Patent Publication Number: US-2021180812-A1

Title: System, apparatus and method for conditioning a space

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation application, claiming benefit to U.S. application Ser. No. 16/581,013, filed Sep. 24, 2019, entitled: “System Apparatus and Method for Conditioning a Space,” which claims the benefit of priority to provisional application 62/735,415, filed Sep. 24, 2018, entitled: “System Apparatus and Method for Conditioning a Space,” and 62/777,645, filed Dec. 10, 2018, entitled: “System Apparatus and Method for Conditioning a Space,” the entirety of which is incorporated herein by reference as if set forth in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The disclosure relates generally to environmental maintenance and, more specifically, to an apparatus, system and method of conditioning an interior space. 
     DESCRIPTION OF THE BACKGROUND 
     Existing Induction designs typically provide 40%-60% of the entire cooling capacity of the building. However, most large buildings only have a heating load on the perimeter. 
     Perimeter induction units were typically designed to have 50 deg F. supply secondary water for cooling and up to 180 deg hot water for heating. Primary high-pressure air for the nozzles was designed to be 52-55 deg F. for cooling and typically 75-120 deg F. for heating. However, it is difficult if not impossible to operate at these conditions, since the drain pans on the units are not piped to drains and thus spill over on the floor when they sweat at high entering dewpoint temperatures to the perimeter coils. In the cooling mode, they therefore typically operate between 55 and 65 degree F. secondary water and at 55 to 65 degree F. primary air temperatures. The operating temperatures typically become a function of outside dry bulb and wetbulb conditions as well as sun load. 
     Both the air and water may or may not be zoned according to exposure. Air and water may thus be zoned differently. There are typically upper house zones and lower house zones fed by different piping, AHU&#39;s with water systems isolated by pressure break heat exchangers. 
     Up until now, modulating the water through the coil was used to control capacity of almost all induction units. This method of control does not modulate the 40% of the Induction units&#39; capacity that comes from the primary air. 
     Building pressurization is another critical issue with perimeter induction systems. Many buildings with perimeter induction systems were designed to have primary air supplied with 100% outside air. Building engineers quickly realized this as an energy intensive process and converted them to 50% outside air by installing return air ductwork. Unfortunately, in most cases, little or nothing was done to correct the building imbalance of exhaust and outside air caused by this modification. This has led to most of these buildings being very negative. 
     Newer designed induction units typically require less primary air for the same capacity as older units; forty percent in many cases. This further reduces outside air and results in more a negative pressure in the building. Negative pressure in the building causes unconditioned air to be pulled into the building at any opening in the skin of building. This can cause unwanted condensing at the perimeter coils requiring the operators to raise secondary water temperatures. 
     The foregoing can increase the heat load on the perimeter. It also causes jet-streaming at the minimum outside air dampers increasing flow and causing nuisance freezestat trip outs. 
     Fan tracking systems where the supply air and the return air flow is measured and controlled can help reduce negative pressure in the building caused by reductions in supply fan capacity. Shutting off or better control of unnecessary systems such as MER, elevator and garage exhausts can also reduce negative pressures in the building. Further, if at all possible, fan tracking control systems are added to buildings when changes are made to the perimeter induction systems. 
     SUMMARY OF THE DISCLOSURE 
     Improved conditioning control is provided herein. The improved conditioning assumes, at a minimum: two analog outputs and one analog input from the building automation system for each induction unit to be controlled; control of the primary air temperature and the secondary water temperature for each zone; a dew point sensor, located close to the perimeter, for at least one area in each zone; and VFD on the each induction system fan controlled by the discharge air pressure of the fan. 
     For all the cooling control schemes, a dewpoint sensor should be located near the inlet of an induction unit coil on the windward side of the building zone on the highest floor served by the secondary water system being controlled. The secondary water system that serves this unit should always be held at least one degree higher than the dewpoint (as measured by the dewpoint sensor for the zone) at the pump discharge that supplies that zone. The primary air temperature that supplies the zone may be held two degrees below the dewpoint as measured by the dewpoint sensor for this zone. 
