DOUBLE TANK ELECTRIC WATER HEATER EQUIPPED WITH AN ELECTROMECHANICAL THERMOSTAT CONTROL SYSTEM AND ITS CONTROL METHOD

Abstract

DOUBLE TANK ELECTRIC WATER HEATER WITH AN ELECTROMECHANICAL THERMOSTAT CONTROL SYSTEM, AND ITS CONTROL METHOD The invention relates to a double tank electric water heater (1) comprising a first tank (2) equipped with a first heating element (2c), a second outlet tank (3) equipped with a second heating element (3c) and a control system comprising: a first electromechanical thermostat (5) controlled by a first temperature probe (6) located in the first tank (2); and a second electromechanical thermostat (7) controlled by a second temperature probe (8) located in the second tank (3); the first and second electromechanical thermostats (5, 7) being respectively connected to the first and second heating elements (2c, 3c) and being configured to allow heating in the first tank (2) only when the heating in the second tank (3) has reached its control setpoint. Figure to be published with the abbreviation: Figure 1

Description

Title of the invention: DOUBLE TANK ELECTRIC WATER HEATER WITH A CONTROL SYSTEM AN ELECTROMECHANICAL THERMOSTAT, AND ITS REGULATION METHOD

[0001] The present invention relates to the field of electric water heaters, and in particular to a double tank electric water heater equipped with an electromechanical thermostat control system and to a method of controlling such a double tank electric water heater.

[0002] A double tank electric water heater is a known type of compact water heater with two tanks, namely a first inlet tank and a second outlet tank, the first tank having an electric resistance and an inlet called cold water inlet, the second tank having another electric resistance and an outlet called hot water outlet, and the outlet of the first tank being connected to the inlet of the second tank.

[0003] The electrical resistances of the first and second tanks of existing double tank water heaters are typically regulated using an electronic regulation system, generally associated with a capillary safety device.

[0004] However, due to its electronic nature, this existing regulation system has a high cost, is not easy for the user to use (because of its human-machine interface for adjustment which can lead to errors), is not very robust because of possible failures of its electronic components which are subject to potential obsolescence, and also has the disadvantage of consuming energy when it is in standby.

[0005] Electromechanical solutions also exist for the regulation and safety of dual-tank water heaters, in which case each of the two tanks of the water heater has its own electromechanical thermostat, the two electromechanical thermostats of the dual-tank water heater being completely independent of each other. However, with this type of existing electromechanical solution, the electrical heating elements of both tanks of the water heater can be powered simultaneously, which can lead to significant power consumption.

[0006] The present invention aims to resolve the disadvantages of the prior art by proposing a double tank electric water heater equipped with an electromechanical regulation system which, compared to an electronic solution, offers a cost benefit and better robustness.

[0007] The present invention therefore relates to a double tank electric water heater comprising a first tank and a second tank, the first tank having a first heating element, an inlet called cold water inlet and an outlet, the second tank having a second heating element, an inlet and an outlet called hot water outlet, the outlet of the first tank being connected to the inlet of the second tank, characterized in that said double tank electric water heater further comprises a control system comprising: a first single-pole electromechanical thermostat controlled by a first temperature probe disposed in the first tank; and a second single-pole electromechanical thermostat controlled by a second temperature probe disposed in the second tank;The first and second single-pole electromechanical thermostats are configured to: electrically supply the second heating element and cut off the power to the first heating element when the second temperature probe detects a temperature below a second tank temperature threshold; electrically supply the first heating element and cut off the power to the second heating element when the second temperature probe detects a temperature greater than or equal to the second tank temperature threshold and the first temperature probe detects a temperature below a first tank temperature threshold; and cut off the power to both the first and second heating elements when the second temperature probe detects a temperature greater than or equal to the second tank temperature threshold and the first temperature probe detects a temperature greater than or equal to the first tank temperature threshold.

