Abstract:
A user-programmable monitoring and dispensing system for controlling the dispensing of water vapor and various other media into an HVAC air stream in residential or commercial structures. The various media to be dispensed are preferably water-soluble, and mixed with the system water supply to be dispensed with the water vapor added to the HVAC air stream. These materials may be fragrances or aromas, intended to produce an aesthetic effect, or they can be agents capable of pesticidal, bacteriacidal, fungicidal or sporacidal effect for use as acute or prophylactic treatment for infestation. The dispensing system central processor is pre-programmed with a default concentration algorithm for each media to be dispensed. The concentration of media in aqueous solution is initially controlled by this default algorithm at each of several concentration levels, from lowest to highest. After being exposed to the air containing the dispensed media at a medium concentration of the default algorithm for a default time period, the user may indicate, via a data entry/display, whether the perceived concentration is higher or lower than that desired. This input from the user to the central processor acts to replace the default concentration algorithm with a new, preferred algorithm wherein the scale of media concentration is shifted to correspond to the user&#39;s preference.

Description:
REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of application Ser. No. 09/796,177, filed Feb. 28, 2001 by the present inventor, now U.S. Pat. No. 6,553,777. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to a dispensing system for use in a heating, ventilating or air conditioning (HVAC) air stream and, in particular, to a central or zoned forced air HVAC media dispensing system for dispensing water vapor and/or other water soluble air-flow borne materials. 
     More specifically, but without restriction to the particular embodiment and/or use which is shown and described herein for purposes of illustration, this invention relates to a user-programmable central or zoned HVAC dispensing system for introducing various media such as water vapor, fragrances or other air-treating materials to improve living and working environments. Further, the invention of this application relates to dispensing systems for HVAC applications wherein the individual user may selectively shift the range of concentrations of media according to the level of concentration perceived by the user. 
     2. Description of Related Technology 
     The use of a humidification device for a central or zoned forced air HVAC system to improve living and working environments is known to those skilled in this art. Such systems generally comprise either passive evaporation of water from a reservoir adjacent to the HVAC air stream, or a circulating liquid retaining medium which passes in an endless path of movement through a water bath positioned within the HVAC air stream. While such systems are somewhat effective and simple, they are generally activated when an air stream is moving through the HVAC system and do not provide precise user control. If it is desired to dispense an additional medium into the air stream, the additional medium is manually added to the bath for dispensing into the air flow. Such systems consequently have wide variations in the amount of the media dispensed into the air stream which changes as the concentration of the media being dispensed varies, such as by evaporation, as well as the conditions of the ambient air. 
     In the parent of the present application there is provided a media dispensing system for use in HVAC applications including a central processor providing, in response to user-programmable data entry, control signals to a dispensing system for discharging a quantity of media into the air stream of the HVAC system. The media is supplied, also in accordance with user-selected inputs, from a plurality of media reservoirs to a manifold wherein the media is diluted to a level of concentration selected by the user through the data entry. The user may choose from a plurality of concentrations, e.g., five levels from lowest to highest, and the central processor controls discharge valves to provide the proper amount of media to the dilution manifold for the selected concentration. The central processor is programmed with a concentration algorithm specifying the amount of media corresponding to each selected level of concentration. For example, for user-selected concentrations or intensities of media, the proportions of media to water may be 1.3%, 3%, 5%, 10% and 20% for low, medium low, medium, medium high and high, respectively. However, there is no means for making the media concentration less than 1.3% or greater than 20% should the user desire lower or higher concentrations than those established by the concentration algorithm which is pre-programmed in the central processor. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of this invention to improve central and zoned dispensing systems for dispensing materials into a HVAC air stream. 
     Another object of this invention is to provide a range of user-programmable operational controls for the dispensing of materials into an HVAC air stream. 
     A further object of this invention is to provide a user-programmable central dispensing system for dispensing and monitoring the dispensing of one or more water-soluble materials into the air stream of an HVAC system in a predetermined and programmable quantity. 
     A more particular object of the present invention is to provide a system for dispensing media into the air stream of an HVAC system which offers the user a greater degree of control over the concentration or intensity of the media at various specified concentration levels. 
     These and other objects are attained in accordance with the present invention wherein there is provided a user-programmable monitoring and dispensing system for controlling the dispensing of water vapor and various other media into an HVAC air stream in residential or commercial structures. The various media to be dispensed are preferably water-soluble, and mixed with the system water supply to be dispensed with the water vapor added to the HVAC air stream. These materials may be fragrances or aromas, intended to produce an aesthetic effect, or they can be agents capable of pesticidal, bacteriacidal, fungicidal or sporacidal effect for use as acute or prophylactic treatment for infestation. 
     Among the user inputs is the desired concentration or intensity (which words are used interchangeably herein) of the media in the water solution. The user may choose from, for example, five concentration levels, denoted low, medium low, medium, medium high and high. The central processor is programmed with a concentration algorithm which establishes the actual percentage of media in the solution at each level. However, particularly when the dispensed media is a fragrance, one user may perceive the concentration at the level established by the processor to be lower or higher than another user, based on their individual sense of smell and preference for the particular fragrance being dispensed. In fact, the user may prefer a concentration, at least at certain times, which is lower than the concentration at the lowest selectable level, or higher than the highest level. The present invention addresses, and successfully solves, this problem by permitting the user to change the concentration algorithm after being exposed to the concentration at the default (original) setting for a predetermined time. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Further objects of this invention, together with additional features contributing thereto and advantages accruing therefrom, will be apparent from the following description of a preferred embodiment of the present invention which is shown in the accompanying drawings with like reference numerals indicating corresponding parts throughout and which is to be read in conjunction with the following drawings, wherein: 
     FIG. 1 is a mechanical schematic of a preferred embodiment of the dispensing system to better illustrate the components thereof and the manner in which such components interrelate in the system operation; 
     FIG. 2 is a logic block diagram of the system operation; 
     FIG. 3 is a logic block diagram of the operation of the user interface keypad/display through which the system is programmed; 
     FIG. 4 is a logic block diagram of the system controls through which materials are dispensed into the HVAC air stream in response to the user-defined program inputs; 
     FIGS. 5 and 5A are graphs illustrating the default and user calibrated output scales, respectively, of the concentration algorithm; and 
     FIG. 6 is a logic block diagram of the user calibrated concentration level selection system. 
    
