Patent Publication Number: US-2011056479-A1

Title: Variable ventilation method and system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. Provisional Patent Application No. 61/240,472, filed on Sep. 8, 2009 and entitled “Variable Ventilation Method and System,” the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates to a variable ventilation system. More specifically, the present disclosure relates to a variable ventilation system for a kitchen wherein exhaust rates are determined based upon the current operation of one or more kitchen appliances. 
     Commercial kitchen ventilation systems, such as those in most restaurants, serve several purposes. Primarily, ventilation systems are configured to draw air away from one or more appliances, thereby dissipating excess heat created by various kitchen appliances, removing any smoke or air-borne particulate created during a cooking process, and eliminating any odors or smells produced during the cooking process. Typical kitchen ventilation systems include one or more hoods positioned above one or more kitchen appliances, ducting connecting the hoods to one or more exhaust fans, and the exhaust fans which regulate the amount of air sucked through the hoods, thereby determining the amount of ventilation. 
     One important consideration when designing a ventilation system is to determine the amount of air removed from the kitchen during the ventilation process. Depending on the arrangement of the kitchen and the ventilation system, air may also be removed from the restaurant by the ventilation system. Any air removed from the kitchen and/or restaurant must be replaced or a low pressure vacuum is created, causing potential problems such as difficulty in opening doors in the restaurant area. Thus, air must be replaced in volume substantially equal to the volume of air removed by the ventilation system. Typically, depending on the climate in which the kitchen/restaurant is located, this air must be conditioned before being returned to the restaurant. For example, in cooler climates during winter, the air must be heated before being returned to the kitchen and/or restaurant as “make-up air.” Similarly, in warmer climates in the summer, air must be cooled before being returned to the kitchen and/or restaurant. 
     Conditioning the make-up air can be a great expense to a restaurant. Thus, money is lost when conditioned air is unnecessarily exhausted. When only a few appliances are operating, such as during a slow dining time between common meal times, early in the morning or late at night, the ventilation system may be running at too high of a level, thereby sucking conditioned air from the restaurant that does not need to be ventilated. 
     Variable ventilation systems have been designed to address this drawback. Variable ventilation systems use various techniques to provide multiple ventilating levels. The simplest approach is to use a multi-speed exhaust fan with manual controls. The manual control allows an operator to set the individual exhaust fans speeds. This has inherent drawbacks however as an operator must monitor the kitchen appliance use and determine an appropriate ventilation level. If the operator does not adjust the ventilation system when one or more additional appliances are turned on, the ventilation system may not be able to handle the heat, smoke and/or odor produced by the increased number of cooking events or appliances operating. 
     Another approach is to use a sensor system to determine the temperature of the air, the temperature of any appliances, and the level of smoke or air-borne particulates. Based upon these levels, the ventilation level may be determined. However, these are gross approximations as to the overall condition of the kitchen as only the environments directly around the sensors are determined. Thus, these gross approaches can still lead to conditioned air being wastefully ventilated. 
     SUMMARY 
     This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope. 
     As used in this document, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this document is to be construed as an admission that the embodiments described in this document are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term “comprising” means “including, but not limited to.” 
     In one general respect, the embodiments disclose a system for providing variable ventilation for a cooking environment. The system includes a plurality of cooking appliances, wherein each appliance has various operating parameters indicative of a cooking level of each appliance; a cooking event monitor operably connected to each of the cooking appliances and configured to: (1) determine a level of ventilation for each of the plurality of appliances based upon the cooking level of each appliance, (2) determine a control signal based upon the determined level of ventilation, and (3) transmit the control signal; a motor speed controller operably connected to the cooking event monitor and configured to receive the control signal; and at least one exhaust fan operably connected to the motor speed controller, wherein the motor speed controller adjusts a speed of the exhaust fan based upon the control signal. 
     In another general respect, the embodiments disclose a system for providing variable ventilation for a cooking environment. The system includes a cooking event monitor configured to be operably connected to each of a plurality of cooking appliances and configured to: (1) query a database stored on a computer readable medium operably connected to the cooking event monitor to determine a cooking level of each appliance based upon one or more operating parameters of each appliance, wherein each operating parameter is indicative of a cooking level of the appliance, (2) query the database to determine a level of ventilation for each appliance based upon the determined cooking level of each appliance, (3) determine a control signal based upon the determined level of ventilation, and (4) transmit the control signal; and a motor speed controller operably connected to the cooking event monitor and configured to receive the control signal, wherein the motor speed controller is further configured to adjust the speed of an exhaust fan based upon the control signal. 
