Electric boiler

Abstract

The present invention provides an electric boiler (1) having a heating element (10a) surrounded by a heat-conducting inner container (5) to define an inner channel around the heating element, the inner container (5) having an inlet (13, 14) and an outlet (3) for water flow and arranged such that water received at the inlet of the inner container flows along the inner channel near the surface of the heating element (10a), the boiler further comprising an outer container (6) substantially located therein, the outer container (6) defining an outer channel around at least a portion of the inner container (5), the outer container having an outlet to the inner container, wherein the outer container (6) is arranged to cause water to flow along the outer channel near the surface of the inner container, such that water received in the boiler passes through the boiler at least twice to increase potential heat transfer to the water.

Description

Technical Field

[0001] This invention relates to an electric boiler, and particularly, but not exclusively, to an electric boiler suitable for heating sanitary water in residential or commercial premises or suitable for use in central heating systems. Background Technology

[0002] Generally, electric boilers have historically been primarily used for single-point supply applications, such as electric showers, hot water supply for a single (or localized) washbasin, or similar applications where a traditional central regenerative heater or fossil fuel boiler is not required. This was likely to avoid the costs and potential disruptions associated with installing a larger heating system, or to ensure a reliable, instantaneous supply of hot water. However, more recently, electric boilers have also been more commonly used to replace more traditional fossil fuel boilers, where they centrally supply hot water to multiple sanitary outlets and / or form a central heating system. These new applications of electric boilers require boilers with significantly higher power outputs compared to those traditionally used in the examples described above. Summary of the Invention

[0003] The objective of this invention is to provide a particularly compact electric boiler capable of providing instantaneous hot water supply, suitable for domestic hot water supply or central heating systems.

[0004] According to the present invention, an electric boiler is provided, comprising a heating element and a heat-conducting inner container, the inner container generally surrounding the heating element to define an inner channel around the heating element, the inner container having an inlet and an outlet for water flow and arranged such that water received at the inner container inlet flows along the inner channel near a surface of the heating element to the inner container outlet, the boiler further comprising an outer container in which the inner container is generally located, the outer container defining an outer channel around at least a portion of the inner container, the outer container having an inlet and an outlet for water flow, wherein the outer container outlet is fluidly connected to or forms the inner container inlet, and wherein the outer container is arranged such that water received at the outer container inlet flows along the outer channel near a surface of the inner container to the outer container outlet.

[0005] By having an inner container that substantially surrounds the heating element, the inner container can be arranged to concentrate the water flow onto the surface of the heating element, providing only a small gap between the surface of the container and the surface of the heating element, thus providing a low-volume space that forces water to flow through at a high velocity, providing a high heating surface area to volume ratio. The advantage of this arrangement is that, due to the low volume of water stored within the boiler, there is minimal inertia within the boiler, allowing it to function as an instantaneous hot water heater, at least at the point where the water leaves the boiler. This not only has the benefit of being able to provide a hot water source quickly (without the need for a cylinder to preheat the hot water), but it also minimizes the residual energy stored within the boiler after the hot water has been extracted.

[0006] The provision of an outer container (inner container generally located therein) allows water drawn into the boiler inlet to be preheated by first passing through the outer container and absorbing heat from the inner container before being drawn through it (where it contacts the heating element), particularly if the inner and outer containers share a common heat-conducting wall. Therefore, the boiler according to the invention can be used to increase the area of ​​the heating surface in contact with a smaller volume of water, which allows significantly more energy to be extracted from the heating element without causing the water to boil at any point.

[0007] Preferably, the inner and outer channels are arranged such that, in use, water in the first inner channel travels along the first channel in a direction opposite to the direction in which the water travels along the second channel.

[0008] The above arrangement can provide a particularly compact boiler arrangement that can be constructed at a lower cost, but it can also be arranged such that the coldest water entering the outer chamber contacts the hottest part of the inner container, thereby maximizing heat transfer from the water in the inner container to the water in the outer container.

