Method for the predictive maintenance of a boiler heat exchanger
Patent Information
- Application Number
- PCT/IB2024/062203
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-03-05
- Filing Date
- 2024-12-04
- Publication Date
- 2025-10-02
AI Technical Summary
Existing gas boiler systems face inefficiencies due to limescale deposits and obstructions in the secondary heat exchanger, which can lead to reduced performance and potential damage to other components, necessitating timely maintenance without requiring additional devices.
A predictive control method using flow rate values of the heat transfer fluid and user-set temperature to forecast the likelihood of secondary exchanger efficiency loss, employing a control unit to process and emit notifications for maintenance, utilizing existing boiler components.
The method effectively predicts and alerts users to potential efficiency degradation, preventing critical boiler failures and ensuring it can reach set temperatures, thus maintaining system integrity.
Smart Images
Figure IB2024062203_02102025_PF_FP_ABST
Abstract
Description
[0001] METHOD FOR THE PREDICTIVE MAINTENANCE OF A BOILER
[0002] HEAT EXCHANGER
[0003] DESCRIPTION
[0004] The object of the present invention is a predictive control method for monitoring the efficiency status of a heat exchanger of a gas boiler, aimed at promptly reporting the need for maintenance interventions in case that the efficiency of such exchanger degrades excessively.
[0005] More in detail, the method proposed herein aims to monitor over time the obstruction status of the secondary heat exchanger, primary side, of a gas boiler. Like other components of the primary circuit of a boiler, the secondary heat exchanger can also be subject to the formation of limescale deposits and obstructions, caused by the precipitation of salts, impurities and solid compounds transported by the heat transfer fluid that circulates at high temperature in the system.
[0006] As time passes, the aforementioned formations cause increases in the surface friction resistance in the delivery and return ducts and a reduction in the heat exchange efficiency inside the secondary exchanger: it is therefore necessary to periodically check the functionality status thereof and subject it to maintenance before it breaks or causes more serious damage to the other components of the boiler.
[0007] The object of the present invention is to obviate such type of drawbacks, by providing a control method to monitor the efficiency status of the secondary exchanger of a boiler. Another object of the present invention, at least for some variants thereof, is that of providing a method operating with the means normally present in a typical gas boiler, without the need to resort to additional devices or outer components.
[0008] A further object of the present invention, at least for some of its variants, is to report the need to subject the secondary exchanger to maintenance, through timely warning systems that are practical for the user.
[0009] Another object of the present invention, at least for some variants thereof, is to warn the user about the possibility that the boiler may not be able to reach the set temperature or that it may block due to overheating, due to the deterioration of the efficiency status of the secondary exchanger.
[0010] These and other objects, which shall become clear hereinafter, are achieved with a control method for monitoring the efficiency status of the secondary exchanger on the primary side of a gas boiler, in accordance with the provisions of the independent claims. Other objects may also be achieved by means of the additional features of the dependent claims.
[0011] Further features of the present invention shall be better highlighted by the following description of a preferred embodiment, according to the patent claims and illustrated, purely by way of a non-limiting example, in the accompanying drawing tables, wherein:
[0012] - Figure 1 shows the hydraulic diagram of a typical gas boiler, wherein the control method according to the invention may be implemented;
[0013] - Figure 2. A shows an example of a signal of the flow rate of the heat transfer fluid of the boiler, as measured during an initial step of the control method according to the invention;
[0014] - Figures 2.B and 2.C show examples of signals of the flow rate of the heat transfer fluid of the boiler, as measured and / or processed in an intermediate step of the control method according to the invention;
[0015] - Figures 3. A and 3.B show comparison diagrams, respectively, between the signal of the flow rate of the heat transfer fluid and the power that may be delivered by the boiler, as processed in a final step of the control method according to the invention and representative of production conditions of a first type of notification;
[0016] - Figures 4. A and 4.B show the comparison diagrams of Figures 3. A and 3.B, with the schematic indication of conditions representative of a first type of notification in accordance with the control method according to the invention;
[0017] - Figures 5. A and 5.B show comparison diagrams, respectively, between the signal of the flow rate of the heat transfer fluid and of the power that may be delivered by the boiler, as processed in a final step of the control method according to the invention and representative of production conditions of a second type of notification;
[0018] - Figures 6. A and 6.B show the comparison diagrams of the Figures 5.A and 5.B, with the schematic indication of conditions representative of a second type of notification in accordance with the control method according to the invention.
[0019] It should be noted that such figures 3. A to 6.B are not correlated and consequential to the figures 2. A, 2.B and 2.C, referring to different periods of execution of the method.
[0020] The features of a preferred variant of the control method according to the invention and of the relative boiler implementing such method are now described using the references contained in the figures.
[0021] With the aid of the figure 1, it is useful to quickly outline the constituent components of a gas boiler 1, at least those necessary for the intelligibility of the present invention.
[0022] The boiler 1 comprises a primary circuit 100 and a secondary circuit 200, provided with a corresponding heat exchanger, i.e. a primary heat exchanger 10 (hereinafter “primary exchanger 10”) for the heat transfer fluid and a secondary heat exchanger 20 (hereinafter “secondary exchanger 20”) for the sanitary water.
[0023] Reference 4 indicates the gas valve, which modulates the inflowing gas via the gas inlet C to send it to feed the burner 3 (located in the combustion chamber 2 housing the primary exchanger 10), after mixing with the combustion air modulated by the fan 5.