     In another general respect, the embodiments disclose a method for providing variable ventilation for a cooking environment. The method includes determining, at a cooking event monitor, one or more operating parameters for each of a plurality of appliances operably connected to the cooking event monitor; querying, by the cooking event monitor, a database stored on a computer readable medium operably connected to the cooking event monitor to determine a cooking level of each appliance based upon the operating parameters of each appliance; querying, by the cooking event monitor, the database to determine a level of ventilation for each appliance based upon the determined cooking level of each appliance; transmitting, by the cooking event monitor, a control signal based upon the determined level of ventilation; receiving, at a motor speed controller operably connected to the cooking event monitor, the control signal; and adjusting, by the motor speed controller, a speed of at least one exhaust fan operably connected to the motor speed controller based upon the control signal. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  illustrates an exemplary embodiment of a variable exhaust ventilation system. 
         FIG. 2  illustrates an exemplary process for determining a ventilation level according to an embodiment. 
         FIG. 3  illustrates an exemplary embodiment of a variable exhaust ventilation system. 
         FIG. 4  illustrates various embodiments of a computing device for implementing various methods and processes described herein. 
     
    
    
     DETAILED DESCRIPTION OF THE FIGURES 
       FIG. 1  illustrates an exemplary variable exhaust ventilation (VEV) system  100 . In the VEV system  100 , a cooking event monitor  102  may measure one or more aspects of operation that may be used to determine the various operating parameters of one or more appliances  104 . The cooking event monitor  102  may include a memory and software/firmware configured to measure and/or calculate one or more operating parameters of the appliances  104  based upon one or more measured characteristics of the appliances. For example, if the appliance  104  is a multi-vat deep fryer, the cooking event monitor  102  may detect how much current the multi-vat deep fryer is using via a current sensor integrated into the electrical connection of the multi-vat deep fryer. Based upon this detected current level, the cooking event monitor  102  may determine how many of the vats of the deep fryer are currently cooking. The cooking event monitor may then determine what level of ventilation is required for the deep fryer. 
     For example, when a three-vat deep fryer is installed in a kitchen, the manufacturer of the fryer may provide a recommended ventilation level. An exemplary fryer may require a ventilation level of 1000 cubic feet per minute (CFM) of air flow for proper ventilation at full capacity (i.e., all three vats of the deep fryer cooking a product). However, when installed, the three-vat deep fryer may be tested with various food products at various cooking levels. For example, the three-vat deep fryer may be tested with only one vat cooking, two vats cooking, and all three vats cooking. During these tests, multiple ventilation levels may be used to determine adequate ventilation levels for each cooking level. For example, zero or one vats cooking may require 60% of the manufacturer&#39;s recommended level of ventilation at full capacity (e.g., 600 CFM). Two vats cooking may require 80% of the manufacturer&#39;s recommended level of ventilation (e.g., 800 CFM), and three vats cooking may require 100% of the manufacturer&#39;s recommended level of ventilation (e.g., 1000 CFM). After testing, a database, or other data structure like a linked list, may be produced or supplemented to include cooking level indicators such as current usage patterns at various cooking levels, as well as proper ventilation levels for the three-vat deep fryer corresponding to the various cooking levels. Based upon a monitored current usage pattern at the deep fryer, the cooking event monitor may reference this database to determine (1) the current cooking level of the three-vat deep fryer (i.e., how many vats are cooking product) and (2) the corresponding ventilation level for the three-vat deep fryer as determined based upon the current cooking level. 
     Similar to detecting current usage at an appliance, the cooking event monitor  102  may detect the position of a solenoid on a gas supply line, thus approximating the amount of gas being supplied to a multi-vat deep fryer. Based upon this approximation, the cooking event monitor  102  may reference the database to determine at what cooking level the multi-vat deep fryer is operating and, accordingly, the level of ventilation for that individual multi-vat deep fryer. Similar approaches may be used for other appliances  104 . For example, the cooking event monitor may detect a level of current being used by a multi-platen grill via a current sensor integrated into the electrical connection of the multi-platen grill. Current usage or patterns of use may indicate whether an individual platen is being used to cook a food product. Similarly, current sensing may be used to determine the position of individual platens on a multi-platen grill to determine whether an individual platen is positioned down in a cooking position or up in a non-cooking position. Based upon a monitored current usage pattern, the cooking event monitor may reference the database to determine how many platens of the multi-platen grill are currently cooking as well as a proper level of ventilation for that multi-platen grill. 