[0009] In one embodiment, the boiler may include multiple heating elements located within a common inner container. This allows the heating elements to be arranged compactly while allowing water within the inner container to flow freely between them. It also allows the use of multiple standard heating elements, such as multiple standard, off-the-shelf, two-kilowatt box-type heating elements.

[0010] In an alternative arrangement, the boiler may include a plurality of elongated heating elements and a plurality of tubular inner containers, each heating element being concentrically arranged within its associated inner container. Thus, each of the plurality of heating elements has its own inner container, thereby forcing water entering the inner container to flow over the surface of the associated heating element. This maximizes the volume of water contacting the surface area of ​​the heating elements by avoiding any “backflow” that might otherwise occur. With this arrangement, it is preferable for the boiler to include a single outer container in which the plurality of inner containers, along with their associated heating elements, are arranged.

[0011] Multiple inner containers can be arranged side-by-side in a cylindrical pattern and connected to each other to define a central channel within the boiler, thereby aligning the inner containers with the longitudinal axis of the boiler; and wherein the boiler is arranged such that water enters through an outer container at or toward a first end of the boiler and travels along the outer channel in a first longitudinal direction to exit the outer channel at or toward a second end of the boiler opposite the first end through an outer container outlet. Water can then enter the inner containers through corresponding inner container inlets located at or toward the second end of the boiler, and then travel along corresponding inner channels to exit via corresponding outlets of the inner containers located at or toward the first end of the boiler. From there, water can enter the central channel and travel along the central channel toward the second end of the boiler. Thus, the inner containers can form the walls of the outer container, thereby defining the outer channel, can form the inner channel, and can also form a third central channel, thereby allowing water to flow directly onto the heating element in one return (second return) and indirectly onto the heating element in two additional returns (first and third returns).

[0012] The boiler's outer container may include at least two end portions and a cylindrical portion in which multiple inner containers are located, extending between the at least two end portions, wherein each heating element is fixed in a suitable position in one of the two end portions. This arrangement provides a particularly compact arrangement and may require machining of only the end portions (or only one end portion) to allow the heating elements to be properly installed.

[0013] The outer container inlet can be arranged to tangentially guide water into the outer channel, so that as the water travels along the channel to the outer container outlet, it circulates around the inner container. This arrangement ensures that the water in the outer container circulates throughout the inner container, thereby cooling the entire surface area of ​​the inner container without the need for baffles installed in the outer container or otherwise directing the flow.

[0014] The electric boilers described above may also include one or more ultrasonic transducers arranged to break down or remove any scale buildup on surfaces within the boiler. This can be important in applications where the boiler is used to heat domestic water and is therefore not a sealed system. Consequently, the system will not be able to include inhibitors and will be subject to a continuous supply of fresh impurities, such as scale. However, internal or external filters can be used to reduce the amount of impurities entering the boiler.

[0015] In one embodiment, the outer container is a first outer container, and the boiler further includes a second outer container in which the first outer container is located, wherein the first and second outer containers share a common heat-conducting wall, the second outer container has an inlet and an outlet and defines a second outer container passage arranged to deliver water near the common heat-conducting wall from the inlet of the second outer container to the outlet, wherein the passage of the second outer container is fluidly isolated from the passage of the first outer container and the passage of the inner container, or fluidly isolated from the inner container.

[0016] Using the boiler arrangement described above, a first outer container and an inner container define a first flow path, and one or more heating elements are available to heat the water flowing along the first flow path. However, when water is not being drawn through this first flow path, the water in that first flow path can still be heated, which will heat the water flowing in the second outer container, thereby defining a second flow path separate from the first flow path. In this way, two fluid-isolated independent water supplies or flow paths can be heated without the need for diverter valves, etc. The above arrangement can be used to form a combined boiler for a central heating system according to a second aspect of the invention.

[0017] According to a second aspect of the invention, the central heating system includes a boiler as described above, wherein domestic water to be heated enters through a first inlet of the boiler, is then received and passed through by a passage in a first outer container and a passage in an inner container (in which the domestic water is heated), and then exits through a first outlet of the boiler. The boiler additionally has a second inlet to which the return flow of the central heating system is connected, wherein water entering the second inlet passes through a passage in a second outer container to recirculate around the central heating system and exits the boiler through a second outlet.

