Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H9/00—Details
  • F24H9/20—Arrangement or mounting of control or safety devices
  • F24H9/2007—Arrangement or mounting of control or safety devices for water heaters
  • F24H9/2014—Arrangement or mounting of control or safety devices for water heaters using electrical energy supply
  • F24H9/2021—Storage heaters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/10—Control of fluid heaters characterised by the purpose of the control
  • F24H15/174—Supplying heated water with desired temperature or desired range of temperature
  • F24H15/175—Supplying heated water with desired temperature or desired range of temperature where the difference between the measured temperature and a set temperature is kept under a predetermined value
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/20—Control of fluid heaters characterised by control inputs
  • F24H15/212—Temperature of the water
  • F24H15/223—Temperature of the water in the water storage tank
  • F24H15/225—Temperature of the water in the water storage tank at different heights of the tank
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/20—Control of fluid heaters characterised by control inputs
  • F24H15/269—Time, e.g. hour or date
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/20—Control of fluid heaters characterised by control inputs
  • F24H15/281—Input from user
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
  • F24H15/355—Control of heat-generating means in heaters
  • F24H15/37—Control of heat-generating means in heaters of electric heaters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
  • F24H15/395—Information to users, e.g. alarms
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/40—Control of fluid heaters characterised by the type of controllers
  • F24H15/414—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based
  • F24H15/421—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based using pre-stored data
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H15/00—Control of fluid heaters
  • F24H15/40—Control of fluid heaters characterised by the type of controllers
  • F24H15/486—Control of fluid heaters characterised by the type of controllers using timers

Definitions

• the present invention relates to a new method for the management of water maintenance temperature in a generic storage water heater controllable by an electronic control.
• An instant water heater can dispense a hot water flow rate strictly proportional to the thermal power installed. Installing high powers is generally difficult and this poses a limit to the dispensable flow rate.
• the advantage of water storage heaters is to be able to dispense very high water flow rates while limiting the thermal power installed.
• the amount of water that can be dispensed at the usage temperature T u during a single tapping may be larger than the volume of the storage tank as this is especially kept at a storage temperature T.acc higher than said usage temperature T u and the water withdrawn is then used mixing it with cold water.
• the selected storage volume is sufficient for meeting the largest of the expectable drawings for that specific utility keeping the storage temperature T.acc to the maximum possible value while the thermal power installed must be such as to restore a sufficient water reserve for the next drawing.
• the minimum requirement for the service to always be met is that the water heater should in any case be kept at a minimum temperature not lower than the usage temperature T 11 so as to meet small unexpected drawings, and the storage volume should be sufficiently large to ensure the largest drawing expected for that utility while keeping the temperature to the maximum value allowed.
• drawing pattern consisting in tapping times and amounts
• drawing profile If it is true that the drawing time is very uneven during the day, it is highly repetitive during predetermined time cycles that repeat, equal to one another: in particular for the one week interval. In fact, user's behaviours are little changing so that a typical drawing profile can be recognised for Mondays, Tuesdays, and so on, with in particular, clear differences between working days and holidays, as well as, of course, for midweek holidays and for holiday periods. This cyclic nature of the drawing profiles therefore allows expecting them with reasonable certainty and it is therefore possible to carry out methods for controlling the water heater temperature so that it is variable during the day.
• Each of said repetitive time intervals is hereinafter referred to as drawing cycle.
• the simple method that has always been used is to enable and disable the heating element by a clock so that the desired temperatures are only ensured within the time period when drawings are expected.
• Another simple method, less effective from the energy point of view for the user but more economically advantageous for the same, is to actuate the heating element only during any time bands with a lower rate; the water may uselessly be too hot with a certain advance compared to the needs, but in any case it was obtained at relatively low cost.
• thermostat T set is simply set to a fixed value; however, the storage temperature T.acc drops because the heating element is forcedly deactivated.
• Those methods that allow the storage temperature T.acc to change over time in a scheduled manner are more effective for limiting consumptions.
• Document EP 0 866 282 provides for a device wherein it is possible to program the desired drawing sequence, that is, the drawing profile.
• the amount of the n drawings envisaged in the time sequence t.l, t.2, ... t.k, ... t.n is recorded by setting for each time t.k the temperature T se t.k deemed able to meet the k-th drawing Pk.
• a limit of the method consists in the difficulty of a correct programming, because the user cannot be aware of the actual drawing times of the hot water or of the actual values T set.k to set to obtain the desired amount of hot water at the usage temperature T u .
• the programming method therefore implies a series of adjustments for tests and errors with the high probability that the user stops correcting the program when he/she assesses that the services is met, but without knowing whether he/she could obtain this with greater efficiency.
