Abstract:
The present invention provides a system and single controller for receiving constant and individualized information from a plurality of air control systems. A single controller is capable of controlling and interacting with at least two separate air control systems to control an environmental characteristic, and in the process, reduces the costs associated with the manufacturing and every day operation of the individual systems. In addition, the controller is capable of intelligently communicating with the input and output devices of the system, and particularly with each individually interfaced appliance, such that the controller can adaptively control the system through the use of stored historical data.

Description:
CLAIM TO PRIORITY  
       [0001]    The present application is a divisional application of U.S. patent application Ser. No. 09/922,934, entitled “Method And Apparatus For Centrally Controlling Environmental Characteristics Of Multiple Air Systems,” filed Aug. 6, 2001, which claims priority to U.S. Provisional Application No. 60/223,026 entitled “Constant Pressure Controlled Vent System,” filed Aug. 4, 2000. The contents of both of which are hereby incorporated by reference in their entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to air control systems. More specifically, the present invention relates to a system capable of maintaining constant environmental characteristics in more than one air control system through the use of a single controller that receives and processes detailed input from each of the air control systems and interfaced appliances.  
         BACKGROUND OF THE INVENTION  
         [0003]    The need for air control systems first became apparent in the 16 th  century with the advent of chimneys in Europe. Despite improvements since then, most chimneys still operate on a natural draft system. A natural draft chimney operates by force of gravity. That is, the hot flue gases in the chimney are lighter than the surrounding ambient air. Being lighter, flue gases are displaced by cooler, heavier air and rise buoyantly through the chimney flue creating a natural draft.  
           [0004]    This natural drafting is affected by a host of environmental factors. Ambient air temperature and atmospheric pressure affect the density of the ambient air mass. If the density of the ambient air mass is reduced, the efficiency of the natural drafting is reduced as well. For example, wind can either increase draft by blowing across the intake portion of a natural drafting system creating a venturi effect, or reduce draft if turbulent. In addition, wind can cause a back draft, a reverse flow through a system. In the case of a chimney, this can cause flue gases to be vented within a building.  
           [0005]    Over the years, systems have been developed where appliances are designed to operate in modular or modulated fashion. Boilers, heaters, water heaters, and other appliances operate in groups. Each unit may fire or power up at different times in response to specific demands. As a result of this modular configuration, the demand upon the pressure, temperature, and the like, within the enclosed building can vary greatly depending on the operation of these appliances.  
           [0006]    These factors create the potential for insufficient draft and overdraft which may cause undesirable, and even unsafe conditions within the enclosed air system. In addition, failure to control the quality of air within an enclosed environment, or the flues connected to the appliances for exhausting air, may drastically impede the efficiency and general operation of the appliances since an appliance or group of appliances require specific air flow rates for optimal performance.  
           [0007]    With regard to draft systems, power venting systems have increased in popularity. The conventional power draft systems fall into two basic classes. The traditional mechanical draft system is a so-called constant volume system in which a fan provides a constant volume gas flow through a flue to carry exhaust gases to the exterior. Likewise, the mechanical draft system could also be set up to provide an intake air flow for bringing air into an enclosed environment or air system. This constant flow of air thorough an air system is inefficient and costly. Three to five thousand cubic feet per minute of air may be expelled by these systems causing loss of heat in the winter and loss of cooled air in the summer. In the case of intake flows, the mechanically drawn air brought into an air system could provide an undesirable pressure within the system. In addition, this inflexible flow of air in or out of the air system can again impede the efficiency and general operation of any appliances.  
