Method for predictive maintenance of a boiler heat exchanger

Abstract

The object of the present invention is a method for checking the efficiency status of a secondary exchanger (20) of a gas boiler (1), comprising at least the following sequential steps: - Step 1: when the boiler (1) is in a "sanitary water heating" operating mode, acquiring the maximum values of the temperature of the sanitary water (T.setpoint) and of the flow rate of the heat transfer fluid (Q.RAW) in an observation time window (T.analysis); - Step 2: reprocessing the more coherent flow rate signal (Q.DHW) by linear regression thereof to obtain flow rate signals (Q.REG... Q.REG.prox) in the observation time window (T.analysis) and in a future time window (T.prox); - Step 3: calculating the values of the maximum deliverable power (P.MAX... P.MAX.prox) of the boiler (1) in the observation time windows (T.analysis, T.prox); - Step 4: calculating two respective average values (Q.REG.med, Q.REG.prox.med) of the flow rate signals (Q.REG... Q.REG.prox) obtained by the Step 2 and two respective average values (P.MAX.med, P.MAX.prox.med) of the maximum power signals (P.MAX... P.MAX.prox) obtained by the Step 3; - comparing the two average values (Q.REG.med, Q.REG.prox.med) of the flow rate with a threshold value (Q.T) of the flow rate and the two average values (P.MAX.med, P.MAX.prox.med) of the maximum power with a threshold value (P.T) of the power.

Description

[0001] The purpose of this invention is to provide a predictive control method for monitoring the efficiency status of a heat exchanger in a gas-fired boiler, aiming to promptly report the need for maintenance intervention in the event of an excessive decline in the efficiency of such an exchanger.

[0002] More specifically, the method presented in this paper aims to monitor the blockage status of the secondary heat exchanger (primary side) of a gas-fired boiler over time.

[0003] Like other components of the boiler's primary circuit, the secondary heat exchanger can also be subject to the formation of scale deposits and blockages caused by the precipitation of salts, impurities, and solid compounds carried by the heat transfer fluids circulating at high temperatures in the system.

[0004] Over time, the aforementioned formations lead to increased surface frictional resistance in the delivery and return pipes, and reduced heat exchange efficiency inside the secondary heat exchanger. Therefore, it is necessary to periodically check its functional status and maintain it before it fails or causes more serious damage to other components of the boiler.

[0005] The purpose of this invention is to eliminate this type of drawback by providing a control method for monitoring the efficiency status of a boiler's secondary exchanger.

[0006] At least for some variations of the invention, another object of the invention is to provide a method of operation using devices commonly found in typical gas boilers, without resorting to additional equipment or external components.

[0007] At least in some variations of the invention, a further object of the invention is to report the need for maintenance of the secondary switch by providing a timely warning system that is useful to the user.

[0008] At least for some variations of the invention, another objective of the invention is to warn users that the boiler may fail to reach the set temperature or may become clogged due to overheating, due to a decrease in the efficiency of the secondary exchanger.

[0009] According to the independent claim, these and other objectives, which will become clear hereinafter, are achieved by a control method for monitoring the efficiency status of a secondary exchanger on the primary side of a gas-fired boiler. Other objectives may also be achieved by additional features of the dependent claims.

[0010] Further features of the invention will be better highlighted by the following description of preferred embodiments according to the patent claims, and are shown only by way of non-limiting example in the accompanying drawings, in which:

[0011] - Figure 1 A typical hydraulic diagram of a gas-fired boiler is shown, in which the control method according to the present invention can be implemented;

[0012] - Figure 2.A An example is shown of a signal of the flow rate of the heat transfer fluid in the boiler, as measured during the initial steps of the control method according to the invention.

[0013] - Figure 2.B and Figure 2.C An example is shown of a signal indicating the flow rate of the heat transfer fluid in a boiler, as measured and / or processed in an intermediate step of the control method according to the invention.

[0014] - Figure 3.A and Figure 3.B Comparison diagrams are shown between the flow rate signal of the heat transfer fluid and the power signal that can be delivered by the boiler, as processed in the final step of the control method according to the invention and representing the generation conditions of the first type of notification;

[0015] - Figure 4.A and Figure 4.B It shows Figure 3.A and Figure 3.B A comparison diagram, wherein schematic indications represent the conditions of a first type of notification according to the control method of the present invention;

[0016] - Figure 5.A and Figure 5.B Comparison diagrams are shown between the flow rate signal of the heat transfer fluid, which is processed in the final step of the control method according to the invention and represents the generation conditions of the second type of notification, and the power signal that can be delivered by the boiler.

[0017] - Figure 6.A and Figure 6.B It shows Figure 5.A and Figure 5.B The comparison diagram illustrates the conditions of a second type of notification according to the control method of the present invention.

[0018] It should be noted that this Figures 3.A to 6.B and Figure 2.A , Figure 2.B and Figure 2.C They are unrelated and not sequential; they involve different execution phases of the method.

[0019] Preferred variations of the control method according to the invention and the characteristics of the relative boilers implementing this method will now be described using the reference numerals included in the accompanying drawings.

[0020] With the help of Figure 1 It is useful to quickly outline the components of the gas boiler 1, at least to quickly outline the components necessary for the understanding of the invention.