     A temperature sensor in the space or return air to the induction unit may compare this temperature to the set point temperature. In cooling mode, if the space temperature is above the set point temperature, the water valve is modulated open using a P+I control algorithm, and on a decrease in temperature below setpoint, the valve is modulated closed. The setpoint can either be set locally with an input from the occupant or at a central computer. 
     If the space temperature continues to drop below setpoint and the water valve is fully closed, the second analog output modulates the air valve closed, using a P+I algorithm, to reduce the cooling effect from the primary air to maintain room setpoint. It modulates the air closed until it meets a minimum output that has been predetermined to provide a minimum ventilation rate. As an alternate, if there is a CO2 sensor in the area supplied by this unit, CO2 can be used to control the minimum output of the air valve and an alternate minimum can be set to prevent odors. 
     If the space temperature exceeds room setpoint and the output of the valve controller is at maximum, an alarm can be sent to the operator recommending that the primary water temperature be lowered or the primary air temperature be lowered depending on the condition of other units in the same zone. 
     In heating mode, if the room temperature is above setpoint temperature, the water valve modulates closed, using a P+I algorithm, in response to an increase in room temperature above setpoint. It may be possible to overheat the room when the secondary water valve is closed. 
     If, in the heating mode, the secondary water valve is closed and the primary air temperature, as measured at the AHU, is above the room temperature setpoint, the air valve can be modulated closed to maintain room temperature. Again this would modulate to some minimum point that represents a minimum ventilation standard, CO2 level or odor removal level, whichever is applicable. 
     If the primary air temperature is below room temperature and the room temperature continues to rise (typically from a sun load) the system can be alarmed to recommend to the operator that the primary air temperature be reduced to satisfy the cooling load. In addition, the action of the controller can be reversed to a cooling controller and the air valve can be modulated to maintain. 
     Likewise, when using primary air to control room temperature, in cooling mode, the secondary water valve is opened fully and the primary air is modulated by a P+I controller to maintain room temperature at setpoint as set at the computer. The valve is modulated to a minimum point as determined by ventilation, CO2 or odor requirements, whichever is applicable. 
     If the room temperature continues to drop, the secondary water valve is modulated closed to maintain room temperature. The reverse occurs as room temperature rises. 
     In heating mode, the water valve remains fully open. The Air valve modulates closed to maintain room temperature, again to its minimum point as limited by ventilation, CO2 or odor control requires. 
     If the room continues to overheat, the secondary water valve modulates closed. If the room continues to overheat above its setpoint, and the primary air is below room setpoint by two degrees, the controller reverses action and the air valve modulates open to cool the spaces. If the spaces drop two degrees below setpoint for 10 minutes after the air valve closes fully, the hot water valve opens, the air valve reverses action and opens to warm the spaces. 
     The AHU may be fitted with a VFD that is controlled from discharge air pressure. The setpoint of the discharge air controller is set from the BAS. As the pressure increases, the speed of the motor decreases bringing the pressure back to setpoint. The pressure setpoint varies with load. 
     The system pressure drop is very high and, as flow decreases, the system pressure drop may decrease by as much as 4-6″ wc. The change in setpoint is best done in steps to prevent interaction with the pressure controller. 
     As an alternate, the pressure before the induction unit can be measured. This pressure can be compared to the designed pressure for the induction units. This pressure can be used to control the supply fan speed directly or can be cascaded and become the setpoint of the fan discharge pressure controller. Numerous pressure sensors could be used and fed to a signal selector so that the zone requiring the highest pressure at the fan, to achieve design setpoint at the induction unit inlet, is satisfied. 
