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(11) | EP 4 343 219 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | METHOD OF OPERATING A VENTILATION SYSTEM, VENTILATION SYSTEM AND VALVE FOR A VENTILATION SYSTEM |
| (57) The method of operating a ventilation system that comprises an adjustable ventilation
system device (1, 5) having at least two different set points, the selected set point
of the ventilation system device (1, 5) affecting the air pressure in a first location
(A) of the ventilation system, comprises the steps of operating the ventilation system
with a first set point of said ventilation system device (1, 5) (101), measuring air
pressure in the first location (A) by means of a first pressure sensor (2) while the
ventilation system is operated with the first set point (102), operating the ventilation
system with a second set point of said ventilation system device (1, 5) (103), measuring
air pressure in the first location (A) by means of said first pressure sensor (2)
while the ventilation system is operated with the second set point to detect the pressure
change caused by the changing of the set point (104), and using the measured pressures
to determine at least one value of at least one flow rate parameter representing the
flow rate in the first location (A) (105).
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Technical field of the invention
[0001] The present invention concerns a method of operating a ventilation system that comprises an adjustable ventilation system device, as defined in claim 1. The invention further concerns a ventilation system and a valve for a ventilation system, as defined in other independent claims.
Background of the invention
[0002] The purpose of the ventilation system of a building is to keep the indoor air quality at an acceptable level. Indoor activities, such as taking showers or cooking, evaporate water into the indoor air. When the amount of water exceeds a certain level, the air is perceived as damp, or the water may condense into building structures and thus result in structural damage. On the other hand, when the moisture content of air is too low, people in the space may suffer from skin irritation, dry eyes, or equivalent ailments.
[0003] In addition to humidity, human activity and building materials may release other impurities into the air. The most important impurity is carbon dioxide resulting from human metabolism. High carbon dioxide levels in indoor air result in general tiredness, headache, inability to concentrate, and similar unwanted effects.
[0004] Thus, sufficient ventilation is needed to remove the unwanted impurities. On the other hand, excessive ventilation may result in high energy use, dry air, and even feeling a cold draft.
[0005] To keep the air flow through a ventilation system at a suitable level, the system needs control elements to adjust the air flow in each space. In building ventilation systems, the flow through ventilation inlets and outlets is typically controlled by mechanical valves.
[0006] In practice, the need for ventilation varies between different spaces and as a function of time. Some spaces may be unused, whereas there may be a number of people in other spaces. Manually operated ventilation valves cannot take this into account and the airflow in each space is constant regardless of the actual need of ventilation.
[0007] This variation may be taken into account by controlling the overall airflow in the building. As an example, the airflow in a residential building may be increased during the evening hours, when people typically are at home and cook. This clock-based control may improve the situation, but it still produces overventilation and underventilation of individual spaces.
[0008] Demand-based ventilation valves are also available. The valves have a motor instead of manual operation of the valve disc, and the valves can be controlled by different measurement signals. To improve the controllability of the ventilation system, these electrically operated valves may measure the airflow through the valve. In a known solution, a ventilation valve is provided with a differential pressure sensor, which allows determining the airflow through the valve.
[0009] A drawback of differential pressure sensors is that they are relatively expensive, and they often require calibration or zeroing arrangements using switchable air channels, which further increase expense and space use.
[0010] An alternative way for determining the airflow through the valve is to use two absolute pressure sensor that are arranged to measure the absolute pressure on the downstream and upstream sides of the valve. However, the use of two absolute pressure sensors significantly increases the measurement uncertainty. The most common source for measurement uncertainty in an absolute pressure sensor is the pressure offset drift. The measurement errors of two absolute pressure sensors often change differently over time, and therefore the measurement uncertainty may increase over time.
[0011] Demand-based ventilation to individual spaces enables obtaining optimal indoor air quality. However, as measuring of the differential pressure reliably and with sufficient precision is complicated and requires costly measurement solutions, many known solutions suffer from either high cost or insufficient precision.