[0024] The primary circuit 100, in addition to the primary exchanger 10 (which, in the example of the variant of figure 1, consists of a helical coil exchanger), also comprises:
[0025] - a return duct 11 which, through the inlet E, leads the heat transfer fluid coming from the heating bodies of the system (not shown) towards the primary exchanger 10, where such fluid is subjected to the hot combustion fumes produced by the aforementioned burner 3;
[0026] - a circulation pump 30 (hereinafter “pump 30”), preferably located on said return duct 11 ;
[0027] - a feeding duct 12 of the heat transfer fluid, which starts from the primary exchanger 10 to be sent to the heating bodies of the heating system (hereinafter “system”) via the outlet A.
[0028] When the boiler 1 operates in “space heating” operating mode, the path of the heat transfer fluid therefore provides for the entry into the primary circuit 100 via the inlet E, the passage in the return duct 11 and the transit through the burner 3, the passage through the feeding duct 12 and the sending to the heating bodies of the system via the outlet A.
[0029] When, on the other hand, the boiler 1 operates in “sanitary water heating” operating mode, the heat transfer fluid is diverted (via an inlet duct 21, derived from the feeding duct 12) towards the secondary exchanger 20, wherefrom it then exits by means of a return duct 22 so as to flow back into the return duct 11 of said primary circuit 100.
[0030] The secondary circuit 200, in addition to the aforementioned secondary exchanger 20 (which, in the example of the variant of figure 1, consists of a plate exchanger) further comprises a feeding duct 23 of the cold water entering the secondary exchanger 20 via the inlet D, said cold water being heated by the aforementioned inlet 21 and return 22 ducts of the primary circuit 100 for producing hot sanitary water to be sent to the user through the outlet B via a delivery pipe 24.
[0031] The switching of the operation of the boiler 1 from the “space heating” operating mode to the “sanitary water heating” mode occurs via a three-way diverter valve 40, adapted to direct the heat transfer fluid towards the heating bodies of the system through the outlet A (thus by-passing the secondary exchanger 20) or, vice versa, towards the secondary exchanger 20 for the production of hot sanitary water to be sent to the user via the outlet B.
[0032] With 70 is schematically indicated the control unit of the boiler 1, hereinafter abbreviated to “control unit 70”.
[0033] In the system described above, the components of the boiler 1 most at risk of efficiency loss due to precipitation of impurities and formation of limescale deposits are those crossed by the heat transfer fluid at high temperature, specifically the pump 30, the primary exchanger 10, the secondary exchanger 20, both on the primary side thereof (i.e. on the side connected to the inlet 21 and return 22 ducts of the primary circuit 100), and on the secondary side thereof (i.e. on the side connected to the feeding 23 and delivery 24 ducts of the secondary circuit 200).
[0034] Patent EP4278135, owned by the same applicant of the present application, describes a control method for monitoring the efficiency status of such components, using the flow rate value of the heat transfer fluid circulating in the primary circuit 100 as a signal representing the loss of efficiency.
[0035] The invention described herein, instead, proposes a control method for monitoring the secondary exchanger 20 on its primary side (hereinafter summarised as “secondary exchanger 20”), through a predictive model that, using the flow rate values of the heat transfer fluid as input signals in certain operating conditions and the value of the temperature of the hot sanitary water requested by the user, is capable of returning a forecast, within a future time window, of the more or less high probability of the loss of efficiency of said secondary exchanger 20.
[0036] According to the preferred variant of the invention, the values of the flow rate of the heat transfer fluid, the value of the temperature of the hot sanitary water requested by the user, the further parameters that shall be described shortly, the reprocessing thereof and the consequent forecast in the output of the efficiency status of the secondary exchanger 20 are all processed by the control unit 70, normally adapted to manage the usual functionalities of the boiler 1 and of the components thereof, with which it can communicate bidirectionally according to the most appropriate methods, for example via wired and / or wireless connections (of radio type, such as WLAN, ZigBee, Bluetooth protocols or the like).
[0037] However, for the purposes of the invention, nothing prevents all or some of the data processing means used for the operation of the method of the invention from being managed by additional control units or performed on devices external to the heating system: by way of a non-limiting example, such additional means may comprise smartphones, tablets, PDAs, remote servers (e.g. in the Cloud), provided that they are appropriately provided with software and / or applications suitable and compatible for the purpose.
[0038] For the sake of brevity, hereinafter the description of the invention shall assume that all the processing capabilities reside in the control unit 70 of the boiler 1 but, more generally, “control unit” 70 shall mean all the set of data processing elements, united or distributed in multiple subsets that are necessary to implement the method according to the invention.
[0039] Such control unit 70 is advantageously provided and / or cooperating with:
[0040] - means of acquisition and / or reception of input data for the method of the invention,
[0041] - means for calculating and processing said input data, adapted to provide output data and / or information aimed at determining the efficiency status of the secondary exchanger 20,
[0042] - memory means for storing, at least temporarily, said input and / or output data,
[0043] - means for transmitting said output data and / or information to a display and notification interface, said interface being able to consist of a typical HMI interface integrated in the boiler 1, in the system and / or in the aforementioned outer devices.
[0044] The control method shall now be described in detail with reference to the various sequential steps of which it is composed. Step 1: Extrapolation of the flow rate values of the flow and of the temperature of the sanitary water.