    
     These and additional embodiments of the invention may now be better understood by referring to the following detailed description of the invention wherein the illustrated embodiment is described. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than limitations on the apparatus and methods of the present invention. 
     Referring now to the drawings, there is illustrated in FIG. 1 the various air flow components of an HVAC system and the central dispensing system of this invention. The portion of the HVAC system illustrated includes an air movement generating device, such as a blower  10  which generates an air stream which pass through duct work  11  to a desired residential or commercial space. The HVAC system includes a heat exchanger  12  positioned in the air stream path to heat the air moving through the duct  11  in response to the temperature set by a HVAC thermostat controller  20 , the input of which is entered through a user operated keypad/display unit  100 . In addition, an A/C coil  14  is positioned in the air stream to cool the temperature thereof in response to the temperature programmed through the thermostat  20 . The blower  10 , duct work  11 , heat exchanger  12  and A/C coil  14  are standard components utilized in HVAC forced air systems. Positioned down stream from the blower  10 , heat exchanger  12  and A/C coil  14 , in the direction of air movement, is a pressure or flow sensor  21 , such as available from Sensotec Inc., 2080 Arlingate Lane, Columbus, Ohio 43228, a humidity sensor  23  and a temperature sensor  25 , such as a HE-6310 Series Duct-mount humidity/temperature sensor, available from Johnson Controls, Inc., 507 East Michigan Street, Milwaukee, Wis. 53202, all of which are connected to a system central processor  50 , such as an Intel Type 8051 Microcontroller DS89C420-QCS Dallas Semiconductor Ultra High Speed 8051 Based Microcontroller PLCC Package available from Newark Electronics, 3 Marcus Boulevard, Albany, N.Y. 12205-1129, for providing air stream sensor inputs as to the air movement, moisture content of the air stream and the air stream temperature to the system central processor. Further down stream from these sensors, is a dispenser  16  which may be in the form of an ultrasonic transducer, available from Keramos Advanced Piezoelectrics, 5460 W. 84 th  Street, Indianapolis, Ind. 46268 and Etalon Innovative Piezo Transducers, P.O. Box 127, Lebanon, Ind. 46052, or vaporizer through which water vapor and/or water-soluble materials, available from AromaTech Co., 130 Industrial Parkway, Somerville, N.J. 088076, are dispensed into the HVAC air stream in response to a user-defined program input to the system central processor  50  by means of the keypad/display unit  100 , such as a Type XK-5LC or Type LCD-96M Multi Menu Keypad available from FBII, 149 Eileen Way, Soyosset, N.Y. 11791-5316 or JDS Technologies, 12200 Thatcher Ct., Poway, Calif. 92064-6876. While a single dispenser  16  is illustrated, it is to be understood that a single dispensing head may be utilized as illustrated or multiple dispensing heads may be utilized with each one of the multiple dispensing heads being connected by means of a dilution manifold to each individual media reservoir. The dispensing heads may be piezo-electric ultrasonic transducers, atomizer spray nozzles or a media saturated evaporation wick. The dispenser  16 , as illustrated in FIG. 1, is shown dispensing into the main plenum of an HVAC system for a centralized effect from the medium dispensed. However, it is to be understood that separate dispensers may be utilized in various trunk ducts as well as the central plenum for dispersal of the medium into specific locations serviced by the HVAC system. 
     The display/HVAC thermostat portion  20  of the keypad/display unit  100  is coupled to the system central processor  50  to provide the inputs illustrated in FIG. 2 to control the heating/cooling operation of the system central processor  50 . 
     The system central processor  50  is connected to a suitable standard power supply  51  to provide power to the unit upon start up. At this time a thermostat control signal is sent  20   c  from the system central processor  50  to actuate one or more of the blower  10 , heat exchanger  12 , or A/C coil  14 , in response to an on/off signal determined from the thermostat setting. 
     The system central processor  50  is programmed in the manner illustrated in FIG. 3, to control the operation of the media dispensing system on a daily basis, to control the dispensing of a selected medium or media, and to control the intensity thereof during the programmed cycle. The system operation, in response to the user-defined program inputs, and the output from various component sensors used in controlling system operations, are controlled in the manner illustrated in FIG.  4 . 
     Referring again to FIG. 1, the input from the user-defined program keypad/display unit  100 , including the thermostat signal, is coupled  20   a  to the system central processor  50  and appropriate display information is coupled  20   b  from the system central processor  50  back to the keypad/display  100  to confirm that the signals input from the keypad/display unit  100  have been received and processed by the system central processor  50 . While in the preferred embodiment disclosed herein as the best mode contemplated by the inventor for practicing the invention the keypad/display unit  100  is utilized, it is to be understood that the input coupled  20   a  to the dispenser system central processor  50  could be from a home automation control system commonly used to network and integrate the control and function of several subsystems in the space being controlled, with the feedback  20   b  from the system central processor  50  being coupled to such an automation control system instead of a keypad/display unit  100 . A suitable home automation control system, not shown, has been found to be an Omni, Omni LT, and Omni Pro models available from Home Automation, Inc., 5725 Powell Street, Suite A, New Orleans, La. 70123. 