Summary of the invention
[0012] An object of the present invention is to provide an improved method of operating a ventilation system that comprises an adjustable ventilation system device having at least two different set points, the selected set point of the ventilation system device affecting the air pressure in a first location of the ventilation system. The characterizing features of the method according to the invention are presented in claim 1. Another object of the invention is to provide an improved ventilation system, as defined in another independent claim. A further object of the invention is to provide an improved valve for a ventilation system.
[0013] The method according to the invention comprises the steps of
- operating the ventilation system with a first set point of said ventilation system device,
- measuring air pressure in the first location by means of a first pressure sensor while the ventilation system is operated with the first set point of said ventilation system device,
- operating the ventilation system with a second set point of said ventilation system device,
- measuring air pressure in the first location by means of said first pressure sensor while the ventilation system is operated with the second set point of said ventilation system device to detect the pressure change caused by the changing of the set point of said ventilation system device, and
- using the pressures measured in the first location by means of the first pressure sensor with the first set point and the second set point of said ventilation system device to determine at least one value of at least one flow rate parameter representing the flow rate in the first location.
[0014] The method according to the invention provides a simple, reliable and inexpensive way to determine a flow rate in a certain location of a ventilation system. Because of the at least two pressure measurements, measurement uncertainty caused by drifting of the pressure sensor can be eliminated. The method allows optimization of the flow rate to ensure sufficient ventilation and to minimize energy consumption of the ventilation system. In a ventilation system ventilating several spaces, the method can be used to determine flow rates in several locations to allow individual control of ventilation in different locations. Even existing ventilation systems can be easily and with a relatively low cost be upgraded to utilize the method according to the invention.
[0015] According to an embodiment of the invention, the first pressure sensor is an absolute pressure sensor. Absolute pressure sensors provide an inexpensive way of determining the air pressure.
[0016] According to an embodiment of the invention, the method further comprises operating the ventilation system with at least one further set point of the ventilation system device, measuring the air pressure in the first location by means of said first pressure sensor while the ventilation system is operated with said further set point of said ventilation system device to detect the pressure change caused by the changing of the set point, and using the pressure measured in the first location by means of the first pressure sensor with said at least one further set point to determine said at least one value of said at least one flow parameter. The use of the further pressure measurement as a further input improves the accuracy of the determination of the flow rate parameter.
[0017] According to an embodiment of the invention, the method comprises changing the set point according to a predetermined pattern, monitoring the air pressure in the first location by means of the first pressure sensor during the changing of the set point, and using air pressures measured in the first location by means of the first pressure sensor to determine said at least one value of said at least one flow rate parameter. The method can thus comprise even further measurements, which further improve the accuracy.
[0018] According to an embodiment of the invention, the method further comprises measuring pressure by means of a second pressure sensor in a second location where the pressure is affected by the set point of the ventilation system device while the ventilation system is operated with different set points of the ventilation system device, and using the pressures measured in the second location by means of the second pressure sensor as further inputs to determine said at least one value of said at least one flow rate parameter. The pressure measurement in the second location improves the accuracy of the method. The second pressure sensor can be located in a space ventilated by the ventilation system.
[0019] According to an embodiment of the invention, the ventilation system device is a valve for controlling air flow into a space ventilated by the ventilation system or out of a space ventilated by the ventilation system, and the different set points of the ventilation system device correspond to different opening degrees of the valve. The ventilation system device can thus be an exhaust air valve or a supply air valve. This allows determining a flow rate parameter for each space ventilated by the ventilation system. Also, an existing ventilation system can be easily upgraded to utilize the present invention by providing existing, remotely operable valves with pressure sensors, or by replacing the valves with new valves.
[0020] According to an embodiment of the invention, the first set point and the second set point comprise the fully closed position of the valve and the fully open position of the valve. This ensures that the change in the air pressure is sufficient to reliably determine the value of the flow rate parameter.