           [0008]    In recent years, power venting systems have been implemented in HVAC, kitchen, and other systems to deal with the inherent drawbacks of a mechanical draft system. Namely, controller devices have been advanced which connect to intake and outtake fans for controlling air system characteristics in a single system. Generally, these systems are most often utilized in detecting and controlling the pressure characteristic within a vent flue. Two sensors are placed within the venting system to sense pressure changes. These sensors are in communication with one electronic controller for processing data and controlling input and output devices, such as the sensors and fan. Typically, these two switch sensors are used with one sensor defining the low pressure point and the other defining the high pressure point. Each pressure setting is defined by inputted parameters. These two pressure points define a window of acceptable pressure within the venting flue. If the pressure in the flue falls outside this window, the relevant sensor is triggered and provides a closed circuit for sending a signal to power the fan up or down, depending on which sensor is triggered. In such a system, the fan adjusts the pressure by fully powering up or down, or in the alternative, by switching to predetermined limited speeds such as high, medium, low, or some other variation. While an improvement over more traditional mechanical draft systems, this method of adjustment is costly and inefficient, and fails to make the precise system-wide adjustments needed to maintain a truly “continuous” pressure system. While such systems may be referred to as “constant” pressure systems, such a designation is not a true characterization of their operation.  
           [0009]    The innate drawback of such an “on-off” air control system is that it is incapable of providing and maintaining a constant pressure within the system. The pressure window may be so large as to permit a great range of pressure deviation before any adjustments are made by the turning on of a fan. Similarly, if the pressure window is made small in an attempt to maintain pressure, the fan is frequently turned on and off to adjust for fluctuations in pressure. On-off switches and non-variable fan motors may continuously jump through pressure levels in an attempt to maintain pressure, but they are incapable of keeping pressure at precise levels, especially when an air system is dynamically effected by the demands of multiple appliances and changing environmental factors such as wind.  
           [0010]    Even those systems that have attempted to implement a single sensor to measure and maintain a characteristic such as pressure do so using these “on-off” techniques, and inevitably jump the fan speed to predetermined and limited levels. In addition, conventional systems fail to maximize the efficiency and effectiveness, and reduce the cost, associated with controlling their systems since they implement an independent controller for each system, and fail to arm the controllers they do use with effective appliance interfacing and adaptive technology.  
           [0011]    Those conventional systems attempting to monitor and maintain an environmental characteristic, unfortunately, do assign one controller to each air control system. For example, one controller would receive sensor input and provide control over a venting system, and a separate controller would be assigned to a combustion intake system. Consequently, repetitive circuitry and control structures are required for each system, even when numerous air systems (i.e., venting, combustion, and heating) are contained within one building. This presents a significant cost problem, as well as a training and standardization problem. The cost problem is significant at the production level, and at the purchasing level. A purchaser would obviously prefer not to expend monies on a controller for each individual air control system contained within a particular enclosed environment. In addition, the training and standardization problem likely increases over time. As time passes, it is quite possible that vastly different controllers will be purchased and implemented for the different air control systems within one enclosed environment. Each controller will operate differently, varying in operating parameters, inputting methods, and other functions. Training, usage, and maintenance costs will also increase with the employment of an individual controller at each air control system. The standardization benefits and cost savings would be substantial if only one controller was used to monitor and control a plurality of air control systems.  
           [0012]    In addition, the conventional wisdom is to collectively deal with appliances within an air control system. Regardless of the individual effect of any one appliance on the system, the appliances are addressed as a group. For instance, if one appliance fires up and causes a significant pressure change in the system, and the controller is unable to control the pressure through an exhaust fan adjustment, an entire block or group of appliances will be shut down until the problem can be addressed. In addition, this restrictive view of appliance groups does not permit the system to retain historical data representative of each individual appliance tied into the overall air control system. If historical data could be stored, modified, and utilized by the controller for each appliance, efficiency and system performance could be significantly increased.  
           [0013]    For example, in the previously given scenario, it was merely the firing up of the last appliance that caused the system to exceed the bounds of the acceptable pressure parameters. Ideally, an intelligent air control system, and specifically the controller, would be operably interfaced with all of the appliances individually within the system, such that the last fired appliance would be the only appliance shut down to keep the system within the acceptable parameters.  
           [0014]    Another application of an intelligent controller centers around the ability to bypass time consuming and costly operational steps. For the sake of illustration, it would be beneficial for a controller to keep track of what system adjustments were needed under specific pressure requirements, taking into account the demands of the appliances, wind, and other factors. For example, instead of systematically adjusting fan speed to obtain a desired pressure based on a system demand, it would be more efficient to immediately adjust the speed of the fan to a specific acceptable level based on known past historical data for an identical or similar demand. This historical data could be stored and evaluated for a nearly endless array of appliance combinations, pressure requirements, and environmental factors. Such a controller would be able to learn from past operations and adapt in a manner permitting more efficient operation any time a specific situation arises in the future. Along these same lines, it would be beneficial if this valuable data regarding system operations, appliance functioning, system demand, and the like could be made available through electronic communication to other independent systems such as those used for building and facility management.  