     Similar to the multi-vat deep fryer discussed above, the multi-platen grill may be tested during installation to determine proper levels of ventilation for each level of cooking as compared to the manufacturer&#39;s recommended level of ventilation for full capacity. 
     For example, when a three-platen grill is installed in a kitchen, the manufacturer of the three-platen grill may provide a recommended ventilation level. An exemplary three-platen grill may require a ventilation level of 1500 CFM of air flow for proper ventilation at full capacity (i.e., all three platens of the grill cooking a product). However, when installed, the three-platen grill may be tested with various food products at various cooking levels. For example, the three-platen grill may be tested with only one platen cooking, two platens cooking, and all three platens cooking. During these tests, multiple ventilation levels may be used to determine adequate ventilation levels for each cooking level. For example, zero or one platens cooking may require 60% of the manufacturer&#39;s recommended level of ventilation at full capacity (e.g., 900 CFM). Two platens cooking may require 80% of the manufacturer&#39;s recommended level of ventilation (e.g., 1200 CFM), and three platens cooking may require 100% of the manufacturer&#39;s recommended level of ventilation (e.g., 1500 CFM). After testing, the database may be updated to include cooking level indicators such as current usage patterns at various cooking levels, as well as proper ventilation levels for the three-platen grill corresponding to the various cooking levels. Based upon a monitored current usage pattern at the three-platen grill, the cooking event monitor may reference the database to determine (1) the current cooking level of the three-platen grill (i.e., how many platens are cooking product) and (2) the corresponding ventilation level for the three-platen grill as determined based upon the current cooking level. 
     It should be noted that current usage monitoring and determining as discussed above to determine a cooking level of an appliance is shown by way of example only. Additional sensors and monitoring techniques may be incorporated as well. For example, an appliance may include a built-in timer that is started when a cooking cycle begins. The cooking event monitor  102  may monitor the activity of the timer to determine when an appliance has changed its cooking level (e.g., when a vat of a deep fryer begins a cooking cycle). 
     By having or acquiring information related to the current cooking levels at each individual appliance  104  installed in the kitchen such as current usage patterns, as well as having access to the database storing the various operating parameters for each cooking level and corresponding ventilation levels for each appliance, the cooking event monitor  102  may determine what ventilation level is required for each appliance based upon the present cooking level of that appliance. 
     The VEV system  100  may also include one or more intelligent or “smart” appliances  104 . A smart appliance may include one or more microprocessors that monitor and record activity and current operating parameters such as cooking level for the appliance. The smart appliance may be operably connected to the cooking event monitor  102  via a data network. The smart appliance may be capable of transmitting various operating parameters to the cooking event monitor  102  such as cooking status, cooking temperature, time since transitioning to cooking mode, and other related information. Thus, a smart appliance may eliminate any sensors used to monitor the operating parameters and cooking level of an individual appliance. Rather, the one or more microprocessors of the smart appliance may communicate directly with the cooking event monitor, thereby directly transmitting the operating parameters and cooking level of the smart appliance. It should be noted that the VEV system  100  may include all conventional appliances  104 , all smart appliances, or a combination of both types of appliances. 
     It should be noted that the cooking event monitor  102  and the corresponding database may be pre-programmed for a specific collection of appliances  104  that are located in a cooking area such as a kitchen or restaurant section. For example, if a typical fast food restaurant uses a common set of appliances  104 , the cooking event monitor  102  may be programmed in firmware with various information related to that common set of appliances such as heat and amount of smoke produced during standard operation, maximum required level of ventilation, warm-up and cool-down times, and other operational information. Conversely, the cooking event monitor  102  may be programmed via software on-site for a unique collection of appliances  104 . Both alternatives, however, may share common algorithms for determining appliance operating parameters and related ventilation levels. Exemplary algorithms, along with an exemplary process for determining ventilation levels, are discussed below with respect to  FIG. 2 . 
     The database configured to store operating parameters and information related to cooking levels and the corresponding ventilation levels may be included on a computer readable medium integrated in or operably connected to the cooking event monitor. 