[0021] According to an embodiment of the invention, the method comprises measuring the pressure in the first location at least twice with a specific opening degree of the valve and using both measured pressures as inputs to determine said at least one value of said at least one flow rate parameter, wherein one of the measurements with said specific opening degree is conducted when the opening degree has been changed from a greater opening degree towards said specific opening degree and one of the measurements is conducted when the opening degree has been changed from a smaller opening degree towards said specific opening degree. This duplicated information allows for compensating for any linear changes in time in pressure difference and hence makes the measurement more robust towards changes in pressure difference.
[0022] According to an embodiment of the invention, the first pressure sensor is arranged in a valve of the ventilation system.
[0023] According to an embodiment of the invention, the method further comprises adjusting the air flow in the first location based on the determined value of the flow rate parameter.
[0024] The ventilation system according to the invention comprises a first pressure sensor for measuring air pressure in a first location of the ventilation system and is configured to be operated according to the method defined above. The valve according to the invention for use in the method defined above is connectable to a ventilation duct conveying incoming air into a space ventilated by the ventilation system or out of a space ventilated by the ventilation system and comprises a valve member that is moveable for adjusting the opening degree of the valve and thereby the air flow through the valve, an electrical actuator for moving the valve member, control means for controlling the operation of the electrical actuator, and a first pressure sensor located such that when the valve is connected to a ventilation duct, the pressure of the incoming air or extracted air conveyed in the ventilation duct can be measured by means of the first pressure sensor.
[0025] The valve according to the invention allows an existing ventilation system to be easily updated such that the operation of the ventilation system can be optimized.
[0026] According to an embodiment of the invention, the valve comprises a second pressure sensor located such that when the valve is connected to a ventilation duct, the pressure in the space ventilated by the ventilation system can be measured by means of the second pressure sensor. The second pressure sensor improves the accuracy of the method, and by arranging the second pressure sensor in the valve, the second pressure sensor can utilize other components of the valve, such as a power source and communication means.
[0027] According to an embodiment of the invention, the valve comprises communication means configured to transmit data based on pressure measurements conducted by means of the first pressure sensor and/or an optional second pressure sensor. The transmitted pressure measurement data can be used for optimizing the functioning of other parts of the ventilation system.
Brief description of the drawings
[0028] Embodiments of the invention are described below in more detail with reference to the accompanying drawings, in which
Fig. 1 shows schematically a simplified view of a ventilation system according to an embodiment of the invention,
Fig. 2 shows a pressure sensor arrangement of a ventilation system according to an embodiment of the invention,
Fig. 3 shows as a flowchart the method according to the invention,
Fig. 4 illustrates the dependencies between the valve opening and pressure differences,
Fig. 5 shows an alternative location for a pressure sensor,
Fig. 6 shows another alternative location for a pressure sensor, and
Fig. 7 shows a valve according to an embodiment of the invention.
Detailed description of embodiments of the invention
[0029] Figure 1 shows a ventilation system according to an embodiment of the invention. The ventilation system is configured to ventilate at least one space 4A, 4B, 4C within a building or another construction, such as a ship or a vehicle. The ventilation system comprises a ventilation duct 6. In the embodiment of figure 1, the ventilation duct 6 is an exhaust air duct that is configured to discharge air from the spaces 4A, 4B, 4C ventilated by the ventilation system. However, the ventilation duct 6 could also be a supply air duct that is configured to convey air into the spaces 4A, 4B, 4C ventilated by the ventilation system. The ventilation system further comprises a blower 5 that is configured to convey air in the ventilation duct 6. In the embodiment of figure 1, the blower 5 is an exhaust air blower that is configured to discharge air from the spaces 4A, 4B, 4C ventilated by the ventilation system. However, the blower 5 could also be a supply air blower that is configured to convey air into the spaces 4A, 4B, 4C ventilated by the ventilation system.
[0030] In the embodiment of figure 1, the ventilation system is configured to ventilate several spaces 4A, 4B, 4C within a building. However, the ventilation system could also be configured to ventilate a single space. The spaces 4A, 4B, 4C can be separated from each other by walls 8 such that the air pressures of the spaces 4A, 4B, 4C are different. However, some of the spaces can also be sub-spaces of a larger space such that the air pressures of the spaces are substantially equal.
[0031] In the embodiment of figure 1, the ventilation system comprises a plurality of valves 1 for controlling air flow in the ventilation duct 6. In the embodiment of figure 1, the valves 1 are exhaust air valves that are configured to control the flow rate of exhaust air from the spaces 4A, 4B, 4C ventilated by the ventilation system. However, the valves 1 could also be supply air valves that are configured to control the flow rate of supply air into the spaces 4A, 4B, 4C ventilated by the ventilation system.
[0032] In the embodiment of figure 1, the supply air is introduced into the spaces 4A, 4B, 4C ventilated by the ventilation system via supply air valves 7. The supply air valves 7 could have a fixed flow area, or the supply air valves 7 could be manually adjustable valves or temperature-controlled valves.
[0033] The ventilation system according to the invention comprises at least one first pressure sensor 2. The first pressure sensor 2 is configured to measure pressure in a first location A within the ventilation system. The first pressure sensor 2 can be an absolute pressure sensor. The first location A is selected such that the pressure in the first location A is affected by a set point of a ventilation system device. The ventilation system device is preferably a valve 1. However, the ventilation system device could also be a blower 5. Figure 2 shows an example of the location of the first pressure sensor 2. The first location A can be on the ventilation duct side of a moveable valve member 10 of the valve 1, as shown in figure 2. In the embodiments of figures 1 and 2, where the valve 1 is an exhaust air valve, the first location A is on the downstream side of the moveable valve 10 member of the valve 1. If the valve 1 was a supply air valve, the first location A could be on the upstream side of the moveable valve member 10 of the valve 1. In the embodiment of figure 2, the first pressure sensor 2 is attached to the moveable valve member 10. However, the first pressure sensor 2 could also be attached to a body of the valve 1 or to the inner surface of the ventilation duct 6.
[0034] In the method according to the invention, the ventilation system is operated such that at least one value of at least one flow rate parameter representing the flow rate in the first location A can be determined. The relation between the flow rate in the first location A and the pressure difference over the valve 1 can be expressed by the following equation:
where
Q is the flow rate,
k a constant depending on the flow properties of the valve, and
Δp the pressure difference between the inlet and outlet of the valve.
[0035] If the valve is a control valve whose flow properties, such as the position of the moveable valve member 10, are changed during the operation, k is a function of said change.
[0036] As the flow rate depends on the pressure difference over the valve 1, the flow rate parameter could thus be the pressure difference over the valve 1. However, the flow rate parameter could also be a flow rate calculated based on the pressure difference, or some other parameter calculated on the basis of the pressure difference or a flow rate and describing the flow rate in the first location A.
[0038] In the method according to the invention, the ventilation system is operated with a first set point of the ventilation system device 1, 5 (step 101). If the ventilation system device is a valve 1, the first set point can be a first opening degree of the valve 1. The opening degree could be expressed as a percentage of a fully open position of the valve 1, or as a position of a moveable valve member 10.
[0039] While the ventilation system is operated with the first set point of the ventilation system device 1, air pressure in the first location A is measured by means of the first pressure sensor 2 (step 102).
[0040] After operating the ventilation system with the first set point of the ventilation system device 1, the ventilation system is operated with a second set point of the ventilation system device 1 (step 102). The second set point is different from the first set point. If the first set point is a specific opening degree of the valve, the second set point is a different opening degree.
[0041] While the ventilation system is operated with the second set point of the ventilation system device 1, air pressure in the first location A is measured by means of the first pressure sensor 2 to detect the pressure change caused by the changing of the set point of the ventilation system device 1.
[0042] The air pressure in the first location A is also affected by other factors than the set point of the ventilation system device. For instance, a change in the atmospheric pressure affects the air pressure in the first location A. Also, if a window or door in the space 4A, 4B, 4C ventilated by the ventilation system is opened or closed, the air pressure in the first location A can change. Therefore, for detecting the change that is caused by the changed set point, the measurement with the second set point should take place immediately after or relatively soon after the measurement with the first set point. For a reliable measurement, the pressure difference between the ventilation duct 6 and the ventilated space 4A, 4B, 4C should remain substantially constant during the measurements, or the pressure difference should be known. Preferably, the second measurement takes place within a minute from the first measurement. However, the time interval between the measurements can be longer, in particular if changes in other factors can be identified and preferably also quantified to compensate for their effect. For instance, if the atmospheric pressure is monitored, it may not be necessary to carry out the pressure measurement with the second set point immediately after measuring the pressure with the first set point.
[0043] The pressures measured in the first location A by means of the first pressure sensor 2 with the first set point and the second set point of the ventilation system device 1 are then used to determine at least one value of at least one flow rate parameter representing the flow rate in the first location A (step 105).
[0044] In the method according to the invention, the first pressure sensor 2 does not need calibration or zeroing, and the value of the flow rate parameter can be reliably determined even if the absolute pressure values given by the first pressure sensor 2 change over time.
[0045] The first set point could correspond to a fully open position of the valve 1 and the second set point could correspond to a fully closed position of the valve 1, or vice versa. However, the first and second set point could correspond to some other opening degrees of the valve 1.
[0046] One way to implement the method according to the invention is described by referring to figures 2 and 4. In the embodiment of figure 2, the first pressure sensor 2 is arranged on the downstream side of the moveable valve member 10 of the valve 1, which is an exhaust air valve. In the embodiment of figure 2, the ventilation system further comprises a second pressure sensor 3, which is configured to measure pressure in a second location B. Also the pressure in the second location B is affected by the set point of the valve 1. In the embodiment of figure 2, the second pressure sensor 3 is arranged on the upstream side of the moveable valve member 10. Both the first pressure sensor 2 and the second pressure sensor 3 are absolute pressure sensors.
[0047] The pressure difference Δp experienced by the first pressure sensor 2 and the second pressure sensor 3 depends on the opening degree of the valve 1 and on the pressure difference Δp2 between the ventilation duct 6 (location D) and the space 4A, 4B, 4C ventilated by the ventilation system (location C).
[0048] Thus, if the pressure difference Δp2 between the ventilation duct 6 and the ventilated space 4A, 4B, 4C is constant, the pressure difference Δp over the valve member 10 will track a curve if the valve opening is adjusted between fully closed and fully open. These curves 20 are depicted in Figure 4, each curve representing a certain pressure difference Δp2 between the ventilated space 4A, 4B, 4C and the ventilation duct 6.
[0049] It should be noted that these curves 20 only depend on mechanical and aerodynamic factors, and they can be determined beforehand by calculations, or in situ at the installation time of the valve 1.
[0050] It is also important to note that each of the curves 20 has a different shape from all other curves. This property makes it possible to compensate for the sensor offset resulting in measurement offset of the pressure difference Δp over the valve member 10. One way to achieve this is to measure a pressure difference curve 21 by moving the valve 1 from the fully closed to the fully open position and recording the pressure difference Δp at all positions. Fitting the shape of the curve 21 to the theoretical curves 20 gives the pressure offset 22, which can then be subtracted from the measured pressure difference Δp to remove the offset error.
[0051] One advantageous way of performing the offset determination is to adjust the opening degree of the valve 1 gradually starting from fully closed to fully opened and back to fully closed. This way each position receives two measurements of the pressure difference Δp, one in the opening direction, and the other in the closing direction. This duplicated information allows for compensating for any linear changes in time in the pressure difference Δp2 between the ventilation duct 6 and the ventilated space 4A, 4B, 4C and hence makes the measurement more robust towards changes in the pressure difference Δp2.
[0052] As an example, with a typical valve, the offset determination could take approximately 10 seconds, and it could be made, for instance, once a day for a sufficiently low differential pressure measurement uncertainty.
[0053] As is obvious to a person skilled in the art, the opening degree of the valve 1 can be adjusted with a multitude of time-varying signals, e.g., a sinusoid or a pseudo-noise signal, and the offset signal can be extracted by using several known correlation methods, such as spectral analysis.
[0054] Instead of using the first pressure sensor 2 and the second pressure sensor 3 for determining the pressure difference Δp over the valve member 10, the pressure difference could be determined by means of the first pressure sensor 2 only using curve shape fitting methods or correlations as described above. The measurement uncertainty would increase to some extent, but the use of a single pressure sensor 2 would make the valve 1 simpler.
[0055] In the embodiment of figure 2, the pressure in the location B of the second pressure sensor 3 is close to the static pressure in the ventilated space 4A, 4B, 4C. However, the airflow across the valve 1 may introduce error or noise to the readings of the second pressure sensor 3. Also, some holes may be needed in the valve member 10 of the valve 1 for attaching the second pressure sensor 3 to the valve 1. To avoid these problems, the second pressure sensor 3 can be located elsewhere in the ventilated space 4A, 4B, 4C. For instance, the second pressure sensor 3 can be attached to a wall 8 of the ventilated space 4A, 4B, 4C, as shown in figures 1 and 5. The second pressure sensor 3 can be configured to communicate with other parts of the ventilation system for example via wired or wireless communication means.
[0056] In the embodiments of figures 1, 2 and 5, the first and second pressure sensors 2, 3 are arranged in locations with negligible airflow.
[0057] As is well-known to a person skilled in the art, airflow creates dynamic pressure, and the sensors measure static pressure at their installation position. If the sensors are installed at positions with very little airflow, the static pressure measured by the sensors is equivalent to the total pressure.
[0058] However, it may be advantageous to install a sensor in a position with fast airflow as depicted in figure 6. The pressure sensor 2 is installed at such a position at a narrow part of the air channel to use the Venturi effect which lowers the static pressure experienced by the sensor 2. This installation position does not change the basic principles outlined above, but it changes the relation between the valve opening, pressure differential between the ventilated space 4A, 4B, 4C and the ventilation duct 6, and the opening degree of the valve 2. In other words, the curves 22 in figure 4 will assume a different shape.
[0059] The sensor installed in a position with a strong Venturi effect may be the first pressure sensor 2. However, the sensor could also be an additional sensor that is used to give lower measurement uncertainty. The venturi pressure may be sampled from several points by either using several pressure sensors or by connecting the said points with tubing or piping and measuring the combined pressure with a single pressure sensor.
[0060] In the embodiments described above, the value of the flow rate parameter is determined by operating the ventilation system with different set points of the valve 1. However, the flow rate parameter could be determined similarly by operating the ventilation system with different set points of the blower 5. The pressures in the first location A and optionally in the second location B, C could thus be measured by means of the pressure sensors 2, 3 while operating the blower 5 with different set points.
[0061] Figure 7 shows a ventilation valve 1 according to an embodiment of the invention. The valve 1 can be used in the method and ventilation system according to the invention. In the embodiment of figure 7, the valve 1 is an exhaust air valve 1. The valve 1 is connectable to a ventilation duct 6 for conveying air out of a space 4A, 4B, 4C ventilated by the ventilation system. In many older buildings, exhaust air is discharged from the ventilated spaces by means of an exhaust air blower, whereas replacement air flows into the spaces through replacement air valves due to the underpressure created by the exhaust air blower. An exhaust air valve according to the invention can thus be used for replacing existing exhaust air valves and to improve the functioning of a ventilation system. However, the valve 1 could also be a supply air valve that is connectable a ventilation duct 6 conveying incoming air into a space 4A, 4B, 4C ventilated by the ventilation system.
[0062] The valve 1 comprises a valve member 10 that is moveable for adjusting the opening degree of the valve 1 and thereby the air flow through the valve 1. The valve 1 is provided with an electrical actuator 11 for moving the valve member 10. In the embodiment of figure 7, the electrical actuator is an electric motor 11. In the embodiment of figure 7, the motor 11 is arranged within the moveable valve member 10. When the valve member 10 moves, the motor 11 thus moves together with the valve member 10.
[0063] The motor 11 is connected to a valve shaft 15 via a gear 12. The gear 12 is not an essential part of the valve 1, but depending on the type of the motor 11, the motor 11 could be connected directly to the valve shaft 15. In the embodiment of figure 7, the valve shaft 15 is a threaded shaft. The valve 1 further comprises a valve body 16. The shaft 15 is connected to the valve body 16. As the valve shaft 15 is rotated by means of the motor 11, the valve shaft 15 moves relative to the valve body 16 and moves the valve member 10. Moving of the valve member 10 could also be implemented in many alternative ways. For instance, the electrical actuator 11 could be a linear actuator.
[0064] The valve 1 further comprises a control unit 14 for controlling the electrical actuator 11. The valve 1 comprises a first pressure sensor 2 located such that when the valve 1 is connected to a ventilation duct 6 the pressure of the incoming air or extracted air conveyed in the ventilation duct 6 can be measured by means of the first pressure sensor 2. The valve 1 can further comprise a second pressure sensor 3 located such that when the valve 1 is connected to a ventilation duct 6, the pressure in the space 4A, 4B, 4C ventilated by the ventilation system can be measured by means of the second pressure sensor 3.
[0065] In the embodiment of figure 7, the valve 1 further comprises communication means 17 configured to transmit data based on pressure measurements conducted by means of the first pressure sensor 2 and the second pressure sensor 3. The communication means 17 are wireless communication means. The valve 1 also comprises a battery 13 for powering the motor 11, control unit 14, pressure sensors 2, 3 and communication means 17.
[0066] The valve 1 according to the invention can be configured to implement the method according to the invention. The valve 1 can thus be configured to automatically determine the value of the flow rate parameter, for instance at regular intervals. Alternatively, the valve 1 can be configured to measure the pressures in the first location A and optionally in the second location B and to transmit data relating to the pressure measurements to an external unit, which is configured to determine the value of the flow rate parameter based on the measured pressures. The valve 1 can be further configured to adjust the flow through the valve 1 based on the determined value of the flow rate parameter.
1. A method of operating a ventilation system that comprises an adjustable ventilation
system device (1, 5) having at least two different set points, the selected set point
of the ventilation system device (1, 5) affecting the air pressure in a first location
(A) of the ventilation system, the method comprising the steps of
- operating the ventilation system with a first set point of said ventilation system device (1, 5) (101),
- measuring air pressure in the first location (A) by means of a first pressure sensor (2) while the ventilation system is operated with the first set point of said ventilation system device (1, 5) (102),
- operating the ventilation system with a second set point of said ventilation system device (1, 5) (103),
- measuring air pressure in the first location (A) by means of said first pressure sensor (2) while the ventilation system is operated with the second set point of said ventilation system device (1, 5) to detect the pressure change caused by the changing of the set point of said ventilation system device (1, 5) (104), and
- using the pressures measured in the first location (A) by means of the first pressure sensor (2) with the first set point and the second set point of said ventilation system device (1, 5) to determine at least one value of at least one flow rate parameter representing the flow rate in the first location (A) (105).
2. A method according to claim 1, wherein the first pressure sensor (2) is an absolute
pressure sensor.
3. A method according to claim 1 or 2, wherein the method further comprises operating
the ventilation system with at least one further set point of the ventilation system
device (1, 5), measuring the air pressure in the first location (A) by means of said
first pressure sensor (2) while the ventilation system is operated with said further
set point of said ventilation system device (1, 5) to detect the pressure change caused
by the changing of the set point, and using the pressure measured in the first location
(A) by means of the first pressure sensor (2) with the at least one further set point
to determine said at least one value of said at least one flow parameter.
4. A method according to any of the preceding claims, wherein the method comprises changing
the set point according to a predetermined pattern, monitoring the air pressure in
the first location (A) by means of the first pressure sensor (2) during the changing
of the set point, and using air pressures measured in the first location (A) by means
of the first pressure sensor (2) to determine said at least one value of said at least
one flow rate parameter.
5. A method according to any of the preceding claims, wherein the method further comprises
measuring air pressure by means of a second pressure sensor (3) in a second location
(B, C) where the pressure is affected by the set point of the ventilation system device
(1, 5) while the ventilation system is operated with different set points of the ventilation
system device (1, 5), and using the pressures measured in the second location (B,
C) by means of the second pressure sensor (3) as further inputs to determ ine said
at least one value of said at least one flow rate parameter.
6. A method according to claim 5, wherein the second pressure sensor (3) is located in
a space (4A, 4B, 4C) ventilated by the ventilation system.
7. A method according to any of the preceding claims, wherein the ventilation system
device (1, 5) is a valve (1) for controlling air flow into a space (4A, 4B, 4C) ventilated
by the ventilation system or out of a space (4A, 4B, 4C) ventilated by the ventilation
system, and the different set points of the ventilation system device correspond to
different opening degrees of the valve (1).
8. A method according to claim 7, wherein the first set point and the second set point
comprise the fully closed position of the valve (1) and the fully open position of
the valve (1).
9. A method according to claim 7 or 8, wherein the method comprises measuring the pressure
in the first location (A) at least twice with a specific opening degree of the valve
(1) and using both measured pressures as inputs to determine said at least one value
of said at least one flow rate parameter, wherein one of the measurements with said
specific opening degree is conducted when the opening degree of the valve (1) has
been changed from a greater opening degree towards said specific opening degree and
one of the measurements is conducted when the opening degree of the valve (1) has
been changed from a smaller opening degree towards said specific opening degree.
10. A method according to any of the preceding claims, wherein the first pressure sensor
(2) is arranged in a valve (1) of the ventilation system.
11. A method according to any of the preceding claims, wherein the method further comprises
adjusting the air flow in the first location (A) based on the determined value of
the flow rate parameter.
12. A ventilation system comprising a first pressure sensor (2) for measuring air pressure
in a first location (A) of the ventilation system, wherein the ventilation system
is configured to be operated according to the method of any of the preceding claims.
13. A valve (1) for a ventilation system for use in the method according to any of claims
1-11, the valve (1) being connectable to a ventilation duct (6) conveying incoming
air into a space (4A, 4B, 4C) ventilated by the ventilation system or out of a space
(4A, 4B, 4C) ventilated by the ventilation system, the valve (1) comprising
- a valve member (10) that is moveable for adjusting the opening degree of the valve (1) and thereby the air flow through the valve (1),
- an electrical actuator (11) for moving the valve member (10),
- control means (14) for controlling the operation of the electrical actuator (11), and
- a first pressure sensor (2) located such that when the valve (1) is connected to a ventilation duct (6), the pressure of the incoming air or extracted air conveyed in the ventilation duct (6) can be measured by means of the first pressure sensor (2).
14. A valve (1) according to claim 13, wherein the valve (1) comprises a second pressure
sensor (3) located such that when the valve (1) is connected to a ventilation duct
(6), the pressure in the space (4A, 4B, 4C) ventilated by the ventilation system can
be measured by means of the second pressure sensor (3).
15. A valve (1) according to claim 13 or 14, wherein the valve (1) comprises communication
means (17) configured to transmit data based on pressure measurements conducted by
means of the first pressure sensor (2) and/or an optional second pressure sensor (3).