           [0015]    As a result of each of these existing deficiencies, there is a need for an air control system which is capable of maintaining an environmental characteristic, such as pressure, at a constant rate within an enclosed environment, even when the enclosed environment is periodically subject to system-altering internal factors, such as the powering up of appliances, and external factors, such as wind gusts entering the system. Additionally, there is a need for one centralized system controller equipped to monitor and control two or more systems in their corresponding enclosed environments, doing so in a manner that reduces costs and increases efficiency and standardization. This system controller should be able to individually interface with each appliance within the air control system such that system-wide needs can be more clearly understood, enabling the controller to make more accurately focused adjustments to meet those needs. Moreover, there is a need for this controller to be equipped with adaptive technology, enabling it to again increase efficiency, and to better enable it to make informed decisions to control and maintain an environmental characteristic parameter within each attached system.  
         SUMMARY OF THE INVENTION  
         [0016]    The present invention provides an air control system which, in large part, solves the problems referred to above by providing a system and single controller for receiving constant and individualized information from a plurality of air control systems. The single controller is capable of controlling and interacting with at least two separate air control systems to control an environmental characteristic, and in the process, reduces the costs associated with the manufacturing and every day operation of the individual systems. In addition, the controller is capable of intelligently communicating with the input and output devices of the system, and particularly with each individually interfaced appliance, such that the controller can adaptively control the system through the use of stored historical data.  
           [0017]    The single controller can be attached to a plurality of air control systems controlling environmental characteristics within their own enclosed environments, with each system providing input to the controller, the controller processing the input and providing output to each system individually. In addition to the one shared controller, each system can include a separate variable speed fan, attached appliances for which the system is centered around, and an enclosed environment such as an exhaust duct for pulling air into, or pushing air out of, the system. The individual air control systems can vary in function from pressure controlled venting and combustion systems to temperature controlled heating systems. Regardless, an ideal environmental characteristic parameter, such as pressure, is inputted into the controller and the controller monitors at least one sensor, such as a transducer, for a specific sensor reading, making needed adjustments to the speed of the variable speed air intake or outtake fans to maintain a constant parameter at the inputted level.  
           [0018]    Each appliance is individually interfaced with the controller such that each appliance is individually monitored and controlled. Power for the appliances is routed through the one controller so that power up calls by the appliances are first intercepted by the controller, with approval from the controller required before any system appliance can be fired up. This power control over the appliances is continuous and permits the controller to shut down the appliances at any time, individually, or as a group.  
           [0019]    The controller includes a microcontroller microchip which is the centralized sequential logic processor for the controller and the system. The microcontroller monitors and devices attached to the controller. Control codes and algorithms in the microcontroller make this possible. In addition, the microcontroller of the present invention includes adaptive technology.  
           [0020]    The microcontroller electronically stores historical data pertaining to each of the input and output devices, and specifically, historical data relating to the operation of the interfaced appliances. With this stored historical data, the microcontroller is able to make individualized and increasingly informed decisions regarding the operation of the devices. Namely, adjustments to the system based on the demand and system-wide influence of the appliances can be analyzed based strictly on relevant appliances, with the solution specifically directed to those relevant appliances. For instance, if the appliance that last powered up is keeping the system from maintaining a constant pressure level, just that appliance can be shut down to bring the system within acceptable operational levels. In addition, historical data can improve system efficiency. By storing data depicting timing and system procedures, the microcontroller creates a reference database should future system demands require the same procedures. For example, if a specific output to the fan is needed to get the system under pressure control when a particular boiler powers up while two other boilers are powered up, the microcontroller can store that data to memory so that the next time such a procedural configuration arises, the fan can be immediately adjusted to the appropriate speed. Systematic and time-consuming measurements and adjustments can be significantly decreased by referencing and utilizing this historical data. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 shows the major aspects of the air control system in accordance with the present invention.  
