Abstract:
Fan coil thermostats can provide energy savings by, for example, not unnecessarily running a fan for longer than necessary or at a higher speed than necessary. Fan coil systems employing such a fan coil thermostat may be more energy efficient. A fan coil system may include a fan coil, a valve that controls fluid flow through the fan coil and a fan that blows air across the fan coil. The fan coil thermostat may include a controller that implements a control algorithm that may include an Auto fan speed mode. The controller may be programmed to permit a user to manually select a fan speed setting using the user interface. In response, the controller may initiate a timer, and may automatically return to the Auto fan speed mode once the timer expires.

Description:
[0001]    This is a continuation application of co-pending U.S. patent application Ser. No. 11/833,685, filed Aug. 3, 2007, and entitled “FAN COIL THERMOSTAT WITH AUTOMATIC FAN RESET”, which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure pertains generally to thermostats and more particularly to thermostats adapted for use with fan coils. 
       BACKGROUND 
       [0003]    A variety of buildings such as hotels, apartment buildings and the like are heated and cooled using fan coil systems. In a fan coil system, a heat transfer fluid such as water is pumped or otherwise forced through a fan coil. A fan is used to blow air across the fan coil. If the heat transfer fluid was heated, heated air will blow out of the fan coil system. Conversely, if the heat transfer fluid was cooled, cool air will blow out of the fan coil system. 
         [0004]    Like other HVAC systems, fan coil systems often consume significant amounts of energy. For many buildings, such as hotels and other structures, a number of rooms may, at any given time, be unoccupied. A significant amount of energy may be saved by not running a fan at a higher than necessary speed, particularly when a room or other space is not occupied. 
       SUMMARY 
       [0005]    The present disclosure pertains to fan coil thermostats that can provide energy savings by, for example, not unnecessarily running a fan longer than necessary and/or at a higher speed than necessary, particularly when a room or other space is not occupied. Fan coil systems employing such a fan coil thermostat may be more energy efficient. 
         [0006]    In an illustrative but non-limiting example of the present disclosure, a fan coil thermostat is configured for use with a fan coil system. In some cases, a fan coil system may include a fan coil that is configured for fluid communication with a source of heated fluid and/or a source of cooled fluid, a valve that controls fluid flow through the fan coil and a fan that blows air across the fan coil. 
         [0007]    The fan coil thermostat may include a controller that implements a control algorithm that is adapted to at least partially control one or more components of the fan coil system and that may include an Auto fan speed mode. The fan coil thermostat may include a user interface as well as a timer that is controlled by the controller. The controller may be programmed to permit a user to manually select a fan speed setting using the user interface. In response, the controller may initiate the timer, and may return to the Auto fan speed mode once the timer has expired. 
         [0008]    The above summary is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures and Detailed Description that follow more particularly exemplify these embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0009]    The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
           [0010]      FIG. 1  is a schematic view of an illustrative but non-limiting fan coil system; 
           [0011]      FIG. 2  is a schematic view of an illustrative but non-limiting fan coil thermostat as may be used in the fan coil system of  FIG. 1 ; 
           [0012]      FIG. 3  is a front view of an illustrative embodiment of the fan coil thermostat of  FIG. 2 ; 
           [0013]      FIG. 4  is a flow diagram showing an illustrative method that may be carried out using the fan coil system of  FIG. 1 ; and 
           [0014]      FIG. 5  is a flow diagram showing an illustrative method that may be carried out using the fan coil system of  FIG. 1 . 
       
    
    
       [0015]    While the invention 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 invention to the particular illustrative embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
       DETAILED DESCRIPTION 
       [0016]    The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials may be illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized. 
         [0017]      FIG. 1  is a schematic view of an illustrative but non-limiting fan coil system  10 . While the illustrative fan coil system  10  is schematically shown as a two-pipe fan coil system including a single supply line and a single return line, it will be appreciated that fan coil system  10  may instead be a four-pipe fan coil system having heated water supply and return lines as well as cooled water supply and return lines. In some cases, a four-pipe system may include a single fan coil while in other cases, a four-pipe system may include two fan coils, with one dedicated to heated and one dedicated to cooling. In a two-pipe fan coil system, the single supply line may, for example, provide heated water during the heating season and may provide cooled water during the cooling season. 
         [0018]    The illustrative fan coil system  10  includes a fan coil  12 . Fan coil  12  is a heat exchanger through which heated or cooled fluid flows. A fan  14  blows air across fan coil  12  as schematically shown by arrows  16 . In some cases, fan  14  pulls ambient air from within the space and/or from outside the building. The ambient air is then heated or cooled by the fan coil  12  and provided into the space. In some cases, fan coil system  10  may be disposed within a housing (not shown) having a first vent or opening upstream of fan  14  and a second vent or opening downstream of fan coil  12 . Fan  14  may pull air through the first vent or opening and then exhaust the heated or cooled air through the second vent or opening and into the space. The components may be arranged either horizontally or vertically within such a housing, as desired or perhaps as dictated by space considerations. 
         [0019]    In order to accommodate fluid flow through fan coil  12 , fan coil system  10  includes a supply line  18  and a return line  20 . During the heating season, supply line  18  provides a source of heated fluid (such as water) from a suitable source such as a boiler or water heater, geothermal and/or the like. During the cooling season, supply line  18  provides a source of cooled fluid (such as water) from a suitable source such as an evaporative cooling tower or the like. 
         [0020]    A valve  22  is disposed within supply line  18 , upstream of fan coil  12 , in order to control fluid flow through fan coil  12 . In some cases, valve  22  may provide binary, i.e., on/off control while in other cases it is contemplated that valve  22  may be configured to provide a plurality of flow rates into fan coil  12 . 
         [0021]    Fan coil system  10  may include a fan coil thermostat  24  that controls operation of valve  22  and/or operation of fan  14  in order to achieve a desired temperature level within a space that is conditioned by fan coil system  10 . Fan coil thermostat  24  is better described with respect to  FIG. 2 .  FIG. 2  schematically shows various components of an illustrative fan coil thermostat  24 . The illustrative fan coil thermostat  24  includes a user interface  26  that may include a display  28  and a keypad  30 . Display  28  may be any suitable alphanumeric display medium that is capable of displaying visually discernible information. In some cases, display  28  may be a liquid crystal display (LCD), but this is not required. Keypad  30  may include one or more individual electromechanical buttons such as such as an on/off button, a temperature up button, a temperature down button, a fan speed up button, a fan speed down button, and the like. In some cases, it is contemplated that user interface  26  may be a touch screen LCD that encompasses the function of display  28  as well as keypad  30 . That is, the buttons of keypad  30  may include, for example, electromechanical buttons, soft buttons, and/or touch regions on a touch screen display, as desired. 
         [0022]    The illustrative fan coil thermostat  24  may include a controller  32 . In some cases, controller  32  may implement a control algorithm that is adapted to at least partially control one or more components of fan coil system  10  and that may include an Auto fan speed mode setting. In some cases, the Auto fan speed mode may include an algorithm that determines fan speed based at least in part on if valve  22  ( FIG. 1 ) is open or closed and/or how far valve  22  is open. In some instances, the Auto fan speed mode may dictate that fan  14  ( FIG. 1 ) is off if valve  22  is closed. As valve  22  opens, the Auto fan speed mode may dictate that fan  14  is running at, for example, a low speed, a medium speed, a high speed or the like. In some cases, the Auto fan speed mode may determine a fan speed also based at least in part on a temperature differential between a current sensed temperature and a current temperature set point, and/or a current sensed humidity and a current humidity set point. 
         [0023]    Controller  32  may be adapted to provide information to and/or receive information from user interface  26 . Controller  32  may, for example, display a current temperature and/or a current temperature set point on display  28 . Other examples of information that may be provided by controller  32  include a current fan speed, current fan mode, equipment status (on/off), current time, and the like. Examples of information that may be received from keypad  30  may include changes in a temperature set point, changes in fan speed and the like. 
         [0024]    In some cases, the illustrative fan coil thermostat  24  may include a memory block  34 . Memory block  34  may be used, for example, to store one or more unoccupied temperature set points, a current temperature set point, and/or programming that instructs controller  32  how to regulate valve  22  ( FIG. 1 ) and/or fan  14  ( FIG. 1 ) in order to obtain and maintain a particular temperature set point. Memory block  34  may store, for example, the aforementioned control algorithm. 
         [0025]    In some instances, fan coil thermostat  24  may include a sensor  36  that provides controller  32  with information pertaining to current conditions within a space conditioned by fan coil system  10  ( FIG. 1 ). Sensor  36  may be a temperature sensor, a humidity sensor and/or any other suitable sensor, as desired. In some cases, sensor  36  may be located internally to fan coil thermostat  24 , although in some instances, sensor  36  may instead be located remotely from fan coil thermostat  24 . 
         [0026]    Fan coil thermostat  24  may include a timer  38 . In some cases, timer  38  may be an electromechanical timer while in other instances timer  38  may be an electronic timer or may even be manifested in programming run by controller  32 . In some instances, if a user operates one or more buttons of keypad  30 , such as changing a temperature set point or perhaps changing the speed of fan  14  ( FIG. 1 ), user interface  26  may provide a signal to controller  32  that provides controller  32  with a user-chosen temperature or perhaps a manually-selected fan speed setting. From this, controller  32  may also determine an indication of occupancy. i.e., that someone is in the space. In response, controller  32  may temporarily change the temperature set point from the unoccupied temperature setting to the user-chosen temperature setting, and/or change the fan speed setting to a manually-selected fan speed setting. 
         [0027]    When the user first changes the fan speed setting, the controller  32  may temporarily change the fan speed from that specified by the default Auto fan speed mode to the manually-selected fan speed. In some cases, the manually-selected fan speed may be selected irrespective of a difference, if any, between an ambient temperature and a current temperature set point. For example, an individual may decide to set the fan speed to high even if the ambient temperature is equal or nearly equal to the current temperature set point. In some cases, the manually-selected fan speed may specify a fan speed that is higher and/or lower than what would otherwise be specified by the Auto fan speed mode. In some instances, the manually selected fan speed setting specifies a non-zero fan speed under conditions in which the Auto fan speed mode would specify a zero fan speed. 
         [0028]    In addition to changing the fan speed in response to the signal from keypad  30  ( FIG. 1 ), controller  32  may also initiate timer  38 . Once the timer  38  expires after a predetermined time, controller  32  may change the fan speed of fan  14  ( FIG. 1 ) to a fan speed that is specified by the Auto fan speed mode. The timer  38  may expire in any suitable time period. In some cases, the timer  38  may expire after about 1 hour. In some instances, the timer  38  may expire after about 2 hours, about 4 hours, about 6 hours, about 12 hours, or any other suitable time period, as desired. In some instances, and while waiting for the timer  38  to expire, controller  32  may be adapted to restart timer  38  if controller  32  receives an additional signal from the user interface  26  that indicates occupancy of the space. 
         [0029]      FIG. 3  is a front view of an illustrative fan coil thermostat  40 . Fan coil thermostat  40  may be considered as an embodiment or perhaps as a particular example of fan coil thermostat  24  ( FIG. 2 ). The illustrative fan coil thermostat  40  includes a housing  42  that may be formed of any suitable material such as molded plastic. The illustrative fan coil thermostat  40  also includes a display  44  that may be any suitable display such as an LCD display. 
         [0030]    The illustrative fan coil thermostat  40  also includes several buttons that may be considered as examples of keypad  30  ( FIG. 2 ). The buttons illustrated are not to be considered as limiting in any way, but are merely provided to show examples of buttons that may be included. As illustrated, fan coil thermostat  40  includes a fan speed up button  46  and a fan speed down button  48 . In some cases, it is contemplated that fan coil thermostat  40  may include a single fan speed button (not shown) that can be pressed repeatedly to step through the available fan speed settings. In some instances, a slider button or even a rotary dial may be provided to select a fan speed setting. 
         [0031]    As illustrated, fan coil thermostat  40  includes a temperature up button  50  and a temperature down button  52 . A user may select and/or alter a temperature setting by pressing temperature up button  50  and/or temperature down button  52 , as appropriate. A power button  54  may also be provided. It is contemplated that fan coil thermostat  40  may instead have a touch screen LCD that provides the functionality of display  44  as well as fan speed up button  46 , fan speed down button  48 , temperature up button  50 , temperature down button  52 , and power button  54 . In some cases, the various buttons may be provided as touch regions on the touch screen display. 
         [0032]      FIG. 4  is a flow diagram that shows an illustrative method that may be carried out by fan coil thermostat  24  ( FIG. 2 ) and/or fan coil thermostat  40  ( FIG. 3 ). At block  56 , controller  32  ( FIG. 2 ) regulates a fan speed of fan  14  ( FIG. 1 ) in accordance with an Auto fan speed mode. At block  58 , a manually selected fan speed setting is received from user interface  26  ( FIG. 2 ), and then controller  32  initiates timer  38  ( FIG. 2 ) as shown at block  60 . The timer  38  may be adapted to expire after, for example, about 1 hour, about 2 hours, about 4 hours, about 6 hours, about 12 hours, or any other suitable time period. While waiting for the timer  38  to expire, controller  32  may instruct timer  38  to restart if, for example, another manually selected fan speed setting is entered via user interface  26 . In some cases, controller  32  may instruct timer  38  to restart if, for example, any predetermined user input is received via the user interface  26  (e.g. the fan speed up button  46 , the fan speed down button  48 , the temperature up button  50 , the temperature down button  52 , and/or the power button  54  is pressed by the user). 
         [0033]    Control passes to block  62 , where controller  32  ( FIG. 2 ) regulates the fan speed of fan  14  ( FIG. 1 ) in accordance with the manually selected fan speed setting. At block  64 , controller  32  reverts back to a fan speed specified by the Auto fan speed mode once timer  38  ( FIG. 2 ) expires. 
         [0034]      FIG. 5  is a flow diagram showing another illustrative method that may be carried out by fan coil thermostat  24  ( FIG. 2 ) and/or fan coil thermostat  40  ( FIG. 3 ). At block  66 , controller  32  ( FIG. 2 ) controls fluid flow through fan coil  12  ( FIG. 1 ) by opening and/or closing valve  22  ( FIG. 1 ). Control passes to block  56 , where controller  32  ( FIG. 2 ) regulates a fan speed of fan  14  ( FIG. 1 ) in accordance with an Auto fan speed mode. At block  58 , a manually selected fan speed setting is received from the user interface  26  ( FIG. 2 ), and then controller  32  initiates timer  38  ( FIG. 2 ) as shown at block  60 . In some instances, the timer  38  may expire after about 1 hour, about 2 hours, about 4 hours, about 6 hours, about 12 hours, or any other suitable time period. 
         [0035]    Control passes to block  62 , where controller  32  ( FIG. 2 ) regulates a fan speed of fan  14  ( FIG. 1 ) in accordance with the manually selected fan speed setting. In some cases, this may mean running fan  14  even when no fluid is flowing through fan coil  12  ( FIG. 1 ). In some instances, this may mean running fan  14  at a speed that is higher or lower than a speed that would otherwise be designated by the Auto fan speed mode with respect to a flow rate of fluid through fan coil  12 . At block  64 , controller  32  reverts back to a fan speed specified by the Auto fan speed mode once timer  38  ( FIG. 2 ) expires. 
         [0036]    While the present disclosure has been described with respect to illustrative fan coil systems that include one or more pipes carrying heated water for heating and/or cooled water for cooling, it should be noted that the inventive concepts described herein are not limited to such systems. Some systems may be hybrid-type systems, with an A/C compressor for cooling and heated water for heating. Some systems may be through-the-wall systems, having one or more of a compressor for air conditioning, an electric or gas heating element for heating, and a heat pump. Fan coil thermostat  40  may, for example, be used with these systems as well as the systems described herein. 
         [0037]    The present disclosure should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention can be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the instant specification.