[0021] Boiler 1 includes a primary circuit 100 and a secondary circuit 200, which are equipped with corresponding heat exchangers, namely a primary heat exchanger 10 (hereinafter referred to as "primary exchanger 10") for heat transfer fluid and a secondary heat exchanger 20 (hereinafter referred to as "secondary exchanger 20") for domestic water.

[0022] Reference numeral 4 indicates a gas valve that regulates the gas flowing in through the gas inlet C to supply the gas to the burner 3 (located in the combustion chamber 2 housing the primary exchanger 10) after mixing with the combustion air regulated by the blower 5.

[0023] Except for one switch 10 (in Figure 1 In the example of the variant, in addition to the primary switch (which includes a spiral coil switch), the primary loop 100 also includes:

[0024] - Return pipe 11, which leads the heat transfer fluid from the heating element (not shown) of the system to the primary exchanger 10 through inlet E, where the fluid is subjected to the hot combustion flue gas generated by the aforementioned burner 3;

[0025] - A circulation pump 30 (hereinafter referred to as "pump 30") is preferably located on the return pipe 11;

[0026] - A heat transfer fluid supply pipe 12, which is delivered from the primary heat exchanger 10 to the heating element of the heating system (hereinafter referred to as the "system") via outlet A.

[0027] When boiler 1 is operating in the "space heating" mode, the path of the heat transfer fluid is as follows: it enters the primary loop 100 via inlet E, passes through the return pipe 11 and through the burner 3, and is delivered to the heating element of the system via the supply pipe 12 and outlet A.

[0028] On the other hand, when the boiler 1 is operating in the "domestic water heating" operation mode, the heat transfer fluid (via the inlet pipe 21 originating from the supply pipe 12) is directed toward the secondary exchanger 20, and then the heat transfer fluid leaves the secondary exchanger by means of the return pipe 22 so as to flow back to the return pipe 11 of the primary loop 100.

[0029] In addition to the aforementioned secondary exchanger 20 (in Figure 1 In a variant example, in addition to the secondary exchanger (which includes a plate exchanger), the secondary circuit 200 further includes a supply pipe 23 for cold water entering the secondary exchanger 20 via inlet D, the cold water being heated by the aforementioned inlet pipe 21 and return pipe 22 of the primary circuit 100 to produce hot sanitary water to be delivered to the user via delivery pipe 24 and outlet B.

[0030] The switching of boiler 1 from "space heating" mode to "domestic water heating" mode occurs via a three-way diverting valve 40, which is adapted to direct the heat transfer fluid through outlet A toward the heating element of the system (thus bypassing the secondary exchanger 20), or vice versa, toward the secondary exchanger 20 to produce hot domestic water to be delivered to the user via outlet B.

[0031] 70 schematically indicates the control unit of boiler 1, hereinafter abbreviated as "control unit 70".

[0032] In the above system, the components of boiler 1 that are at greatest risk of efficiency loss due to the precipitation of impurities and the formation of scale deposits are those through which the high-temperature heat transfer fluid flows. Specifically, these are the pump 30, the primary exchanger 10, the primary side of the secondary exchanger 20 (i.e., the side connected to the inlet pipe 21 and return pipe 22 of the primary circuit 100), and the secondary side of the secondary exchanger (i.e., the side connected to the supply pipe 23 and delivery pipe 24 of the secondary circuit 200).

[0033] Patent EP4278135, owned by the same applicant as this application, describes a control method for monitoring the efficiency state of such a component, which uses the flow rate value of the heat transfer fluid circulating in the primary loop 100 as a signal representing efficiency loss.

[0034] The present invention described herein proposes a control method for monitoring a secondary exchanger 20 (hereinafter collectively referred to as "secondary exchanger 20") on the primary side of the secondary exchanger 20 using a predictive model. Under certain operating conditions, the flow rate of the heat transfer fluid is used as an input signal, and the temperature of the hot sanitary water requested by the user is used. The predictive model is able to return a prediction of the probability of efficiency loss of the secondary exchanger 20 within a future time window.

[0035] According to a preferred variant of the invention, the values ​​of the flow rate of the heat transfer fluid, the temperature of the hot sanitary water requested by the user, further parameters to be described, their reprocessing, and the subsequent prediction of the output of the efficiency state of the secondary exchanger 20 are all handled by the control unit 70, which is generally adapted to manage the general functions of the boiler 1 and its components, and can communicate bidirectionally with the boiler and its components according to the most suitable method, such as via wired and / or wireless connections (e.g., WLAN, ZigBee, Bluetooth protocols, etc.).

[0036] However, for the purposes of this invention, nothing prevents all or part of the data processing apparatus used to operate the methods of this invention from being managed by an additional control unit or executed on a device outside the heating system: by way of non-limiting example, such additional apparatus may include smartphones, tablets, PDAs, remote servers (e.g., in the cloud), provided that they are properly configured with software and / or applications suitable for and compatible with the purposes of this invention.

[0037] For the sake of brevity, the description of the invention below shall assume that all processing capacity is in the control unit 70 of the boiler 1, but more generally, “control unit” 70 shall refer to the collection of all data processing elements necessary to implement the method according to the invention, whether these data processing elements are combined or distributed in multiple subsets.

[0038] This control unit 70 is advantageously configured to cooperate with the following:

[0039] - A device for acquiring and / or receiving input data for the method of the present invention.

[0040] - A means for calculating and processing the input data, the means being adapted to provide output data and / or information aimed at determining the efficiency state of the secondary exchange 20.

[0041] - A memory device for at least temporarily storing the input data and / or output data.

[0042] - A means for transmitting the output data and / or information to a display and notification interface, which may be composed of a typical HMI interface integrated in the boiler 1, the system and / or the aforementioned external devices.

[0043] The control method will now be described in detail with reference to the sequential steps that constitute the control method.

[0044] Step 1: Extract the flow rate and temperature of the sanitation water.

[0045] In step 1, the method of the present invention considers the maximum flow rate Q.RAW of the heat transfer fluid circulating in the primary loop 100 of boiler 1 after the user requests domestic water, i.e., when the boiler is in the "domestic water heating" mode.

[0046] More precisely, this maximum flow rate value Q.RAW is measured or calculated over consecutive time intervals T.cons (e.g., each interval is 60 minutes) within an observation time window T.analysis corresponding to a given number of days.

[0047] For the sake of brevity, but without any intention of limitation, it should be assumed in the following text that this observation time window T.analysis is equal to 14 days.

[0048] The flow rate value Q.RAW is realized within the time interval T.cons under the following conditions:

[0049] - When there is a demand for sanitary water, pump 30 performs circulation at maximum speed, and control unit 70 stores the maximum flow rate value Q.RAW (under this condition, the flow rate of the heat transfer fluid can also be defined as "post-circulation flow rate").

[0050] - If the user does not request sanitary water, the control unit 70 will store the flow rate value Q.RAW obtained at the last time interval T.cons during which water was used in memory.

[0051] The flow rate value Q.RAW can be measured using a known device (such as a flow switch or other type of flow rate sensor (not shown)) present in the primary loop 100, which is capable of transmitting a signal representing the same flow rate to the control unit 70.

[0052] Alternatively or additionally, the flow rate value Q.RAW can be determined indirectly by sensor devices that detect and report a set of one or more physical quantities (e.g., the physical quantities indicated below), from which the same flow rate can be calculated.

[0053] However, according to a preferred variant of the invention, the flow rate value Q.RAW is provided by a signal emitted by the so-called smart pump 30, without the need for a dedicated flow rate sensor; in other words, the smart pump is equipped with a sensor device that is at least sufficient to infer its flow rate Q.RAW by calculating and / or querying a pre-stored data table.

[0054] As is well known, this type of intelligent pump is a circulator type capable of bidirectionally exchanging information with the control unit 70 of the boiler 1. In addition to informing the pump 30 of its operating speed, the control unit can also query the pump to receive specific information about its status, such as:

[0055] - revolutions,

[0056] - The electrical power absorbed,

[0057] - Operating status (working, standby, error).

[0058] - And precisely, the flow rate Q.RAW processed from the previous parameters.

[0059] According to a preferred variant of the invention, this flow rate value Q.RAW is an indirectly obtained quantity, calculated based on the electrical power absorption and revolutions of the pump 30, detected by the pump and transmitted to the control unit 70 of the boiler 1.

[0060] However, as mentioned, it should be understood that, in order to implement the method described herein, when boiler 1 includes a classic type pump 30 instead of a smart pump, the flow rate value Q.RAW can also be obtained by a specially designed flow rate sensor.

[0061] Figure 2.A The graph shows an example of the flow rate value Q.RAW obtained within the observation time window T.analysis; in this graph, compared with the following Figure 2.B and Figure 2.C Similarly, the flow rate is indicated on the vertical axis, while time is represented on the horizontal axis.

[0062] Once these flow rate values ​​Q.RAW have been obtained, they are discarded from the limiting and / or anomalous conditions and a resampling step is performed to obtain the flow rate signal Q.DHW (see [link to relevant documentation]). Figure 2.C For the purposes of this invention, the signal is more coherent and effective.

[0063] By way of non-limiting example, this method does not take into account the oscillations of the flow velocity value Q.RAW, particularly its depth and sudden drops or increases, thereby excluding flow velocity values ​​falling into the following categories from the calculation of the acquired flow velocity value Q.RAW:

[0064] - A flow rate of 0 l / h indicates a measurement error.

[0065] - The flow rate value before the measured flow rate value Q.RAW (which makes the value Q.RAW exceed 1,000 l / h) is at least 200 l / h higher than the flow rate value obtained in the previous time interval T.cons: This sudden increase in flow rate is likely due to maintenance intervention on the exchanger 20, obviously cleaned or replaced by a technician, and therefore the method according to the invention does not take into account the entire stretch of the flow rate value before such measurement.

[0066] exist Figure 2.B and Figure 2.C In the figure, reference numeral Q.RAW.0 shows an example of the measurement of flow rate values ​​Q.RAW, which fall within the just-mentioned case and are therefore removed from the series of values ​​Q.RAW considered in the control method according to the invention.

[0067] Preferably, the method also verifies whether there is a sufficient amount of flow rate value Q.RAW measured within the observation time window T.analysis, for example, equal to at least 5 days of data, of which 4 days are during the last week.

[0068] In order to obtain Figure 2.C The method further provides, in step 1, resampling the flow velocity values ​​Q.RAW that have been measured in a specific continuous time interval T.cons, i.e., measuring the flow velocity Q.RAW again in a time interval T.cons2 that is at least twice the time interval T.cons, and calculating the average of these values: this sampling activity is useful for minimizing possible oscillations in the measurement and obtaining a more uniform and coherent flow velocity signal Q.DHW.

[0069] Preferably, this time interval T.cons2 is four times the time interval T.cons, and therefore, the average value of the flow rate value Q.RAW is the average of the four measurements.

[0070] In summary, obtain after at least the following activities Figure 2.C The flow velocity signal Q.DHW depicted in the image:

[0071] - Measure the maximum flow velocity value Q.RAW within consecutive time intervals T.cons within the observation time window T.analysis.

[0072] - Eliminate the value Q.RAW.0 from the maximum flow rate value Q.RAW.

[0073] - If the new value Q.RAW is higher than 1,000 l / h, eliminate the previous value Q.RAW.0 that is at least 200 l / h higher than the flow rate value obtained in the previous time interval T.cons.

[0074] - Resample the maximum flow rate value Q.RAW within a time period T.cons2 that is at least twice the continuous time interval T.cons, and calculate its average value within such a time period T.cons2.

[0075] In step 1 of the method according to the invention, in addition to the flow rate signal Q.DWH obtained as described above, the control unit 70 also acquires a signal T.setpoint indicating the temperature of the sanitary water requested by the user.

[0076] This signal, T.setpoint, is manually set by the user and is typically between 35°C and 60°C. Therefore, it usually remains constant within the observation time window, T.analysis, and is thus not processed during the steps of the method of the present invention.

[0077] If the user modifies the previous setting value of T.setpoint during the observation time window T.analysis, in such step 1, the control unit 7 stores the updated value without ever reprocessing it.

[0078] Step 2: Regression is performed on the past and future flow velocities.

[0079] Linear regression is performed on the flow velocity signal Q.DHW obtained at the end of step 1 to obtain a straight line signal Q.REG, which represents the flow velocity value within the observation time window T.analysis and the flow velocity value Q.REG.prox within the future time window T.prox.

[0080] By way of a non-restrictive example, this future observation time window T.prox is equal to 5 days.

[0081] In other words, by using this linear regression, the overall trend Q.REG of the flow velocity signal Q.DHW is obtained within the observation time window T.analysis, and coherently with this overall trend Q.REG, an estimate of the trend Q.REG.prox in the future time window T.prox is also obtained.

[0082] Figure 3.A and Figure 5.A Two examples of flow rate signals “Q.REG…Q.REG.prox” obtained after step 2 of this method are shown (it should be noted that...) Figure 3.A and Figure 5.A and Figure 2.C The signals Q.DHW are unrelated and do not have a continuous relationship because they involve different execution phases of the method.

[0083] The reference numeral T.0 in the attached figure indicates a vertical line corresponding to the current execution date of the method, which separates the following:

[0084] - Time window T.analysis, including the straight line Q.REG obtained from the linear regression of the flow velocity signal Q.DHW as obtained at the end of step 1 of this method.

[0085] - and the future time window T.prox, including the straight line Q.REG.prox, which represents the flow rate signal in the days following date T.0 (e.g., 5 days) and at the end of date T.0.prox.

[0086] exist Figure 3.AIn the example, the flow rate signal “Q.REG…Q.REG.prox” takes a value between approximately 1,050 l / h (at the extreme value represented by the beginning of the time window T.analysis) and approximately 800 l / h (at the extreme value represented by the end of the future time window T.prox).

[0087] However, in Figure 5.A In the example, the flow rate signal "Q.REG…Q.REG.prox" takes a value between approximately 600 l / h (at the extreme value represented by the beginning of the time window T.analysis) and approximately 300 l / h (at the extreme value represented by the end of the future time window T.prox).

[0088] Step 3: Calculate the maximum output power of the boiler.

[0089] Starting from the flow rate signal “Q.REG…Q.REG.prox” obtained in step 2, the maximum power “P.MAX…P.MAX.prox” that can be delivered by boiler 1 is calculated according to the method of the present invention, taking into account the specific flow rate “Q.REG…Q.REG.prox” and the hot sanitary water temperature T.setpoint value requested by the user.

[0090] Using the well-known heat transfer formula:

[0091] P.MAX…P.MAX.prox = Q cp (T.max – T.setpoint)

[0092] In the formula:

[0093] Q = the flow rate value "Q.REG … Q.REG.prox" obtained through step 2;

[0094] cp = the specific heat of water (in this case, the heat transfer fluid);

[0095] T.max = the maximum temperature of the heat transfer fluid. When this maximum temperature is exceeded, boiler 1 enters a shut-down state for safety reasons (preferably, this value T.max is carefully reduced by a few degrees Celsius compared to the actual nominal maximum value).

[0096] T.setpoint = The temperature of the hot water requested by the user;

[0097] This method calculates the maximum power “P.MAX…P.MAX.prox” that can be delivered by boiler 1, that is, the power value that boiler 1 can reach before entering lockout, which is caused by the excessively high temperature of the heat transfer fluid due to the need to reach the temperature T.setpoint of the hot sanitary water requested by the user.

[0098] Therefore, with the same flow rate value "Q.REG…Q.REG.prox", when the value of T.setpoint is lower, the maximum power "P.MAX…P.MAX.prox" that can be delivered by boiler 1 is higher, and vice versa.

[0099] For example, assuming the flow rate value “Q.REG…Q.REG.prox” is 800 l / h, and the user requests a hot sanitary water temperature T.setpoint of 45°C, then the maximum power value “P.MAX…P.MAX.prox” is approximately 35 kW.

[0100] However, if T.setpoint equals 55°C, the maximum power value “P.MAX…P.MAX.prox” is approximately 26kW. This is precisely because the heat transfer fluid will have to operate at a higher temperature, allowing boiler 1 to reach the maximum T.setpoint value for the hot sanitary water requested by the user, thereby increasing the risk of shutdown even at lower power values.

[0101] Through this calculation, a linear signal P.MAX is obtained, representing the maximum power value within the observation time window T.analysis and the maximum power value P.MAX.prox within the future time window T.prox.

[0102] Figure 3.B and Figure 5.B Two examples of the maximum power signals P.MAX and P.MAX.prox obtained after step 3 of this method are shown (it should be noted that...). Figure 3.B and Figure 5.B and Figure 2.C The signals Q.DHW are unrelated and do not have a continuous relationship because they involve different execution phases of the method.

[0103] Similar to what we saw in step 2, the reference numeral T.0 indicates a vertical line corresponding to the current execution date of the method, which separates the following:

[0104] - Time window T.analysis, including the straight line P.MAX derived by reprocessing the velocity signal Q.REG according to the heat transfer formula above.

[0105] - and the future time window T.prox, including the straight line P.MAX.prox, which is obtained by reprocessing the flow rate signal Q.REG.prox according to the heat transfer formula above, and represents the maximum power signal that boiler 1 can deliver a few days (e.g., 5 days) after date T.0 and at the end of date T.0.prox.

[0106] Assuming boiler 1 has a nominal power of 30 kW and considering a value T.setpoint (the temperature of the hot domestic water requested by the user) of 40°C, based on... Figure 3.A By applying the flow rate signal “Q.REG…Q.REG.prox” to the heat transfer formula described above, hypothetical values ​​for the maximum power “P.MAX…P.MAX.prox” will be obtained. These hypothetical values ​​are between the following:

[0107] - When the flow rate signal “Q.REG…Q.REG.prox” has a value of about 1,050 l / h, that is, at the extreme value indicated by the start of the time window T.analysis, it is about 53 kW (hypothetical value and obviously not actually available from boiler 1, which has a given nominal power of 30 kW).

[0108] - And when the flow rate signal “Q.REG…Q.REG.prox” has a value of about 800 l / h, that is, at the extreme value represented by the end of the future time window T.prox, about 40 kW (which is also a hypothetical value that boiler 1 cannot achieve, with a nominal power of 30 kW).

[0109] However, considering that in the example discussed, boiler 1 has a nominal power of 30 kW, Figure 3.B In this context, the maximum power signal “P.MAX…P.MAX.prox” is taken as a constant value exactly equal to 30 kW.

[0110] By applying this step 3 Figure 5.B The flow rate signal “Q.REG…Q.REG.prox” shown, always at a constant value T.setpoint equal to 40°C, yields the maximum power “P.MAX…P.MAX.prox” that can be delivered by boiler 1, and these values ​​are between the following:

[0111] - When the flow rate signal “Q.REG…Q.REG.prox” has a value of approximately 600 l / h, that is, at the extreme value represented by the beginning of the time window T.analysis, approximately 30 kW,

[0112] - And when the flow rate signal “Q.REG…Q.REG.prox” has a value of approximately 300 l / h, i.e., at the extreme value indicated by the end of the future time window (T.prox), approximately 15 kW,

[0113] like Figure 5.B As shown in the example.

[0114] In other words, for the purposes of the method according to the invention, it can be assumed that, considering a specific flow rate "Q.REG…Q.REG.prox" and the temperature T.setpoint of the sanitary water, the hypothetical maximum power values ​​"P.MAX…P.MAX.prox" derived by applying the above heat transfer formula are all higher than the nominal power of boiler 1 (e.g., ...). Figure 3.B In the case of the graphical example in the figure, the maximum power signal “P.MAX…P.MAX.prox” can be graphically approximated as a straight line of constant value and is substantially equal to the nominal power.

[0115] According to Figure 5.B For example, if by applying the heat transfer formula and according to the specific flow rate "Q.REG…Q.REG.prox" and the temperature T.setpoint value of the sanitary water, at least some of these maximum power values ​​"P.MAX…P.MAX.prox" take values ​​lower than the nominal power of boiler 1, then the maximum power signal "P.MAX…P.MAX.prox" takes a linear shape with a non-constant trend in the graph.

[0116] Step 4: The flow rate and maximum deliverable power signals are compared with the corresponding limit thresholds, and a warning notification may be issued.

[0117] Step 4 of the method according to the invention provides: calculating two average values, Q.REG.med and Q.REG.prox.med, of the flow rate signal “Q.REG…Q.REG.prox” obtained in step 2.

[0118] The values ​​Q.REG.med and Q.REG.prox.med are calculated by averaging the flow velocity values ​​“Q.REG…Q.REG.prox” within two time periods T.med and T.prox.med, which are respectively composed of a portion of the time window T.analysis and a portion of the future time window T.analysis.

[0119] Preferably, the two time periods T.med and T.prox.med have a duration of 2 days and include the date immediately preceding the end of the time window T.analysis and the future time window T.prox: in other words, the time period T.med ends on the date T.0, and the time period T.prox.med ends on the date T.0.prox.

[0120] More specifically, the two values ​​Q.REG.med and Q.REG.prox.med are calculated by considering the following:

[0121] - Average the value of the flow velocity signal Q.REG within the time period T.med to obtain the value Q.REG.med;

[0122] - Average the value of the flow velocity signal Q.REG.prox within the time period T.prox.med to obtain the value Q.REG.prox.med.

[0123] According to the method of the invention, when at least one of the two values ​​Q.REG.med and Q.REG.prox.med is below the flow rate threshold QT, a first type of notification is issued indicating that the efficiency state of the secondary exchanger 20 is likely to decline or that such a state may occur within a future time window T.prox.

[0124] This threshold QT is preset by the manufacturer and / or technicians based on laboratory tests and / or periodic monitoring during actual use of boiler 1 and / or other factors inferred by those skilled in the art from the specific type of boiler 1 and reference systems.

[0125] In the example in the attached figure, this threshold QT for the flow rate is equal to 900 l / h. When the value is below this threshold, it can be presumed that the secondary exchanger 20 is deteriorating due to the formation of scale deposits and blockages.

[0126] However, the threshold QT can be modified by storing the new value in the control unit 70.

[0127] Step 4 of the method according to the invention further provides: calculating two average values, P.MAX.med and P.MAX.prox.med, of the maximum power signal “P.MAX … P.MAX.pro” that can be delivered by boiler 1 as obtained in step 3.

[0128] The values ​​P.MAX.med and P.MAX.prox.med are calculated by averaging the power values ​​“P.MAX…P.MAX.prox” within the two time periods T.med and T.prox.med.

[0129] More specifically, the two values ​​P.MAX.med and P.MAX.prox.med are calculated by considering the following:

[0130] - Average the value of the maximum power signal P.MAX within the time period T.med to obtain the value P.MAX.med;

[0131] - Average the value of the maximum power signal P.MAX.prox within the time period T.prox.med to obtain the value P.MAX.prox.med.

[0132] According to the method of the invention, if at least one of the two values ​​Q.REG.med and Q.REG.prox.med is below the flow rate threshold QT, and at the same time that at least one of the maximum power values ​​P.MAX.med and P.MAX.prox.med is also below the power threshold PT, a second type of notification is issued, indicating that the efficiency of the secondary exchanger 20 has significantly decreased, or that this condition may occur within a future time window T.pro, causing the boiler 1 to fail to reach the temperature value T.setpoint of the domestic hot water requested by the user, or causing the boiler 1 to enter a lockout due to overheating.

[0133] This threshold PT is preset by the manufacturer and / or technicians based on laboratory tests and / or periodic monitoring during actual use of boiler 1 and / or other factors inferred by those skilled in the art from the specific type of boiler 1 and reference systems.

[0134] In the example in the attached figure, this power threshold PT is equal to 80% of the nominal power of boiler 1: for example, if boiler 1 has a nominal power of 30 kW, the power threshold PT is equal to 24 kW.

[0135] However, the threshold PT can be modified by storing the new value in the control unit 70.

[0136] Figure 4.A / 4.B shows an example of the flow rate signal “Q.REG…Q.REG.prox” and the maximum power signal “P.MAX … P.MAX.prox” that generate the first type of notification, because:

[0137] - The following condition was confirmed: at least one of the values ​​between Q.REG.med and Q.REG.prox.med (in this case both) is below the flow rate threshold QT;

[0138] However, the following condition will not occur: at least one of the values ​​P.MAX.med and P.MAX.prox.med is below the threshold PT.

[0139] and Figure 6.A / 6.B shows an example of the flow rate signal “Q.REG…Q.REG.prox” and the maximum power signal “P.MAX … P.MAX.prox” that generate the second type of notification, because:

[0140] - The following condition was confirmed: at least one of the values ​​between Q.REG.med and Q.REG.prox.med (in this case both) is below the flow rate threshold QT;

[0141] - And it was also confirmed that at least one of the values ​​between P.MAX.med and P.MAX.prox.med (in this case both) is below the threshold PT.

[0142] Preferably, the method according to the invention also provides a third type of notification, which can be issued if the first or second type of production conditions are not met: that is, this third type of notification indicates the fact that the efficiency state of the secondary exchanger 20 (or will be in a future time window T.prox) is high enough to guarantee that the values ​​Q.REG.med and Q.REG.prox.med are not lower than the flow rate threshold QT, and the values ​​P.MAX.med and P.MAX.prox.med are also not lower than the power threshold PT.

[0143] The first and second types of notifications (and, where provided, a third type of notification) preferably consist of visual and / or auditory signals perceptible to the user, provided by the control unit 70 to the boiler 1's display and / or to the user's connectivity services and / or sent to the auxiliary center via email.

[0144] More generally, this type of notification can be visual and / or auditory, for example, displayed on the interface of boiler 1 and / or the interface of possible external devices connected thereto, and / or sent by written means, email, SMS, etc. to the same external devices that can be directly used by the user, or sent to a remote server that can be accessed by the support center.

[0145] It is clear from the above description how the method of the present invention can achieve the object of interest, proving to be particularly effective in timely signaling the secondary exchanger 20 to the possibility of efficiency degradation and the resulting loss of heat exchange capacity.

[0146] In this way, users are prevented from facing critical situations, thereby avoiding major problems caused by the blockage of the secondary exchanger 20 to other components of the same exchanger and primary circuit 100, and preventing the boiler from locking up due to excessive temperature and / or failing to reach the user-set temperature value T.setpoint for hot domestic water.

[0147] In summary, the method of the present invention uses only the value of the flow rate Q.RAW of the heat transfer fluid and the value of the temperature T.setpoint of the sanitary water requested by the user as input data in order to provide a prediction in the output of the probability of the secondary exchanger 20 of boiler 1 suffering efficiency loss within a future time window T.prox.

[0148] For this purpose, the method provides:

[0149] - Step 1, in which the following occurs:

[0150] - Obtain the flow rate Q.RAW of the heat transfer fluid and the temperature T.setpoint of the sanitary water within the observation time window T.analysis.

[0151] - And reprocess the flow rate value Q.RAW to obtain a more coherent flow rate signal Q.DHW;

[0152] - Step 2, in which the following occurs:

[0153] - Perform linear regression on the flow velocity signal Q.RAW to obtain the flow velocity signal Q.REG…Q.REG.prox within the observation time window T.analysis and the future time window T.prox;

[0154] - Step 3, in which the following occurs:

[0155] - Considering the flow velocity Q.REG…Q.REG.prox and the temperature T.setpoint signal, calculate the maximum power P.MAX…P.MAX.prox that can be delivered by boiler 1;

[0156] - Step 4, in which the following occurs:

[0157] - Calculate the average values ​​of the flow velocity signals Q.REG…Q.REG.prox within two time periods, T.med and T.med.prox, for a portion of the observation time window T.analysis and a portion of the future time window T.prox.

[0158] - Calculate the average values ​​of the maximum power signals P.MAX…P.MAX.prox within the time periods T.med and T.med.prox, namely P.MAX.med and P.MAX.prox.med.

[0159] - Compare the average values ​​Q.REG.med and Q.REG.prox.med with the flow rate threshold QT.

[0160] - Compare the average values ​​P.MAX.med and P.MAX.prox.med with the power threshold PT.

[0161] - A first-type notification is issued when at least one of the average values ​​Q.REG.med and Q.REG.prox.med is below the flow rate threshold QT.

[0162] A second type of notification is generated when at least one of the average values ​​between Q.REG.med and Q.REG.prox.med is below the flow rate threshold QT and at the same time, at least one of the average values ​​between P.MAX.med and P.MAX.prox.med is below the power threshold PT.

[0163] - A third type of notification can be issued when both the average values ​​P.MAX.med and P.MAX.prox.med are above the power threshold PT and both the average values ​​Q.REG.med and Q.REG.prox.med are above the flow rate threshold QT.

Claims

1. A method for checking the efficiency status of a secondary heat exchanger (20) of a gas-fired boiler (1), said boiler comprising at least: - A primary loop (100) having a primary exchanger (10) for heating a heat transfer fluid intended to power a heating element for space heating. - Secondary circuit (200), the secondary circuit having a secondary exchanger (20) for heating sanitary water intended for use by users. - Circulation pump (30) - A three-way diverting valve (40), the three-way diverting valve being adapted to switch the operation of the boiler (1) from a "space heating" operation mode to a "domestic water heating" operation mode, and vice versa. - A sensor device adapted to measure the flow rate (Q.RAW) of the heat transfer fluid. - Control unit (70), the control unit being adapted to manage the steps of the method and to acquire and process the value of the flow rate (Q.RAW) and the temperature value (T.setpoint) of the sanitary water intended for use by the user. The method is characterized in that it comprises at least the following steps in sequence: - Step 1: When the boiler (1) is in the "Household water heating" operation mode, obtain the maximum value of the temperature value (T.setpoint) of the household water and the maximum value of the flow rate (Q.RAW) of the heat transfer fluid, and the acquisition is carried out in a continuous time interval (T.cons) within the observation time window (T.analysis) corresponding to a given number of days before the date (T.0) of implementing the method; - The maximum flow rate value (Q.RAW) is reprocessed to remove it from extreme and / or abnormal conditions, thereby obtaining a more consistent flow rate signal (Q.DHW). - Step 2: Reprocess the more consistent flow rate signal (Q.DHW) by performing linear regression to obtain flow rate signals (Q.REG…Q.REG.prox), which represent the flow rate values ​​(Q.REG) within the observation time window (T.analysis) and the flow rate values ​​(Q.REG.prox) within a future time window (T.prox), the future time window corresponding to a given number of days after the date (T.0) on which the method is implemented; - Step 3: Based on the flow rate signal (Q.REG…Q.REG.prox) obtained through Step 2 and the temperature value (T.setpoint) of the sanitary water, calculate the maximum output power (P.MAX…P.MAX.prox) that the boiler (1) can deliver within the observation time window (T.analysis, T.prox); - Step 4: Within a portion (T.med, T.med.prox) of each of the observation time windows (T.analysis, T.prox), calculate two corresponding average values ​​(Q.REG.med, Q.REG.prox.med) of the flow velocity signal (Q.REG…Q.REG.prox) obtained in step 2 and two corresponding average values ​​(P.MAX.med, P.MAX.prox.med) of the maximum power signal (P.MAX…P.MAX.prox) obtained in step 3; - Compare the two average values ​​of the flow rate (Q.REG.med, Q.REG.prox.med) with the threshold value of the flow rate (QT), and compare the two average values ​​of the maximum power (P.MAX.med, P.MAX.prox.med) with the threshold value of the power (PT); - If at least one of the two average values ​​of the flow rate (Q.REG.med, Q.REG.prox.med) is below the threshold (QT) of the flow rate, a first type of notification is issued, indicating that the efficiency state of the secondary exchange (20) may decline, or such a condition may occur within the future time window (T.prox), or - If at least one of the two average values ​​of the flow rate (Q.REG.med, Q.REG.prox.med) is lower than the threshold (QT) of the flow rate, and at the same time, at least one of the two average values ​​of the maximum power (P.MAX.med, P.MAX.prox.med) is lower than the threshold (PT) of the power, a second type of notification is issued, indicating that the efficiency state of the secondary exchanger (20) has significantly decreased, or that such a condition may occur within the future time window (T.prox).

2. The method according to the preceding claim, Its features are, The method further includes the following steps: - Issue a third type of notification stating that if both average values ​​of the flow rate (Q.REG.med, Q.REG.prox.med) are higher than the threshold (QT) of the flow rate and both average values ​​of the maximum power (P.MAX.med, P.MAX.prox.med) are higher than the threshold (PT) of the power, then the efficiency state of the secondary exchanger (20) remains high and even in the future time window (T.prox).

3. The method according to any of the preceding claims, Its features are, The notification is sent to the technical support center and / or to the user via the control unit (70) that provides the notification transmission and display device and / or the control unit (70) that cooperates with the notification transmission and display device.

4. The method according to any of the preceding claims, Its features are, In step 1, reprocessing the maximum flow rate value (Q.RAW) to obtain a more consistent flow rate signal (Q.DHW) includes the following activities: - Eliminate the value equal to 0 l / h (Q.RAW.0) from the maximum flow rate value (Q.RAW). - If the new value (Q.RAW) is greater than 1,000 l / h, the value (Q.RAW.0) before the value (Q.RAW) that is at least 200 l / h higher than the value measured in the previous consecutive time interval (T.cons) is removed from the maximum flow rate value (Q.RAW). - Resample the maximum flow rate value (Q.RAW) over a time period (T.cons2) that is at least twice the continuous time interval (T.cons), and calculate its average value over such a time period (T.cons2).

5. The method according to claim 1, Its features are, In step 3, the maximum output power (P.MAX…P.MAX.prox) from the boiler (1) is calculated using the following heat transfer formula: P.MAX…P.MAX.prox = Q cp (T.max – T.setpoint) In the formula: - "Q" is the flow rate signal (Q.REG … Q.REG.prox) obtained through step 2. - "cp" is the specific heat of the heat transfer fluid; - "T.max" is the maximum temperature of the heat transfer fluid. When the maximum temperature is exceeded, the boiler (1) enters a locked state for safety reasons. - "T.setpoint" is the temperature value of the domestic hot water requested by the user.

6. The method according to claim 1, Its features are, In step 4, each part (T.med, T.med.prox) of the observation time window (T.analysis, T.prox) includes a time period immediately preceding the end (T.0, T.0.prox) of each of the observation time windows (T.analysis, T.prox).

7. The method according to any of the preceding claims, Its features are, - The observation time window (T.analysis) is equal to 14 days, which corresponds to a given number of days prior to the date (T.0) on which the method was implemented. - The future time window (T.prox) is equal to 5 days, and the future time window corresponds to a given number of days after the date (T.0) on which the method is implemented.

8. The method according to any of the preceding claims, Its features are, Each consecutive time interval (T.cons) within the observation time window (T.analysis) is equal to 60 minutes.

9. The method according to claim 6, Its features are, Each of the portions (T.med, T.med.prox) of the observation time window (T.analysis, T.prox) is equal to 2 days.

10. The method according to any of the preceding claims, Its features are, - The threshold (QT) for the flow rate is equal to 900 l / h. - The threshold (PT) of the power is equal to 80% of the nominal power of the boiler (1).

11. The method according to the preceding claim, Its features are, The threshold values ​​(QT; QP) for the flow rate and the power are predetermined by the manufacturer of the boiler (1) and / or by the technicians of the boiler. QP can be modified by storing the new value in the control unit (70) of the boiler (1).

12. A gas-fired boiler (1), comprising at least: - A primary circuit (100) for heating a heat transfer fluid intended to power a heating element for space heating, the primary circuit comprising: - Combustion chamber (2), which houses a primary heat exchanger (10) and a burner (3), the burner being powered by a fan (5) and an air-fuel mixture supplied by a gas valve (4). - A secondary circuit (200) for heating sanitary water intended for use by a user, the secondary circuit including a secondary exchanger (20). - Circulation pump (30) - A three-way diverting valve (40), the three-way diverting valve being adapted to switch the operation of the boiler (1) from a "space heating" operation mode to a "domestic water heating" operation mode, and vice versa. - Control unit (70) - A sensor device adapted to measure the flow rate (Q.RAW) of the heat transfer fluid. Its features are, The control unit (70) is adapted to receive, in input, the value of the flow rate (Q.RAW) and the value of the temperature of the sanitary water (T.setpoint) requested by the user, process them to perform the steps of the method according to claims 1 to 11.

13. The gas-fired boiler (1) according to the preceding claim. Its features are, The sensor device includes: - A flow switch or another equivalent type of flow rate sensor located on the primary circuit (100), - and / or smart pump (30). - and / or a sensor device that detects one or more physical quantities, thereby calculating the flow rate (Q.RAW) of the heat transfer fluid.

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