         [0022]    [0022]FIG. 2 shows a circuit diagram of the controller of a preferred embodiment of the present invention.  
         [0023]    [0023]FIG. 3 shows a circuit diagram of the appliance interface circuitry in a preferred embodiment of the present invention.  
         [0024]    [0024]FIG. 4 shows a wiring and circuit diagram of communication between a venting fan and the controller of a preferred embodiment of the present invention.  
         [0025]    [0025]FIG. 5 shows a wiring diagram for the parallel control device, microcontroller, and serial interface of a preferred embodiment of the present invention.  
         [0026]    [0026]FIG. 6 shows a wiring diagram of the appliance interface of a preferred embodiment of the present invention.  
         [0027]    [0027]FIG. 7 shows a wiring diagram of sensor connections to analog-to-digital and digital-to-analog converters for a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Referring to FIG. 1, a preferred embodiment of the air control system  10  of the present invention is shown. The air control system  10  generally includes an electronic controller  12 , at least one variable speed fan  14 , at least one enclosed environment  16 , and at least one sensor  18 .  
         [0029]    The air control system  10  is primarily housed within the confines of a building or enclosed structure. However, specific system components can be housed elsewhere, such as outside of the building on a roof or on the exterior surface of a wall.  
         [0030]    The controller  12  of a preferred embodiment of the present invention is detailed in FIG. 2. The controller  12  ordinarily comprises the following input and output (I/O) devices: sensor inputs  20 ,  22 ,  24 ,  26 , a power supply interface  32 , prover circuitry  34 , fan control circuitry  36 , appliance interfaces  38 ,  40 , appliance expansion board interfaces  42 ,  44 ,  46 , display circuitry  48 , keypad circuitry  50 , a display  54 , a keypad  56 , and a serial interface  57 . Additionally, the controller  12  comprises a microcontroller  28 , and a parallel device controller  30 . A memory  52  is preferably contained within microcontroller  28  and handles all of the electronic data storage for the controller  12 .  
         [0031]    The above listed components and circuitry of the controller  12  are contained on a circuit board with each I/O device being in electronic communication with the microcontroller  28  and the parallel device controller  30 , with the parallel device controller  30  generally providing intermediate communication between each I/O device and the microcontroller  28 .  
         [0032]    Referring to FIGS. 1 and 4, the power supply interface generally accepts a switchable 120/230 VAC 50/60 Hz fused power supply for powering the controller  12 . The fan  14  generally comprises a variable speed drive  60  which is a variable speed motor capable of receiving varying signals for adjusting the speed at which the motor runs, and consequently turns the fan. The variable speed motor described in U.S. patent application Ser. No. 09/774,277 is hereby incorporated by reference as an example of a motor which can be used to drive the fan  14 . The fan control circuitry  36  of the controller  12  controls this signal to the fan  14  motor.  
         [0033]    The enclosed environment  16  of a preferred embodiment of the present invention is the area for which the air control system  10  maintains specific characteristics such as pressure, heat, airborne particulates, and the like. For instance, the vent ducts  62  connected within a building for exhausting gases, heat, or for simply transferring controlled air from one area to another, is an enclosed environment  16 . In addition, the building itself, and any individual room  64  or section within a building could be the enclosed environment  16  for purposes of the air control system  10  of the present invention.  
         [0034]    The sensor  18  of a preferred embodiment of the present invention is a transducer pressure sensor  18 . However, any variable sensor could be substituted without deviating from the scope of the invention. Namely, a heat sensor  18  and a particulate sensor  18  are examples of sensors envisioned as being compatible with the air control system  10 .  
         [0035]    Appliances  72 ,  74 ,  76  are interfaced and connected to the controller  12  via the appliance interfaces  38 ,  40 , and additional appliances are interfaceable via further connections supplied by the expansion board interfaces  42 ,  44 ,  46 . As a result, it should be understood that the use of a finite number of appliances is only for the purpose of illustration and explanation and is not to be interpreted as limiting the number of appliances interfaceable with the controller  12 . For example, a preferred embodiment of the controller  12 , as seen in FIG. 2, shows two appliance interfaces  38 ,  40  on the controller  12  circuit board, and expansion board interfaces  42 ,  44 ,  46  for interfacing numerous additional appliances. For explanation purposes, discussions of appliances will generally be directed to fuel burning appliances such as boilers, water heaters, and furnaces. However, it is envisioned that other appliances, including non-fuel-burning appliances will be just as interfaceable with the controller  12 .  