     Pressure control is a very fast control loop and control using a primary variable passed across a communications network should be avoided unless the speed of these communications can be assured. A cascaded control loop, where the remote sensor is used to reset the setpoint of the local pressure controller, is a preferred method. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In order to better appreciate how the above-recited and other advantages and objects of the inventions are obtained, a more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. It should be noted that the components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. Moreover, in the figures, like reference numerals may or may not designate corresponding parts throughout the different views. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely. More specifically, in the drawings: 
         FIG. 1  illustrates aspects of the embodiments; 
         FIG. 2  illustrates aspects of the embodiments; 
         FIG. 3  illustrates aspects of the embodiments; 
         FIG. 4A  illustrates aspects of the embodiments; 
         FIG. 4B  illustrates aspects of the embodiments; 
         FIG. 4C  illustrates aspects of the embodiments; 
         FIG. 4D  illustrates aspects of the embodiments; 
         FIG. 4E  illustrates aspects of the embodiments; 
         FIG. 5A  illustrates aspects of the embodiments; 
         FIG. 5B  illustrates aspects of the embodiments; 
         FIG. 5C  illustrates aspects of the embodiments; 
         FIG. 5D  illustrates aspects of the embodiments; 
         FIG. 5E  illustrates aspects of the embodiments; 
         FIG. 6A  illustrates aspects of the embodiments; 
         FIG. 6B  illustrates aspects of the embodiments; 
         FIG. 6C  illustrates aspects of the embodiments; 
         FIG. 6D  illustrates aspects of the embodiments; 
         FIG. 6E  illustrates aspects of the embodiments; 
         FIG. 7A  illustrates aspects of the embodiments; 
         FIG. 7B  illustrates aspects of the embodiments; 
         FIG. 7C  illustrates aspects of the embodiments; 
         FIG. 7D  illustrates aspects of the embodiments; 
         FIG. 7E  illustrates aspects of the embodiments; and 
         FIG. 8A  illustrates aspects of the embodiments; 
         FIG. 8B  illustrates aspects of the embodiments; 
         FIG. 8C  illustrates aspects of the embodiments; 
         FIG. 8D  illustrates aspects of the embodiments; 
         FIG. 8E  illustrates aspects of the embodiments. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE PRESENT INVENTION 
     The figures and descriptions provided herein may have been simplified to illustrate aspects that are relevant for a clear understanding of the herein described apparatuses, systems, and methods, while eliminating, for the purpose of clarity, other aspects that may be found in typical similar devices, systems, and methods. Those of ordinary skill may thus recognize that other elements and/or operations may be desirable and/or necessary to implement the devices, systems, and methods described herein. But because such elements and operations are known in the art, and because they do not facilitate a better understanding of the present disclosure, for the sake of brevity a discussion of such elements and operations may not be provided herein. However, the present disclosure is deemed to nevertheless include all such elements, variations, and modifications to the described aspects that would be known to those of ordinary skill in the art. 
     Embodiments are provided throughout so that this disclosure is sufficiently thorough and fully conveys the scope of the disclosed embodiments to those who are skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. Nevertheless, it will be apparent to those skilled in the art that certain specific disclosed details need not be employed, and that embodiments may be embodied in different forms. As such, the embodiments should not be construed to limit the scope of the disclosure. As referenced above, in some embodiments, well-known processes, well-known device structures, and well-known technologies may not be described in detail. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. For example, as used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The steps, processes, and operations described herein are not to be construed as necessarily requiring their respective performance in the particular order discussed or illustrated, unless specifically identified as a preferred or required order of performance. It is also to be understood that additional or alternative steps may be employed, in place of or in conjunction with the disclosed aspects. 
     When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present, unless clearly indicated otherwise. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). Further, as used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Yet further, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the embodiments. 
     Induction heating and/or cooling (herein referred to as “conditioning”) systems are generally known. Induction Systems are generally employed for perimeter heating and cooling zones of multi-room, multi-story buildings; such as office buildings, patient wings of hospitals, apartments and hotels. By giving each room its own individual induction unit, it is generally possible to satisfy the individual cooling and heating loads in these perimeter zones. 
     A perimeter zone may be generalized as the area running along the exterior walls of the building and extending 10 to 20 feet into the building (about 15 feet may be commonly assumed in the design of the system). These perimeter zones are subjected to relatively constant heat gains from lights, people and equipment in the spaces. In addition these areas may be subjected to highly variable temperature gains from sunlight through windows, and/or by heat transmission through the exterior walls/windows. 
     There will be times when some of the perimeter zones generally need cooling to remain near a desired temperature (herein referred to as a “setpoint”) while others need heating. For example, perimeter zones facing east may need cooling in the morning while the perimeter zones facing west at the same time may need heating. In these instances it may be desired the building HVAC system have a flexibility to alternatively provide either heating or cooling to every zone. When properly designed an induction system using a two-pipe water distribution network offers this flexibility. 
     An induction system generally uses two air streams and cooling/heating water supplied to the induction unit to provide this flexibility. One air stream is delivered from the central air handlers and is referred to as the primary air. The other is referred to as secondary air, and is the space, zone or room air that is induced to flow over the water coil in the induction unit by the primary air. The water is called secondary water and serves the water coil in the induction units. 
     Primary air (which may be inlet from outside the building, i.e., outside air) may be filtered, cooled or heated, and dehumidified or humidified for the building (e.g., at the central air handlers in the building). The primary air may be supplied to the induction units through a ductwork system. The primary air passes through the induction unit into the room where it adds or removes sensible heat and moisture. In passing through the induction unit it also draws or induces secondary room air through the water coil in the induction unit. The primary air provides the necessary ventilation, some heating or cooling and supplies the necessary motive power for inducing secondary airflow. 
     The secondary room air is induced and flows over the coil of the induction unit. Through the secondary water supplied to the induction unit&#39;s coil this secondary room air is heated or cooled, depending on the water temperature, the quantity of heat added to or removed from the secondary air may be controlled by the room thermostat to satisfy the room demands, e.g., maintain room conditions at or near setpoint(s) by controlling the quantity of water flowing through the coil. 
     The two air streams and water loop conditions can be controlled/manipulated to provide alternately either cooling or heating to the perimeter zones. The system can be designed to deliver: cold primary air and cold water in the coil; warm primary air and cold water in the coil; cold primary air and warm water in the coil; or warm primary air and warm water in the coil. 
     In general a typical induction system design provides occupant comfort as follows. 
     Humidity is controlled by controlling the dew point temperature of the primary air. 
     Cleanliness is controlled by filtering the primary air at the central air handlers. Lint screens may also be used in the room induction unit to filter the secondary air. 
     Air movement is controlled by the amount of primary air delivered and the amount of secondary air induced by the primary air. 
     The room&#39;s dry bulb temperature is controlled by varying the temperature of the primary air, and varying the secondary water flow and temperature so that the sensible heat gains or losses to the space are balanced. 
     There will likely be times, such as during intermediate seasons like spring and fall, when some amount of reheating/re-cooling will occur to simultaneously satisfy zones&#39; heating or cooling loads. This possibility can be largely eliminated if separate air handlers are used to serve each exposure and the interior zones. 
     Induction units conventionally operate with a constant volume primary air, meaning the volume of primary air provided to the induction unit does not substantially vary regardless of load. For clarity, load as used herein, refers generally to the sum of heat sources of a space to be conditioned, and is generally expressed either in BTU (British Thermal Units) or Kw (Kilowatts). For an air conditioner to cool a space, such as a room or building, its output must be greater than the heat load. 
     An induction unit conditioning may be modulated dependently upon the temperature and volume of water circulated through an induction unit coil, which is used to exchange heat with the air being conditioned, e.g., cooled or heated. 
     In conventional applications, the primary air typically consists of between about 50% and 100% outside air, meaning ambient air from outside the building. This ambient air is cooled in the summer and heated in the winter to meet space occupancy requirements, e.g., temperature and/or humidity setpoints. In many environments, this leads to substantial inefficiencies in providing conditioned air to a space, as the outside temperature may vary widely, e.g., depending upon location and season. For example, a desired space temperature may be around 72 degrees Fahrenheit, regardless of whether outside air being provided as primary air is 0 degrees Fahrenheit or 100 degrees Fahrenheit. 
     Referring now to  FIG. 1 , there is shown an exemplary induction unit  10 . Unit  10  generally includes a coil  4  that receives room air  3 . Air  3  is mixed with primary air being ejected at a high velocity from nozzle  2 . This high velocity air induces a low pressure area behind the coil  4  which draws room air  3  across the coil  4 , where it mixes with the primary air. This mixed air  1  is provided to the room or space to be heated or cooled, e.g., conditioned, discharge  5 , e.g., a grill or grate. 
     The nozzles require high pressure primary air in order to induce the air from the space to be circulated across the coils for heating and cooling. It is expensive to raise the pressure of the primary air to these high pressures, as required fan horsepower to provide these pressures may be expected to increase non-linearly, e.g., by the square, compared to a desired pressure to be induced. 
     Certain embodiments of the invention advantageously allow for lower velocity primary air to be effectively utilized, resulting in significant energy efficiencies to be realized. An unanticipated advantage of the present invention is that such savings may be realized in retrofitted induction units even when high loads or demands are present, where modulation would not be expected to be useful. 
     Referring now to  FIG. 2 , there is shown a diagrammatic representation of an induction unit system  100  according to an embodiment of the present invention. System  100  includes an induction unit  110 , a controller  120  a sensor  130 . In certain embodiments of the present invention, induction unit  110  may be retrofitted according to embodiments of the present invention. 
     In the illustrated embodiment, induction unit  110  includes a coil  140 , nozzles  150 , a water valve  160 , air valve  170 , sensors  180 ,  190  and  200 , control valve  210 , pneumatic valve  220  and a termination block  230 . Coils  140  may be analogous to conventional induction coils for exchanging heat between supplied heating/cooling water and the air to conditioned. Nozzles  150  may take the form of conventional induction unit nozzles for providing the primary air as discussed. Water valve  160  may take the form of a conventional induction unit water valve used to modulate the volume of heating or cooling water supplied to the coil  140 , e.g., responsively to a thermostat. 
     Referring still to  FIG. 2 , according to certain embodiments of the present invention, unit  110  may include an air valve  170 . Valve  170  may take the form of an inline, induction air valve (IAV) suitable for modulating the amount of primary air provided to the nozzles  150 . 
     Sensors  180 ,  190  and  200  may take the form of a temperature sensors. Sensor  180  may monitor primary air temperature. Sensor  190  may monitor the temperature of water entering the coil, secondary water temperature being circulated around a building perimeter. Sensor  200  may monitor the induction unit  110  discharge air temperature, e.g., the air being provided to the space. Valve  220  may modulate the amount of control air provided to control valve  210 . Control valve  210  modulates the amount of water provided to the coil. A termination area, box or other mechanism may be used to provide for electrical connectivity, such as when an otherwise conventional induction unit is being retrofitted. 
     As will be appreciated by those of ordinary skill in the pertinent arts, in a conventional induction unit system  100 , valve  210  may take the form of a pneumatic valve that responds to a pneumatic signal or pressure, e.g., from a thermostat for the space. In the embodiment of  FIG. 2 , valve  210  may take the form of a pneumatic valve that controls the amount of water supplied to the coil responsively to electronic solenoid valve  220 . 
     In certain embodiments of the present invention, controller  120  may take the form of an application specific integrated circuit or microprocessor based controller. It may provide control signals whether in heating or cooling. 
     In certain embodiments of the present invention, sensor  130  may take the form of a room temperature, humidity and/or carbon dioxide sensor, for example. 
     Referring now to  FIG. 3 , there is shown an exemplary valve  370  according to certain embodiments of the present invention. Valve  370  generally includes body sections  380 ,  390  that mate together to form an elongated, cylinder valve body through which primary air may be directed. Valve disc  400  may be within the valve body and rotated via an actuator (e.g., up to 90 deg.) to modulate the amount of primary air that passes through the valve body. The actuator may be of any form suitable to rotate disc  400  dependently upon controller  120  signaling, e.g., it may be pneumatic or electro-mechanical in nature. 
     Valve disc  400  generally includes first and second mating bodies or portions  400   a ,  400   b . Disc  400  generally includes first and second sections or portions  430 ,  440 . Section  430  may generally take the form of stem suitable for mechanically coupling to the actuator, to enable the actuator to rotate the disc  400 . Disc  400  further includes bearings  450   a ,  450   b . Bearing  450   a  is generally positioned at an end of stem portion  430  proximate the second portion  440 . Bearing  450   b  is generally disposed on the opposite side of second portion  440  from bearing  450   a . The bearings  450   a  facilitate rotation of disc  400  within the housing or valve body formed of portions  380 ,  390 . 
     Referring still to  FIG. 3 , the second portion may be substantially ovoidal. This may facilitate passing air through the valve body with less pressure drop and less noise than a substantially circular in cross-section second portion of the disc. Portion  440  also includes first and second oppositely disposed faces or surfaces  480   a ,  480   b . In certain embodiments of the present invention, these surface may each be convex in nature. This convex shaping my further reduce pressure drop and noise as well or in lieu of the above discussed ovoidal shaping. In certain embodiments of the present invention, surfaces  480   a ,  480   b  may be smooth to further or alternatively, mitigate operational pressure drops and noise. Such smoothness may be accomplished in the case of a molded embodiment of disc  400  by polishing the corresponding mold face(s), for example. In certain embodiments of the present invention, the faces  480   a ,  480   b  may be substantially smoother than other surfaces of the valve. 
     In certain embodiments of the present invention, a plurality of fins  460  that longitudinally project from a periphery, or thereabout, of surfaces  480   a ,  480   b , at least where those peripheries will become proximate to portions  380 ,  390  when disc  400  is rotated to a closed position, may be provided. Fins  460  may advantageously guide air flow through the body when disc  440  approaches a closed positioning, as it opens and/or closes, which may prevent so-called jet streaming. Jet streaming may create noise and undesirable pressure losses, that may even be downstream unrecoverable pressure losses. 
     In certain embodiments of the present invention, disc portion  440  further includes a flange  470  about at least a portion of the periphery, and in some embodiments at least most of the periphery, to seat against a lip  490  of portions  380 ,  390  to help seal the valve in the closed position. 
     Certain unanticipated advantages of such embodiments may include user acceptance of retrofitted induction units, as air volume is not typically throttled, and throttling primary air volume as discussed herein may otherwise lead to undesirable air circulation noise through the valve that otherwise may not exist. 
     In certain embodiments of the present invention, valve  400  may be molded of plastic. In certain embodiments of the present invention, it may be formed of a molded ABS plastic. In certain embodiments it may be molded of Acrylonitrile Butradiene Styrene, such as is sold under the brand name POLYLAC PA-765A, for example. 
     Bearings  450   a ,  450   b  may be composed of nylon or another self lubricating material, for example, such as bunting type NN08, by way of example. 
     In certain embodiments of the present invention, valve  400  may include one or more mounting portions  500  for mounting an actuator mechanically coupled to the stem, e.g., mounted directly or via a platform, for example. 
     In certain embodiments of the present invention, the valve may be sized, e.g., have an outside diameter and/or other dimensions, to make it well suited to directly mount within a spigot of a conventional induction unit, thereby simplifying retrofitting of existing induction units. Exemplary dimensions may be seen  FIG. 3 . The relative short length of the valve may be further advantageous, as induction units are conventionally positioned along the outside walls of a building, where space is at a premium and conventional air valving may not fit. 
     In certain embodiments of the present invention, valve  400  may advantageously provide for a pressure recovery factor of greater than about 60% or even 70%, 80% or 81%, meaning pressure available downstream of the valve for application to the nozzles is high, even at reduced flows when less primary air volume is called for by space demand. 
     In a cooling mode, in a conventional induction unit, a controller would modulate valve  210  to control the amount of cooling water provided to coil  140 , and a constant volume of air would pass through nozzles  150  to induce a constant volume of airflow across coil  140  and thus to the space to be cooled. 
     According to embodiments of the present invention, upon a detected increase in room temperature above a desired setpoint, as sensed by sensor  130  for example, controller  120  may signal valve  170  to open, e.g., by increasing or decreasing a voltage or current provided to valve  170 . Upon a detected decrease in room temperature below a desired setpoint, as sensed by sensor  130  for example, controller  120  may signal valve  170  to close, e.g., by increasing or decreasing a voltage or current provided to valve  170  in a substantially opposite manner to that provided when an increase in temperature is detected. An opening of valve  170  increases primary air flow, while closing valve  170  decreases primary air flow across a secondary side of the coil  140 . In such an embodiment, valve  210  may remain in a substantially constant position, e.g., fully open. The required horsepower to produce the necessary primary air volume for nozzles  150  may advantageously be reduced depending on cooling load, as opposed to constantly running it at a sufficiently high speed to induce the necessary induction across coil  140  at full load. In such an embodiment the power required to provide air volume and pressure may be reduced. It has been found that while a constant demand of cooling water at or near full load requirements may be expected to increase the ongoing demand for pumping horsepower, a typical amount of horsepower needed for increased cooling water flow may be substantially less than the savings effected by fan power reductions, such that the overall system efficiency still improves. An unanticipated advantage of the present invention is that such a savings may be experienced even at full load conditions, where fan throttling may not be expected, but may nonetheless be effected. 
     Upon valve  170  being sufficiently closed to or beyond an operational threshold, the amount of primary air provided by nozzles  150  may become sufficiently low that induction of room return air across coils  140  may substantially cease. Upon such an occurrence, which may be determined by the operational position of the disc  400  by controller  120 , cooling by the coil  140  will no longer be efficiently effected, and depending upon desired operational parameters the cooling valve  210  can be opened or closed, or fixed in a predetermined or current position, for example. 
     In a heating mode, in a conventional induction unit, a controller would modulate valve  210  to control the amount of heating water provided to coil  140 , and a constant volume of air would pass through nozzles  150  to induce a constant volume of airflow across coil  140  and to the space to be heated. 
     According to embodiments of the present invention, upon a detected decrease in room temperature below a desired setpoint, as sensed by sensor  130  for example, controller  120  may signal valve  170  to open, e.g., by increasing or decreasing a voltage or current provided to valve  170 . Upon a detected increase in room temperature to or above a desired setpoint, as sensed by sensor  130  for example, controller  120  may signal valve  170  to close, e.g., by increasing or decreasing a voltage or current provided to valve  170  in a substantially opposite manner to that provided when a decrease is detected. An opening of valve  170  increases primary air flow, while closing valve  170  decreases primary air flow across a secondary side of the coil  140 . In such an embodiment, valve  210  may remain in a substantially constant position as discussed. The required horsepower to produce the necessary primary air volume for nozzles  150  may advantageously be reduced depending on heating load, as opposed to constantly running it at a sufficiently high speed to induce the necessary induction across coil  140  at full load or demand. In such an embodiment the power required to provide air volume and pressure may be reduced. It has been found that while a constant demand of heating water at or near full load requirements may be expected to increase the ongoing demand for pumping horsepower, a typically amount of horsepower needed for increased heating water flow may be substantially less than the savings effected by fan power reductions, such that the overall system efficiency still improves. An unanticipated advantage of the present invention is that such a savings may be experienced even at full load conditions, where fan throttling may not be expected, but may nonetheless be effected. 
     Further, when the valve  170  has been signaled to its minimum position, and air volume and pressure is at or near a minimum operating state, undesired further heating may nonetheless still occur. In a certain embodiments of the present invention, when the room temperature is sensed in such a condition and exceeds the primary air temperature as sensed by sensor  180  (e.g., by  1  or degrees for 1 or more minutes) controller  120  may automatically, temporarily switch to cooling mode, as discussed above, from heating mode. In such a case it may operate as discussed above for cooling, but with valve  210  in a closed position, thereby using primary air for direct cooling on an induction unit by induction unit basis. In such an embodiment improved space by space heating/cooling control and efficiency may be effected. 
     Induction units are designed to operate for both cooling and heating. The nozzles in the units create a lift to pull the air over the coil and propel the air into the room to about 15 feet into the room back from the perimeter. The amount of energy that needs to be imparted to the room air to pull it through the coil and propel it into the room varies greatly from winter to summer. This is because the cool air for air conditioning is heavier that the warm air for heating. Heating does not have to be propelled into the core of the building since there is already a heating load in the core from lights and people. Cooling has to be propelled from the induction units to pick up this load. 
     Therefore the induction units can be provided with much less energy from the primary air in the winter than in the summer. Embodiments of the present invention reduce energy demand and consumption by throttling the primary air to the nozzles thereby reducing the pressure and flow of primary air so as to provide only the amount of energy required to induce air across the coils in sufficient quantity to provide heat to the space at the perimeter. 
       FIGS. 4A-4E  illustrate an exemplary center valve disc. As illustrated in  FIG. 4A , the center valve disc may comprise a 2 piece design, such as having 2 identical components molded as a single cavity. The center disc may have continuous Interlocking rib/channel design for precise alignment and assembly—that is, no welding or glue may be required—as shown in  FIG. 4B . A stopper Lug to prevent the disc from over turning, i.e., the lugs may stop on the interior ribs of the housing in the valve-open position, as shown in  FIG. 4C . As illustrated in  FIG. 4D , bunting bearings may be used to assure tight assembly. 
       FIGS. 5A-5E  illustrate a housing halved with mounting holes. The housing halves are designed with a snap-fit assembly eliminating the need for welding or glue, as shown in  FIG. 5 . One housing half has snap ins, and one housing half has the snap windows (such as in 4 places).  FIG. 5  also show that bosses were designed for a screw, such as a #10 self-tapping screw.  FIG. 5  show an interlocking rib/channel design for air tight assembly. A similar design is currently used on a medical blower housing. This housing half has the channel side of the assembly. 
     Location of the bunting bearings may be uniquely redesigned. The bottom is closed off and the top has an enclosed area for the bearing. This will help locate the disc-assembly properly every time and reduce noise. Further, the stop rib may be slightly modified to allow for more economical molding (no side action mechanisms), i.e., it may be extended up to the hole opening. 
       FIGS. 6A-6E  illustrate a molding/assembly process for the elements discussed above. The disc may be molded in a single cavity tool (standard open/close design with no additional mechanical actions). Once the discs are molded, they are press fit together (this may occur during the molding process). The bunting bearing may then be assembled onto the top and bottom shaft of the disc assembly. 
     The 2 housing halves can be molded in a 2 cavity family tool that produces one of each side every cycle. The disc assembly with bearings is then aligned and assembled into the housing. The housing snaps together holding the disc and bushings in place. 
       FIG. 7  illustrate, in  FIG. 7A , a top bearing assembly.  FIG. 7B  shows a bottom bearing assembly.  FIG. 7C  shows a disc assembly cross-section.  FIG. 7D  shows a housing interlock/snap-fit cross-section.  FIG. 7E  illustrates a housing rib/lug—open position embodiment. 
     Finally,  FIGS. 8A-8E  show various positions of the valve referenced above in at least  FIG. 3 . Positions include valve open and closed, and in the process of both opening and closing. 
     Yet further, in support of the foregoing description, attached hereto are a plurality of graphs and diagrams which may include additional description related to the foregoing. As such, these additional attachments are incorporated in this description by reference. 
     In the foregoing detailed description, it may be that various features are grouped together in individual embodiments for the purpose of brevity in the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that any subsequently disclosed or claimed embodiments require more features than are expressly recited. 
     Further, the descriptions of the disclosure are provided to enable any person skilled in the art to make or use the disclosed embodiments. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but rather is to be accorded the widest scope consistent with the principles and novel features disclosed herein.