[0045] In Step 1, the method of the invention takes into account the maximum flow rate values Q.RAW of the heat transfer fluid circulating in the primary circuit 100 of the boiler 1 following a request for sanitary water by the user, i.e. with the boiler in “sanitary water heating” mode.
[0046] More precisely, such maximum flow rate value Q.RAW is measured or calculated in consecutive time intervals T.cons (e.g. of 60 minutes each) within an observation time window T. analysis, corresponding to a given number of days.
[0047] For the sake of brevity but without any limiting intent, hereinafter it shall be assumed that such observation time window T. analysis is equal to 14 days.
[0048] The achievement of the flow rate values Q.RAW in said time intervals T.cons occurs according with the following conditions:
[0049] - in case there is a request for sanitary water, the pump 30 performs a cycle at maximum speed and the control unit 70 stores the maximum flow rate value Q.RAW (in such conditions, the flow of the heat transfer fluid may also be defined as “post-circulation flow”);
[0050] - in case of no request for sanitary water by the user, the control unit 70 keeps in memory the flow rate value Q.RAW obtained in the last time interval T.cons in which a withdrawal took place.
[0051] Said flow rate values Q.RAW can be measured with known means such as a flow switch or other type of flow rate sensor (not shown in figure), present on the primary circuit 100, capable of transmitting a signal representing the same flow rate to the control unit 70.
[0052] Alternatively or in addition, the flow rate values Q.RAW may be ascertained indirectly by sensor means that detect and report a group of one or more physical quantities (such as, for example, those indicated below) from which it is possible to calculate the same flow rate.
[0053] However, according to the preferred variant of the invention, the flow rate value Q.RAW is provided by signals emitted by a so-called smart pump 30, without the need to provide for a special flow rate sensor; in other words, the smart pump has the sensor means incorporated at least sufficient to deduce, through calculations and / or consultation of pre- stored data tables, the flow rate Q.RAW thereof.
[0054] As is known, such kind of smart pump is a type of circulator able to exchange information bidirectionally with the control unit 70 of the boiler 1 which, in addition to communicate to the pump 30 the speed at which it should operate, may interrogate it to receive specific information on its status, such as for example:
[0055] - the number of revolutions,
[0056] - the electrical power absorbed,
[0057] - the operating status (work, stand-by, error),
[0058] - and, precisely, the flow rate Q.RAW processed starting from the previous parameters.
[0059] In accordance with the preferred variant of the invention, such flow rate value Q.RAW is a quantity acquired indirectly, calculated as a function of the electrical power absorption and of the number of revolutions of the pump 30, detected and transmitted by the same to the control unit 70 of the boiler 1.
[0060] As mentioned, it is however understood that, for the implementation of the method herein described, the flow rate value Q.RAW may also be obtained with an ad hoc flow rate sensor, when the boiler 1 comprises a classic type of pump 30 instead of a smart pump.
[0061] The graph of figure 2. A shows an example of the flow rate values Q.RAW obtained within the observation time window T.analysis; in this figure, like the following figures 2.B and 2.C, the value of the flow rate is indicated on the ordinate axis while the time is represented on the abscissa axis.
[0062] Once such flow rate values Q.RAW have been obtained, they are purified from limit and / or anomalous conditions and subjected to a resampling step, in order to obtain a signal of the flow rate values Q.DHW (see figure 2.C), more coherent and functional for the purposes subtended by the present invention.
[0063] By way of a non-limiting example, the method does not take into account the oscillations of the flow rate value Q.RAW, and in particular its deep and sudden drops or sudden increases, excluding from the calculation of the acquired flow rate values Q.RAW those falling within the following cases:
[0064] - flow rate values equal to 0 1 / h, exemplifying a measurement error,
[0065] - flow rate values prior to the measurement of a flow rate value Q.RAW higher by at least 2001 / h compared to the flow rate value obtained in the previous time interval T.cons, which causes the value Q.RAW to exceed by over 1,0001 / h: such sudden increase in the flow, very probably, derives from a maintenance intervention on the exchanger 20, evidently subjected to cleaning or replacement by a technician, and therefore the method according to the invention does not take into account the entire stretch of the flow rate values prior to such measurement. In the figures 2.B and 2.C, the reference Q.RAW.O shows examples of measurements of flow rate values Q.RAW that fall within the cases just mentioned and that, therefore, are removed from the series of values Q.RAW taken into consideration by the control method according to the invention.
[0066] Preferably, the method also verifies that, within the observation time window T.analysis, there is a sufficient quantity of measurements of the flow rate values Q.RAW, equal for example to at least 5 days of data, of which 4 during the last week.
[0067] To obtain the signal Q.DHW of figure 2.C, the Step 1 of the method further provides for a resampling of the flow rate value Q.RAW already measured in the specific consecutive time interval T.cons, that is, the flow rate Q.RAW is measured again in a time interval T.cons2 at least double with respect to said time interval T.cons and the average of the values is calculated: such sampling activity is useful for minimising possible oscillations in the measurements and obtaining a more homogeneous and coherent flow rate signal Q.DHW.
[0068] Preferably, such time interval T.cons2 is four times the time interval T.cons and, therefore, the average of the flow rate values Q.RAW is the average of four measurements.