     When the HVAC system is in operation, an input  21   a  will be received from the pressure or flow sensor  21  to the system central processor  50  confirming the movement of the air stream in the duct  11 , and input signals will be received  23   a  from the humidity sensor  23  and from the temperature sensor  25  to provide input  25   a  to the system central processor  50  as to the moisture content and the temperature of the air stream moving through the duct  11 . This information will be processed through the system central processor  50  and control  30   a  the operation of a water intake control valve  30 , available from South Bend Controls, 1237 Northside Boulevard, South Bend, Ind. 46615; HydraForce, Inc., 500 Barclay Boulevard, Lincolnshire, Ill. 60069; and Deltrol Controls, 2740 South 20 th  Street, Milwaukee, Wis. 53215, through which water passes from a suitable municipal or domestic supply source  32  into a dilution manifold  34  wherein water soluble media to be dispensed into the air stream are added for dilution prior to dispensing. 
     The water from water supply  32  is also connected to one or more media reservoir tanks, illustrated in the preferred embodiment as three reservoirs  35   a ,  35   b  and  35   c . These reservoirs may be either permanent containers which are refillable, or be replaceable as modular units. In addition, each reservoir  35   a ,  35   b  and  35   c  incorporates a recognition media such as a bar code, magnetic strip or holographic symbol so that the system central processor  50  will receive a signal that the reservoir is in proper position and the information contained therein will effect display of the particular medium being dispensed on the keypad/display unit  100 . In addition, it is to be understood that the contour of each of the reservoirs may be such that when the reservoir is properly positioned, such a signal will be provided to the system central processor. 
     Each of the reservoirs  35   a ,  35   b  and  35   c  preferably contain an inner bladder which effectively creates a second chamber within the media reservoir and the space around the inner bladder is connected in parallel to the water supply  32  such that the water fills the space around the bladder to displace the media contained within the reservoir towards the mixing manifold. Each of the media reservoirs is connected to the dilution manifold  34  by media output valves  36   a ,  36   b  and  36   c  such as inert proportional valves available from the water intake control valve supplier and which are individually activated  37   a ,  37   b  and  37   c  by the system control processor  50  to control the dispensing of water soluble media into the dilution manifold  34  from the respective media reservoirs  35   a ,  35   b  and  35   c . The water soluble media is mixed with water in the dilution manifold  34  and passes to the ultrasonic transducer or vaporizer  16  in response to the actuation  38   a  of a dispensing control valve  38  available from the water intake control valve suppliers previously identified and operated by the system central processor  50  in accordance with the information coupled to the central system processor by the temperature and humidity sensors  25  and  23 , respectively, and the programmed input entered by the user through the keypad/display unit  100 . The intensity of the media contained within the media reservoirs may be achieved by varying the amount of media dispensed during and “on” cycle wherein the media reservoirs contain a constant concentration of the media or the quantity of the medium dispensed may be held constant with the concentration of the media being controlled by controlling the dilution of the medium in the dilution manifold  34 . 
     The media reservoirs  35   a ,  35   b  and  35   c  are each provided with a sensor  39   a ,  39   b  and  39   c , respectively, available from Gems Sensors, 1 Cowles Road, Plainville, Conn. 06062, coupled to the system central processor  50  to monitor the level of the medium contained within each reservoir for proper dispensing of the medium contained therein. Sensors  39   a ,  39   b  and  39   c  may be mounted directly upon the respective reservoirs, or upon the chassis or other mounting means for the reservoirs. Alternatively, instead of actively monitoring the level of the medium in the reservoirs  35   a ,  35   b  and  35   c , the system central processor  50  could calculate the quantity dispensed and thereby derive the amount remaining, assuming that the initial amount supplied to these reservoirs is constant, or otherwise “known” by the system central processor. The system central processor  50  can be programmed, as illustrated in FIG. 3, to dispense one or more of the media from the reservoirs  35   a ,  35   b  and  35   c  into the dilution manifold  34  in increments stepped to vary the intensity or concentration of the media in the dilution manifold in accordance with the input to the system central processor  50  through the keypad/display unit  100 . A water supply pressure feedback input  33   a  is connected to the system control processor  50  from a check valve and pressure sensor  33 , available from Sensotec Inc. 2080 Arlingate Lane, Columbus, Ohio 43228, carried in the municipal or domestic water supply line to ensure that an adequate supply of domestic water  32  at a desired pressure is available for use in the dispensing system. 