         [0036]    The at least one sensor  18  is in electronic communication with controller  12  with the sensor  18  being placed somewhere in the enclosed environment  16 , such as in the vent duct  62  for venting configurations, and within the room  64  for combustion intake configurations. For communication between the sensors and the controller  12 , analog-to-digital and digital-to-analog converters are used, as shown in FIG. 7. Analog-to-digital converters are used to convert the analog sensor  18  signals for use by the controller  12 . Digital-to-analog converters are used to convert the controller  12  communications for use by the variable speed fan  14 .  
         [0037]    The fan  14  is also in electronic communication with the controller  12 , with the fan  14  location within the enclosed environment  16  depending upon the particular focus or configuration of the system  10 . For instance, in a venting air control system  100  for venting exhaust from a vent duct  62 , the fan  14  is preferably located at the end of the duct  62 , which feeds outside the system  100 . For comparison purposes, in a combustion air control system  200  for bringing ambient air into the system  200 , the fan  14  can be located somewhere in the room  64  with communication with the exterior.  
         [0038]    The display  54  and the keypad  56  are in electronic communication with the controller&#39;s  12  display circuitry  48  and keypad circuitry  50 , respectively.  
         [0039]    In operation, the air control system  10  controls environmental characteristics within at least one enclosed environment  16  primarily by using a controller  12  and a variable speed fan motor  14 , adjusting the characteristics so that an environmental characteristic parameter is continuously monitored and maintained.  
         [0040]    In a preferred embodiment, as seen in FIGS. 2 and 3, the continuous monitoring and maintenance of the parameter setting is controlled by the controller  12 , with the controller  12  obtaining sensing input from at least one sensor  18  at one of the sensor inputs  20 ,  22 ,  24 ,  26  on the controller  12 . For the purpose of describing a preferred embodiment, pressure will be the designated environmental parameter, and the parameter will be sensed by a transducer pressure sensor  18 , with the variable data from the transducer  18  being fed into the controller  12  through sensor input  20 . Multiple sensors  18  can be controlled by the controller  12  through one of the multiple sensor inputs  20 ,  22 ,  24 ,  26 .  
         [0041]    The keypad  56  of the controller  12  is designed to take input for setting the desired parameter characteristic (i.e., temperature, pressure, or particulate density) and a numeric parameter setting (i.e., a −0.10 in WC pressure setting) which the system  10  will achieve and continuously maintain. In addition, the controller  12  can be configured to receive inputted data at the keypad  56  relating to safety shut-offs, setup settings, and other similar inputs. Located proximate the keypad  56  is the display  54  which, in a preferred embodiment, is a two-line display visually outputting the inputted pressure parameter along with the actual real-time pressure reading from the transducer  18 . The display  54  and keypad  56  are controlled by the FPGA  30 , which is in turn controlled by the microcontroller  28 .  
         [0042]    Still referring to FIGS. 2 and 3, a preferred embodiment of the controller  12  depicts a unit capable of controlling at least two different, and possibly autonomous enclosed environments  16 . Rather than using an individual controller for each environment, as is the conventional practice, this controller  12  shares common circuitry to read and process incoming sensor  18  data, and to provide the output signal to the appropriate fan  58  for controlling the variable speed drive  60  of the fan  60 , for maintaining a constant pressure within the environment  16 . For example, one sensor  18  may feed data back from a combustion intake system  100 , while another may receive feedback from a venting system  200 . The parameter settings, such as pressure, are inputted at one controller  12 , with the one controller  12  controlling the pressure in each environment  100 ,  200 .  
         [0043]    The readings from sensor  18  are fed back to the controller  12  through a sensor input  20 . Generally, this data is communicated to the FPGA  30  at the rate of approximately 50,000 times a second with the microcontroller  28  preferably only samples at a rate which is a fraction of that, such as 10 times a second. This rate can be adjusted according to the needs of the particular system by having the microcontroller  28  increase the sampling rate. This selective monitoring is indicative of all interactions between the microcontroller  28  and the I/O devices. In conventional controllers, the microcontroller is equipped with an operating system such as a Real Time Operating System (RTOS) in addition to the processing and sampling control code. RTOS provides control over the I/O devices. I/O signals are queued up within the microcontroller  28  for processing. However, this additional processing task, within small and relatively inexpensive microcontrollers, reduces sampling accuracy and reduces the ability of the microcontroller to use processing resources to process increasingly complex sampling algorithms and procedures.  
         [0044]    A preferred controller  12  of the present invention uses the parallel device controller  30 , such as a field programmable gate array (FPGA), so that a microcontroller operating system is not required within the microcontroller  28  to control and organize the I/O devices. Instead, all I/O communication goes through the FPGA  30 , with the microcontroller selectively receiving input data from the FPGA  30  for processing, and sending output data to the FPGA  30  for routing to connected devices, as shown in FIG. 5. It is then easier to incorporate true sample data control strategies imbedded within the microcontroller  28  without the restriction imposed by RTOS. However, it is envisioned that alternative embodiments of the present invention could utilize a microcontroller using an operating system rather than a parallel device controller.  
         [0045]    Referring to FIG. 3 and FIG. 6, the circuitry central to interfacing the appliances to the controller  12  is shown. Appliance interfaces  38 ,  40  receive appliances through a wired electronic connection such that there are, generally speaking, two lines of communication between the controller  12  and the appliance, an input line from the internal activation controls of the appliance to the controller  12  and an output line from the controller  12  back to the appliance. Appliances with control circuitry in the voltage range of 18 to 240 VAC are generally preferred in a preferred embodiment. A boiler appliance  72  will be used as an example to describe the interaction between an appliance and the controller  12  at appliance interface  38 . Controls lines coming from the appliance  72  are fed directly into the controller  12 , with the appliance  72  needing a closed circuit through the appliance interface  38  in order to activate the boiler appliance  72  for any requested operational requests at the appliance  72 . This closed circuit is preferably provided by the switching of a relay switch  41 . Identical interfaces are available for each appliance connected to the controller  12 .  
         [0046]    When the appliance  38  needs to start up, the appliance  38  will initiate its start up procedures. This start up request will be intercepted by the controller  12  through the appliance interface  38 , and will be processed by the microcontroller  28 . Selected data relating to the appliance power up requests can be stored in memory  52  for later use by the microcontroller  28 .  
         [0047]    If the microcontroller  28  determines that power up of the appliance  72  is allowable, the circuit will be closed, thus triggering the relay switch  41 , and start up will be granted for the appliance  72  to begin operation. The microcontroller  28  can place restrictions on start up. For example, start up may only be granted when readings from sensor  18  are within a specific range, after a specific time, within a specific time interval, if other appliances are not currently up on the system  10 , or based on a myriad of other computations and processing algorithms within the microcontroller  28 .  
         [0048]    The controller  12  interface with each appliance is continuous. Furthermore, at any point, the controller  12  can deny activation to the interfaced appliance. Specifically, this becomes important in dealing with system-wide difficulties in maintaining a specific environmental parameter, such as pressure. If the controller  12  is unable to maintain a requisite parameter setting, such as pressure, power adjustments are first made to the fan  14  in an attempt to bring the deviating pressure within the enclosed environment  16  under control. If the microcontroller  28  determines that if after a specific time count, such as 10 seconds, the variable adjustments to the fan  14  have failed to rectify the problem (the inputted pressure parameter is not met), an adjustment on the demands of the system  10  will be addressed before performing a general shut down of all the interfaced appliances. For instance, using the previous boiler analysis, the microcontroller  28  will review the stored time data for power ups in memory  52 . The last appliance to start up will be pulled from this data and the appliance interface  38  circuitry within the appliance  72  will be opened so that the appliance  72  is shut down. Using control code and algorithms imbedded within the microcontroller  28 , similar decisions can be made by the microcontroller  28  due to the individual information being stored for each appliance and the ability of the microcontroller  28  to selectively control each individual appliance interfaced with the controller  12  through the appliance interfaces  38 ,  40  and any expansion board interfaces  42 ,  44 ,  46 .  