• Another difficulty lies in the fact that the actual time of achievement of the desired temperature depends on the heating time, difficult to assess and in any case variable over time for the same water heater for various reasons, such as scale deposits, seasonal temperature variations in the room where the water heater is placed or of the water entering the storage tank, reduction of the actual thermal power of the heating element over time.
• the prior document GB 2 146 797 acquires information on the drawing times and amounts through flow sensors and for each drawing, it brings the storage temperature T.acc to an intermediate value between the minimum and maximum allowed and proportional to the expected drawing volume.
• the method has the disadvantage of requiring the presence of flow sensors for sensing the drawings; moreover, it does not allow for corrections, meaning that it learns the drawing variability but, assigning an unchangeable temperature to each drawing amount as it is generated by a preset formula, it is not able to correct it if it is too high or too low.
• the sequence of the drawing times and of the corresponding desired storage temperatures T.acc are set in an electronic processor; the processor consequently determines the values that the thermostat adjustment temperature must take in each time interval. Afterwards, such adjustment temperatures are changed rising them for the intervals in which the desired storage temperatures T.acc have not been reached, and dropping them in the opposite case.
• a limit of the method, as in the first document mentioned, is the need of having to preset the times of the expected drawings; another limit, as in the second document mentioned, is that the desired and preset storage temperature T.acc is kept, however it may not be the best one for ensuring the service in the most effective manner.
• An object of the present invention in a water heater is to keep a storage temperature T.acc thereof such as to meet all the drawings that may be expected by the usual behaviour of the utility while minimising thermal dispersions.
• a second object of the present invention is to automatically learn and store, at least for cycles of weekly drawings, the drawing profile consisting in times and amounts of the same without needing manual settings or flow detectors.
• a third object of the present invention is to detect utility behaviour changes changing the learnt and stored drawing profile accordingly.
• a further object of the present invention is to allow an amount of water a little higher than that consumed in the previous cycle at each drawing.
• Fig. 1 shows a schematic cross-sectional view of the tank of a water heater.
• Fig. 2 shows a schematic view of the logical device that manages the water heater according to the methods of the invention.
• tank 2 With reference to fig. 1, of a water storage heater 1, hereinafter simply referred to as water heater 1, there is shown tank 2 provided with a cold water inlet 2.1, a hot water outlet 2.2.
• a heating element 3 which in the figure is schematically shown as an electrical resistor but which could consist of any other equivalent means, such as a gas combustion unit or a heat exchanger or else, is in charge of water heating.
• said regulator 4 is provided with means IN suitable for introducing first data therein from the outside, for example during production through input IN.l and/or upon installation through input IN.2 and/or at a later time by the user through input IN.3.
• regulator 4 receives second data from one or more sensors
• a single sensor S; Sl is provided, it is placed where the thermostat sensor of a water heater 1 is normally placed according to the prior art, that is, substantially 1/3 away from the bottom.
• said sensor Sl is placed lower, 100 ⁇ 200 mm away from the bottom and in any case in the proximity of the cold water inlet 2.1.
• sensors are all distributed so as to sense the temperature pattern along the vertical axis with certain accuracy; however, it has been found that only two sensors Sl and S2 are sufficient for a good application of the method according to the invention.
• sensor Sl arranged at about 190 mm from the bottom and sensor S2 at about 260 mm from the same bottom.
• regulator 4 it is further provided with a memory MEM suitable for storing: said first data received from the outside; said second data received from said one or more sensors S, Sl, S2; - as well as further parameters that regulator 4 processes from said first and second data. Consequently, regulator 4 is provided with a processing unit UE suitable for processing said first and second data for obtaining said parameters and a clock CLOCK for associating at least some of said parameters to corresponding times.
• a processing unit UE suitable for processing said first and second data for obtaining said parameters and a clock CLOCK for associating at least some of said parameters to corresponding times.
• regulator 4 is provided with first means Ul for sending output signals for the ON- OFF or modulating control of the heating element 3 besides any second output means U2 for signalling the system status to the user and/or to the operator.
• the output means U2 may consist of a display capable of showing the storage temperature, the drawing profile and so on.
• the data said regulator 4 is capable of acquiring allow it to process further data representing
• the water heater 1 features (that is, water heating speed) the utility features (that is, drawing amounts and times)
• regulator 4 is capable of piloting the heating element 3 so that, in the drawing cycles following the first one, during which the utility behaviour is assumed to be substantially equal to that of the previous drawing cycles, the storage temperature is kept to the minimum value required to meet the single drawings as much as it is physically possible. Moreover, regulator 4 is capable of detecting, as the subsequent drawing cycles run, any considerable changes of the utility behaviour that may require a corresponding change of the drawing profile sensed and stored, or of the water heating speed that may require a corresponding change of the water heating start times.