     Referring now to FIG. 2, there is illustrated the informational inputs that a user enters into the system through operation of the keypad/display unit  100  to control operation of the system central processor  50  to perform the desired functions. Upon initial system power-up, the user manually enters the time and date through the keypad/display unit  100  which is coupled  102  to the system central processor  50 . This information, once coupled to the system central processor  50 , will be used by the processor to accurately maintain current time in a manner known to those skilled in the art, and displayed on the keypad/display unit  100 . 
     The user then enters information to place the system central processor in either an “Active” or “Standby” mode. If the “Standby” mode is selected, the system central processor  100  will be idle and the keypad/display unit  100  will display that the system is in the “Standby” mode awaiting further instruction. If the user elects to operate the system, the “Active” mode is selected, displayed, and the user may elect to have the system operated in either a “Manual” or “Program” mode. If the “Manual” mode of operation is selected, the user can either elect to have the system operate in a “Default” sequence or a “Specified” sequence of operation. 
     In the “Default” sequence of operation, the system central processor  50  will sequentially actuate the first medium dispenser  35   a  which will continue to operate to depletion. Upon depletion a signal will be sent by the sensor  39   a  to the system central processor  50  which will then actuate the next available medium dispenser, e.g.: 35   b , which will continue to operate to depletion. At that time the sensor  39   b  will send a signal to the system central processor  50  which will actuate the next available medium dispenser until all of the medium has been dispensed, at which time the system central processor  50  will cause a message to be displayed on the keypad/display unit  100  that the dispensers are empty and the system has been placed on “Standby”. 
     If the user elects to choose a “Specified” sequence rather than the “Default” sequence, the user can input a particular order by which the media will be used to depletion, by entering instructions through the keypad/display unit  100  for the system central processor  50  to start with a first programmed medium dispenser and then proceed upon depletion to a second specified medium dispenser and upon the depletion thereof to proceed to another specified medium dispenser. However, regardless of which mode of operation the user selects, in either of these modes the user is required to set the intensity level of each of the media to be discharged from the dispenser  35   a ,  35   b , and  35   c  into the dilution manifold  34 . The manner in which the intensity parameters are input to the system central processor  50  is illustrated in FIG.  3 . 
     If the user chooses to operate the system in a “Program” mode; whereby individual medium and intensity parameters can be selected and set for individual days of the week, the user selects the “Program” option when the system “Active” display is presented. 
     Referring to FIG. 3, upon entering the “Program” mode the user is instructed to either accept or edit a previous program setting. If at this time the user elects not to enter the “Program” mode, an “Escape” instruction is provided which returns the user to the “Active” display whereby the system may be operated in the “Manual” mode or the user may return the system to the “Standby” mode. If, however, the user elects to proceed with the “Program” mode, the user must either “Accept” the previous program settings (or the factory settings if this is an initial installation) or select the “Edit” option if it is desired to make changes in the program previously entered. Throughout the operation in the “Program” mode, an “Escape” option is available to enable the user to return to the “Active” input level thereby cancelling all instructions entered to that point and the system returning to the previous program settings, or a “Menu Step Back” option is also available to permit the user to correct an entry error without losing the settings previously entered. 
     Upon selecting the “Edit” option, the user sequentially selects each day of the week to define the parameters of operation of the system for that day. These parameters include the time of program operation, identified as “Cycle 1”, “Cycle 2”, “Cycle 3” and “Cycle 4”. These times of operation are set for each day and may be individually accepted as presented previously, or edited. After the program cycle is selected, the particular medium, water vapor only or one of the media  35   a ,  35   b ,  35   c  which is to be dispensed, maybe chosen. The intensity level (concentration) of the selected medium which is to be dispensed may be selected as well as the time period selected for operation during the program cycle can be chosen and entered through the keyboard/display unit  100  into the system central processor  50 . This information is sequentially entered into the system central processor  50  through the keypad/display unit  100  for each day of the week. 
     Although the system described above allows the user to choose from a plurality of concentration levels for each of a plurality of media, the percentage of media in the dispensed solution remains the same for each level any time the system is in use. For example, “Media A” may have a concentration of 1.3% at the “Low” setting and 20% at the “High” setting. Thus, if the user wants a concentration of Media A which is less than 1.3% or greater than 20%, this cannot be achieved with the system as described to this point. This is illustrated by the graph of FIG. 5, providing an example of the concentration algorithm, a line of constant slope, for Media A. The concentration algorithm and percentages of media at each of five intensity levels are as follows: 
     
