Patent Description:
More specifically, the present invention is directed to balometer used to measure airflow from diffusers in heating, ventilation, and air conditioning (HVAC) systems in commercial buildings or similar structures.

Architects and engineers that design HVAC systems for commercial buildings and other structures go to great lengths to ensure that those systems provide a consistent and reliable level of comfort to the occupants of those structures. HVAC designers carefully size the HVAC units to ensure delivery of the appropriate volume of conditioned air. Additionally, they design the ductwork to distribute the conditioned air to the various rooms and other areas of the structure at adequate rates and proportions. Furthermore, the designers select the spacing and configuration of the diffusers, registers, or terminals through which airflow is discharged (hereafter referred to generally as "diffusers") to distribute and disperse the conditioned air into the rooms/areas so as to provide the desired level of comfort for the occupants.

Integral to this design is the need for the conditioned air to be dispersed from each diffuser at a volumetric flow rate that is at or within a predetermined range of a rate specified by the designer. Flow rates that deviate from those specified by the designers will result in room or area temperatures that deviate from the target temperature set at the controller/thermostat, which can compromise the comfort of the building occupants.

When new commercial HVAC systems are commissioned, the system requires balancing to ensure that the conditioned air is delivered from each diffuser at a volumetric flow rate that is at or within a range specified by the system designers. Balancing can also be required as a part of routine HVAC system maintenance or when the floor plan within a building is reconfigured.

Balancing a commercial HVAC system is not a trivial matter and requires the services of a qualified HVAC technician. Commercial HVAC duct runs can be complicated and can have many branches or zones, each of which has many diffusers, or nodes. Not only does each diffuser have its own damper for adjusting flow through that particular node, there are also dampers within the ductwork that can be used to control airflow to the various zones within the system. Once one considers that adjusting a damper for any zone or node will necessarily create a change in backpressure that affects the airflow through all other zones and nodes in the system, the complexity of the balancing task becomes clear.

Ceiling mounted diffusers of commercial HVAC systems are selected by the system designer from a finite number of configurations to diffuse and direct conditioned air into the building space in a predetermined pattern. While there are many different diffuser configurations from which to choose, a vast majority of the diffuser designs fall within or are based around a standard <NUM>-inch by <NUM>-inch footprint common to commercial drop ceiling tiles.

The National Environmental Balancing Board ("NEBB") is an international certification association that, among other functions, certifies individuals and firms to commission, test, adjust, and balance HVAC systems. In addition to certifications, NEBB also provides equipment specifications and procedural standards. On the equipment side, one piece of equipment for which NEBB issues specifications is referred to a direct reading hood, which is used to measure air flow through a ceiling mounted diffuser. In this description, the more generic term "air flow hood" is used to describe a most commonly used form of a direct reading hood device. Those skilled in the art will appreciate that "direct reading hood" and "air flow hood," as used in this description, are essentially interchangeable, i.e., the air flow hood described herein can be characterized as a direct reading hood within the NEBB specification.

Air flow hoods are instruments that are used by HVAC technicians to measure the airflow discharged through ceiling mounted diffusers of commercial HVAC systems. Air flow hoods are designed to be held in place over the diffuser. The hood acts as a duct that collects and redirects the air that is discharged from the diffuser. The air flow hood has the configuration of a converging-diverging nozzle with a throat through which the conditioned air is directed in order to measure its volumetric flow rate. Differential pressure is measured across an averaging pitot tube manometer located in the throat.

Averaging pitot tube manometers used in conventional air flow hoods typically include a plurality of tubes arranged in an array across the throat. The tubes define two channels (one for averaging upstream pressure and one for averaging downsteam pressure) that are fluidly connected to a single manometer. Ports spaced about the tubes face in upstream and downstream directions in the hood and are connected to the upstream and downstream channels, respectively. The airflow in the hood therefore creates a velocity pressure across the pitot tube array, with the high side total pressure being averaged by the upstream channel and the low side static pressure being averaged by the downstream channels. The intent is that, since the ports are spaced about the array, which extends across the cross section of the throat, the velocity pressure sensed via the array is an average velocity in the throat. This average velocity pressure can be used to calculate an average air velocity through the hood, from which a volumetric flow rate can be calculated. Document <CIT> discloses a balometer for measuring airflow through a diffuser of an HVAC system, comprising: a hood which has an overall boxed rectangular configuration configured to cooperate with the configuration of the diffuser and be positioned squarely over the diffuser along a diffuser perimeter so that all the airflow discharged from the diffuser is directed into the hood; and wherein the hood comprises an upper portion, and wherein the hood comprises four quadrants, each quadrant including one of a plurality of discharge channels, and wherein the hood comprises internal walls configured to divide and funnel the airflow through the plurality of discharge channels, and defining the quadrants through which the divided airflow is directed, the internal walls and the discharge channels being positioned downstream of the upper portion. Document <CIT> also discloses such a balometer.

Averaging pitot tube array manometers can be susceptible to errors. The differential pressures measured across the averaging pitot tube are very sensitive to variances in air velocity across the many ports, which can relieve pressure at some of the openings. This can be the case, for example, with highly non-uniform flow concentrations, where areas of relatively high or low concentrations happen to be located in the area of the pitot tube ports. In either case, the measured differential pressure will not produce an accurate airflow measurement.

Regardless of the particular configuration of the HVAC diffuser, the conventional air flow hood collects the discharged air and redirects the air toward the throat where the differential pressure measurements used to calculate the volumetric airflow through the air flow hood are taken. This collection and redirection, however, reduces the airflow rate through the hood, which creates backpressure in the HVAC system. As a result of this backpressure created by the air flow hood, airflow through the diffuser is reduced. Left unchecked, this will produce a corresponding error in the air flow hood airflow reading. Realizing that the differential pressures measured with a air flow hood can necessarily require a resolution of up to. <NUM> inches of water column (IWC), these errors can become significant.

Additionally, conventional air flow hoods typically have an open cross section and the air directed through the hood is free to follow whatever flow path and pattern that physics dictates. Because of this, the bulk flow through the air flow hood is not uniform across the cross section of the hood, and the accuracy of the flow measurement can suffer. The redirection of flow in the hood can cause recirculation patterns in some regions of the hood, for example toward the middle regions of the hood, while the majority of the bulk flow is directed along other regions of the hood, such as along the sides. The conventional air flow hood thus can suffer from a lack of mixing, wherein the flow has a more blended, uniform flow pattern across the cross section of the hood.

Furthermore, the non-uniformity of the flow through the air flow hood will change depending on the configuration of the diffuser discharging the air. Because the averaging pitot tube manometers in the conventional air flow hood have fixed positions within the cross section of the hood, the accuracy of the net pressure measured can vary substantially with varying velocity profiles and the flow calculations resulting from these measurements, are unreliable and left to chance. In view of the above, it is readily apparent that the conventional air flow hood suffers from inaccuracies due to non-uniformity of flow and due to flow variances brought about by different diffuser configurations.

A balometer according to the invention is defined in independent claim <NUM>.

According to one aspect, the sensor probes can include hot point anemometer sensors.

According to another aspect, the hood can include flow disrupting structures for mixing and distributing the airflow evenly throughout the discharge channels. The flow disrupting structures can comprise turbulators. Each flow disrupting structure can include a plurality of tooth-shaped fins arranged in saw tooth-like rows. The flow disrupting structures can be positioned adjacent inlets of the discharge channels.

According to the invention, the hood includes internal walls that divide the airflow and funnel the airflow into the discharge channels. The internal walls have a peaked configuration and slope in a converging manner toward the discharge channels. The hood includes an upper portion that defines an open space into which airflow is discharged. The internal walls and the discharge channels are positioned downstream of the upper portion.

According to the invention, the hood includes four quadrants through which the divided airflow is directed. Each quadrant includes one of the discharge channels. The hood further includes internal walls that define the quadrants and that divide the airflow in the hood and funnel the airflow into the discharge channels.

According to another aspect, each quadrant can include at least one flow disrupting structure for mixing and distributing the airflow evenly throughout the discharge channels. The flow disrupting structures can be positioned adjacent inlets of the discharge channels.

According to another aspect, the apparatus can include a planar surface, positioned in an upper portion of the hood, which streamlines and directs the airflow toward the discharge channels. The planar surface can reduce the volume of the upper portion and thereby help prevent swirling in the airflow in the upper portion of the hood. The planar surface can be an upper portion of a cover under which instrumentation and electronics are located. The instrumentation can include at least one of pressure and temperature transducers.

According to another aspect, the apparatus can also include electronics for interrogating the sensor probes and transmitting wireless signals comprising measurement data obtained via the sensor probes. The apparatus can also include a smart device for receiving the wireless signals and processing the measurement data to provide airflow measurement data for the diffuser. The smart device can include one of a smart phone or tablet equipped with an application for processing the airflow measurement data and comprising a graphical user interface for displaying information related to the measurement data and the HVAC system.

According to a further aspect, the apparatus can include a pole mounting structure located centrally on an underside of the hood. The pole mounting structure can be adapted to receive a pole that a user can manipulate to maneuver the hood to a desired position adjacent the diffuser. The pole mounting structure can include a swivel mechanism for permitting the pole to pivot relative to the hood. The pole can have a telescoping construction that permits the length of the pole to be adjusted in order to facilitate positioning the hood adjacent the diffuser while positioning a base of the pole against a surface so that the surface supports at least a portion of the weight of the hood. The pole can include a handle that the user can grasp to maneuver the hood. The handle can include a trigger actuatable via finger to provide a wireless signal for activating system electronics.

A method for measuring airflow through a diffuser of an HVAC system according to the invention is defined in independent claim <NUM>.

According to one aspect, the method also includes disrupting the airflow to mix and distributing the airflow evenly throughout the discharge channels.

According to another aspect, the method also includes streamlining the airflow in the region close to the diffuser and directing the airflow toward structure for dividing the airflow.

The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:.

Referring to <FIG>, a system <NUM> for measuring airflow through a diffuser <NUM> of an HVAC system <NUM> includes an apparatus <NUM> that includes a balometer <NUM> and a pole <NUM> upon which the balometer can be mounted. As shown in <FIG>, the HVAC system <NUM> can be a commercial HVAC system typically found in commercial buildings, such as office buildings, and the diffuser <NUM> can be one that is used in the drop ceiling structures, indicated generally at <NUM>, that are common to the office spaces of those structures. As such, the diffuser <NUM> can, for example, have a <NUM> * <NUM> (24x24 inch) footprint that is commensurate with the typical grid structure of the commercial drop ceiling <NUM>. The diffuser <NUM> can be fed conditioned air from the HVAC system <NUM> via ductwork <NUM> and a hood <NUM>.

The balometer <NUM> includes a hood <NUM> that has an overall boxed rectangular configuration that is adapted to cooperate with the configuration (e.g., the <NUM> * <NUM> equivalent to 24x24 inch square configuration) of the diffuser <NUM>. The pole <NUM> facilitates a user, indicated generally at <NUM>, to maneuver the balometer hood <NUM> to fit squarely over the diffuser <NUM> and against the ceiling <NUM> along the diffuser perimeter so that all of the air discharged from the diffuser is directed through the balometer <NUM>. In this position, the user <NUM> can activate the system <NUM>, for example, via a trigger <NUM> on the handle <NUM>.

The trigger <NUM> activates instrumentation and electronics of the balometer <NUM> via wireless communications, such as Bluetooth or single mode wireless connectivity. The instrumentation and electronics are at least partially hidden within the balometer hood <NUM> and therefore not shown in <FIG>. The instrumentation and electronics obtains airflow measurement data that is transmitted wirelessly (again, e.g., via Bluetooth) to a smart device <NUM>, such as a smart phone. The smart device <NUM> is equipped with an application ("HVAC balancing app") that is adapted to use the measurement data received from the balometer <NUM> to calculate or otherwise determine the volumetric flow rate of the air discharged from the diffuser <NUM>.

This process can be repeated for all of the diffusers <NUM> of a given portion of the HVAC system, e.g., for a given building, room, zone, branch, etc. Once this process is completed for all of the diffusers <NUM>, the measured flow rates can be compared to the desired or specified rate to determine whether any adjustments are required. These adjustments can be determined in a variety of manners. For example, the adjustments can be determined by a skilled user, such as a HVAC technician specializing in building balancing. This can be extremely cumbersome and prone to errors, especially where a large number of diffusers are involved. Therefore, as another example, the HVAC balancing app installed on the smart device <NUM> can include a portion that determines the appropriate adjustments for each diffuser based on the measured flow rates and given the appropriate information regarding the HVAC system, or portion thereof, that is being balanced.

The system <NUM> is designed to facilitate ease of use for the user <NUM>. Noting that ceiling-mounted HVAC diffusers <NUM> can be numerous and positioned at locations where access is difficult to obtain, such as above cubicles or other furniture. Because of this, the user <NUM> may have manually position and hold the system in place while the measurements are taken (see <FIG>). Since commercial buildings can have hundreds of diffusers <NUM> that require balancing, this can be a burdensome and arduous task. The system <NUM> is constructed with these considerations in mind.

The balometer hood <NUM> is constructed of a molded, thin-walled construction formed with a lightweight polymer material, such as polypropylene. The balometer <NUM> can thus have a comparatively lightweight construction such as <NUM>,<NUM> (<NUM> pounds) or less, which can be less than half the weight of conventional balometers.

The pole <NUM> can also be constructed of lightweight materials, such as carbon fiber or aluminum. The pole <NUM> is adjustable in length (telescopically via lock <NUM>) so that the user <NUM> can maneuver the balometer <NUM> to reach ceilings of different heights and to reach over or around obstacles, such as furniture or cabinets. The gripping handle <NUM> affords the user <NUM> a comfortable and convenient grip with the trigger being positioned for ease of access and actuation. A base portion <NUM> of the pole <NUM> can also have an ergonomic construction for adding to the user's comfort and ease of use. To facilitate the user <NUM> manipulating the balometer <NUM> to the desired position in use, the balometer includes a centrally located swivel connector <NUM> on the underside of the hood <NUM>. The swivel connector <NUM> (<FIG>)allows the position of the pole <NUM> relative to the balometer hood <NUM> to be manipulated so that the user can access the diffuser <NUM> from different lines of approach.

Advantageously, the system <NUM> is also configured so that the user <NUM> is not required to hold the balometer <NUM> in place manually via the pole <NUM>. Since the balometer hood <NUM> has an extremely lightweight construction, and since the pole <NUM> is telescopically adjustable, the pole can be positioned beneath the balometer hood <NUM> and its length adjusted so that the balometer <NUM> is supported by a rigid surface, such as the floor <NUM> or a surface of furniture, such as a desk, cabinet, or table. Additionally, to facilitate this function, the base portion <NUM> of the pole <NUM> can include an end portion or cap <NUM> that has a construction, such as a ribbed or knurled rubber construction, that will facilitate a good frictional "grip" with the surface upon which it is supported.

Supporting the system between the floor <NUM> and the ceiling <NUM> is illustrated generally in dashed lines at <NUM>' in <FIG>. In this application, the user <NUM> is relieved of the need to support the full weight of the system <NUM>. Even if space or furniture does not permit the pole <NUM> to be placed at an angle sufficient to allow the pole to support the balometer <NUM> on its own, it still relieves the user <NUM> of some of the burden by supporting some of the weight while the user steadies the system <NUM>, for instance, with one hand.

Referring to <FIG>, the hood <NUM> has an upper portion <NUM> with a generally square, box-shaped configuration with four intersecting side walls <NUM> that intersect each other and define a peripheral end <NUM> for being placed against the ceiling <NUM> (see <FIG>). The side walls <NUM> also define an inner space <NUM> of the balometer hood <NUM>. The inner space <NUM> of the upper portion <NUM> has an open configuration and leads to a downstream lower portion <NUM> of the hood <NUM>, which is divided into quadrants <NUM>, each of which is identical in configuration and structure.

The balometer hood <NUM> also includes a cover <NUM> for concealing and protecting at least a portion of the instrumentation and circuitry components (see <FIG>) of the balometer <NUM>, and for helping to direct airflow in the upper portion <NUM> of the balometer hood <NUM>.

Each quadrant <NUM> is partially defined internally within the hood <NUM> by respective pairs of internal walls <NUM>. The internal walls <NUM> each have a sloped or angled configuration and form roof-like pitches within the inner space <NUM> of the hood <NUM>. Within each quadrant <NUM>, the internal walls <NUM> intersect each other at right angles, defining a valley <NUM> at this intersection. Intersecting internal walls <NUM> of adjacent quadrants <NUM> define peaks <NUM> at the intersection. Each peak <NUM> extends perpendicularly from a respective one of the side walls <NUM> toward the center of the inner space <NUM> of the hood <NUM>, where the peaks intersect each other. Each valley <NUM> bisects the intersecting pair of peaks <NUM> that define its quadrant <NUM>. The valleys <NUM> also extend toward and intersect at the center of the inner space <NUM> of the hood <NUM>.

In each quadrant <NUM>, the intersecting internal walls <NUM> and the respective portions of the intersecting side walls <NUM> define an inlet portion <NUM> of the quadrant. Each quadrant <NUM> also includes a discharge channel <NUM> that extends downward (as viewed in <FIG>) from its associated the inlet <NUM>. The discharge channels <NUM> have a generally tubular, rectangular configuration. Each discharge channel <NUM> is defined on two sides by intersecting portions of the side walls <NUM>, and on two sides by intersecting channel walls <NUM> that extend generally perpendicularly inward from the side walls toward the center of the hood <NUM>. At their upper extent, the channel walls <NUM> intersect lower edge portions <NUM> (see <FIG>) of the intersecting internal walls <NUM> associated with that quadrant <NUM>.

Each quadrant <NUM> also includes a flow disrupting structure in the form of a turbulator <NUM> that is positioned in mating engagement with the inlet portion <NUM> of the quadrant at or near the mouth of the discharge channel <NUM>. The turbulators <NUM> can, for example, be secured to the hood <NUM> via a snap fit connection. The turbulators <NUM> extend along at least a portion of the periphery of the inlet portion <NUM> of each quadrant, along the perimeter of the mouth of the discharge channel <NUM>. An example of a turbulator <NUM> is illustrated in <FIG>. In the example embodiment, the turbulator <NUM> is a singular part that includes a pair of inner legs <NUM> and a pair of outer legs <NUM> that intersect each other at right angles. The inner legs <NUM> mate with and follow the slope of the intersecting internal walls <NUM> of the quadrant <NUM>, and the outer legs <NUM> mate with and follow the generally vertically extending side walls <NUM> of the quadrant <NUM> (see, e.g., <FIG>).

Each leg <NUM>,<NUM> of the turbulator includes a plurality of tooth-shaped fins <NUM> arranged in saw tooth-like rows along the length of each leg. Each leg <NUM>,<NUM>, includes an upper row <NUM> and a lower row <NUM> of fins <NUM>. The fins <NUM> of the upper and lower rows are staggered and extend away from each other in opposite directions. On the outer legs <NUM>, the fins <NUM> are spaced along the entire length of the legs. On the inner legs <NUM>, the fins <NUM> are spaced along approximately half the length of each leg - the half that intersects with the adjacent outer leg <NUM>. The portions <NUM> of the inner legs <NUM> that are free from fins <NUM> have a smooth, contoured configuration, with upper edges that merge smoothly with the internal walls <NUM>.

Each fin <NUM> has a configuration that tapers from a widened base to a pointed tip. The fins <NUM> of both the upper and lower rows <NUM>,<NUM> of fins taper along the width of the fin as measured in the direction of the length of the legs <NUM>,<NUM>. Additionally, the fins <NUM> of the upper row <NUM> also taper towards the wall <NUM>,<NUM> against which they abut.

Referring to <FIG>, which illustrates the cover <NUM> inverted for convenience, the cover has a generally square configuration with a planar square top wall <NUM> and four side walls <NUM> that extend perpendicularly from the top wall along its periphery. A cylindrical electronics covering wall <NUM> is located centrally on the top wall <NUM> extends perpendicularly from the top wall. A plurality of reinforcing ribs <NUM> extend from the wall <NUM> radially outwardly to the side walls <NUM>.

The side walls <NUM> each include a centrally located, generally V-shaped notch <NUM> that has a profile that matches that of the intersecting internal walls <NUM> of each quadrant <NUM>. The internal walls <NUM> can thus mate with the notches <NUM> and thereby help support the cover <NUM> when assembled with the balometer hood <NUM>. Outside these notches <NUM>, the side walls <NUM> have lower edge portions <NUM> that include a plurality of tooth-shaped notches that define a plurality of teeth <NUM>. The teeth <NUM> extend along the length of the lower edge portions <NUM> and have a configuration and shape similar to the lower rows <NUM> of fins <NUM> on the turbulators <NUM>. The positions and spacing of the teeth <NUM> on the side walls <NUM> of the cover <NUM> coincide with the portions <NUM> of the inner legs <NUM> of the turbulators <NUM> that are free from fins <NUM>.

The balometer <NUM> also includes instrumentation and electronics for measuring conditions associated with ambient room conditions and the airflow through the diffuser <NUM>. The balometer <NUM> includes airflow sensing probes <NUM> for sensing airflow through each quadrant <NUM> of the balometer hood <NUM>. An airflow probe <NUM> is positioned in each discharge channel <NUM>. In the example embodiment of <FIG>, the probe <NUM> enters the discharge channel <NUM> through the channel walls <NUM> at the location where the walls intersect. To facilitate this, the discharge channel <NUM> is fit with a probe support <NUM> that has portions that interlock with mating portions of the probe <NUM>. The probe <NUM> extends through the probe support <NUM> and enters the discharge channel <NUM> through the intersecting channel walls <NUM>. The probe <NUM> extends at an angle that bisects the intersecting walls <NUM>, and is held in place by the probe support <NUM> so that an end portion <NUM> of the probe is positioned centrally and in the proper orientation within the discharge channel <NUM>.

The airflow sensing probes <NUM> can have a variety of configurations. In the example embodiment disclosed herein, the probes <NUM> comprise hot point anemometer airflow sensing probes. Alternative probe configurations, such as a monometer probe, could also be used.

Referring to <FIG>, located centrally in the upper portion <NUM> of the hood <NUM> beneath the cover <NUM> lie four differential pressure transducers <NUM>, one per quadrant <NUM>, for sensing the pressure differential between the air flowing through each quadrant and the ambient air into which the airflow is discharged. To do so, each pressure transducer <NUM> has a pressure port in fluid communication with the air pressure in the discharge channel <NUM> of the associated quadrant <NUM>, and a port in fluid communication (e.g., via a tube) with the air pressure outside the balometer hood <NUM>.

The instrumentation of the balometer <NUM> also includes temperature sensing components for measuring the temperature of the air flowing through the balometer. The temperature sensing components can, for example, be a resistive, e.g., thermocouple-type, element. According to one example, where the airflow probes <NUM> include hot point anemometers, the resistive elements of the anemometers themselves can also be used to measure the airflow temperature. Alternatively, one or more separate temperature sensors can be employed.

The pressure transducers <NUM> and the airflow probes <NUM> are connected electrically to an electronics unit <NUM> that is mounted to the balometer hood <NUM>, centrally beneath the cover. The electronics unit <NUM> includes a circuit board <NUM> to which the pressure transducers <NUM> can be mounted. Alternatively, the pressure transducers can be mounted to the structure of the balometer <NUM>. The electronics unit <NUM> includes various electronic components <NUM>, such as processors, communication (e.g., Bluetooth) components, signal conditioning components, power and grounding circuits, communication buses, and any other components necessary to operate as described herein. The pressure transducers <NUM> and airflow probes <NUM> can be connected to the electronics unit <NUM>, for example, via cables that interconnect with sockets mounted on the circuit board <NUM>. The balometer <NUM> also includes a power supply <NUM>, such as a battery pack, that is also located under the cover <NUM>. The power supply can, for example, be mounted to the circuit board <NUM>, on a side that is the same or opposite that to which the electronic components <NUM> are mounted.

Referring to <FIG> and <FIG>, in operation, the user <NUM> positions the balometer <NUM> over the diffuser <NUM> using the pole <NUM>. The upper portion <NUM> of the balometer hood <NUM> collects the air discharged from the diffuser <NUM> and directs it into the quadrants <NUM>. The air directed into each quadrant <NUM> passes through the discharge channel <NUM> and over the sensor probes. The user <NUM> activates the balometer <NUM> via the trigger <NUM> on the handle <NUM>, and the flow rate is measured via the sensor probes <NUM>.

The electronics unit <NUM> transmits readings obtained from the probes <NUM> wirelessly to the smart device <NUM>. The smart device <NUM> receives and processes the readings, and displays data related to the readings for the user to interpret. Since the readings from each sensor probe <NUM> is related to the flow through an associated discharge channel <NUM>, and because the total air flow is divided between the discharge channels, calculating the total flow through the balometer <NUM> requires a summation of the flows through individual discharge channels.

Since the position of the sensor probe <NUM> in each discharge channel <NUM> is fixed, it is important that the bulk flow through each discharge channel is as uniform as possible so that an accurate flow measurement can be obtained. This holds true even if the airflow is distributed unevenly through the four quadrants <NUM>. As long as the bulk flow through each discharge channel <NUM> is distributed evenly within that channel, the flow measurement for that quadrant will be accurate, as will the calculated total flow for the diffuser <NUM>.

Conventional commercial HVAC ceiling mounted diffusers can have a variety of configurations. Examples of these diffuser configurations are illustrated in <FIG>, which are summarized in the following table:.

The configuration of the diffuser will help dictate the airflow pattern in any balometer. The diffuser configuration will also determine whether the airflow is distributed evenly or unevenly across the balometer. All of the diffuser designs illustrated in <FIG> direct the discharged air in an outward and downward direction. Diffusers 12a-12c, <NUM>, and 12j direct the air in four directions and would theoretically direct the air evenly in terms of direction into the balometer hood. Diffusers 12d-12f direct the air in three directions and would therefore direct the air unevenly into the balometer hood. Diffusers <NUM> and 12i direct the air in two and one direction, respectively, and would therefore also direct the air unevenly into the balometer hood.

Testing has shown that, in conventional balometer hood designs, the bulk flow through the hood tends to be concentrated along the edges or side walls of the hood, while a portion of the air re-circulates toward the center of the hood, primarily in the upper regions of the hood. Depending on the configuration of the diffuser (see above), the bulk flow may not only be concentrated along the side walls, but also concentrated unevenly along the side walls. Since the positions of the flow measuring devices in the conventional balometer hood are positioned at fixed locations in the hood, it is easy to see that the accuracy of the conventional balometer is somewhat left to chance. Knowing this, one skilled in the art can appreciate that the accuracy and reliability of the conventional balometer designs can come into question. There is a need to account for these issues.

According to the present invention, the balometer <NUM> is adapted to help account for these deficiencies. To do so, the balometer <NUM> is configured to divide the airflow from the diffuser <NUM> into the quadrants <NUM> in order to confine the divided flows to a more manageable space. The turbulators <NUM> in each quadrant <NUM> disrupt and mix the airflow to produce an even bulk flow through each discharge channel <NUM>. This having been done, the airflow measurements taken in each discharge channel <NUM> are accurate and will produce an accurate calculation of total airflow through the diffuser.

For instance, in the example illustrated in <FIG>, the diffuser <NUM> has a <NUM>-cone square <NUM>-way configuration and therefore directs the airflow toward all four side walls <NUM> of the balometer hood <NUM>. Because of this, the bulk airflow, if left unchecked, would tend to flow along the side walls <NUM> toward the discharge channels <NUM>. At the same time, the portion of the airflow that does not flow along the side walls <NUM> is collected and funneled toward the discharge channel <NUM> by the converging, sloped configuration of the internal walls <NUM>. As the airflow is directed toward the discharge channel <NUM>, however, the turbulators <NUM> redirect portions of the airflow, causing it to mix and distribute more uniformly across the discharge channel. Because the airflow is distributed uniformly across the channels <NUM>, the small portions of the airflow that is sampled by the sensor probes <NUM> is much more likely to present an accurate measurement of the airflow through the discharge channel <NUM>.

The combination of dividing the airflow from the diffuser <NUM> into the four quadrants <NUM> and mixing the airflow in each quadrant via the turbulators <NUM> helps produce these results. The accuracy of the balometer <NUM> can be affected by the amount of airflow resistance, or backpressure, that is introduced by placing the balometer in the airstream. Generally speaking, the lower the backpressure introduced by the presence of the balometer <NUM>, the better. Mixing the flow to improve the uniformity of the airflow through the balometer <NUM>, however, necessarily adds to the backpressure introduced by the balometer. To adequately mix the flow through the single flow channel of a conventional balometer hood would require a high degree of mixing and yet still may not result in even flow distribution. In fact, the magnitude of flow mixing necessary to produce uniform flow through the conventional balometer would likely create airflow disruptions of such a high magnitude that an undesirably high backpressure would result.

Advantageously, the balometer hood <NUM> of the balometer of the present invention avoids this problem by first dividing the airflow into quadrants <NUM> of a more manageable space. In the quadrants <NUM>, the amount of flow disruption required to adequately mix and distribute the airflow across the discharge channels <NUM> is minimized. Thus, the size of the turbulator fins <NUM>, and the magnitude of the airflow disruption within the channels <NUM>, can be kept at a minimum, which helps minimize the amount of backpressure created by the balometer <NUM>.

Additionally, the fundamental difference in the manner in which calculations are performed in the conventional balometer versus the balometer <NUM> of the present invention facilitates this improved functionality. Conventional balometer hoods average airflow measurements taken from an array of elements distributed across the hood. The balometer <NUM>, however, sums the individual airflows measured in each channel of the divided hood. Because of this, the balometer <NUM> of the present invention does not rely on airflow being directed from the diffuser into the balometer hood to the same degree as conventional balometers.

Different diffuser configurations (see <FIG>) are of little or no consequence to the ability of the balometer <NUM> to provide accurate airflow measurements. In a conventional balometer configuration, a non-uniform diffuser configuration could overload certain regions of the balometer hood, creating concentrated bulk flow paths that may or may not be accounted for in the averaged measurement. This is not the case with the balometer <NUM> of the present invention.

Because the balometer <NUM> is divided into quadrants <NUM> and relies on summing the airflow measured through each quadrant as opposed to the averaging the flow across the entire hood, there is no concern over a particular diffuser configuration causing an imbalance in certain regions of the balometer. This is because, in each quadrant <NUM>, the airflow is funneled to the discharge channel <NUM> and mixed by the turbulators <NUM> to ensure uniform airflow distribution through the channel. Since each quadrant is measured separately, flow variances between quadrants will signal the level of imbalance across the diffuser <NUM>. This can be due, for example, to an elbow leading to the diffuser <NUM>, and the system <NUM> can compensate for any inaccuracy associated with the level of imbalance. The airflow measurement for each quadrant <NUM> will be accurate and, therefore, so will the total airflow measured by the system <NUM>. Traditional air flow hoods use an averaging pitot tube with a signal differential pressure measurement, so they can neither detect these imbalances nor compensate for them.

To further improve the accuracy of the system <NUM>, the application implemented by the smart device <NUM> can be adapted to compensate for different backflows realized by the balometer <NUM> for the different configurations of the diffuser and the HVAC system under test. To do this, compensation factors can be determined through air flow bench testing. The air flow bench can be configured to discharge air at a known volumetric flow rate through each of various diffuser configurations. This known flow rate can be compared to the flow rate measured via the balometer <NUM>, and the error can be used to generate a compensation factor that will be programmed into the smart device application. The testing can be repeated to establish reliability and also in order to take into account other factors, such as compensation for any elbows in the ductwork leading to the diffuser and the distance between the elbow and the diffuser.

All of these factors can be programmed into the smart application. In use, the user <NUM> simply selects via the application on the smart device <NUM> the type of diffuser and any additional information, such as elbow distance, via the application graphical user interface (GUI). The application will take these factors into account by applying the appropriate compensation factor to the readings obtained from the sensors <NUM>.

Additionally, the implementation of the application on the smart device allows for further efficiencies, such as a predictive balancing algorithm that indicates to the user <NUM> which flows (i.e., which diffusers <NUM>) to measure, in which order, and how to adjust the dampers on each diffuser in order to obtain system balance. To do this, the user <NUM> may be queried to enter HVAC system information via the GUI, such as the number and type of diffusers <NUM> in a given room or for a given branch of the VAC system, and information on elbow distances for each diffuser. Given this information, the smart device <NUM> running the application can give the user <NUM> step-by-step instructions on how to balance the system in the most accurate and time efficient manner.

To illustrate the efficacy of the system <NUM>, <FIG> compare and contrast flow patterns and velocity vectors obtained via computational fluid dynamics (CFD) modeling for a prior art air flow hood (<FIG>) versus the balometer <NUM> (<FIG>). In <FIG>, the CFD modeling illustrates airflow with vector arrows. The direction in which the vectors arrows point is the direction of the modeled airflow. The size of the vector arrows indicates the velocity of the airflow. The density of the vector arrows in any particular area is indicative of the density or concentration of the modeled airflow in that area.

Referring to <FIG>, the conventional air flow hood H is positioned over a <NUM>-cone, square, <NUM>-way diffuser 12a (see <FIG>). In this example, the airflow is concentrated along the exterior walls W of the hood H, in the areas indicated generally at A in <FIG>. In these areas A, the concentrated airflow flows along the walls W toward the throat T of the air flow hood H. Additionally, in a central region of the hood, in the area indicated generally at B, airflow is less concentrated, but still flows toward the throat T. In an upper region of the hood, in the areas indicated generally at C, the airflow tends to re-circulate or swirl, as indicated by the swirling and upward pointing arrows of the CFD model. At or near the throat T, the flow is highly concentrated along the walls W, as indicated by the dense, dark collection of arrows, in the areas indicated generally at C.

From this, it will be appreciated that, for the conventional air flow hood H on the <NUM>-cone, square, <NUM>-way diffuser 12a, swirling in the upper central region C of the hood results in bulk airflow along the walls W all the way to and through the throat T, with low airflow concentrations through the central portion B of the hood. The averaging pitot tube manometer, intended to measure average velocities across the hood, is unlikely to accurately measure the velocity of the highly non-uniform airflow pattern illustrated in <FIG>.

Additionally, the swirling and recirculation in the upper region C of the hood H will inhibit flow through the register 12a, which will cause an increase in backpressure in the HVAC system. Increased backpressure will reduce the flow through the register 12a and through the air flow hood H. Thus, not only does the conventional air flow hood H suffer from the non-uniform flow patterns through the hood, it also suffers from the reduced flow that results from its use. Therefore, the accuracy and repeatability of the measurements obtained via the conventional air flow hood H is therefore questionable.

These issues exist with the use of the conventional air flow hood for other register types as well. Referring to <FIG>, the conventional air flow hood H is positioned over a square, one way diffuser 12i (see <FIG>). In this example, the airflow is concentrated along the exterior wall W of the hood H toward which the one-way diffuser 12i directs the air, as shown in the area indicated generally at A in <FIG>. As indicated generally at B, there is an area of less concentrated airflow toward the throat T, but this area is small and irregular. As indicated generally at C, there are many areas where swirling and recirculation takes place. As indicated generally at D, at or near the throat T, airflow is highly concentrated along the walls W, especially the wall along which the bulk airflow A occurs.

From this, it will be appreciated that the square, one way diffuser 12a directs the bulk airflow along one wall W of the conventional air flow hood H and also produces a high degree of swirling and recirculation throughout the hood. In this scenario, the averaging pitot tube manometer is unlikely to accurately measure the velocity of the highly non-uniform airflow pattern illustrated in <FIG>, and the high degree of swirling and recirculation will increase backpressure, which will reduce the flow through the air flow hood H. Again, the accuracy and repeatability of the measurements obtained via the conventional air flow hood H is therefore questionable.

Comparing <FIG> and <FIG>, it is easy to see that it would be difficult for the conventional air flow hood H to provide accurate and reliable airflow measurements, given the difference in flow profiles and backpressures produced by various diffuser configurations. The balometer <NUM> of the present overcomes these problems.

<FIG> and <FIG> illustrate CFD models for the balometer <NUM> implemented in scenarios that correspond to those illustrated in <FIG> and <FIG>, respectively. As shown in <FIG> and <FIG>, the presence of the hood <NUM> streamlines flow in the upper portion <NUM> of the balometer hood <NUM>, which inhibits or prevents swirling and re-circulation. The hood <NUM> directs the streamlined airflow laterally into the quadrants <NUM>, which then direct the airflow through the discharge channels <NUM>.

In the case of the <NUM>-way register 12a (<FIG>), airflow is discharged into the balometer hood <NUM> in substantially equal rates toward all four quadrants <NUM>. Along the outer walls of the balometer hood <NUM>, airflow does tend to concentrate, as indicated generally by the region identified at F in <FIG>, but the presence of the turbulators <NUM> introduce turbulence that mixes the flow entering the discharge channels <NUM>. As shown in <FIG>, the airflow vectors in the discharge channels <NUM> are uniform in magnitude, direction, and density in the various regions of the balometer hood <NUM>. There is little, if any, swirling or re-circulation in the hood <NUM> and the flow in the discharge channels <NUM> is highly uniform. The sensor probes (not shown), located in the discharge channels <NUM>, would therefore produce substantially equal measurements that can be summed to calculate airflow through the balometer <NUM>. The balometer <NUM> produces accurate measurements, and those accurate measurements would yield accurate and repeatable airflow calculations.

The one-way register 12i (<FIG>) does not significantly affect the accuracy of the balometer <NUM>. Airflow is discharged into the balometer hood <NUM> in unequal rates, skewed toward one of the walls, and two of the quadrants <NUM> (one of which is shown in <FIG>). The airflow is therefore unequally distributed in the discharge channels <NUM>. Along the outer walls of the balometer hood <NUM> on the strong side of the diffuser 12i, airflow does tend to concentrate, as indicated generally by the regions identified at F in <FIG>. Additionally, on this side, there is some recirculation under the hood <NUM>, as indicated generally by the regions identified at F in <FIG>. The presence of the turbulators <NUM>, however, introduce turbulence that mixes the flow entering the discharge channels <NUM>. The flow in each of the discharge channels <NUM>, again, is substantially uniform, even if unequal. The sensor probes (not shown), located in the discharge channels <NUM>, would produce measurements that, while not equal, are accurate, and those accurate measurements would yield accurate and repeatable airflow calculations.

Claim 1:
A balometer (<NUM>) for measuring airflow through a diffuser (<NUM>) of an HVAC system (<NUM>), comprising:
a hood (<NUM>, <NUM>) which has an overall boxed rectangular configuration configured to cooperate with the configuration of the diffuser (<NUM>) and be positioned squarely over the diffuser (<NUM>) and against the ceiling along a diffuser perimeter so that all the airflow discharged from the diffuser (<NUM>) is directed into the hood (<NUM>, <NUM>),
wherein the hood (<NUM>) comprises an upper portion (<NUM>) that defines an open space into which airflow is discharged, and wherein the hood (<NUM>) comprises four quadrants (<NUM>), each quadrant (<NUM>) including one of a plurality of discharge channels (<NUM>),
and wherein the hood (<NUM>, <NUM>) comprises internal walls configured to divide and funnel the airflow through the plurality of discharge channels (<NUM>) and defining the quadrants (<NUM>) through which the divided airflow is directed, the internal walls (<NUM>) and the discharge channels (<NUM>) being positioned downstream of the upper portion (<NUM>), and wherein the internal walls have a peak configuration and slope in a converging manner toward the discharge channels, and
wherein the balometer (<NUM>) further comprises instrumentation and electronics for measuring conditions associated with ambient room conditions and the airflow through the diffuser (<NUM>), said instrumentation comprising sensor probes (<NUM>) for measuring the airflow through each discharge channel (<NUM>), wherein a sensor probe (<NUM>) is positioned in each discharge channel (<NUM>).