     The cooking event monitor  102  may be operably connected to a motor speed controller  106 . Similarly, the motor speed controller  106  may be operably connected to one or more exhaust fans  108 . Depending on the design of the kitchen or area to be ventilated, each appliance  104  may have a corresponding exhaust fan  108 . An exhaust hood may be placed above the appliance  104  and ducting may be placed between the exhaust hood and the corresponding exhaust fan  108  such that any heat, smoke, odor or other by-product produced by the appliance is ventilated via the corresponding exhaust fan. It should be noted that multiple appliances may share a single exhaust fan  108 . Alternatively, a large appliance may be ventilated via multiple exhaust fans  108 . 
     The cooking event monitor  102  may be configured to communicate a control signal including a determined level of ventilation to the motor speed controller  106 . Depending on the configuration of both the cooking event monitor and the motor speed controller, the control signal may be a digital control signal including what exhaust fan  108  to adjust the speed of as well as a value for speed. For example, the control signal may read as “fan 001 at 80%.” Based upon the control signal, the motor speed controller  106  may adjust the speed of one or more of the exhaust fans  108  to achieve the desired level of ventilation for the current appliance use. To continue the above example, the motor speed controller  106  may adjust exhaust fan 001 to 80% of its rated speed. As the cooking level of an appliance  104  changes, the cooking event monitor  102  may detect the change based upon either a signal received from a smart appliance or based upon operating parameters monitored at the appliance (e.g., current usage patterns). Based upon this detected change in cooking level, the cooking event monitor  102  may determine an updated level of ventilation, and communicate a new control signal including the updated level of ventilation to the motor speed controller  106 . In response to receiving the updated level of ventilation, the motor speed controller  106  may adjust the speed of one or more of the exhaust fans  108 . To continue the above example, the cooking event monitor  102  may update the control signal to be “fan 001 at 60%.” Based upon this control signal, the motor speed controller  106  may adjust exhaust fan 001 to 60% of its rated speed. 
     It should be noted that exhaust fans  108  may be three phase fans, single phase fans, and may be single speed or multi-speed (e.g., high, medium, low and off) in operation. The motor speed controller  106  may be a variable frequency drive (VFD) or similar circuit, such as a triac controller, configured to control the exhaust fans at variable speeds. Thus, using a combination of the VFD controller and a single speed fan, multiple fan speeds may be used. Alternatively, instead of a motor speed controller, another form of control may be used. 
     It should also be noted that the motor speed controller  106  may be configured such that all exhaust fans  108  are run at 100% when the VEV system  100  is initiated. Once cooking levels and corresponding ventilation levels for each appliance  104  is determined by the cooking event monitor  102 , the motor speed controller  106  may then reduce the ventilation levels of one or more exhaust fans  108 . 
     It should also be noted that the VEV system  100  may include various other appliances  104 . For example, the appliances  104  may include a single-vat deep fryer or a single-platen grill. For these such appliances, the exhaust level may be set at 60% when the appliance is not cooking, and 100% when the appliance is cooking. Various other appliances  104  may be include, and the above discussed appliances are included by way of example only. 
     The motor speed controller  106 , or a different motor speed controller, may also be in communication with the make-up air system  110 , e.g., the air conditioning units. Based upon the level of ventilation being created by the exhaust fans  108 , the motor speed controller  106  may communicate to the make-up air system  110  what level of make-up air should be produced to maintain a constant pressure level in the cooking area and/or restaurant. For example, if the ventilation level for all exhaust fans is halved, the motor speed controller  106  may indicate to the make-up air system  110  to produce less conditioned make-up air, thus reducing the operating cost of the make-up air system while maintaining building air balance or pressure. 
       FIG. 2  illustrates an exemplary process for determining the operating parameters and, thus, cooking level and corresponding ventilation levels for one or more appliances at a cooking event monitor (e.g., cooking event monitor  102 ), and adjusting the level of ventilation for each appliance accordingly. The cooking event monitor may determine  202  one or more operating parameters for each appliance. Operating parameters may include, for example, cooking temperature, cooking time, amount of current being used by an appliance, amount of gas being used by an appliance, and other related information. The operating parameters may be collected via one or more sensors such as current sensors, timer activation sensors, gas flow sensors, or other similar sensors. The operating parameters may also be received directly from a microprocessor integrated into a smart appliance as discussed above. Based upon the determined operating parameters, the cooking event monitor may determine  204  a cooking level at each appliance. For example, the cooking event monitor may determine  202  that a current usage pattern for a specific appliance is spiking every 10 seconds to a particular level. The cooking event monitor may query the database of operational parameters, cooking levels and corresponding ventilation levels. The query may include this usage pattern and any additional monitored operating parameters. Based upon the query, the database may be searched and the cooking level for that appliance may be determined  204 . Based upon the determined  204  cooking level, the cooking event monitor may further query the database to determine  206  a corresponding ventilation level for the appliance. It should be noted that the determinations  204  and  206  of both the cooking level and corresponding ventilation level may be combined into a single query and are shown herein as two queries merely for exemplary purposes. 