[0069] In summary, the flow rate signal Q.DHW depicted in figure 2.C is obtained after at least the following activities:
[0070] - measurement of the maximum flow rate values Q.RAW in consecutive time intervals T.cons within an observation time window T.analysis,
[0071] - elimination of the values Q.RAW.O from said maximum flow rate values Q.RAW,
[0072] - elimination of the values Q.RAW.O preceding a value Q.RAW of at least 2001 / h higher than the flow rate value obtained in the previous time interval T.cons, in case that the new value Q.RAW is higher than 1,0001 / h,
[0073] - re-sampling of the maximum flow rate values Q.RAW in a time period T.cons2 at least double than said consecutive time interval T.cons and calculating the average thereof within such time period T.cons2.
[0074] In Step 1 of the method according to the invention, in addition to the flow rate signal Q.DWH as obtained above, the control unit 70 also acquires a signal T. setpoint, representative of the temperature of the sanitary water requested by the user.
[0075] Such signal T. setpoint is set manually by the user and is typically comprised between 35 and 60 °C: thus, it usually remains constant within the observation time window T.analysis and is therefore not reprocessed during the steps of the method of the invention.
[0076] In the event that, during the observation time window T.analysis, the user modifies the previously set value of T. setpoint, in such Step 1 the control unit 7 stores the updated value, always without it being subjected to any reprocessing.
[0077] Step 2: regression of the past flow rate values of the flow and of the future flow rate values of the flow.
[0078] The flow rate signal Q.DHW, as obtained at the end of Step 1, is subjected to a linear regression, in order to obtain a rectilinear signal Q.REG representative of the flow rate values within the observation time window T.analysis and of the flow rate values Q.REG.prox within a future time window T.prox.
[0079] By way of a non-limiting example, such future observation time window T.prox is equal to 5 days.
[0080] In other words, with such linear regression the overall trend Q.REG of the flow rate signal Q.DHW is obtained in the observation time window T. analysis and, coherently with such overall trend Q.REG, also the estimate of the trend Q.REG.prox in the future time window T.prox.
[0081] Figures 3. A and 5.A show two examples of the flow rate signal “Q.REG... Q.REG.prox” as obtained following such Step 2 of the method (it should be noted that figures 3.A and 5. A are not correlated or consequential to the signal Q.DHW of figure 2.C, since they refer to different execution periods of the method).
[0082] Reference T.O indicates the vertical line corresponding to the current day of execution of the method, which separates respectively:
[0083] - the time window T.analysis, comprising the straight line Q.REG obtained from the linear regression of the flow rate signal Q.DHW as obtained at the end of the Step 1 of the method,
[0084] - and the future time window T.prox, comprising the straight line Q.REG.prox, representing the flow rate signal of the flow in the days following day T.O (for example 5 days) and ending on day T.O.prox.
[0085] In the example of figure 3.A the flow rate signal “Q.REG... Q.REG.prox” takes values comprised between approximately 1,0501 / h (at the extreme represented by the start of the time window T.analysis) and approximately 8001 / h (at the extreme represented by the end of the future time window T.prox).
[0086] Whereas, in the example in figure 5. A the flow rate signal “Q.REG... Q.REG.prox” takes values comprised between approximately 600 1 / h (at the extreme represented by the start of the time window T.analysis) and approximately 300 1 / h (at the extreme represented by the end of the future time window T.prox).
[0087] Step 3: calculating the value of the maximum output power by the boiler.
[0088] Starting from the flow rate signal “Q.REG...Q.REG.prox” obtained with the Step 2, the method according to the invention continues with the calculation of the maximum power “P.MAX...P.MAX.prox” that may be delivered by the boiler 1, taking into account the specific flow rate “Q.REG...Q.REG.prox” and hot sanitary water temperature T. setpoint values requested by the user.
[0089] Using the well-known heat transfer formula:
[0090] P.MAX... P.MAX.prox = Q * cp • (T.max - T. setpoint) wherein:
[0091] Q = the flow rate values “Q.REG ... Q.REG.prox” obtained with the Step 2; cp = the specific heat of the water (in this case of the heat transfer fluid);
[0092] T.max = the maximum value of the temperature of the heat transfer fluid, beyond which the boiler 1 goes into a block condition for safety reasons (preferably such value T.max is cautiously reduced by a few degrees Celsius compared to the actual nominal maximum value);
[0093] T. setpoint = the temperature of the sanitary hot water requested by the user; the method calculates the values of the maximum power “P.MAX...P.MAX.prox” that may be delivered by the boiler 1, i.e. those power values that may be reached by boiler 1 before going into lockout due to too high temperatures of the heat transfer fluid, resulting from the need to reach the temperature of the hot sanitary water T. setpoint requested by the user.
[0094] It follows that, with the same flow rate value “Q.REG... Q.REG.prox”, the maximum power “P.MAX... P.MAX.prox” that may be delivered by the boiler 1 is greater when the value of T. setpoint is lower, and vice versa.
[0095] For example, assuming a flow rate value “Q.REG... Q.REG.prox” of 800 1 / h, if the value of the hot sanitary water temperature T. setpoint requested by the user is equal to 45 °C, the maximum power value “P.MAX... P.MAX.prox” is approximately 35 kW.
[0096] Whereas, if the T. setpoint is equal to 55° C, the maximum power value “P.MAX... P.MAX.prox” is approximately 26 kW, precisely because the heat transfer fluid will have to work at higher temperatures so that boiler 1 can reach the highest value of T. setpoint of the hot sanitary water requested by the user, increasing the risk of blocking even from lower power values.
[0097] Through such calculation, a rectilinear signal P.MAX representative of the maximum power values within the observation time window T. analysis and the maximum power values P.MAX.prox within the future time window T.prox is obtained.
[0098] Figures 3.B and 5.B show two examples of the maximum power signal P.MAX and P.MAX.prox as obtained following such Step 3 of the method (it should be noted that figures 3.B and 5.B are not correlated or consequential to the signal Q.DHW of figure 2.C, since they refer to different execution periods of the method).
[0099] Similar to what seen in Step 2, reference T.O indicates the vertical line corresponding to the current day of execution of the method, which separates respectively:
[0100] - the time window T.analysis, comprising the straight line P.MAX deriving from the reprocessing of the flow rate signal Q.REG according to the heat transfer formula described above,
[0101] - and the future time window T.prox, comprising the straight line P.MAX.prox, obtained from the reprocessing of the flow rate signal Q.REG.prox in accordance with the heat transfer formula described above and representative of the maximum power signal that may be delivered by the boiler 1 in the days following day T.O (for example 5 days) and ending on day T.O.prox.
[0102] Assuming a boiler 1 with a nominal power equal to 30 kW and considering a value T. setpoint (temperature of the hot sanitary water requested by the user) equal to 40 °C, based on the flow rate signal “Q.REG...Q.REG.prox” shown in figure 3. A and applying the above-mentioned heat transfer formula, hypothetical values of the maximum power “P.MAX... P.MAX.prox” would be obtained comprised between:
[0103] - about 53 kW (hypothetical value and obviously not actually deliverable by the boiler 1, given the nominal power thereof of 30 kW), when the flow rate signal “Q.REG...Q.REG.prox” has a value of about 1,0501 / h, i.e. at the extreme represented by the start of the time window T.analysis,
[0104] - and about 40 kW (even this is a hypothetical value not achievable by the boiler 1, the nominal power whereof is 30 kW), when the flow rate signal “Q.REG... Q.REG.prox” has a value of about 800 1 / h, i.e. at the extreme represented by the end of the future time window T.prox.
[0105] However, considering that in the example in question the nominal power of the boiler 1 is 30 kW, in figure 3.B the maximum power signal “P.MAX...P.MAX.prox” takes a constant value equal to, precisely, 30 kW.
[0106] By applying such Step 3 to the flow rate signal “Q.REG...Q.REG.prox” shown in figure 5.B, always with a constant value T. setpoint equal to 40 °C, values of the maximum power “P.MAX... P.MAX.prox” that may be delivered by the boiler 1 are obtained, comprised between:
[0107] - about 30 kW, when the flow rate signal “Q.REG...Q.REG.prox” has a value of about 600 1 / h, i.e. at the extreme represented by the start of the time window T.analysis,
[0108] - and about 15 kW, when the flow rate signal “Q.REG... Q.REG.prox” has a value of about 3001 / h, i.e. at the extreme represented by the end of the future time window T.prox), as shown in the example of figure 5.B.
[0109] In other words, for the purposes of the method according to the invention, it can be assumed that the maximum power signal “P.MAX... P.MAX.prox” may be graphically approximated to a straight line of constant value and substantially equal to the nominal power of the boiler 1 when, in consideration of the specific flow rate “Q.REG... Q.REG.prox” and temperature T. setpoint values of the sanitary water, from the application of the above mentioned heat transfer formula, hypothetical maximum power values “P.MAX... P.MAX.prox” derive, all higher than said nominal power (as per the graphic example in figure 3.B).
[0110] While, as per the example of figure 5.B, the maximum power signal “P.MAX...P.MAX.prox” graphically takes the shape of a straight line with a non- constant trend if, from the application of the heat transfer formula and as a function of the specific flow rate “Q.REG...Q.REG.prox” and temperature T. setpoint values of the sanitary water, at least some of such maximum power values “P.MAX...P.MAX.prox” take values lower than the nominal power of the boiler 1.
[0111] Step 4: comparison of the flow rate and maximum deliverable power signals with respective limit thresholds and possible emission of warning notifications. The Step 4 of the method according to the invention provides for the calculation of two average values Q.REG.med and Q.REG.prox.med of the flow rate signal “Q.REG...Q.REG.prox” as obtained in the Step 2.
[0112] The calculation of such two values Q.REG.med and Q.REG.prox.med occurs by averaging the flow rate values “Q.REG...Q.REG.prox” within two time periods T.med and T.prox.med, respectively consisting of a portion of the time window T.analysis and of the future time window T.prox.
[0113] Preferably, said two time periods T.med and T.prox.med have a duration of 2 days and comprise the days immediately preceding the end of the time window T.analysis and of the future time window T.prox: in other words, such time period T.med ends on day T.O, while the time period T.prox.med ends on day T.O.prox. More in detail, the calculation of said two values Q.REG.med and Q.REG.prox.med occurs by considering:
[0114] - the average of the values of the flow rate signal Q.REG within the time period T.med to obtain the value Q.REG.med;
[0115] - the average of the values of the flow rate signal Q.REG.prox within the time period T.prox.med to obtain the value Q.REG.prox.med.
