . However, it is contemplated that the controller  48  may instead use a different method to determine the number of interrupts per unit of time, if desired. 
     In block  124 , the controller  48  may compare the time needed to reach the predefined count value when the igniter is activated and to the time needed when the igniter is deactivated. In decision block  125 , the controller may determine if the time needed when the igniter is activated is less than the time needed when the counter is deactivated. If the time needed when the ignition system is activated is less than when the ignition system is deactivated, in block  128 , the ignition module may be determined to be operational during the ignition trial. If the time needed when the ignition system is activated is not less than when the ignition system is deactivated, in block  126 , the ignition module may be determined to be non-operational during the ignition trial. Although not shown in  FIG. 7 , in some embodiments the controller  48  may issue a spark error notification when the spark is absent, but this is not required. 
       FIG. 8  is a flow diagram of an illustrative method of determining if a spark is present or absent during an ignition trial using a detector  88 . The illustrative method may be employed by the controller  48  shown in  FIG. 4 , if desired. As shown in block  132 , the controller  48  may monitor an electrical characteristic (e.g. resistance, current, voltage, etc.) of a detector  88  (e.g. CAD cell, etc.). For example, the controller  48  may monitor the electrical characteristic before, during, and/or after one or more ignition trials. In some cases, the controller  48  may track the electrical characteristic of the detector  88  and/or changes in the electrical characteristic of the detector  88  and store them in memory  84 . 
     In decision block  134 , the controller  48  may determine if the electrical characteristic of the detector  88  changed by more than a predetermined amount during an ignition trial. In some cases, the predetermined amount may be determined according to a percentage of the electrical characteristic or, in other cases, may be a change in value. Example changes in percentages may be 5 percent, 6 percent, 7.5 percent, 10 percent, 15 percent, 25 percent, 40 percent and/or other percentages, as desired. If the electrical characteristic of the detector  88  is resistance, the predetermined amount may be 5 ohms, 10 ohms, 20 ohms, 50 ohms, 100 ohms, 200 ohms, 1 kilohms, 5 kilohms, 10 kilohms, 15 kilohms, 20 kilohms, 25 kilohms, 40 kilohms, 50 kilohms, or any other change in resistance, as desired. 
     If the electrical resistance of the detector  88  was determined to have changed by more than a predetermined amount in decision block  134 , then in block  138 , the controller  48  may determine that a spark is present during the ignition trial. If the electrical characteristic of the detector  88  did not change by more than a predetermined amount, then, as in block  136 , the controller  48  may determine that a spark was absent during the ignition trial. In some embodiments, as shown in block  140 , the controller  48  may then issue a spark error notification indicating that the ignition assembly is not providing sufficient sparking. 
     In some instances, the predetermined amount can be updated or change over time. For example, if it is determined that the predetermined amount that the electrical characteristic of the detector changes in response to a detected spark begins to reduce over time, the controller may adjust the predetermined amount accordingly. Limits may be placed on the amount of adjustment. Under some circumstances, this may help reduce the number of false alarms and/or false lockouts within a fuel fired appliance. 
     Having thus described the preferred embodiments of the present invention, those of skill in the art will readily appreciate that yet other embodiments may be made and used within the scope of the claims hereto attached.