     For example, the cooking event monitor may determine  202  various operating parameters for a multi-vat deep fryer. The operating parameters include a gas usage reading. Based upon this operational parameter, the cooking event monitor may query the database and determine  204  that one vat of the multi-vat deep fryer is being used to cook a product. The cooking event monitor may further query the database to determine  206  the corresponding ventilation level for the multi-vat deep fryer when one vat is being used to cook. 
     In addition to querying a database, additional algorithms or logic may be used to determine  206  a corresponding ventilation level for an appliance. For example, a software routine may be run including a series of if-then statements. For example, a software routine for a three-vat fryer may include “if zero vats are cooking, ventilation equals 60%; if one vat is cooking, ventilation equals 60%; if two vats are cooking, ventilation equals 80%; if three vats are cooking, ventilation equals 100%.” Similar software programs may be written for other appliances. Likewise, the software may be updated throughout the life of the appliance to adjust the percentages or other values used as based upon historical operation data or the introduction of a new menu item. 
     After determining  206  a level of ventilation for each appliance, the cooking event monitor may transmit  208  a control signal to a motor speed controller. The control signal may be a digital signal indicating an exhaust fan and a speed adjustment value. The motor speed control may adjust the speed of one or more exhaust fans based upon the control signal. The cooking event monitor may continue to monitor the various appliances to determine  210  if there are any changes to the operating parameters for the appliances. If there are no changes, the cooking event monitor may continue to monitor  212  the appliances. If the cooking event monitor determines  210  there is a change to the operating parameters of one or more appliances, the cooking event monitor may determine  202  the new operating parameters and the process for determining a level of ventilation is repeated. 
       FIG. 3  illustrates an alternative exemplary VEV system  300  using a single, central exhaust fan  308 . Similar to the VEV system  100 , in the VEV system  300 , a cooking event monitor  302  may measure one or more aspects of operation that may be used to determine the various operating parameters of one or more appliances  304 . Based upon these various determinations, the cooking event monitor  302  may determine the cooking level at each appliance as well as the corresponding level of ventilation for each of the appliances  304 . This determination may include querying a database listing various operating parameters, cooking levels and corresponding ventilation levels for each appliance. 
     The cooking event monitor  302  may be operably connected to a motor speed controller  306 . Similarly, the motor speed controller  306  may be operably connected to the central exhaust fan  308 . The central exhaust fan  308  may be operably connected to a manifold configured to receive ducts from each of the appliances  304  such that the central exhaust fan may ventilate each appliance simultaneously. 
     Based upon the determined level of ventilation for each appliance  304 , the cooking event monitor  302  may determine a level of ventilation for the entire kitchen. As a single central exhaust fan  308  may be used, the ventilation level at the central exhaust fan may be determined based upon the highest level of ventilation required by an individual appliance. Thus, the cooking event monitor  302  may use a “highest wins” logical algorithm to determine a ventilation level to send to the motor speed controller  306 . For example, the cooking event monitor  302  may determine based upon a database query that a multi-vat deep fryer is using two vats to cook, and thus requires 800 CFM, or 80% of the manufacturer&#39;s recommended ventilation level for a full cooking load. The cooking event monitor  302  may also determine based upon a database query that a three-platen grill is using one platen to cook, and thus requires 900 CFM, or 60% of the manufacturer&#39;s recommended ventilation level for a full cooking load. Thus, the cooking event monitor  302  may determine the corresponding ventilation level for the kitchen as 900 CFM. However, if a third vat of the multi-vat deep fryer is being used to cook, the cooking event monitor may determine that the multi-vat deep fryer requires 1000 CFM, or 100% of the manufacturer&#39;s recommended ventilation level. Thus, the cooking event monitor  302  may determine the corresponding ventilation level for the kitchen as 1000 CFM. 