         [0049]    In addition to the storage of appliance interface data, the microcontroller  28  can also direct other data to be stored within memory  52 . Data from I/O device signals being directed to the microcontroller  28  can be selectively stored to memory  52  in conjunction with corresponding timing information from an internal clock. For example, the microcontroller  28  can retrieve from memory  52  the exact speed the fan  14  was at when a specific pressure reading was reached and maintained, the pressure reading the last twenty times a specific interfaced appliance powered up, and the time required over the last two hundred appliance power ups for a fan  14  to get the pressure in the system up to the inputted level. The microcontroller  28  can rely on the stored data in making system control decisions. For instance, if the controller  12  receives a pressure reading indicating that the pressure in the enclosed environment  16  is beyond the set level, an adjustment will be made to the fan  14  speed. Historical data in memory  52  can assist the microcontroller  28  in more efficiently reaching the requisite pressure. If data has been stored in memory  52  indicating, for example, the average output signal required to get the fan  14  up to speed to obtain a specific pressure level when specific powered up appliances are effecting the pressure within the system, and those same factors are currently at play, the controller  12  can immediately send the appropriate output signal to the fan  14 . This gives the controller  12  the flexibility to avoid the sequential process of receiving a sensor reading from the sensor  18 , making a speed adjustment to the fan  14 , taking another reading, and continuing this process until the desired sensor reading has been obtained. Instead, the controller  12  can send a signal to the fan  14  which immediately takes the fan  14  to a speed that has historically solved the pressure problem in the past. After that, pressure readings from sensor  18  and processing at the microcontroller  28  will determine whether additional adjustments to the speed of the fan  14  must be made. Again, while pressure was used as the example here, the specific sensor and environmental characteristic can vary greatly, as already described.  
         [0050]    The stored historical data can be used by the microcontroller  28  to make internal control decisions for operating all I/O devices of the controller  12 , and the data can be used in communications with external electronic systems, such as a building management computer control system, interfaced with the controller  12  via the serial interface  57 . The data stored in memory  52  can be selectively provided to serial interface  57 , and instructions and/or data can be downloaded from the external electronic system to be selectively stored and processed by the microcontroller  28 .  
         [0051]    In a preferred embodiment of the present invention a prover switch  33  is operably connected to the controller  12  and is in fluid communication with the enclosed environment  16 . The prover switch  33  is a mechanical safety backup for shutting down all appliances when the controller  12  is incapable of keeping the system  10  within a predetermined acceptable parameter level after a specified period of time. The prover switch  33  preferably has a predetermined set pressure point generally equivalent to the operating level of the transducer  18 . If, for instance, the transducer  18  malfunctions and is incapable of providing accurate readings, and as a result, the controller is unaware of deviating pressure readings within the enclosed environment  16 , the prover switch  33  will shut down the appliances until corrections are made. The prover switch  33  is operably connected to the controller  12  through the prover circuitry  34 , allowing for shut down control of the interfaced appliances.  
         [0052]    The prover switch  33  operates using a prover orifice  35  that shares the fluid communication between the prover switch  33  and the enclosed environment  16 . The orifice  35  retards the pressure to the prover switch  33 , providing a slow pressure release effect through the switch  33 , thus establishing a predetermined duration of time, or grace period, for pressure adjustments to take place before shut down procedures will be initiated. This grace period prevents undesirable false shut downs that occur under conventional mechanical backup techniques. If the orifice  35  effect passes and the pressure level is still not acceptable, appliances will be shut down as the prover switch  33  will communicate shut down to the controller  12  through the prover circuitry  34 . The amount of time allowable is generally 10 seconds, and is determined by the configuration and size of the orifice  35 . This window of allowable adjustment time of 10 seconds is preferable in light of current regulations regarding pressure venting systems.  
         [0053]    The present invention may be embodied in other specific forms without departing from the essential attributes thereof, therefore, the illustrated embodiment should be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.