[0116] The method according to the invention provides that, in case that at least one of such two values Q.REG.med and Q.REG.prox.med is lower than a threshold value Q.T of the flow rate, a first type of notification is emitted, representative of the fact that it is probable that there is a degradation of the efficiency status of the secondary exchanger 20 or that such condition is likely to occur within the future time window T.prox.
[0117] Such threshold value Q.T is preset by the manufacturer and / or by the technician, in accordance with laboratory tests and / or periodic monitorings during the actual use of the boiler 1 and / or with other elements deduced by a man skilled in the art, with reference to the specific type of boiler 1 and to the system.
[0118] In the examples of the attached figures, such threshold value Q.T of the flow rate is equal to 900 1 / h, a value below which it is presumable to consider that the secondary exchanger 20 is degrading due to the formation of limescale deposits and obstructions.
[0119] The threshold value Q.T may however be modified by storing a new value in the control unit 70.
[0120] The Step 4 of the method according to the invention also provides for the calculation of two average values P.MAX.med and P.MAX.prox.med of the maximum power signal “P.MAX ... P.MAX.prox” that may be delivered by the boiler 1, as obtained in the Step 3.
[0121] The calculation of such two values P.MAX.med and P.MAX.prox.med occurs by averaging the power values “P.MAX ... P.MAX.prox” within the two time periods T.med and T.prox.med mentioned above.
[0122] More in detail, the calculation of said two values P.MAX.med and P.MAX.prox.med occurs by considering:
[0123] - the average of the values of the maximum power signal P.MAX within the time period T.med to obtain the value P.MAX.med;
[0124] - the average of the values of the maximum power signal P.MAX.prox within the time period T.prox.med to obtain the value P.MAX.prox.med.
[0125] The method according to the invention provides that if, simultaneously with the conditions for the emission of the first type of notification (i.e. at least one of the two values Q.REG.med and Q.REG.prox.med is lower than a threshold value Q.T of the flow rate), also at least one of such maximum power values P.MAX.med and P.MAX.prox.med are lower than a threshold value P.T of the power, then a second type of notification is emitted, representative of the fact that there is a higher degradation of the efficiency status of the secondary exchanger 20 or that such condition is likely to occur within the future time window T.prox., such that the boiler 1 is unable to reach the temperature value T. setpoint of the sanitary hot water requested by the user, or that the boiler 1 goes into lockout due to overtemperature.
[0126] Such threshold value P.T is preset by the manufacturer and / or the technician, in accordance with laboratory tests and / or periodic monitorings during the actual use of the boiler 1 and / or with other elements deduced by a man skilled in the art, with reference to the specific type of boiler 1 and to the system.
[0127] In the examples of the attached figures, such threshold value P.T of the power is equal to 80% of the nominal power of boiler 1: for example, in case of boiler 1 having a nominal power of 30 kW, said threshold value P.T of the power is equal to 24 kW.
[0128] The threshold value P.T may however be modified by storing a new value in the control unit 70.
[0129] Figures 4.A / 4.B show examples of signal of the flow rate “Q.REG...Q.REG.prox” and of the maximum power “P.MAX ... P.MAX.prox” producing the first type of notification, since:
[0130] - the condition that at least one (in this case both) between the values Q.REG.med and Q.REG.prox.med is below the threshold value Q.T of the flow rate is verified;
[0131] - but the condition that at least one of the values P.MAX.med and P.MAX.prox.med is below the threshold value P.T. does not occur.
[0132] Figures 6.A / 6.B, instead, show examples of the signal of the flow rate “Q.REG... Q.REG.prox” and of the maximum power “P.MAX ... P.MAX.prox” producing the second type of notification, since:
[0133] - both the condition that at least one (in this case both) between the values Q.REG.med and Q.REG.prox.med is below the threshold value Q.T of the flow rate, is verified;
[0134] - and also the condition that at least one (in this case both) between the values P.MAX.med and P.MAX.prox.med is below the threshold value P.T, is verified.
[0135] Preferably, the method according to the invention also provides for a third type of notification, which may be emitted in case the productive conditions of the first or the second type are not accomplished: i.e., such third type of notification is representative of the fact that the efficiency status of the secondary exchanger 20 is (or will be in the future time window T.prox) sufficiently high to guarantee that none of the values Q.REG.med and Q.REG.prox.med is lower than the threshold value Q.T of the flow rate, nor that none of the values P.MAX.med and P.MAX.prox.med is below the threshold value P.T of the power.
[0136] The first and second types of notification (and, where provided, also the third type of notification) preferably consist of signals perceptible by the user, visual and / or acoustic, that such control unit 70 provides to the display of the boiler 1, and / or to the connectivity services for the user, and / or to communications via email to the assistance centre.
[0137] More generally, such kinds of notification may be visual and / or acoustic, for example shown in the interface of the boiler 1 and / or of the possible outer devices connected thereto and / or through written, email, SMS or similar communications to the same outer devices, that may be referred to directly by the user, or to remote servers that may be accessed by the assistance centre.
[0138] From the above description it is clear how the method of the invention is able to achieve the subtended objects, proving to be particularly effective in promptly signalling the probability that the secondary exchanger 20 suffers from a decay in the efficiency status and from a consequent loss in the heat exchange capacity.
[0139] In such way it is possible to prevent critical situations for the user, avoiding that the obstruction of the secondary exchanger 20 causes major problems, both for the same exchanger and for other components of the primary circuit 100, and that the boiler goes into lockout due to over temperatures and / or it is unable to reach the temperature value T. setpoint of the hot sanitary water set by the user.
[0140] In summary, the method of the present invention uses exclusively the valuesof the flow rate Q.RAW of the heat transfer fluid and of the temperature T. setpoint of the sanitary water requested by the user as input data, in order to provide in output a forecast of the more or less high probability that, within a future time window T.prox, the secondary exchanger 20 of the boiler 1 suffers from an efficiency loss. For this purpose, the method provides for:
[0141] - a Step 1 in which the following occurs:
[0142] - the acquisition of such values of the flow rate Q.RAW of the heat transfer fluid and of the values of the temperature T. setpoint of the sanitary water within an observation time window T.analysis,
[0143] - and the reprocessing of the flow rate values Q.RAW to obtain a more coherent flow rate signal Q.DHW;
[0144] - a Step 2 in which the following occurs:
[0145] - the linear regression of the flow rate signal Q.RAW to obtain a flow rate signal Q.REG...Q.REG.prox within the observation time window T.analysis and a future time window T.prox;
[0146] - a Step 3 in which the following occurs:
[0147] - the calculation of the maximum power P.MAX...P.MAX.prox that may be delivered by the boiler 1, taking into account the flow rate Q.REG...Q.REG.prox and the temperature T. setpoint signal;
[0148] - a Step 4 in which the following occurs:
[0149] - the calculation of the average values Q.REG.med and Q.REG.prox.med of the flow rate signal Q.REG...Q.REG.prox within two time periods T.med and T.med.prox, portions of the observation time window T.analysis and of the future time window T.prox,
[0150] - the calculation of the average values P.MAX.med and
[0151] P.MAX.prox.med of the maximum power signal P.MAX...P.MAX.prox within the time periods T.med and T.med.prox,
[0152] - the comparison between the average values Q.REG.med and
[0153] Q.REG.prox.med and a threshold value Q.T of the flow rate,
[0154] - the comparison between the average values P.MAX.med and P.MAX.prox.med and a threshold value P.T of the power, - the emission of a first type of notification in case that at least one of the average values Q.REG.med and Q.REG.prox.med is lower than the threshold value Q.T of the flow rate,
[0155] - the production of a second type of notification in case that at least one between the average values Q.REG.med and Q.REG.prox.med is lower than the threshold value Q.T of the flow rate and, at the same time, at least one between the average values P.MAX.med and P.MAX.prox.med is lower than the threshold value P.T of the power,
[0156] - the possible emission of a third type of notification in case that both the average values P.MAX.med and P.MAX.prox.med are higher than the threshold value P.T of the power and both the average values Q.REG.med and Q.REG.prox.med are higher than the threshold value Q.T of the flow rate.
Claims
CLAIMS1. Method for checking the efficiency state of a secondary exchanger (20) of a gas boiler (1) comprising at least:- a primary circuit (100) having a primary exchanger (10) for the heating of a heat transfer fluid intended to power heating bodies for the space heating,- a secondary circuit (200) having a secondary exchanger (20) for the heating of the sanitary water intended to the user,- a circulation pump (30),- a three-way diverter valve (40), adapted to switch the operation of said boiler (1) from the “space heating” operating mode to the “sanitary water heating” operating mode and vice versa,- sensor means adapted to measure the flow rate (Q.RAW) of said heat transfer fluid,- a control unit (70) adapted to manage the steps of the method and to acquire and process the values of said flow rate (Q.RAW) and the temperature values (T. setpoint) of the sanitary water intended to the user, said method being characterised in that it comprises at least the following steps in sequence:- Step 1: acquiring said temperature values (T. setpoint) of the sanitary water and the maximum values of said flow rate (Q.RAW) of the heat transfer fluid when said boiler (1) is in “sanitary water heating” operating mode, said acquisition taking place in consecutive time intervals (T.cons) within an observation time window (T.analysis) corresponding to a given number of days preceding the day (T.0) of implementation of said method;- re-processing said maximum flow rate values (Q.RAW) to purify them from limit and / or anomalous conditions, to obtain a more consistent flow rate signal (Q.DHW);Step 2: re-processing said more consistent flow rate signal (Q.DHW) by linear regression thereof, to obtain a flow rate signal (Q.REG... Q.REG.prox) representative of the flow rate values (Q.REG) within said observation time window (T.analysis) and the flow rate values (Q.REG.prox) within a future time window (T.prox), corresponding to a given number of days following the day (T.O) of implementation of said method;Step 3: calculating the value of the maximum output power (P.MAX...P.MAX.prox) deliverable by the boiler (1) within said observation time windows (T.analysis, T.prox), according to the flow rate signal (Q.REG...Q.REG .prox) obtained with said Step 2 and the temperature values (T. setpoint) of the sanitary water;Step 4: calculating, within a portion (T.med, T.med.prox) of each of said observation time windows (T.analysis, T.prox), two respective average values (Q.REG.med, Q.REG.prox.med) of the flow rate signal (Q.REG... Q.REG. prox) obtained with said Step 2 and two respective average values (P.MAX.med, P.MAX.prox.med) of the maximum power signal (P.MAX...P.MAX.prox) obtained with said Step 3; comparing said 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 comparing said two average values (P.MAX.med, P.MAX.prox.med) of the maximum power with a threshold value (P.T) of the power; if at least one of said two average values (Q.REG.med, Q.REG.prox.med) of the flow rate is lower than said threshold value (Q.T) of the flow rate, emitting a first type of notification, representative of the fact that there is likely a degradation in the efficiency state of said secondary exchanger (20) or that such condition is likely to occur within the future time window (T.prox), or if at least one of said two average values (Q.REG.med,Q.REG.prox.med) of the flow rate is lower than said threshold value (Q.T) of the flow rate and, at the same time, at least one of said two average values (P.MAX.med, P.MAX.prox.med) of the maximum power is lower than said threshold value (P.T) of the power, emitting a second type of notification, representative of the fact that there is a higher degradation in the efficiency state of said secondary exchanger (20) or that such condition is likely to occur within the future time window (T.prox).
2. Method according to the previous claim, characterised in that it further comprises the step of:- emitting a third type of notification, representative of the fact that the efficiency state of said secondary exchanger (20) is still high and that it will be so even in the future time window (T.prox), if both said two average values (Q.REG.med, Q.REG.prox.med) of the flow rate are higher than said threshold value (Q.T) of the flow rate and both said two average values (P.MAX.med, P.MAX .prox.med) of the maximum power are higher than said threshold value (P.T) of the power.
3. Method according to any previous claim, characterised in that said notifications are addressed to the technical assistance centre and / or to the user, via said control unit (70) provided and / or cooperating with transmission and display means of said notifications.
4. Method according to any previous claim, characterised in that in said Step 1 the reprocessing of said maximum flow rate values (Q.RAW) to obtain a more consistent flow rate signal (Q.DHW) comprises the activities of:- eliminating from said maximum flow rate values (Q.RAW) the values (Q.RAW.O) equal to 01 / h,- eliminating from said maximum flow rate values (Q.RAW) the values preceding (Q.RAW.O) a flow rate value (Q.RAW) at least 200 1 / hhigher than the value measured in the previous consecutive time interval (T.cons), in the event that said new value (Q.RAW) is higher than 1,0001 / h,- re-sampling said maximum flow rate values (Q.RAW) in a time period (T.cons2) at least double than said consecutive time interval (T.cons) and calculating the average thereof within such at least double time period (T.cons2).
5. Method according to claim 1, characterised in that in said Step 3 the calculation of said maximum output power (P.MAX...P.MAX.prox) from the boiler (1) takes place via the heat transfer formula:P.MAX...P.MAX.prox = Q * cp • (T.max - T. setpoint) wherein:- “Q” is the flow rate signal (Q.REG ... Q.REG.prox) obtained with said Step 2;- “cp” is the specific heat of the heat transfer fluid;- “T.max” is the maximum value of the temperature of said heat transfer fluid, beyond which said boiler (1) goes into a lockout condition for safety reasons;- “T. setpoint” is said temperature value of the sanitary hot water requested by the user.
6. Method according to claim 1, characterised in that in said Step 4 each portion (T.med, T.med.prox) of said observation time windows (T.analysis, T.prox) comprises a time period immediately preceding the end (T.0, T.O.prox) of each of said observation time windows (T.analysis, T.prox).
7. Method according to any previous claim, characterised in that- said observation time window (T.analysis), corresponding to a given number of days preceding the day (T.0) of implementation of saidmethod, is equal to 14 days,- said future time window (T.prox), corresponding to a given number of days following the day (T.O) of implementation of said method, is equal to 5 days.
8. Method according to any previous claim, characterised in that each consecutive time interval (T.cons) within said observation time window (T.analysis) is equal to 60 minutes.
9. Method according to claim 6, characterised in that each of said portions (T.med, T.med.prox) of said observation time windows (T.analysis, T.prox) is equal to 2 days.
10. Method according to any previous claim, characterised in that- said threshold value (Q.T) of the flow rate is equal to 9001 / h,- said threshold value (P.T) of the power is equal to the 80% of the nominal power of said boiler (1)11. Method according to the previous claim, characterised in that said threshold values (Q.T; Q.P) of the flow rate and of the power are predetermined by the manufacturer and / or by the technician of the boiler (1), said threshold values (Q.T; Q.P) being modifiable by the storage of new values in the control unit (70) of the boiler (1).
12. Gas boiler (1) comprising at least:- a primary circuit (100) for the heating of the heat transfer fluid intended to power the heating bodies for the space heating, comprising:- a combustion chamber (2) housing a primary exchanger (10) and a burner (3) powered by an air gas mixture supplied by a fan (5) and by a gas valve (4),- a secondary circuit (200) for the heating of the sanitary water intended to the user, comprising one secondary exchanger (20),- a circulation pump (30),- a three-way diverter valve (40), adapted to switch the operation of said boiler (1) from the “space heating” operating mode to the “sanitary water heating” operating mode and vice versa,- a control unit (70),- sensor means adapted to measure the flow rate (Q.RAW) of said heat transfer fluid, characterised in that said control unit (70) is adapted to receive in input the values of said flow rate (Q.RAW) and the values of the temperature (T. setpoint) of the sanitary water requested by the user, to process them in order to carry out the steps of the method according to claims 1 to 11.
13. Gas boiler (1) according to the previous claim, characterised in that said sensor means comprise:- a flow switch or another equivalent type of flow rate sensor, located on said primary circuit (100),- and / or a smart pump (30),- and / or sensor means detecting one or more physical quantities wherefrom said flow rate (Q.RAW) of said heat transfer fluid is calculated.