     Based upon a determined ventilation level for the kitchen, the cooking event monitor  302  may transmit a control signal including the determined level of ventilation received to the motor speed controller  306 . The motor speed controller  306  may adjust the speed of the central exhaust fan  308  based upon the control signal received from the cooking event monitor  302 . As the cooking level of an appliance  304  changes, the cooking event monitor  302  may detect the change based upon either a signal received from a smart appliance or based upon operating parameters monitored at the appliance (e.g., current usage patterns). Based upon this detected change in cooking level, the cooking event monitor  302  may determine an updated level of ventilation, and communicate a new control signal including the updated level of ventilation to the motor speed controller  306 . 
     It should be noted that central exhaust fan  308  may be a three phase fan, a single phase fan, and may be single speed or multi-speed (e.g., high, medium, low and off) in operation. The motor speed controller  306  may be a variable frequency drive (VFD) or similar circuit, such as a triac controller, configured to control the exhaust fans at variable speeds. Thus, using a combination of the VFD controller and a single speed fan, multiple fan speeds may be used. Alternatively, instead of a motor speed controller, another form of control may be used. 
     The motor speed controller  306 , or a different motor speed controller, may also be in communication with the make-up air system  310 , e.g., the air conditioning units. Based upon the level of ventilation being created by the central exhaust fan  308 , the motor speed controller  306  may communicate to the make-up air system  310  what level of make-up air should be produced to maintain a constant pressure level in the cooking area and/or restaurant. 
     It should be noted that both VEV systems  100  and  300  may include additional features not discussed herein. For example, a bypass device may be included that is operably connected to the motor speed controllers  106  and  306 . The bypass device may permit a user of the VEV systems  100  and  300  to bypass the output of the cooking event monitors  102  and  302  and directly control the speed of the exhaust fans  108  and  308 . Similarly, the VEV systems  100  and  300  may include a failsafe device that monitors the various sensors on the appliances  104  and  304  to ensure the sensors are operating properly. The failsafe device may also set the ventilation level of any exhaust fan to 100% in the event that a failed sensor is detected, or if communication between an appliance and a cooking event monitor is lost. 
       FIG. 4  depicts a block diagram of exemplary internal hardware that may be used to contain or implement the cooking event monitors  102  and  302  as discussed above. A bus  400  serves as the main information highway interconnecting the other illustrated components of the hardware. CPU  405  is the central processing unit of the system, performing calculations and logic operations required to execute a program. CPU  405 , alone or in conjunction with one or more of the other elements disclosed in  FIG. 4 , is an exemplary processing device, computing device or processor as such terms are used within this disclosure. Read only memory (ROM)  410  and random access memory (RAM)  415  constitute exemplary memory devices. 
     A controller  420  interfaces with one or more optional memory devices  425  to the system bus  400 . These memory devices  425  may include, for example, an external or internal DVD drive, a CD ROM drive, a hard drive, flash memory, a USB drive or the like. As indicated previously, these various drives and controllers are optional devices. Additionally, the memory devices  425  may be configured to include individual files for storing any feedback information, common files for storing groups of feedback information, or one or more databases for storing the operation characteristic information as discussed above. 
     Program instructions, software or interactive modules for performing any querying or determining associated with the VEV systems  100  and  300  as discussed above may be stored in the ROM  410  and/or the RAM  415 . Optionally, the program instructions may be stored on a tangible computer readable medium such as a compact disk, a digital disk, flash memory, a memory card, a USB drive, an optical disc storage medium, such as a Blu-ray™ disc, and/or other recording medium. 
     An optional display interface  430  may permit information from the bus  400  to be displayed on the display  435  in audio, visual, graphic or alphanumeric format. The information may include information related to the current operating status of a VEV system. Communication with external devices may occur using various communication ports  440 . An exemplary communication port  440  may be attached to a communications network, such as the Internet or an intranet. 
     The hardware may also include an interface  445  which allows for receipt of data from input devices such as a keyboard  450  or other input device  455  such as a mouse, a joystick, a touch screen, a remote control, a pointing device, a video input device and/or an audio input device. 
     It should be noted that the systems and processes described above are shown by way of example only and could be modified. For example, different appliance configurations may be used. Similarly, a different ventilation level determination process may be used for the motor speed controllers  106  and  306 . 
     Various of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments.