KR100732574B1 - Method and system for determining relative duct sizes by zone in an hvac system - Google Patents

Abstract

A control and method are disclosed for determining the relative duct size of a plurality of ducts leading to a plurality of zones in a multi-zone HVAC system. In the disclosed method, the dampers directed to each zone are operated so that one damper opens more than the other dampers, and system components are monitored as air is blown through the duct. In particular, it is possible to monitor the blower speed. When the blower speed is monitored, with one damper open and the other dampers relatively closed, the other damper is opened and the first damper is closed. This process continues until relative information is obtained for each zone. This relative information is then used to determine the relative size of the duct leading to each zone as a percentage of the overall duct size. Next, relative duct size information is used to perform various control methods.

HVAC, Air Conditioners, Ducts, Dampers, Multi-Zone

Description

METHOD AND SYSTEM FOR DETERMINING RELATIVE DUCT SIZES BY ZONE IN AN HVAC SYSTEM}

This application is filed on Jan. 20, 2004, and entitled U.S. Provisional Application No. 60 / 537,524, entitled "Determination of Regional Relative Duct Size for HVAC Systems," and Jan. 20, 2004; Priority is claimed to U.S. Provisional Application No. 60 / 537,717, entitled "Methods and Systems for Automatically Optimizing Zone Duct Damper Locations". The contents disclosed in these provisional applications are incorporated herein by reference in their entirety.

The present application discloses a method and control for determining the relative size of ducts leading to each of a plurality of individual zones in a multi-zone HVAC system.

Multi-zone HVAC systems are known and include components (heating furnaces, air conditioners, heat pumps, etc.) for changing the temperature and conditions of the air. For simplicity these components are collectively referred to as temperature change components. In addition, an indoor air handler allows air to move from the temperature change component through the supply duct to multiple areas inside the building. Each supply duct generally has a damper that can be controlled to limit or allow the flow of air to each zone to meet the desired temperature.

In such a system, the size of the duct leading to each zone may vary due to restrictions that may occur along the length of the duct. As such, as modern HVAC systems have been retrofitted to take into account complex control elements, it is necessary to know the relative size of the ducts in order to precisely control the flow of air into multiple discrete zones. For example, if there are two ducts leading to two zones and one of the two ducts is smaller than the other, the smaller duct tends to receive less air flow than the larger duct. It is important to know the size of the duct in this way to provide the ability to precisely control the air flow into these zones.

However, methods for determining the duct size for each zone are not known in the prior art. At best, the installer can measure the duct size manually. However, it is relatively impractical and not used.

In the disclosed embodiment of the present invention, the control unit performs an initial determination of the relative duct size for the ducts leading to the individual zones of the multi-zone HVAC system. This decision can be made early in the system setup and should be relatively reliable for the life of the HVAC system. Once completed, the determination of the zone duct size is filed on July 13, 2004 and the pending US patent application Ser. No. 10 / 889,735, entitled “Methods and Systems for Automatically Optimizing Damper Position in Zone Ducts”. And various control features such as those generally disclosed in the foregoing U.S. Provisional Patent Application 60 / 537,717.

In general, the control opens the damper associated with one of the zones while maintaining the remaining dampers in a relatively closed position. The system can then determine conditions such as the relative static pressure of each zone relative to the other zones. This information can then be used in an iterative process to determine the relative duct size of each zone. Knowing the relative duct size allows better control of the air flow through each zone.

In a further refinement of the disclosed embodiment, the system also determines air flow characteristics by all dampers that are considered to be closed. This indicates the outflow across the system, allowing further refinement of the determination of the relative duct size.

These and other features of the present invention can be best understood from the following description and drawings briefly described below.

1 is a schematic diagram of a building HVAC system.

2 is a flow chart of the method of the present invention.

3 is a flow chart of a portion of the present invention.

4 is a flowchart of a subsequent step of the flowchart of FIG.

5 shows an exemplary display at the control.

Although the present invention relates to the determination of relative duct size across a multi-zone system, an exemplary control system using duct size information will be described.

Multi-zone HVAC system 20 is schematically shown in FIG. A temperature change component 22 for changing the condition of the air, such as an indoor unit (heating furnace / heater coil) and / or an outdoor unit (air conditioning / heat pump), is connected with the indoor air conditioner 24. The air regulator 24 draws air from the return duct 26 to the plenum 31 and to the plurality of supply ducts 28, 30, 32 connected to the individual zones 1, 2, 3 in the building. Move to. As shown, dampers 34 are provided on each supply duct 28, 30, 32. A control such as microprocessor control 36 controls the damper 34, temperature changing component 22, and indoor air conditioner 24, and also communicates with control 13 associated with each zone. The controller 130 may basically be a thermostat in which a user may set a desired temperature, a noise level, etc. of each zone relative to other zones. Moreover, the controller 130 preferably includes a temperature sensor for providing the actual temperature back to the controller 36.

In one embodiment, the controller 36 is mounted inside one of the thermostat controllers 130, filed Jan. 7, 2004, and has been filed with the present invention “Serial Communication HVAC System”. The control wiring method as disclosed in U.S. Patent Application Serial No. 10 / 752,626 communicates with all other elements as a system control. As disclosed, the control 36 may receive configuration information associated with each of these system components to recognize the individual characteristics of the elements 22, 24, 30, 34. Details of these features may be those disclosed in US patent application Ser. No. 10 / 752,628, filed Jan. 7, 2004, entitled “Automatic Configuration Control of Heating, Ventilation, and Air Conditioning Systems”. . The contents disclosed in each of these applications are incorporated herein by reference.

In the prior art, the amount of air moved by the air regulator 24 to each zone 1, 2, 3 is sometimes excessive. Damper 34 may be opened or closed to limit or allow additional air flow into zones 1, 2, 3. Although dampers are driven to be fully open or fully closed, the present invention is disclosed as being used with dampers having a plurality of incrementally closed positions as well as fully open and fully closed positions. In one example, the damper has sixteen incremental positions between full open and full close. As any one of the dampers 34 is closed to reduce the air conditioning of the zone, additional air flow is moved towards the more open damper. This can cause too much air to be delivered to one of the zones, causing excessive temperature changes and inadequate noise. In the prior art, a pressure-responsive bypass valve is connected to the ducts 28, 30, 32 or upstream of the plenum 31. Bypassing air has undesirable properties because it requires additional valves, ducts, and the like to complicate the assembly. Typically, the bypass air returns to the temperature change component 22 through the return duct 26. Thus, the air approaching the temperature change component 22 is already different from the ambient atmosphere and may be too cold or too hot to operate efficiently.

For this reason, it is desirable to find an alternative way to prevent inadequate air flow into any of the zones 1, 2, 3 through any of the ducts 28, 30, 32. In many systems, it is of course possible to have three or more zones. However, three zones are sufficient to understand the present invention.

A flow chart of the control for the damper to eliminate the need for bypass is shown in FIG. In step 50, the limits of zone air flow are set in each zone 1, 2, 3. The control unit 30 may be provided with an input setting unit for setting the limit value. For example, the control unit 30 may be provided with a setting unit such that the maximum air flow threshold value is low, standard, high or maximum. These settings increase the weight to allow additional air conditioned air into the zone at the expense of anticipated potential additional noise as the air flow increases. Thus, most users interested in reducing noise may set the control to a low level. It also includes defaults set by some factories. By making it possible to use only the default value and to prevent the operator from changing the default value, the design can be made simpler.

The present invention includes an automatic duct sizing step 52 that is systematically associated with the control unit 36, is performed immediately after installation of the system in the home, and is repeated periodically thereafter. The duct size evaluation process is composed of a measurement process and a calculation process. The duct sizing process provides the control with information that can improve the efficient and accurate control of air flow throughout the zone.

In the initial measurement process, the controller 36 temporarily turns off the temperature change component 22. This process is illustrated overall in FIG. The controller 36 commands the full opening of the dampers 34 in all zones. The control unit 36 then instructs the system air regulator 24 to deliver a portion of the maximum system air flow (test air flow) to the plenum 31 and the ducts 28, 30, 32. The air conditioner 24 determines the speed of the blower motor and conveys this information to the controller 36, which stores it in memory. Then, the control section 36 closes all the dampers 34 except the dampers in the first zone. The air regulator 24 is requested to deliver the same test air flow as before, reporting the new blower motor speed to the controller 36. The relative blower speed indicates that there is a relative limiting element in the duct, as described below. As such, the dampers 34 in each zone in the system are continuously opened while the dampers 34 in all other zones are closed. At each stage of this sequence, the same air flow is delivered by the air regulator 34 and the resulting blower speed is recorded. Finally, the dampers 34 in all zones are closed and the same test air flow is pressurized through the damper 34 or any outlet site of the surrounding ducts 28, 30, 32, 34. Again, the blower speed is recorded. Thus, for a system with n zones, a total of n + 2 blower speed measurements SP is obtained.

SP _open if all zones are _open ;

SP _closure if all zones are blocked; And

If each zone is open on its own, SP i .

In the above measurement process, it should be noted that the damper can be partially opened in two different positions instead of being fully opened and closed. Different levels of test air flow may also be used at other stages of the sequence. If selected, this variation can be accommodated by adjusting the computational process shown below. Those skilled in the art will understand how to adjust the computation to obtain the desired result.

Velocity measurements are converted to duct static pressure measurements shown below. This embodiment has some advantages because there is no sensor. An alternative is to substitute direct duct pressure measurements using economical and reliable pressure transducers instead of speed measurements.

An arithmetic procedure for determining the duct size is shown in FIG. Initially, a series of air regulator static pressures (ASP) are determined based on the blower speed. Algorithms for determining these static pressures are filed on April 30, 2003, and are still pending. The invention is entitled "Method for Determining Static Pressure in a Duct Structure Air Delivery System Using Variable Speed Motors" US Patent Application No. 10 / 426,463. The disclosure disclosed in this application is incorporated herein by reference in its entirety, including in particular an algorithm for determining static pressure across a system. The algorithm depends on the static pressure developed over the air regulator 24 (from inlet to outlet) depending on 1) the air flow delivered by the air regulator, 2) the speed of the blower motor, and 3) the physical characteristics of the air regulator. To a constant.

As described above, the control unit 36 receives initial configuration information for all response components of the system 20. During this automatic configuration and during system installation, the air regulator 24 communicates with the control 36 and provides its characteristic constant. The system control uses an equation in the application, including regulator characteristic constants of the air regulator 24, air flow on command, and measured blower speed to calculate the static pressure across the air regulator. As shown in Fig. 4, these calculations (based on the blower speed) are repeated with all dampers 34 open and closed, and then each with only one open. From this, n + 2 ASP calculations are obtained, one for each measurement. These are designated as ASP _open , ASP _closed , ASP1, ASP2 ... ASPn. In an alternative implementation, the self control of the air regulator 24 may perform the same operation and pass the calculated static pressure to the control 36.

Another principle used in computation is the well known "square law", which relates the air pressure to a static pressure across any duct segment or passive device unit. This law indicates that the static pressure changes with the square of the air flow. This law has proven generally valid in the air velocity used in resident systems, simplifying the more complex relationships between variables.

The ASP value is used to calculate a fixed static pressure (FSP) value. As shown in Fig. 1, the static pressure developed over the air regulator 24 is applied to any external equipment unit (such as a filter and external air conditioning coil) through which the air flow passes and the entire duct system, i.e., the supply side 28, 30, 31, 32) and the return side 26 is dropped. Dampers 34 in each zone control the segments of the supply duct that deliver air to the zone. In the disclosed system, there is no damper in the return duct 26. Thus, the return duct before the damper, the external installation unit and the supply duct constitute the "fixed" part of the system, through which the entire system air always flows. This means that for the same system air flow, the combined pressure drop across the elements, ie fixed static pressure (FSP), is the same regardless of the damper position. Therefore, FSP is the same for all n + 2 measurements. The FSP itself is unknown and determined by the computational process.

A property known as variable static pressure (VSP) is the static pressure across the supply duct segment and downstream of the damper 34. The VSP value changes during the measurement as it directs the same system air flow through different relative sized duct segments for each zone. Since the pressure needs to be equalized over the entire loop (air regulator, supply side, indoor space, return side), for each measurement step the following holds:

ASP = FSP + VSP

The VSP at any measurement stage indicates the size of the open duct segment. The more restrictive (small size) duct segment, the higher the static pressure (VSP) across it for the same system air flow. Thus, the duct segment size is inversely related to the VSP. Duct segment sizes are conveniently calculated in terms of air flow capacity to easily determine the fair share of the overall system air flow. For this reason, using the square law in the relationship between air flow and pressure described above, the duct segment size is inversely proportional to the square root of the VSP. The present need is to determine the relative size of the duct segments, and the duct size of each zone is calculated as the ratio (or percentage) of the entire supply duct system (all zones). Thus, the relative duct size for zone i is calculated as follows:

SL _i = SQRT (VSP _open / VSP _i )

In order to increase the accuracy, the system of the present invention identifies the leakage of the system. Even with all dampers 34 closed, air can still flow. This is because the damper 34 is not perfect and some air may flow through it. There may also be an outflow in the ducts 31, 28, 30, 32. In some households these spills can be important. This is because the final measurement was made with all dampers closed. The "relative size" runoff can be calculated exactly as above:

Flow rate = SQRT (VSP _open / VSP _closed )

The runoff is in fact added to the apparent size of the duct segment in each zone, so it is necessary to subtract it. Thus, the corrected duct size of the zone is as follows:

S _i = SL _i -flow rate

The calculation used ASP value. However, in order to calculate the corresponding VSP value, the FSP value should be determined and then the following equation should be used:

ASP = FSP + VSP

Modeling the entire duct system and applying square law and other relations can lead to very complex mathematical models and requires solving a plurality of nonlinear algebraic equations. Instead, one aspect of the invention starts from the "initial guess" of the FSP value. Then, the corresponding VSP value can be calculated from the already calculated ASP value. The equations can then be used to calculate the relative size and runoff size of each zone. Both of these sizes are expressed as percentages of a fully open duct system, so these percentages should add up to 100%. Using the computer's iterative routine shown in Fig. 4, the FSP value is repeatedly adjusted until the sum of the sizes of all zones and the outflow size is up to 100%. At this time, the correction value of the FSP and the relative sizes of all zones are determined. Figure 5 shows the display screen of the control unit 36 during the duct sizing process, showing the results displayed at the end of the process.

At this point, step 52 is complete and the controller 36 calculates the area duct size relative to the area ducts 28, 30, 32. Once the calculation of the relative zone duct size is complete, it should be relatively reliable over the life of the system. Nevertheless, the calculation can be performed periodically.

In addition to the above-described inventive manner of determining the air regulator static pressure (i.e., the algorithm disclosed in the aforementioned pending application), other methods for determining the static pressure, such as pressure gauges, may be used to manually measure pressure measurements. The method of taking may also be used within the scope of the present invention.

Returning to FIG. 2, in step 54 these amounts of information, as well as information on the size and capacity of the temperature change component 22, and the setpoints (step 50) are given to the maximum air for each zone 1, 2, 3; Used to calculate flow values.

Use the following analytical methods to complete the calculation of the maximum air flow in each zone. Maximum airflow in the system by assuming that the duct system for the entire house (dampers in all zones are fully open) is designed to accommodate the maximum airflow of the system required to operate the temperature change components 22 installed in the home The value is determined. The controller 36 knows the capacity and air flow requirements of the temperature change component 22 (installed furnace, air conditioner or heat pump) by an automatic configuration process. From this, the controller 36 calculates the highest system airflow (HAS) of the system. In one embodiment the following holds:

HAS = x CFM / TON or y * higher in the air flow with higher heating

"CFM" or cubic feet per minute is a unit of measure for air flow. The capacity of the air conditioner and heat pump is typically measured in TON. In one embodiment, x = 450 and y = 1.12. It is a matter of course that the numerical coefficients of x and y can be used differently in this calculation.

Next, determine the maximum air flow in the zone. Again, duct size assessment makes this determination. With all dampers fully open, each zone shares the air flow throughout the system according to the "relative size" of the duct segment delivering air to that zone. The “relative size” of a duct segment is a measure of the ability to allow some air to flow through it at a given system pressure. Thus, a zone with a larger duct size will share more system airflow than a zone with a smaller duct size. The controller 36 determined relative duct sizes for all zones of the system. These relative sizes can be expressed as a percentage of the entire duct system, expressed as S1, S2, S3 ... Sn, where n is the number of zones in the system. Next, for each zone, the zone's highest zone airflow (HZA _i ) is:

HZA _i = S _i * HAS, ( i = 1 to n)

It should be noted that HZA _i is the maximum air flow expected in each zone with dampers in all zones fully open as if the system were not zoned.

Next, determine the maximum air flow limit of the zone. In zoned systems, as certain dampers 34 open and close to redistribute air between different zones to meet changing heating or cooling needs, any particular zone is sometimes more than a "fair share" of the system air flow. You can have a lot. This allows the zone system to give the occupants of the zone a higher level of comfort. However, as the air flow increases, air noise in the zone may not be acceptable at some points. Therefore, there is a need for a maximum air flow threshold in each zone. To some extent, the balance between comfort and noise is a subjective decision that depends on the preferences of the occupants. However, in order to minimize the coordinator's or homeowner's coordination and to make the system setup easy and consistent, the control section 36 sets the Max zone airflow (MZA) limit to the zone maximum airflow calculated above. "Scale". In one embodiment, the user (resident or installer) can select one of four airflow thresholds (low, standard, high and maximum) for each zone. This is provided as an option in the controller 130 and / or controller 36. In one embodiment, the maximum air flow in the zone is calculated as follows.

Selection MZA i

Low HZA i

Standard 1.5 * HZA i (this can be factory default)

High 2 * HZA i

Up to 2 * HZA i

The maximum selection has an air flow threshold, such as high, which is used to reduce the air flow and adjust the set point if possible, as described below. However, if adjustment is not possible, the heating or cooling stage (step 56, described below) should not be reduced at the maximum setting. Comfort in the area with the maximum air flow threshold is achieved even if noise is unacceptable.

As described above, each zone 1, 2, 3 allows the operator to set the desired temperature set point in the control unit 13. Moreover, the control unit 13 provides the actual temperature of each zone along with the actual humidity and humidity set points when the system is complex. In step 58, the controller 36 calculates the desired heating / cooling stage. One way of calculating the desired heating or cooling stage is disclosed in US patent application Ser. No. 10 / 760,664, filed Jan. 20, 2004, entitled “Control of Multi-zone and Multi-Stage HVAC Systems”. Based on the plant size and the heating / cooling stage, the air flow of some entire systems can be known or calculated by the control 36. The control unit 36 may also calculate the desired damper position in each zone so that each zone meets the desired temperature set point in the zone and then take into account the actual temperature of each zone at that time. Algorithms for performing the operation are all known in the art.

Next, in step 60, the controller 36 calculates the predicted air flow in each zone by reconsidering the overall system air flow, the position of the dampers in each zone and the relative zone duct size. The damper 34 is adjusted in that its rotating blade can be controlled to any angular position between opening and closing. As mentioned above, in one embodiment, the damper is adjusted to 16 positions from zero in the fully closed state to 15 in the fully open state, with each position in between being achieved by an equivalent angular movement step. This embodiment also assumes a linear relationship between the angular position of the damper and the relative ability to "open" or allow air flow.

By linear relationship, the relative air flow capacity (D) relative to the position of each damper is as follows for position j :

D = j / 15, ( j = 0 to 15).

Thus, the air flow capacity relative to position 15 (fully open) is 100%, while the value for position 0 (fully closed) is zero.

These relationships may also be non-linear, laboratory tests may be conducted to determine the relationship according to a specific damper method, and then used for the next calculation.

The controller 36 uses the relative duct size for each zone, labeled S1 to Sn, in a system with n zones. The control unit 36 adjusts the zone dampers 34 to deliver some air to each zone in response to the comfort request of each zone. The controller 36 determines the desired damper position for each zone and determines the corresponding air flow capacity. These are represented by D1 to Dn. The controller 36 also knows the total system air flow A s that flows through the entire system. From this value, the controller 36 calculates a part of the air flow and A i is delivered to each zone.

A i = A s * (D i * S i ) / (SUM (D i * S i ), ( i = 1 to n)

In step 62, the controller 36 compares the predicted air flow for each zone with its maximum limit value. If all of the calculated zone air flow calculations are less than the maximum air flow for each of the zones, control 36 goes to step 64 to simply operate the HVAC system.

However, if the predicted zone airflow value exceeds its maximum airflow value, the controller 36 asks if the overall system airflow can be reduced. This is generally a design function of the temperature change component and the air regulator. If the overall system air flow is reduced, then it is reduced to the minimum limit in step 64 and the control returns to step 60 and moves back to step 62 to recalculate the actual air flow for each zone.

However, if the overall system air flow cannot be reduced, control 36 moves to step 66 to consider the possibility of adjustment for the non-residential zone. The controller 30 allows the operator to set whether the zone is a non-resident zone. For example, a room used only for a certain period of the year may remain less air conditioned to reduce operating costs of the HVAC system 20. If such a room is set up as a non-residential zone in the system 20, as part of step 66, the controller 36 considers providing additional air conditioning to the zone.

Typically, the set point of a non-residential zone is set to a minimum heating temperature (eg 60 degrees) or a maximum cooling temperature (eg 85 degrees). By these set points, these zones require little cooling or heating, and these dampers remain closed. This can save energy and also allow more air flow (and capacity) to be delivered to the residential area as needed to achieve a comfortable set point. However, in the event that the predicted air flow to the residential zone exceeds the maximum air flow threshold, the control unit 36 of the present invention may open a damper in any non-residential zone to absorb a portion of the air stream. . This allows the living area to be pleasantly air conditioned while staying within the desired maximum airflow noise limit. Control 36 achieves this by raising the heating set point of the non-residential zone or by lowering the cooling setpoint until the request in the non-residential zone causes the damper to open. In this disclosed embodiment, a limit value is applied to the set point adjustment value. The heating set point is not adjusted above the maximum heating set point in any (resident) zone, whereas the cooling set point is not adjusted below the minimum cooling set point in any zone. In general, the damper 34 in the non-residential zone can also be simply opened directly without adjusting its set point, and the temperature can be adjusted to any predetermined limit value.

Again, if the non-resident zone set point can be adjusted, the adjustment is made and the system returns to step 68 where the zone damper conditions can be recalculated and then moves to steps 60 and 62. If the non-resident zone set point cannot be adjusted (initial or no longer), the system moves to step 70 to consider adjusting the non-resident zone set point.

In the disclosed embodiment, if the zone requiring heating or cooling is above its maximum airflow threshold and all of the non-resident zones are open up to that threshold, the control unit may be configured to direct more airflow to these zones. In a similar manner, adjust the setpoints for other living quarters. In one embodiment, the adjustment threshold for the residential heating set point is set no higher than 3 degrees below the maximum heating set point in any zone. Similarly, the adjustment threshold for the residential cooling set point is set no lower than 3 degrees above the minimum cooling set point. Again, different limit values may be selected.

If the control unit 36 can adjust the living area set point, do so. The control section 36 then returns to step 68 and proceeds to steps 60 and 62. However, if it cannot be adjusted, the system moves to step 56 and considers whether a lower heating or cooling stage is available. If possible, the system moves to the lower stage and returns to step 72 and proceeds to steps 68, 60, 62 and the like to recalculate the overall system air flow. As described above, step 56 may not be executed if the zone is set at the maximum set point and the zone is capable of receiving an air flow exceeding the maximum air flow.

If a low stage is not available, heating and cooling may be stopped until the next calculation period. The calculations are performed periodically.

An embodiment of the present invention has been disclosed. Those skilled in the art will understand that any modifications are included in the scope of the present invention. For that reason, the following claims should be reviewed to determine the true scope and content of this invention.

Claims (9)

A temperature change component for changing the temperature of the air, A duct for supplying air to a plurality of zones and a damper connected to the ducts leading to the respective zones; A system control for controlling the dampers in the respective zones and for moving the dampers to determine information relating to relative air flow through each duct relative to other ducts, The information can be used to calculate the size of each duct relative to the other ducts. The HVAC system of claim 1, wherein the information is static pressure information. 3. The HVAC system of claim 2, wherein the system controller further determines static pressure information with all the dampers closed to determine an outflow value. 3. The HVAC system of claim 2, wherein the static pressure information is determined by measuring a blower speed of an air regulator that moves air from the temperature change component to the duct. 3. The HVAC system of claim 2, wherein a variable static pressure is determined for each zone by using the static pressure information and determining a fixed static pressure. 6. The HVAC system of claim 5, wherein the fixed static pressure is initially determined as a predictive value, which is then refined in an iterative process. 7. The HVAC system of claim 6, wherein said determining information comprises determining leakage information used in said iteration. How to determine the relative size of ducts in an HVAC system, (1) temperature change components for changing the temperature of the air, ducts for supplying air to a plurality of zones, dampers connected to each of the ducts leading to each zone, and actuated to monitor information of the system components Providing a system control unit for controlling the dampers connected to the respective zones; (2) connecting the respective dampers to determine a change in the information of the system component as the dampers in the respective zones are opened and the remaining dampers in the remaining ones of the plurality of zones are relatively closed. Closing the dampers in a serial manner and using the information from each zone to determine the relative duct size of the duct leading to each zone. 9. The method of claim 8, further comprising closing all of the dampers, determining a change in the information to provide an outflow estimate within the system, and using the outflow value in determining a relative duct size. Way.

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