• regulator 4 can carry out for obtaining what described above, upon the first start-up, water heater 1 starts operating keeping the temperature of tank 2 to values stored to memory MEM of regulator
• regulator 4 is capable of calculating the thermal inertia of water heater 1 or better, the water heating speed characteristic of the thermal system, substantially consisting in tank 2 and in heating element 3.
• a higher final water temperature at the end of the drawing than the usage temperature T u denotes that the required drawing has been met; on the other hand, if the final temperature is lower, this means that the user has received too cold water, that is, that the required service has not been provided in full.
• the temperature increase speed allows deducing the time required for changing from any first temperature to a second target temperature without the need of knowing the thermal capacity of tank 2, insulation quality and thermal power of the heating element 3.
• Water heater 1 therefore, at the end of the learning of its internal features and of the utility features, is capable of maintaining the temperature of tank 2 to values that are variable over time and the lowest possible yet always sufficient for ensuring the single drawings, while the information on said temperature provided from the outside through said first data only serves for operating water heater 1 itself during the first cycle of drawings so that the service to the user is certainly ensured since the first start-up.
• T m said water temperature
• T m said water temperature
• T S et.k indicates the drawing temperature P k , and is the temperature to ensure at the beginning of the k-th drawing P k .
• Said drawing temperatures T set .k have a predetermined initial value T set higher than or equal to the value required for meeting the largest drawing expected; afterwards, they take values calculated by regulator 4 for each of the k drawings expected.
• Tsetmax indicates the maximum setting temperature (generally 75 °C) that for safety reasons ensures that the water does not exceed hazardous values.
• Treq.max indicates the maximum temperature required for meeting the largest drawing to be ensured for each model of water heater 1. More precisely, it is clear that the reason why models of water heaters 1 differing by capacity of the storage tank 2 and by power of the heating element 3 are manufactured, is to meet different more or less important utility categories; the largest among the various required drawings thereof is substantially known and as a consequence, said maximum temperature T req . ma ⁇ required to the purpose. In conclusion, the maximum temperature required T req . max is a known and predetermined value associated to each model of water heater 1 and to the corresponding utility category said model of water heater 1 is intended for.
• a preferred value for the maximum required temperature Treq.max is 52 °C.
• Said maximum required temperature T req.m a x of course is lower than the maximum setting temperature T set . max so that water heater 1 is capable of ensuring also larger drawings than those normally expected.
• Tst and -by indicates the maintenance temperature to ensure at times far-off the drawings, preferably but not necessarily sufficient for allowing temperature T m of the water to ensure small unexpected drawings; this is also a parameter with which the actual water temperature T n , is compared.
• the maintenance temperature T stan d- b y has a predetermined value preferably equal to the usage temperature T u and thus comprised between 35 and 45 0 C; it is not subject to processing over time, but for allowing a manual correction thereof if the preset value does not meet the utility or is regarded as excessive.
• Tta r get indicates the target temperature.
• the target temperature Ttarg et is preset equal to T set .
• ⁇ Thystere s is defines the hysteresis associated to said target temperature Ttarget- Similar to a conventional thermostat, in fact, regulator 4 enables the heating element 3 when the water temperature T m drops below the value Ttarget - ⁇ Thysteresis (that is, if T m ⁇ Ttarget - ⁇ T h y S t ere sis) and disables it when the water temperature T m is higher than T ta rget (that is, if T m > T tar get).
• hysteresis ⁇ T h y steres i s is predetermined; it may be very low, as in all electronic temperature regulators (for example 0.5 0 C) if the heating element 3 is a group of electrical resistors piloted by regulator 4 through a TRIAC. On the other hand, if regulator 4 pilots the heating element 3 through relays, hysteresis ⁇ Thysteresis has a considerably higher value to prevent an excessive ON-OFF switching frequency of the same relays.
• the value of hysteresis ⁇ Thysteresis is set equal to 5 °C when the target temperature Ttarget is set equal to the maintenance temperature T st and-by so as to ensure, with good accuracy, that the water temperature T m actually has a useful value for the utility; on the other hand, when the target temperature T ta rg et is set equal to the drawing temperature T S et the value of hysteresis ⁇ Thysteresis may be higher (for example 8 0 C).
• I Wh indicates the inertia of water heater 1 and indicates the rising speed of temperature T m when the water heater 3 is on.
• the value T ml of the water temperature T m at a given time is recorded; this preferably matches the first start-up time of water heater 1; - the value T m2 the water temperature T m has reached after a predetermined measurement interval ⁇ t is recorded; this may match the time when the water temperature T m reached the value of the drawing temperature T set ; the inertia I Wh value of water heater 1 is calculated by formula
• inertia I W h of water heater 1 Since different degradation factors of water heater 1 and environmental factors (for example seasonal variations in the temperature of the room water heater 1 is located in) may have significant influences on the value of inertia I W h of water heater 1, this is preferably recalculated periodically, for example upon each start-up of water heater 1 after a deactivation period (such as during holidays) and/or whenever regulator 4 decides that the target temperature Ttarget must change from the maintenance temperature T sta nd-by to the drawing temperature T S et.