       
         
               
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 User-selectable 
                 Low 
                 MedLow 
                 Med 
                 MedHi 
                 High 
               
               
                 intensity levels: 
               
               
                 Media A dilution 
                 0.5(0.5 * X) 
                 0.5 * X 
                 X 
                 2 * X 
                 2(2 * X) 
               
               
                 algorithm 
               
               
                 Default value 
                 1.3% 
                 3% 
                 5% 
                 10% 
                 20% 
               
               
                   
               
             
          
         
       
     
     In the user calibration procedure of the present invention, the above algorithm is in effect when Media A is recognized by the central processor as the medium in use. At system startup, the default value at the medium intensity level, i.e., 5%, is automatically chosen. The medium, assumed in this case to be a fragrance, is dispensed at this level for a predetermined time period, e.g., one hour. At the end of that time, the display prompts the user to enter the intensity level which most closely corresponds to the user&#39;s perception of the intensity of fragrance at that time. If the user&#39;s sense of smell and personal preference for the fragrance indicate that the intensity level is in the medium-high range, the user presses the “Med/High” button on the data entry/display  100 . Doing so resets the dilution scale by relocating the default X value on the algorithm. That is, the concentration algorithm is shifted from the position shown by the dotted line in FIG. 5A (i.e., the position of FIG. 5) to the solid line position of FIG.  5 A. The concentration of media is reduced at each of the five selectable intensity levels. 
     Using the example above, if the user rates the perceived intensity as: 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Low 
                 Med/Low 
                 Med 
                 Med/High 
                 High 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 1. High, then the 
                 0.31% 
                 0.63% 
                  1.25% 
                  2.50% 
                  5% 
               