[0008] Thus, the electromechanical control system according to the invention is equipped with two electromechanical thermostats, namely the first electromechanical thermostat which regulates the first heating element of the first tank (with the cold water inlet) and the second electromechanical thermostat which regulates the second heating element of the second tank (with the hot water outlet). Furthermore, since the first electromechanical thermostat is only energized when the second electromechanical thermostat reaches its setpoint, priority is given to heating the second tank (with the hot water outlet) by the second electromechanical thermostat.

[0009] Compared to electronic solutions, the electromechanical control system according to the invention offers cost benefits and ease of use for the end user (no human-machine interface for adjustment that could lead to errors). Furthermore, it is more robust and repairable in the long term with standardized components. In addition, it consumes no energy in standby mode and contains no components subject to potential obsolescence.

[0010] In addition, compared to existing electromechanical solutions, the electromechanical regulation system according to the invention makes it possible to maintain a lower instantaneous power (since the two heating elements cannot operate simultaneously), while ensuring user comfort.

[0011] Each of the first and second heating elements can, for example, be an electrical resistance.

[0012] The temperature threshold of the first tank can, for example, be 45°C. The temperature threshold of the second tank can, for example, be 60°C.

[0013] According to a particular feature of the invention, the first single-pole electromechanical thermostat comprises a first power contact actuated by the first temperature probe, and the second single-pole electromechanical thermostat comprises a second reversing power contact actuated by the second temperature probe, the output of the first power contact being connected to a first of the two supply terminals of the first heating element, a first of the two outputs of the second reversing power contact being connected to a first of the two supply terminals of the second heating element, and the second of the two outputs of the second reversing power contact being connected to the input of the first power contact, such that:

[0014] - when the second temperature probe detects a temperature lower than temperature threshold of the second tank, the second reversing power contact is switched to its first output, so as to electrically supply the second heating element while cutting off the supply to the first power terminal of the first heating element;

[0015] - when the second temperature probe detects a higher temperature or equal to the temperature threshold of the second tank and the first temperature probe detects a temperature below the temperature threshold of the first tank, the second reversing power contact is switched to its second output and the first power contact is closed, so as to electrically supply the first heating element while cutting off the power to the first power terminal of the second heating element; and

[0016] - when the second temperature probe detects a higher temperature or equal to the temperature threshold of the second tank and the first temperature probe detects a temperature greater than or equal to the temperature threshold of the first tank, the second reversing power contact is switched to its second output and the first power contact is opened, so as to cut off the power supply to the first power supply terminals of the first and second heating elements.

[0017] Thus, the use of a reversing control (namely the second reversing power contact) makes it possible to give priority to the heating of the second tank (that is- that is, to the outlet tank), which ensures user comfort while minimizing instantaneous electrical power.

[0018] According to a particular feature of the invention, the control system further comprises a bipolar safety thermostat controlled by a safety temperature probe disposed in the first and second tanks, said bipolar safety thermostat being configured to cut off the supply to the first and second heating elements when the safety temperature probe detects a temperature greater than or equal to a safety temperature threshold.

[0019] Thus, the safety thermostat ensures the safety function for the two tanks of the electric water heater by cutting off the power supply to their heating elements in the event of exceeding the safety temperature threshold.

[0020] The safety temperature threshold may, for example, be 90°C.

[0021] According to one embodiment of the invention, the safety temperature probe is a single thermosensitive capillary having a first sensitive zone disposed in the first tank and a second sensitive zone disposed in the second tank, the bipolar safety thermostat comprising third and fourth power contacts actuated by the safety temperature probe, the third power contact being arranged between a first power supply input of the double tank electric water heater and the second power supply terminals of the first and second heating elements, and the fourth power contact being arranged between a second power supply input of the double tank electric water heater and the input of the second reversing power contact of the second unipolar electromechanical thermostat.

[0022] Thus, in this particular embodiment, the bipolar safety thermostat allows the power supply of the two electromechanical thermostats to be cut off simultaneously using a single thermosensitive capillary with two sensitive areas, which reduces the number of components and therefore the cost, and limits the risks of overheating and wiring errors.

[0023] In the event of exceeding the safety temperature threshold, the expansion of an expansion fluid present inside the capillary allows the power contacts of the safety thermostat to be activated.

[0024] According to a particular feature of the invention, the bipolar safety thermostat and the second unipolar electromechanical thermostat are combined into a single thermostat component.

[0025] Thus, the single thermostat component ensures both the regulation of the second tank (i.e., the hot water outlet tank) and the safety function for both tanks of the electric water heater.

[0026] According to another embodiment of the invention, the safety temperature probe comprises a first thermosensitive capillary having a sensitive area disposed in the first tank and a second thermosensitive capillary having a sensitive area disposed in the second tank, the bipolar safety thermostat comprising third and fourth power contacts actuated by the second thermosensitive capillary and fifth and sixth power contacts actuated by the first thermosensitive capillary, the third power contact being arranged between a first power supply input of the double tank electric water heater and the second power supply terminal of the second heating element, the fourth power contact being arranged between a second power supply input of the double tank electric water heater and the input of the second reversing power contact of the second unipolar electromechanical thermostat,the fifth power contact being arranged between the second output of the second reversing power contact of the second single-pole electromechanical thermostat and the input of the first power contact of the first single-pole electromechanical thermostat, and the sixth power contact being arranged between the second power supply input of the double-tank electric water heater and the second power supply terminal of the first heating element.

[0027] Thus, in this other particular embodiment, each tank has its own safety function, that is to say its own pair of safety power contacts connected to its own heat-sensitive capillary.

[0028] According to a particular feature of the invention, each of the first and second temperature probes is of the bulb type.

[0029] Thus, in the event of exceeding the associated tank temperature threshold, the expansion of an expansion fluid present in the bulb installed inside the tank allows the associated power contact of the regulation system to be activated.

[0030] According to a particular feature of the invention, the first single-pole electromechanical thermostat includes a mechanical human-machine interface configured for the adjustment, by a user, of the temperature threshold of the first tank.

[0031] Thus, the temperature threshold of the first tank of the first electromechanical thermostat can be set / repositioned by the user using the mechanical human-machine interface.

[0032] On the contrary, the temperature threshold of the second tank of the second electromechanical thermostat is not adjustable by the user.

[0033] The first electromechanical thermostat is thus equipped with an "Eco" point enabling compliance with the European ErP directive applicable to products which consume energy, while making it possible for the user to adjust the setpoint, which has a direct effect on the level of comfort.

[0034] The present invention also relates to a method for regulating a double-tank electric water heater as described above, characterized in that the first and second unipolar electromechanical thermostats of the regulation system of the double-tank electric water heater are configured to: electrically supply the second heating element and cut off the supply to the first heating element when the second temperature probe detects a temperature below the temperature threshold of the second tank; electrically supply the first heating element and cut off the supply to the second heating element when the second temperature probe detects a temperature greater than or equal to the temperature threshold of the second tank and the first temperature probe detects a temperature below the temperature threshold of the first tank;and cut off the power supply to the first and second heating elements when the second temperature probe detects a temperature greater than or equal to the temperature threshold of the second tank and the first temperature probe detects a temperature greater than or equal to the temperature threshold of the first tank.

[0035] To better illustrate the object of the present invention, we will describe below, by way of illustration and not limitation, preferred embodiments, with reference to the attached drawings.

[0036] On these drawings:

[0037] [Fig.l] is a schematic diagram of a double-tank electric water heater according to a first embodiment of the invention;

[0038] [Fig.2] is a schematic diagram of a dual-tank electric water heater according to a second embodiment of the invention; and

[0039] [Fig.3] is a schematic diagram of a double-tank electric water heater according to a third embodiment of the invention.

[0040] If we refer to [Fig.1], we can see that it represents the schematic diagram of a double tank electric water heater 1 according to a first embodiment of the invention.

[0041] The double tank electric water heater 1 comprises a first tank 2 and a second tank 3 (for example, made of enamelled steel) arranged, preferably, adjacently in an outer casing (not shown in [Fig.1]).

[0042] The first tank 2 includes a water inlet called cold water inlet 2a and a water outlet 2b, and the second tank 3 includes a water inlet 3a and a water outlet called hot water outlet 3b, the water outlet 2b of the first tank 2 being connected to the water inlet 3a of the second tank 3 by means of a conduit 4.

[0043] The first tank 2 comprises a first electric heating element 2c (for example, a first electric resistor) disposed inside it. And, the second tank 3 comprises a second electric heating element 3c (for example, a second electric resistor) disposed inside it.

[0044] The double tank electric water heater 1 further includes a control system comprising a first single-pole electromechanical thermostat 5 controlled by a first temperature probe 6 disposed in the first tank 2.

[0045] The water heater control system 1 further includes a second single-pole electromechanical thermostat 7 controlled by a second temperature probe 8 located in the second tank 3.

[0046] Each of the first and second temperature probes 6 and 8 is of the bulb type and includes a bulb 6a or 8a in which there is an expansion fluid, said bulb 6a or 8a being disposed inside the associated tank 2 or 3 and being fluidically connected to the associated electromechanical thermostat 5 or 7 via a capillary 6b or 8b.

[0047] The first unipolar electromechanical thermostat 5 includes a first power contact 9 actuated by the first temperature probe 6, said first power contact 9 comprising an input 9a and an output 9b.

[0048] The second unipolar electromechanical thermostat 7 includes a second reversing power contact 10 actuated by the second temperature probe 8, said second reversing power contact 10 comprising an input 10a, a first output 10b and a second output 10c.

[0049] The output 9b of the first power contact 9 is electrically connected to a first 2c 1 of the two supply terminals of the first heating element 2c.

[0050] The first output 10b of the second reversing power contact 10 is electrically connected to a first 3c 1 of the two supply terminals of the second heating element 3.

[0051] The second output 10c of the second reversing power contact 10 is electrically connected to the input 9a of the first power contact 9.

[0052] The second supply terminals 2c2 and 3c2 of the first and second heating elements 2 and 3 are electrically connected to a first electrical supply input 11 of the water heater 1 via a bipolar safety thermostat 13 (which will be described in more detail later).

[0053] The input 10a of the first reversing power contact 10 is electrically connected to a second power supply input 12 of the water heater 1 via the bipolar safety thermostat 13.

[0054] The first temperature probe 6 is configured to: close the first power contact 9 of the first electromechanical thermostat 5 when the first probe of temperature 6 detects a temperature below a first tank temperature threshold inside the first tank 2; and opens the first power contact 9 of the first electromechanical thermostat 5 (by expansion of the expansion fluid present in the bulb 6a) when the first temperature probe 6 detects a temperature greater than or equal to the first tank temperature threshold inside the first tank 2.

[0055] The temperature threshold of the first tank can, for example, be 45°C.

[0056] The second temperature setting 8 is configured to: switch the second contact of reversing power 10 of the second electromechanical thermostat 7 in order to electrically connect its input 10a to its first output 10b when the second temperature probe 8 detects a temperature below a second tank temperature threshold inside the second tank 3; and to switch the second reversing power contact 10 of the second electromechanical thermostat 7 in order to electrically connect its input 10a to its second output 10c (by expansion of the expansion fluid present in the bulb 8a) when the second temperature probe 8 detects a temperature greater than or equal to the second tank temperature threshold inside the second tank 3.

[0057] The temperature threshold of the second tank can, for example, be 60°C.

[0058] Therefore, the operation of the water heater 1 control system is the following :

[0059] - when the second temperature probe 8 detects a lower temperature at the temperature threshold of the second tank (and regardless of the state of the first power contact 9 of the first electromechanical thermostat 5), the second reversing power contact 10 is switched to its first output 10b, which allows the second heating element 3c of the second tank 3 to be electrically supplied while cutting off the supply to the first power terminal 2c 1 of the first heating element 2c of the first tank 2;

[0060] - when the second temperature probe 8 detects a higher or equal to the temperature threshold of the second tank and that the first temperature probe 6 detects a temperature lower than the temperature threshold of the first tank, the second reversing power contact 10 is switched to its second output 10c and the first power contact 9 is closed, which allows the first heating element 2c of the first tank 2 to be electrically powered while cutting off the power to the first power terminal 3c 1 of the second heating element 3c of the second tank 3; and

[0061] - when the second temperature probe 8 detects a higher or equal to the temperature threshold of the second tank and that the first temperature probe 6 detects a temperature greater than or equal to the temperature threshold of the first tank, the second reversing power contact 10 is switched to its second output 10c and the first power contact 9 is open, which allows the supply to the first power terminals 2cl, 3cl of the first and second heating elements 2c, 3c of the first and second tanks 2 and 3 to be cut off.

[0062] Table 1 below summarizes the heating state of the water heater 1 as a function of the states of the first and second power contacts 9 and 10.

[0063] [Tables 1] State of the first power contact e9 State of the second power contact reversing switch 10 Heating of the first heating element 12°C of the first tank 2 Heating of the second heating element 3°C ​​of the second tank 3 Closed Switching to second output 10°C Yes No Closed Switching to first output 10°B No Yes Open Switching to first output 10°B No Yes Open Switching to second output 10°C No No

[0064] It should be noted that the first and second heating elements 2c and 3c of the first and second tanks 2 and 3 can never be supplied (and therefore heated) simultaneously.

[0065] It can thus be seen that the use of an inverting regulation (namely the second inverting power contact 10) makes it possible to give priority of heating to the second tank 3 (that is to say, to the hot water outlet tank), which makes it possible to guarantee the comfort of the user while minimizing the instantaneous electrical power.

[0066] Compared to existing electronic solutions, the first and second electromechanical thermostats 5 and 7 of the water heater 1 offer cost benefits and ease of use for the end user (no human-machine interface for adjustment that could lead to errors). Furthermore, they are more robust and repairable in the long term with standardized components. In addition, they consume no energy in standby mode and do not include any components subject to potential obsolescence.

[0067] The water heater control system 1 further comprises the bipolar safety thermostat 13 controlled by a safety temperature probe 14 located in both the first and second tanks 2 and 3, said bipolar safety thermostat 13 being configured to ensure the safety function of both tanks 2 and 3 of the water heater. water 1 by cutting off the power supply to the first and second heating elements 2c and 3c when the safety temperature probe 14 detects a temperature greater than or equal to a safety temperature threshold.

[0068] In this first embodiment, the safety temperature probe 14 is a single thermosensitive capillary having a first sensitive zone 14a disposed in the first tank 2 and a second sensitive zone 14b disposed in the second tank 3, which makes it possible to reduce the number of components and therefore the cost, and to limit the risks of overheating as well as wiring errors.

[0069] The bipolar safety thermostat 13 includes third 15 and fourth 16 power contacts actuated by the safety temperature probe 14.

[0070] The third power contact 15 is arranged between the first power supply input 11 of the water heater 1 and the second power supply terminals 2c2 and 3c2 of the first and second heating elements 2c and 3c.

[0071] The fourth power contact 16 is arranged between the second power supply input 12 of the water heater 1 and the input 10a of the second reversing power contact 10 of the second electromechanical thermostat 7.

[0072] Thus, when the safety temperature probe 14 detects an exceedance of the safety temperature threshold in one or the other of the two tanks 2 and 3, or in both tanks, the expansion fluid present in the single thermosensitive capillary of the safety temperature probe 14 expands, which causes the third and fourth power contacts 15 and 16 of the bipolar safety thermostat 13 to open, so that the latter allows the power supply to be cut off simultaneously to the two heating elements 2c and 3c of the two tanks 2 and 3.

[0073] The safety temperature threshold may, for example, be 90°C.

[0074] Optionally, the temperature threshold of the first tank of the first thermostat electromechanical 9 can be adjusted by the user using a mechanical human-machine interface 17 connected to the first electromechanical thermostat 9.

[0075] On the contrary, the temperature threshold of the second tank of the second electromechanical thermostat 7 is not adjustable by the user.

[0076] If we refer to [Fig.2], we can see that it represents the schematic diagram of a double tank electric water heater 18 according to a second embodiment of the invention.

[0077] The common elements between the first embodiment of the invention in [Fig.1] and this second embodiment of the invention bear the same reference number, and will not be described in more detail here when they are of identical structures.

[0078] The double-tank electric water heater 18 according to the second embodiment is identical to the double-tank electric water heater 1 according to the first embodiment, except that, unlike the first embodiment in which the bipolar safety thermostat 13 and the second unipolar electromechanical thermostat 7 are two separate components, in the second embodiment the bipolar safety thermostat 13 and the second unipolar electromechanical thermostat 7 are combined into a single thermostat component 19 which makes it possible to ensure both the regulation of the second tank 3 (i.e., the hot water outlet tank) and the safety function for both tanks 2 and 3 of the double-tank electric water heater 18.

[0079] Referring to [Fig. 3], it can be seen that it shows the schematic diagram of a double-tank electric water heater 20 according to a third embodiment of the invention.

[0080] The common elements between the first embodiment of the invention in [Fig.[l] and this third embodiment of the invention bear the same reference number, and will not be described in more detail here when they are of identical structures.

[0081] The double-tank electric water heater 20 according to the third embodiment is identical to the double-tank electric water heater 1 according to the first embodiment, except that, unlike the first embodiment in which the bipolar safety thermostat 13 allows the power supply to the first and second heating elements 2c and 3c to be cut off simultaneously using a single thermosensitive capillary 14, in the third embodiment the safety temperature probe comprises a first thermosensitive capillary 22 having a sensitive area 22a disposed in the first tank 2 and a second thermosensitive capillary 21 having a sensitive area 21a disposed in the second tank 3,the bipolar safety thermostat 13 comprising a first part consisting of the third and fourth power contacts 15 and 16 actuated by the second heat-sensitive capillary 21 and a second part consisting of the fifth and sixth power contacts 23 and 24 actuated by the first heat-sensitive capillary 22.

[0082] The third power contact 15 is arranged between the first power supply input 11 of the double tank electric water heater 20 and only the second power supply terminal 3c2 of the second heating element 3c.

[0083] The fourth power contact 16 is arranged between the second power supply input 12 of the double tank electric water heater 20 and the input 10a of the second reversing power contact 10 of the second electromechanical thermostat 7.

[0084] The fifth power contact 23 is incorporated between the second output 10c of the second reversing power contact 10 of the second electromechanical thermostat 7 and the input 9a of the first power contact 9 of the first electromechanical thermostat 5.

[0085] The sixth power contact 24 is arranged between the second power supply input 12 of the double tank electric water heater 20 and the second power supply terminal 2c2 of the first heating element 2c.

[0086] When the second thermosensitive capillary 21 detects an exceedance of the safety temperature threshold in the second tank 3, the expansion fluid present in the second thermosensitive capillary 21 expands, which causes the third and fourth power contacts 15 and 16 of the bipolar safety thermostat 13 to open, so that the supply to the second heating element 3c of the second tank 3 is cut off.

[0087] In addition, regardless of the state of the second thermosensitive capillary 21, when the first thermosensitive capillary 22 detects an exceedance of the safety temperature threshold in the first tank 2, the expansion fluid present in the first thermosensitive capillary 22 expands, which causes the fifth and sixth power contacts 23 and 24 of the bipolar safety thermostat 13 to open, so that the supply to the first heating element 2c of the second tank 2 is cut off.

[0088] Thus, in this third embodiment, each tank 2 or 3 has its own safety function, that is to say its own pair of safety power contacts 23, 24 or 15, 16 connected to its own thermosensitive capillary 22 or 21.

[0089] It is understood that the particular embodiments which have just been described have been given by way of indication and not limitation, and that modifications may be made without departing from the present invention.

Claims

Demands

1. Double tank electric water heater (1; 18; 20) comprising a first tank (2) and a second tank (3), the first tank (2) comprising a first heating element (2c), an inlet called cold water inlet (2a) and an outlet (2b), the second tank (3) comprising a second heating element (3c), an inlet (3a) and an outlet called hot water outlet (3b), the outlet (2b) of the first tank (2) being connected to the inlet (3a) of the second tank (3), characterized in that said double tank electric water heater (1; 18; 20) further comprises a control system comprising: - a first single-pole electromechanical thermostat (5) controlled by a first temperature probe (6) disposed in the first tank (2); and - a second single-pole electromechanical thermostat (7) controlled by a second temperature probe (8) disposed in the second tank (3);the first and second unipolar electromechanical thermostats (5, 7) being configured to: - electrically supply the second heating element (3c) and cut off the supply to the first heating element (2c) when the second temperature probe (8) detects a temperature below a second tank temperature threshold; - electrically supply the first heating element (2c) and cut off the supply to the second heating element (3c) when the second temperature probe (8) detects a temperature greater than or equal to the second tank temperature threshold and the first temperature probe (6) detects a temperature below a first tank temperature threshold;and - cut off the power supply to the first and second heating elements (2c, 3c) when the second temperature probe (8) detects a temperature greater than or equal to the temperature threshold of the second tank and the first temperature probe (6) detects a temperature greater than or equal to the temperature threshold of the first tank.;

2. A double (1; 18; 20) tank electric water heater according to claim 1, characterized in that the first single-pole electromechanical thermostat (5) comprises a first contact of power (9) actuated by the first temperature probe (6), and the second single-pole electromechanical thermostat (7) includes a second changeover power contact (10) actuated by the second temperature probe (8), an output (9b) of the first power contact (9) being connected to a first (2c1) of two supply terminals (2c1, 2c2) of the first heating element (2c), a first (10b) of two outputs (10b, 10c) of the second changeover power contact (10) being connected to a first (3c1) of two supply terminals (3c1, 3c2) of the second heating element (3c), and the second (10c) of the two outputs (10b, 10c) of the second changeover power contact (10) being connected to an input (9a) of the first power contact (9), such that: - when the second temperature probe (8) detects a temperature below the second tank temperature threshold, the second reversing power contact (10) is switched to its first output (10b), so as to electrically supply the second heating element (3c) while cutting off the supply to the first power terminal (2c 1) of the first heating element (2c); - when the second temperature probe (8) detects a temperature greater than or equal to the temperature threshold of the second tank and the first temperature probe (6) detects a temperature less than the temperature threshold of the first tank, the second reversing power contact (10) is switched to its second output (10c) and the first power contact (9) is closed, so as to electrically supply the first heating element (2c) while cutting off the supply to the first power terminal (3c 1) of the second heating element (3c);and - when the second temperature probe (8) detects a temperature greater than or equal to the temperature threshold of the second tank and the first temperature probe (6) detects a temperature greater than or equal to the temperature threshold of the first tank, the second reversing power contact (10) is switched to its second output (10c) and the first power contact (9) is opened, so as to cut off the supply to the first power supply terminals (2c 1, 3c 1) of the first and second heating elements (2c, 3c).

3. Double tank electric water heater (1; 18; 20) according to claim 1 or 2, characterized in that the control system further comprises a bipolar safety thermostat (13) controlled by a safety temperature probe (14; 21, 22) disposed in the first and second tanks (2, 3), said bipolar safety thermostat (13) being configured to cut off the supply to the first and second heating elements (2c, 3c) when the safety temperature probe (14; 21, 22) detects a temperature greater than or equal to a safety temperature threshold.

4. A double-tank (1; 18) electric water heater according to claim 3 depending on claim 2, characterized in that the safety temperature probe (14) is a single heat-sensitive capillary tube having a first sensitive area (14a) disposed in the first tank (2) and a second sensitive area (14b) disposed in the second tank (3), the bipolar safety thermostat (13) comprising third and fourth power contacts (15, 16) actuated by the safety temperature probe (14), the third power contact (15) being arranged between a first power supply input (11) of the double-tank (1; 18) electric water heater and the second power supply terminals (2c2, 3c2) of the first and second heating elements (2c, 3c), and the fourth power contact (16) being arranged between a second power supply input (12) of the double-tank (1; 18) electric water heater. ;18) and an input (10a) of the second reversing power contact (10) of the second single-pole electromechanical thermostat (7).;

5. Double tank electric water heater (18) according to claim 4, characterized in that the bipolar safety thermostat (13) and the second unipolar electromechanical thermostat (7) are combined into a single thermostat component (19).

6. A double-tank electric water heater (20) according to claim 3 depending on claim 2, characterized in that the safety temperature probe comprises a first heat-sensitive capillary (22) having a sensitive area (22a) disposed in the first tank (2) and a second heat-sensitive capillary (21) having a sensitive area (21a) disposed in the second tank (3), the bipolar safety thermostat (13) comprising third and fourth power contacts (15, 16) actuated by the second heat-sensitive capillary (21) and fifth and sixth power contacts (23, 24) actuated by the first heat-sensitive capillary (22), the third power contact (15) being arranged between a first power supply input (11) of the double-tank electric water heater (20) and the second power supply terminal (3c2) of the second heating element (3c), the fourth power contact (16) being arranged between a second power supply input (12) of the double-tank electric water heater (20) and the input (10a) of the second changeover power contact (10) of the second single-pole electromechanical thermostat (7), the fifth power contact (23) being arranged between the second output (10c) of the second changeover power contact (10) of the second single-pole electromechanical thermostat (7) and the input (9a) of the first power contact (9) of the first single-pole electromechanical thermostat (5),and the sixth power contact (24) being arranged between the second power supply input (12) of the double-tank electric water heater (20) and the second power supply terminal (2c2) of the first heating element (2c).

7. Double tank electric water heater (1; 18; 20) according to any one of claims 1 to 6, characterized in that each of the first and second temperature probes (6, 8) is of the bulb type.

8. Dual tank electric water heater (1; 18; 20) according to any one of claims 1 to 7, characterized in that the first single-pole electromechanical thermostat (5) includes a mechanical human-machine interface (17) configured for setting, by a user, the temperature threshold of the first tank.

9. A method for regulating a dual-tank electric water heater (1; 18; 20) according to any one of claims 1 to 8, characterized in that the first and second single-pole electromechanical thermostats (5, 7) of the regulation system of the dual-tank electric water heater (1; 18; 20) are configured to: - electrically supply the second heating element (3c) and cut off the power supply to the first heating element (2c) when the second temperature probe (8) detects a temperature below the second tank temperature threshold; - electrically supply the first heating element (2c) and cut off the power supply to the second heating element (3c) when the second temperature probe (8) detects a temperature greater than or equal to the second tank temperature threshold and the first temperature probe (6) detects a temperature below the first tank temperature threshold; and - cut off the power supply to the first and second heating elements (2c, 3c) when the second temperature probe (8) detects a temperature greater than or equal to the temperature threshold of the second tank and the first temperature probe (6) detects a temperature greater than or equal to the temperature threshold of the first tank.