• the drawing profile is recorded during all of said learning cycle substantially considered as equal and representative of the following drawing cycles. Said recording may then be repeated during the next cycles so as to keep into account any changes in the utility behaviour.
• the recording may start at any time t of the cycle and the start times tik of each drawing P k of the n total drawings that will be comprised in the cycle (where k indicates the subsequent values from 1 to n), as well as the values T m ik and T m fk the water temperature T m has at the drawing start and end, respectively, are recorded during it.
• Said times t, t k may in any case be measured from the time taken as cycle start (for example from hours 0 of Monday if the cycle has a weekly duration).
• Said step is divided into an alternating sequence of n first sub-steps at the end of which the start time ti k of drawing P k and the corresponding drawing start temperature T m jk are detected, followed by as many second sub-steps at the end of which the end time tfk of drawing P k , the corresponding drawing end temperature T mfk are detected, and the amount of the drawing itself is assessed.
• a drawing Pk is regarded as started when, at a time t c , at the end of a sampling interval ⁇ t c , it is noted that the temperature T(t c ) read at said time t c has decreased compared to the value T(t c - ⁇ t c ) read at the previous time t c - ⁇ t c by an amount greater than or equal to a predetermined value ⁇ T p .
• the drawing is deemed as started if T(t c - ⁇ t c ) - TCt 0 ) > ⁇ T p (formula 2)
• Said sampling time intervals ⁇ t c may be quite short, preferably 10 seconds and, correspondingly, said temperature reduction ⁇ T p is preferably equal to 0.2 °C. More explicitly, with said numerical examples the drawing is regarded as started if the temperature decrease speed has exceeded 0.02 °C/sec.
• the drawing start time tj k is not deemed as coinciding with time t c in which said temperature reduction of more than ⁇ T p is verified; in fact, for the thermal inertia of said sensor S, Sl and for its distance from the cold water inlet 2.1, the temperature decrease takes place with a certain delay relative to time tik of actual drawing start that has therefore occurred with an advance interval ⁇ t an t relative to time t c .
• tik - tc - ⁇ tant- (formula 3)
• step of drawing profile recording continues for the entire cycle, alternating said first and second sub-steps that, ending automatically at the beginning and at the end of each drawing respectively, will total the same number as the drawings.
• each drawing P k is determined by two characteristic parameters, drawing start time t;k and temperature drop ⁇ Tk produced thereby.
• regulator 4 maintains the target temperature T tar g et always equal to the maintenance temperature T s tand-by but for ensuring the drawing temperature
• the advance time interval ⁇ t a d V ance.k is calculated, starting from which the heating element 3 must be enabled for the temperature T se t. k of drawing Pk to actually be achieved at said expected drawing start time tik.
• the target temperature Ttarget is led to the drawing temperature P k , T set . k if at said time t the following condition is met: tik - ⁇ t adv ance.k ⁇ t ⁇ tjk + ⁇ t de ] ay (formula 6)
• the delay time interval ⁇ tdeiay has a predetermined value, is optional (that is, it may also be set equal to zero) and has the additional function of allowing the heating element 3 to supply additional thermal energy by which larger drawings than what allowed by the drawing temperature T se t. k are met, this being limited by the maximum setting temperature
• the delay time value ⁇ tdeiay consequently depends on the utility type and on the model of water heater 1 that is most suitable for said utility. By way of a non-limiting example, for a standard water heater 1 such delay time ⁇ t d eia y may be of 15 minutes.
• the method according to the invention sets it equal to said temperature drop ⁇ T k caused by drawing P k to which said predetermined value of the maximum temperature required T req . ma ⁇ and an empirical corrective term of a value of 5 °C are added.
• Tset.k ⁇ Tk + Treq.max + 5 (formula 7)
• formula 7 ensures a reduction of thermal dispersions in the order of 10% in a standard water heater 1 while ensuring the fulfilment of the required service.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Heat-Pump Type And Storage Water Heaters (AREA)
• Control Of Temperature (AREA)

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• 2008
  • 2008-11-28 IT ITAN2008A000052A patent/IT1392118B1/it active
• 2009
  • 2009-11-17 WO PCT/IB2009/007494 patent/WO2010061264A1/en active Application Filing
  • 2009-11-17 PL PL09764038T patent/PL2362931T3/pl unknown
  • 2009-11-17 ES ES09764038T patent/ES2572359T3/es active Active
  • 2009-11-17 EP EP09764038.7A patent/EP2362931B1/de active Active

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