               
                 resulting user- 
               
               
                 calibrated scale, 
               
               
                 for that specific 
               
               
                 fragrance would 
               
               
                 become: 
               
               
                 2. Med/High, then the 
                 0.63% 
                 1.25% 
                  3% 
                  5% 
                 10% 
               
               
                 resulting user- 
               
               
                 calibrated scale, for 
               
               
                 that specific fragrance 
               
               
                 would become: 
               
               
                 3. Med, then the 
                 1.25% 
                 2.5% 
                  5% 
                 10% 
                 20% 
               
               
                 resulting user- 
               
               
                 calibrated scale, for 
               
               
                 that specific fragrance 
               
               
                 would become: 
               
               
                 4. Med/Low, then the 
                 2.5% 
                 5% 
                 10% 
                 20% 
                 40% 
               
               
                 resulting user- 
               
               
                 calibrated scale, for 
               
               
                 that specific fragrance 
               
               
                 would become: 
               
               
                 5. Low, then the 
                 5% 
                 10% 
                 20% 
                 40% 
                 80% 
               
               
                 resulting user- 
               
               
                 calibrated scale, for 
               
               
                 that specific fragrance 
               
               
                 would become: 
               
               
                   
               
             
          
         
       
     
     Once the user has calibrated the output intensity scale for a particular fragrance (or other medium) the system will apply that scale whenever that fragrance (or medium) is recognized. “Recognition” may be implemented, as described earlier herein, by incorporation in each media reservoir of machine readable indicia such as a bar code, magnetic strip, holographic symbol or RFID tag (as commonly used in retail stores for security purposes). The user may re-calibrate at any time, and the system will overwrite the former scale with the newly chosen one. The logic block diagram of FIG. 6 illustrates the sequence of steps in the calibration procedure wherein the user provides inputs based on that user&#39;s perceived (desired) intensity of the medium which is dispensed at the default level for a predetermined (default) time period. 
     Functional Description 
     Referring now to FIG. 4, the user inputs the initial information into the system central processor  50  through the keypad/display unit  100  in the manner previously described, selects the mode of operation and programs the system as desired. The temperature sensor  25 , humidity sensor  23 , flow sensor  21 , media sensors  39   a ,  39   b , and  39   c , and water supply sensor  33   a  all provide their respective input signals to the system central processor  50 . The keyboard/display  100  shows the status of the informational inputs. If the program cycle inputs, the operational sensor inputs and time of operation call for an activation of a dispensing sequence, dispensing operation is initiated and the keypad/display  100  shows that the system is dispensing as instructed. The selected media dispensing valve  36   a ,  36   b  or  36   c  is opened the prescribed extent and duration. The water intake control valve  30  is opened allowing water and the selected medium to mix in the dilution manifold  34 . The dispensing control valve  38  is opened and the dispenser  16  is actuated for a time period determined by the parameters of the ambient air moving through the air duct  11 . The input from the ambient air flow sensors  21 ,  23  and  25  coupled to the system central processor  50  prevent the system from dispensing media at a level beyond the capacity of the air stream flow to move the dispensed medium through the HVAC system. 
     Referring to FIG. 6, upon installation of a media reservoir the indicia thereon is read to indicate presence of the reservoir and identity of the medium. If the medium is recognized as one for which user-programmed functional data has previously been entered, the system proceeds to operate according to such instructions. Otherwise, the user performs, via the keypad data entry, the necessary input instructions to permit the system to operate at a default intensity level. After operation at that level for a predetermined time period, the user is prompted to enter the perceived concentration level. Stated another way, the user enters a level of intensity rating the concentration during the default period relative to the concentration which the user would prefer. This action serves to shift the concentration algorithm in the manner illustrated in FIG.  5 A. 
     It will be understood that, although the invention has been described as having a diffuser and various sensors mounted in an air flow plenum of a heating, ventilating and/or air conditioning system, it could instead be incorporated in a console or table top humidifier located in the occupied living space with the diffuser discharging directly into the living space. 
     While this invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, the structure of which has been disclosed herein, it will be understood by those skilled in the art to which this invention pertains that various changes may be made, and equivalents may be substituted for elements of the invention without departing from the scope of the claims. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed in the specification and shown in the drawings as the best mode presently known by the inventors for carrying out this invention, nor confined to the details set forth, but that the invention will include all embodiments, modifications and changes as may come within the scope of the following claims: