Patent Publication Number: US-10767880-B2

Title: HVAC controller for a variable air volume (VAV) box

Description:
This application is a continuation of co-pending U.S. patent application Ser. No. 14/692,546, filed Apr. 21, 2015 and entitled “HVAC CONTROLLER FOR A VARIABLE AIR VOLUME (VAV) BOX”, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure relates generally to HVAC systems and more particularly to HVAC systems that utilize an HVAC controller to control air handling equipment. 
     BACKGROUND 
     A variety of HVAC systems include air handling equipment such as VAV (variable air volume) boxes. A VAV box generally includes an air inlet that receives conditioned air and one or more air outlets for distributing the conditioned air to a portion of a building such as a room or zone. A VAV box generally includes a damper that can be driven to multiple positions in order to regulate air flow of through the one or more air outlets. The HVAC system may include one or more HVAC controller that control the operation of the VAV boxes. The HVAC controllers are often wall mountable environmental controllers that sense one or more environmental conditions in a room or zone, and control the dampers of the VAV box(es) to achieve desired environmental conditions in the room or zone. In practice, the VAV boxes must be properly configured during installation and/or reconfigured during maintenance. Configuring the VAV boxes is typically done by manually accessing the VAV boxes, performing certain measurements, and based on those measurements, making certain setting changes on the VAV boxes themselves. This can be a time consuming and tedious task. 
     SUMMARY 
     The disclosure pertains to an HVAC Controller for controlling one or more VAV boxes of an HVAC system. The HVAC Controller may be configured to not only control one or more VAV boxes to achieve one or more environmental conditions in a room or zone, but may also be configured to help an installer or other technician configure a VAV box that is operatively connected to the HVAC Controller. In some cases, the HVAC controller may aid an installer or other technician perform a test and balance procedure on a VAV box. 
     In one example, an illustrative HVAC system may include a VAV box with a damper movable between a first damper position and a second damper position. An illustrative HVAC controller mounted remotely from the VAV box may be operatively coupled to the VAV box. The HVAC controller may be configured to control the VAV box in accordance with a temperature (or other) set point entered into the HVAC controller. In some cases, the HVAC controller may include a temperature sensor and a user interface that is configured to display the sensed temperature and to enable a user to input a temperature set point. The HVAC controller may further include a controller that is operatively coupled to the user interface and the temperature sensor, and may regulate operation of the VAV box in accordance with the sensed temperature and the temperature set point. In some cases, the HVAC controller may also be programmed with functionality that facilitates an installer or other technician in configuring and/or reconfiguring an VAV box. This may include providing a user interface that supports a test and balance procedure of the VAV box. Such functionality may be user-accessible via the user interface of the HVAC controller, and in some cases, may be used to drive the damper of the VAV box between various damper positions as well as perform other functionality. 
     In some cases, a test and balance procedure menu may be programmed into the HVAC controller. Using the test and balance procedure menu, an installer or other technician may drive the damper to, for example, a first position. A measured air flow through the damper may be obtained, either from the installer or other technician or from the VAV box itself if so equipped. In some cases, the HVAC controller may compare the measured air flow with a desired air flow value. The first damper position of the VAV box may be adjusted and ultimately set in accordance with the comparison. In some cases, when the VAV box is configured to report a measured air flow to the HVAC Controller, the HVAC controller may automatically titrate the damper position and set the first damper position based on a desired air flow value entered into the HVAC Controller. It is contemplated that other damper positions may be identified and set in a similar manner. 
     The preceding summary is provided to facilitate an understanding of some of the features of the present disclosure and is not intended to be a full description. A full appreciation of the disclosure can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure may be more completely understood in consideration of the following description of various illustrative embodiments of the disclosure in connection with the accompanying drawings, in which: 
         FIG. 1  is a schematic view of an illustrative HVAC system; 
         FIG. 2  is a schematic view of an illustrative single deck HVAC system; 
         FIG. 3  is a schematic view of an illustrative dual deck HVAC system; 
         FIG. 4  is a schematic view of an illustrative VAV box shown with its damper in a fully closed position; 
         FIG. 5  is a schematic view of an illustrative VAV box shown with its damper in a fully open position; 
         FIG. 6  is a schematic view of an illustrative VAV box shown with its damper in a partially open position; 
         FIG. 7  is a schematic view of an illustrative VAV box illustrating relative damper positions; 
         FIG. 8  is a schematic view of an illustrative HVAC system; 
         FIG. 9  is a flow diagram showing an illustrative method that may be carried out via the HVAC system of  FIG. 8 ; 
         FIG. 10  is a flow diagram showing an illustrative method that may be carried out via the HVAC system of  FIG. 8 ; 
         FIG. 11  is a flow diagram showing an illustrative method that may be carried out via the HVAC system of  FIG. 8 ; 
         FIGS. 12 through 18  show illustrative display screens that may be displayed by the illustrative HVAC controller of the HVAC system of  FIG. 8 ; and 
         FIGS. 19 through 31  show illustrative display screens that may be displayed by the illustrative HVAC controller of the HVAC system of  FIG. 8 . 
     
    
    
     While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the disclosure to the particular illustrative embodiments described herein. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. 
     DESCRIPTION 
     The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The description and drawings show several examples that are meant to be illustrative of the disclosure. In some embodiments, the disclosure pertains to an HVAC system including a variable volume air controller. An HVAC system may include a VAV box including a damper movable between a first damper position and a second damper position and an HVAC controller that is mounted remotely from the VAV box. In some instances, the HVAC controller may be configured to control the VAV box in accordance with a temperature (or other) set point entered into the HVAC controller. Other set points may include, for example, a humidity set point, a CO 2  set point (max CO 2  content), an air quality set point, a ventilation set point (e.g. min ventilation), and/or any other suitable set point as desired. 
       FIG. 1  is a schematic view of a building  10  including an HVAC system  12 . In some instances, the building  10  may represent a house and may have a single HVAC system  12  within the building  10 . In some cases, the building  10  may represent a larger structure such as an office building, a shopping center, a library, and the like, and the building  10  may include two or more distinct HVAC systems  12 , as appropriate given the size and layout of the building  10 . In some embodiments, as illustrated, the HVAC system  12  may be a forced air system and may include a conditioned air source  14 . The conditioned air source  14  may provide, for example, cooling air, heating air, and/or ventilation air. In some cases, the conditioned air source  14  may provide conditioned air at a constant temperature, and temperature control within the building  10  may be achieved by regulating the relative amounts of conditioned air and outside air, or the relative amounts of conditioned air and recirculated air, that are provided to a room or zone in the building  10 . 
     In the example shown, the conditioned air source  14  is fluidly coupled with a first supply line  16 , a second supply line  18  and a third supply line  20 . It will be appreciated that this is merely illustrative, as the conditioned air source  14  may be fluidly coupled with just one or two supply lines, or a larger number of supply lines. The first supply line  16  extends to and is fluidly coupled with a first VAV box  22 . The second supply line  18  extends to and is fluidly coupled with a second VAV box  24 . The third supply line  20  extends to and is fluidly coupled with a third VAV box  26 . Again, the number of VAV boxes shown is merely illustrative. Each of the first VAV box  22 , the second VAV box  24  and the third VAV box  26  may include a moveable internal damper that can be actuated between a closed position and an open position, and in some cases may be actuatable to any intermediate position between the closed position and the open position. As a result, each VAV box can control how much of the conditioned air received by the VAV box is permitted to continue downstream of the VAV box and into the room or zone of the building. 
     In some cases, each VAV box may be fluidly coupled to one, two, three or more air vents that distribute any conditioned air that passes through a particular VAV box to a particular room, zone or zones within a building such as building  10 . In the example shown in  FIG. 1 , the first VAV box  22  is fluidly coupled to a total of three air vents  28 , the second VAV box  24  is fluidly coupled to a total of three air vents  30 , and the third VAV box  26  is fluidly coupled to a total of three air vents  32 . It will be appreciated that having three air vents fluidly coupled to each VAV box is merely illustrative. In some embodiments, a particular VAV box will provide conditioned air to a particular space, such as a room, and thus will feed a particular number of air vents as dictated by the spatial arrangement of the space or room. 
     In some instances, the HVAC system  12  may include an HVAC controller  34  that is operably coupled to the conditioned air source  14 , the first VAV box  22 , the second VAV box  24  and the third VAV box  26 . In some cases, for example, the HVAC controller  34  may monitor an ambient temperature (or other environmental condition such as humidity, CO 2  level, air quality, etc.) within the building  10  and may provide instructions to the conditioned air source  14  and/or to one or more of the first VAV box  22 , the second VAV box  24  and the third VAV box  26  as appropriate to alter the temperature (or other environmental condition) within the building  10 . In some cases, a single HVAC controller  34  may control the entire HVAC system  12  for the entire building  10 . In some instances, the HVAC controller  34  may be considered as representing two or more distinct HVAC controllers, each controlling a particular space or zone within the building  10 , and optionally in communication with each other. 
     In some cases, the HVAC controller  34  may be programmed with a temperature set point setback program that enables the building  10  to operate at a more energy efficient temperature at certain times of day and/or particular days, such as when the occupants of the building  10  are away from the building  10 , or perhaps are within the building  10  but are sleeping. In some cases, the HVAC controller  34  is not programmable, and merely maintains a desired temperature set point. In some cases, as will be discussed, the HVAC controller  34  may be configured to enable an installer or other professional to test and calibrate the HVAC system  12  upon initial installation and/or periodically as desired. 
     In  FIG. 1 , the HVAC system  12  is schematically illustrated as having supply lines  16 ,  18  and  20  extending from the conditioned air source  14  to the VAV boxes  22 ,  24  and  26 . In some cases, the HVAC system  12  may be a single deck system in which a single air duct provides conditioned air at a constant or substantially constant temperature to the VAV box to which it is fluidly coupled. In most cases, one or more return ducts (not shown) may return air from the various rooms to the conditioned air source  14 . The temperature of the air exiting the VAV box may be controlled to a certain extent by varying the amount of conditioned air exiting the VAV box. In some cases, the VAV box may include a local heat source that can be used to increase the temperature of the air exiting the VAV box. In some cases, the HVAC system  12  may be a dual deck system, in which a first air duct provides conditioned cool air and a second air duct provides conditioned warm air to the VAV box to which the air ducts are fluidly coupled.  FIG. 2  provides a schematic illustration of a single deck system while  FIG. 3  provides a schematic illustration of a dual deck system. 
       FIG. 2  shows a portion of an HVAC system  36 , including the conditioned air source  14 . In this single deck system, the conditioned air source  14  provides conditioned air to a supply main  38 . A first air duct  40  is fluidly coupled to the supply main  38  and extends to the first VAV box  22 . A second air duct  42  is fluidly coupled to the supply main  38  and extends to the second VAV box  24 . A third air duct  44  is fluidly coupled to the supply main  38  and extends to the third VAV box  26 . For ease of illustration, no corresponding air vents are shown, although it will be appreciated that each of the VAV boxes  22 ,  24 ,  26  may be fluidly coupled to one, two, three or more air vents. 
       FIG. 3  shows a portion of an HVAC system  46 , including the conditioned air source  14 . In this dual deck system, the conditioned air source  14  provides cool conditioned air to a cold supply main  48  and provides warm conditioned air to a warm supply main  56 . A first air duct  50  is fluidly coupled to the cold supply main  48  and extends to the first VAV box  22 . A second air duct  52  is fluidly coupled to the cold supply main  48  and extends to the second VAV box  24 . A third air duct  54  is fluidly coupled to the cold supply main  48  and extends to the third VAV box  26 . A fourth air duct  58  is fluidly coupled to the warm supply main  56  and extends to the first VAV box  22 . A fifth air duct  60  is fluidly coupled to the warm supply main  56  and extends to the second VAV box  24 . A sixth air duct  62  is fluidly coupled to the warm supply main  56  and extends to the third VAV box  26 . For ease of illustration, no corresponding air vents are shown, although it will be appreciated that each of the VAV boxes  22 ,  24 ,  26  may be fluidly coupled to one, two, three or more air vents. 
       FIGS. 4 through 7  provide further details regarding an illustrative VAV box  64 . The illustrative VAV box  64  has a damper  66  that is pivotally secured to a pivot point  68  within a housing  70 . While not illustrated, the illustrative VAV box  64  may include an electric motor or hydraulics configured to rotate the damper  66  relative to the pivot point  68 . The illustrative VAV box  64  may also include a control box that receives control instructions from a remote thermostat or remote HVAC controller, such as the HVAC controller  34  shown in  FIG. 1 , and then regulates operation of the electric motor or hydraulics to rotate the damper  66  in order to control the relative amount of air that is permitted to pass through the illustrative VAV box  64 . In some cases, the control box may be hard-wired to a remote HVAC controller, such as HVAC controller  34 . In some instances, the control box may include a wireless communications module, such as that described in U.S. Ser. No. 14/639,923 filed Mar. 5, 2015 entitled “Wireless Actuator Service”, which application is incorporated by reference herein in its entirety, to communicate with a remote HVAC controller, such as HVAC controller  34 . While a single rotating damper is shown in  FIGS. 4-7 , it is contemplated that the VAV box  64  may include any suitable damper mechanism, including multiple rotatable dampers, one or more longitudinally sliding dampers, one or more inflatable bladder(s), etc. 
     In  FIGS. 4-6 , air flow entering the VAV box  64  is represented by an arrow  72 . In  FIG. 4 , the damper  66  is shown in its fully closed position, as indicated by essentially no air exiting the VAV box  64 . In some cases, there may be some air exiting the VAV box  64 , even with the damper  66  in its fully closed position. This may be intentional, such as to meet certain minimum ventilation requirements. In  FIG. 5 , the damper  66  is shown in its fully open position, as the air exiting the VAV box  64  is represented by an arrow  74  that is roughly the same size as the arrow  72  representing incoming air. In  FIG. 6 , the damper  66  is shown in an intermediate position, as the air exiting the VAV box  64  is represented by an arrow  76  that is smaller than the arrow  72  representing incoming air. 
       FIG. 7  provides a schematic illustration of the various possible damper positions. A fully open position is indicated at a point  78 . A fully closed position is indicated at a point  80 . An intermediate position is indicated at a point  82 . It will be appreciated that the intermediate point  82  may be located at any desired position along curve  84 , between the fully open point  78  and the fully closed point  80 . 
       FIG. 8  provides further details regarding the illustrative HVAC controller  34  ( FIG. 1 ). The illustrative HVAC controller  34  is illustrated in  FIG. 8  as being in operative communication with the first VAV box  22 , the second VAV box  24  and the third VAV box  26 . It will be appreciated that while three VAV boxes are shown, the system may include any desired number of VAV boxes. Communication between the illustrative HVAC controller  34  and the VAV boxes  22 ,  24  and  26  may be wired or wireless communication, and may utilize any desired wired or wireless communications protocol as desired. Illustrative but non-limiting examples of wireless communications protocols include one or more short nominal range wireless communication protocols such as Bluetooth, ZigBee, Ultra-Wideband (UWB), Dedicated Short Range Communication (DSRC), Infrared Data Association (IrDA), EnOcean, REDLINK™, Near field Communication (NFC), RFID, and/or any other suitable common or proprietary wireless protocol, as desired. In some embodiments, BLE (Bluetooth Low Energy) may be employed. 
     In some instances, the illustrative HVAC controller  34  may be configured to control the VAV boxes  22 ,  24  and  26  in accordance with a temperature set point entered into the HVAC controller  34 . As noted, the illustrative HVAC controller  34  may regulate the air temperature, at least in part, by controlling the position of the damper  66  ( FIGS. 4-6 ). In some cases, the illustrative HVAC controller  34  may be configured to instruct the VAV box  22 ,  24 ,  26  to drive the damper  66  from a first damper position, which could for example be the fully open point  78  shown in  FIG. 7  to a second damper position, which could for example be the fully closed point  80  shown in  FIG. 7 . The first damper position could instead be the fully closed point  80 , or the intermediate point  82 . The second damper position could be the fully open point  78 , or the intermediate point  82 . 
     The illustrative HVAC controller  34  further includes a user interface  86  and a controller  88  that is operably coupled to the user interface  86 . In some cases, the user interface  86  is a touch screen user interface, but this is not required. In some instances, the illustrative HVAC controller  34  may include one or more of a temperature sensor  90 , a carbon dioxide sensor  92  and a humidity sensor  94 , but these are not required in all cases. In some cases, the temperature sensor  90  is configured to sense a temperature proximate the HVAC control  34  and communicate the sensed temperature to the controller  88 . The controller  88  may be configured to solicit a desired temperature set point from a user via the user interface  86  and may regulate operation of the VAV boxes  22 ,  24  and  26  in accordance with the sensed temperature and the temperature set point. 
     In some embodiments, the illustrative HVAC controller  34  may also be configured to facilitate a test and balance procedure. In some cases, the illustrative HVAC controller  34  may be configured to initiate a test and balance procedure in response to a user input received via the user interface  86 . This may be done, for example, when initially setting up a new HVAC system in a new building. In some cases, there may be a desire to initiate a test and balance procedure after a remodeling project when physical changes have been made to the layout of the HVAC system. In some instances, the HVAC controller  34  may be configured to initiate a test and balance procedure in response to a calendar reminder that is programmed into the HVAC controller  34 . For example, an installer may instruct the HVAC controller  34  to initiate a test and balance procedure once a year for routine maintenance. 
     A test and balance procedure may permit an installer, for example, to determine actual air flow for a particular VAV box at various damper positions. While a particular VAV box may have design characteristics, such as intended air flow characteristics at particular damper positions, in some cases once installed the actual air flow characteristics may vary from design standards. During a test and balance procedure, an installer can instruct via the HVAC controller  34  a damper in a VAV box to move to a particular damper position, and then resulting air flow may be measured either manually by the installer or automatically if the VAV box has an appropriate flow sensor. Accordingly, determinations may be made regarding appropriate damper positions for various desired air flow values, and the VAV box may be so calibrated. It will be appreciated that air flow is determined in order to achieve desired temperature, humidity and/or other environmental conditions in the space. 
     In some cases, a test and balance procedure may include instructing a particular damper to drive to a first damper position to obtaining a measure of air flow with the damper at the first damper position. The test and balance procedure may also include instructing the damper to drive to a second damper position to obtaining a measure of air flow with the damper at the second damper position. In some instances, the first damper position represents a minimum damper open position and the second damper position represents a maximum damper open position, although this is not required in all cases. In some cases, the test and balance procedure may include instructing a damper to drive to a plurality of different intermediate damper positions, and obtaining air flow measurements for each of those damper positions. In some cases, a damper is driven to a particular position, and the damper is held at that position. An indication of airflow may be obtained (either manually by the installer or automatically via the VAV box if so equipped), and the damper may be released from the particular position. It will be appreciated that in some cases, dampers may be biased to a particular position such as a fully open position. In some cases, other parameters such as humidity and/or carbon dioxide concentration may also be measured. 
     In some embodiments, the test and balance procedure may include sequentially driving the damper to each of a plurality of predetermined positions. Each of the predetermined positions may be displayed on the touch screen user interface. An indication of air flow through the VAV box may be obtained. The indication of air flow through the VAV box may be displayed on the touch screen user interface. 
       FIG. 9  is a flow diagram showing an illustrative method that may be carried out using the HVAC controller  34 . A test and balance procedure may be performed on a VAV box that includes a damper. A test and balance procedure menu programmed into the HVAC controller  34  may be accessed, as generally indicated at block  96 . In some cases, the test and balance menu may be accessed via the user interface  86  ( FIG. 8 ) of the HVAC controller  34 , which is optionally a touch screen user interface. In some instances, the test and balance menu may be an intuitive, user-friendly menu. Using the test and balance menu, and as seen at block  98 , the damper of the VAV box is instructed to drive to a first position. A measured air flow indicator may be compared with a desired air flow indicator, as generally seen at block  100 . In some cases, an air flow indicator may be an air velocity value or a volumetric air flow value. As seen at block  102 , a first damper set position may be set in accordance with the comparison. 
     In some cases, the measured air flow indicator is compared with a desired air flow indicator by the installer. When so provided, the installer may titrates by adjusting the damper position using the user interface  86  of the HVAC controller  34  until the desired air flow is achieved, and then sets the first damper set accordingly. In other cases, the air flow is measured by the installer and a measured air flow indicator is entered into the HVAC controller  34  via the user interface  86 , or a measured air flow indicator is communicated to the HVAC controller  34  from the VAV box if the VAV box is so equipped, and the HVAC controller  34  compares the measured air flow indicator with a desired air flow indicator that is stored in a memory of the HVAC controller  34 . In some cases, the HVAC controller  34  may then titrate by adjusting the damper position based on the comparison, as desired. 
       FIG. 10  shows a flow diagram of another illustrative method that may be carried out using the HVAC controller  34 . A test and balance procedure menu programmed into the HVAC controller  34  may be accessed, as generally indicated at block  96 . In some cases, the test and balance menu may be accessed via the user interface  86  ( FIG. 8 ) of the HVAC controller  34 . Using the test and balance menu, and as seen at block  98 , the damper of a VAV box is instructed to drive to a first position. A measured air flow indicator may be compared with a desired air flow indicator, as generally seen at block  100 . As seen at block  102 , a first damper set position may be set in accordance with the comparison. Using the test and balance menu, the damper of the VAV box may be instructed to drive to a second position that is different from the first position, as seen at block  104 . A measured air flow indicator may be compared with a desired air flow indicator, as seen at block  106 . A second damper set position may be set in accordance with the comparison, as generally indicated at block  108 . It will be appreciated that these steps may be carried out for any desired number of damper positions, and for any number of VAV boxes as desired. 
       FIG. 11  shows a flow diagram of another illustrative method that may be carried out using the HVAC controller  34 . A test and balance procedure menu programmed into the HVAC controller  34  may be accessed, as generally indicated at block  96 . In some cases, the test and balance menu may be accessed via the user interface  86  ( FIG. 8 ) of the HVAC controller  34 . Using the test and balance menu, and as seen at block  98 , the damper is instructed to drive to a first position. A measured air flow indicator may be compared with a desired air flow indicator, as generally seen at block  100 . In some cases, an air flow indicator may be an air velocity value or a volumetric air flow value, for example. As seen at block  102 , a first damper set position may be set in accordance with the comparison. In some cases, and as generally indicated at block  110 , the HVAC controller  34  may control the VAV box in accordance with a sensed air temperature and an inputted temperature set point. 
     The HVAC controller  34  may display a variety of different screens, including a number of different environmental parameters. In some instances, as will be shown, the displayed environmental parameters, when displayed, may be displayed in repeatable locations. For example, a current temperature value may always be displayed in a particular location on the screen. A temperature set point, if displayed, may always be displayed in a particular location on the screen. A sensed humidity value, if displayed, may always be displayed in a particular location on the screen. A sensed carbon dioxide value, if displayed, may always be displayed in a particular location on the screen. A graphical icon indicating mode, such as normal operation mode, temperature set point adjustment mode or commissioning mode in which a test and balance procedure is operated may, if displayed, always be displayed in a particular location on the screen. Any variety of graphical icons may be displayed, including but not limited to a clock icon, a thermometer icon, a fan blade icon, a relative humidity icon, a heating icon and/or a cooling icon. 
     In one example, when the HVAC controller  34  is in a test and balance mode, the HVAC controller  34  may be configured to display a damper time value and up and down arrows for adjusting the damper time value. The damper time value may represent the time it takes to move from a fully open position to a fully closed position, or visa-versa. In some cases, the HVAC controller  34  may be configured to display an air flow volume value and up and down arrows for adjusting the air flow volume value. The air flow volume value may be the desired air flow indicator discussed above.  FIGS. 12 through 18  provide illustrative but non-limiting examples of screen that may be displayable by the HVAC controller  34 .  FIG. 12  shows a screen  112  illustrating a clean, un-cluttered “across the room view” in which a current sensed temperature  114  is displayed in a relatively large size font on an otherwise blank screen. As a result, the current sensed temperature  114  is easy to read.  FIG. 12  may be considered as an example of the HVAC controller  34  being in its normal operation mode. 
       FIGS. 13 through 18  show screens that may be displayed while configuring the HVAC controller  34 .  FIGS. 13 through 18  show a variety of graphical icons. A user may select one of the graphical icons to check or alter a setting for a particular parameter. As illustrated, the graphical icons include a clock icon  118  that may be selected for setting a time, for example. A thermometer icon  120  may be selected for checking or changing a temperature set point. A fan icon  122  may be selected for checking or changing a setting related to fan speed, or whether the fan runs all the time, or automatically with the rest of the HVAC equipment. A raindrop icon  124  may be selected for checking or changing humidity setpoint values. A CO 2  icon  126  may be selected for checking or changing permitted carbon dioxide values, or carbon dioxide alarm values. A blinds icon  128  may be selected for checking or changing window blind positions. A light bulb icon  130  may be selected for changing lighting settings. A house icon  132  may be selected to return to a home screen. 
       FIG. 13  shows a screen  116  in which it can be seen that a user has selected the blinds icon  128 , as the blinds icon  128  is highlighted. The screen  116  includes a blinds display  134 , and the blinds are open. In  FIG. 14 , the blinds can be seen to be closed, as indicated by the blinds display  134  on a screen  136 . It can be seen that the blinds display  134  is shown in the same location in both  FIGS. 13 and 14 . Screens  116  and  136  also displays a Windows text  135  that helps to provide context. 
       FIGS. 15 and 16  show example screens in which the CO 2  icon  126  has been selected as indicated by the CO 2  icon  126  being highlighted.  FIG. 15  provides a screen  138  that includes a CO 2  display  140  that is displayed using 3 digits while  FIG. 16  provides a screen  142  that includes a CO 2  display  140  displayed using 4 digits. It can be seen that the CO 2  display  140  is displayed in the same location in both  FIGS. 15 and 16 . Screens  138  and  142  also include an Air Quality icon  141  that helps to provide context.  FIG. 17  provides a screen  144  in which the humidity icon  124  has been selected and is highlighted. The screen  144  includes a first humidity display  146  and a second humidity display  148 . The screen  144  also includes a humidity text  150  that helps to provide context. 
       FIG. 18  shows a screen  150  that may be displayed when a user selects the thermometer icon  120 , which is shown as illuminated or otherwise selected. This screen may be used, for example, to change a temperature set point. The screen  150  includes a temperature set point display  152  that displays a current temperature set point and an up arrow and down arrow display  154  that may be used by the user to raise or lower the temperature set point. The screen  150  also includes a range display  156  as well as a Temperature text that helps to provide context. 
       FIG. 19  shows another screen  200  that may be displayed on the user interface  86  ( FIG. 8 ) of the HVAC controller  34 . The screen  200  displays at least part of a service mode menu and includes a field service button  202 , a settings button  204 , an exit button  206 , a custom codes button  208  and a balance button  210 . A text  214  indicates that the screen  200  is part of the service mode menu. Buttons  212  permit an individual to scroll forwards and backwards among multiple screens, such as the screen  200 , which are displayable by the HVAC controller  34 . Selecting the balance button  210  may cause the HVAC controller  34  to display additional screens useful in performing a test and balance procedure on one or more VAV boxes. It will be appreciated that in addition to testing damper position and corresponding airflow, as discussed with respect to previous Figures, a test and balance procedure may be used to calibrating various HVAC system components including the VAV boxes in order to achieve desired HVAC system performance, control air pressure within a building (not excessively over-pressurizing or under-pressurizing the building), and/or to control the flow of conditioned air from a conditioned air source in order to not overly stress the HVAC system. 
     When the balance button  21  of  FIG. 19  is selected, the HVAC controller  34  may enter the balance mode and may display a screen  216 , as shown in  FIG. 20 . The screen  216  includes a text message  218  indicating that it is in the balance mode. A cold deck button  220  and a hot deck button  222  permit a user to select whether they wish to calibrate the cold deck or the hot deck. This assumes, of course, that the HVAC system in question has both a cold deck and a hot deck. A dual deck system is shown schematically in  FIG. 3  while a single deck system is shown schematically in  FIG. 2 . If the HVAC system in question is a single deck system, the screen  216  would not include a hot deck button  222 , and perhaps the cold deck button  220  would be labeled differently. Once the user makes a selection, the HVAC controller  34  will display the next screen in the test and balance process, such as the screen  224  shown in  FIG. 21 . 
       FIGS. 21 through 25  show illustrative but non-limiting screens that may be displayed by the HVAC controller  34  when calibrating a cold deck. Similar screens may be displayed when calibrating a hot deck. It will be appreciated that these screens may be accessed in any order, and that some illustrated screens may be omitted in certain installations. It will also be appreciated that the calibration process may include additional screens that are not illustrated.  FIG. 21  shows a screen  224  that permits a user to indicate the size of the cooling apparatus associated with the HVAC system  12 . In some cases, cooling capacity is stated in tons. The screen  224  includes a cooling size value  226  as well as a set  228  of adjusting arrows that may be used to raise or lower the cooling size value  226 . The screen  224  also includes text  230  to help provide context. Once the cooling size has been set as appropriate, the user may use buttons  212  to advance to the next screen. 
       FIG. 22  shows a screen  232  that permits a user to adjust a high limit for the cooling temperature. The screen  232  includes a high limit value  234  as well as a set  228  of adjusting arrows that may be used to raise or lower the high limit value  234 . The screen  232  includes text  236  to help provide context. Once the high limit value has been set as appropriate, the user may use buttons  212  to advance to the next screen. 
       FIG. 23  shows a screen  238  that permits a user to adjust a low limit for the cooling temperature. The screen  238  includes a low limit value  240  as well as a set  228  of adjusting arrows that may be used to raise or lower the low limit value  240 . The screen  238  includes text  242  to help provide context. Once the low limit value has been set as appropriate, the user may use buttons  212  to advance to the next screen. 
       FIG. 24  shows a screen  244  that permits a user to adjust a temperature set point for use in the test and balance procedure. The screen  244  includes a temperature set point  246  and a cooling icon  248  as well as a set  228  of adjusting arrows that may be used to raise or lower the temperature set point  246 . The screen  244  includes text  247  to help provide context. Once the temperature set point has been set as appropriate, the user may use buttons  212  to advance to the next screen. 
       FIG. 25  shows a screen  250  that permits a user to adjust a minimum airflow value. The screen  250  includes a minimum airflow value  252  as well as a set  228  of adjusting arrows that may be used to raise or lower the minimum airflow value  252 . The screen  250  includes text  254  to help provide context. Once the minimum airflow value has been set as appropriate, the user may use buttons  212  to advance to the next screen. 
       FIGS. 26 through 31  show additional illustrative but non-limiting screens that may be displayed by the HVAC controller  34  when calibrating a cold deck. Similar screens may be displayed when calibrating a hot deck. It will be appreciated that these screens may be accessed in any order, and that some illustrated screens may be omitted in certain installations. It will also be appreciated that the calibration process may include additional screens that are not illustrated. 
       FIG. 26  shows a screen  256  in which the HVAC controller  34  displays a current air flow value  258 . In this example, the HVAC controller  34  receives the current air flow value  258  from the VAV box itself, which is equipped to measure and communicate this information to the HVAC controller  34 . The system is still in a balance mode, as indicated by the text message  218 . The screen  256  includes text  260  to help provide context. A calibrate button  262  may be selected to begin a calibration process. Buttons  212  may be used, if desired, to move to a different screen. 
       FIG. 27  shows a screen  264  that may be displayed by the HVAC controller  34 . The screen  264  includes text  268  that informs the user as to what is being done. A display  266  informs the user of the damper position, which as illustrated is 100% open. Text  274  informs the user that the calibration process is underway. A cancel button  270  permits the user to cancel the calibration process, if desired. A start button  272 , if selected, instructs the HVAC controller  34  to proceed with the calibration. Similarly,  FIG. 28  shows a screen  276  in which the damper position is 0% open, or fully closed, as indicated by the display  266 . Buttons  212  may be used, if desired, to move to a different screen. In some cases, the HVAC controller  34  may automatically titrate by moving the damper position, receiving an updated air flow value  258  from the VAV box, and comparing the updated air flow value  258  with a desired air flow value, until a damper positioned is found that corresponds to the desired air flow value. 
       FIG. 29  shows a screen  278  that may be displayed by the HVAC controller  34 . The screen  278  includes text  268  that informs the user as to what is being done. A display  280  allows a user to set a desired airflow, which as illustrated is minimum air flow of 50 CFM. An up and down arrow set  282  displays min flow and permits the user to adjust the minimum flow. Text  274  informs the user that the calibration process is underway. During the calibration process, the HVAC controller  34  may automatically titrate to fine the damper position that delivers the desired minimum air flow (e.g. 50 CFM). A cancel button  270  permits the user to cancel the calibration process, if desired. A start button  272 , if selected, instructs the HVAC controller  34  to proceed. Similarly,  FIG. 30  provides a screen  284  which can be used to determine the damper position that delivers the desired maximum air flow (e.g. 450 CFM). Buttons  212  may be used, if desired, to move to a different screen. 
     In some cases, there may be a desire to lock the damper in a particular position.  FIG. 31  provides a screen  288  that may be displayed by the HVAC controller  34 . The screen  288  includes a current air flow value  290  as well as an arrow set  292  that may be used to adjust the current air flow value  290 . A display  294  provides the maximum air flow value and a display  296  provides the current damper position. A cancel button  270  permits the user to cancel the calibration process, if desired. A lock button  298  may be pressed to lock the damper position. Buttons  212  may be used, if desired, to move to a different screen. 
     The disclosure should not be considered limited to the particular examples described above. Various modifications, equivalent processes, as well as numerous structures to which the disclosure can be applicable will be readily apparent to those of skill in the art upon review of the instant specification.