[0018] Utilizing a central heating system (as described above), the electric boiler of the present invention functions as a combined boiler, in which domestic water is drawn through a first outer container and an inner container and heated therein. Then, when domestic water is not drawn through the boiler, the water in the boiler can be heated to transfer energy to the water in the central heating system passing through a second outer container. Therefore, the flow of domestic water through the boiler can be used to control the transfer of energy from the heating elements to the central heating system without the use of valves, because when domestic water is drawn, this absorbs the heat energy generated by the heating elements. However, when domestic water is not drawn, energy can then be transferred to the central heating system. The main advantage of this arrangement is that domestic water automatically takes precedence over the available heat energy supplied by the heating elements.

[0019] The central heating system described above preferably also includes a pump, a temperature sensor, a flow or pressure sensor, and a controller; the pump circulates water around the central heating system, the temperature sensor detects the temperature of the water returning to the boiler through a second inlet, the flow or pressure sensor detects the flow of domestic water through the boiler, and the controller is arranged to control the pump at least in part based on signals received from the temperature sensor and the flow or pressure sensor. The controller can then be arranged to activate the pump when it detects that domestic water is being drawn from the boiler and the temperature of the centrally heated water returning to the boiler is higher than a predetermined temperature, and configured to shut off the pump when it detects that domestic water is being drawn from the central heating system and the temperature of the water returning to the boiler is lower than a predetermined temperature.

[0020] With the above arrangement, the central heating pump can be shut off when domestic water is drawn through the boiler, so that all the heat generated in the boiler is conducted to the domestic water passing through the boiler. However, if the water returning from the central heating system is above a predetermined temperature, the heat stored in the central heating system can be used to heat the domestic water (as the domestic water passes through the first outer container in its first return stroke), so that the domestic water is then preheated by the central heating return flow before passing through the inner container of the boiler. Attached Figure Description

[0021] Two embodiments of the invention will now be described by way of example only, with reference to the following figures, wherein:

[0022] Figure 1 A side perspective view of the boiler according to the present invention;

[0023] Figure 2 For crossing Figure 1 A vertical sectional view of the boiler;

[0024] Figure 3 For crossing Figure 2 Sectional view of line III-III;

[0025] Figure 4 A vertical sectional view through the boiler according to the invention, similar to Figure 1 Boiler;

[0026] Figure 5 For along Figure 4 A cross-sectional view of line VV;

[0027] Figure 6 Schematic illustration of the use of Figure 2 or Figure 4 The boiler's control system;

[0028] Figure 7 To indicate Figure 6 The flowchart of the control logic of the control system;

[0029] Figure 8 A vertical sectional view through the boiler according to the invention, similar to Figure 2 and Figure 4 The boiler, but with an outer jacket for heating water in the central heating system;

[0030] Figure 9 For crossing Figure 8 A cross-sectional view of line IX-IX;

[0031] Figure 10 A vertical sectional view through the boiler according to the invention, similar to Figure 8 Boiler;

[0032] Figure 11 For along Figure 10 A cross-sectional view of line XI-XI;

[0033] Figure 12 Schematic illustration of the use of Figure 8 or Figure 10 The boiler's control system; and

[0034] Figure 13 To indicate Figure 12 The flowchart of the control logic of the control system. Detailed Implementation

[0035] refer to Figure 1 , Figure 1 A side view of a boiler according to the present invention, generally indicated as 1, showing a cold water inlet 2 and a hot water outlet 3, as illustrated. The positions of the cold water inlet 2 and the hot water outlet 3 correspond to... Figure 2 and Figure 3 The locations shown in the embodiment of the boiler are illustrated. However, the cold water inlet 2 and hot water outlet 3 can be located in any convenient location, with suitable piping provided within the outer casing 4 of the boiler 1. However, to minimize the overall casing size, the inlet 2 and outlet 3 can be positioned as shown, such that they are directly connected to the main heating vessel within the boiler 1, which will be described below with reference to subsequent figures.

[0036] Although not shown, Figure 1 The boiler will also have electrical connections for receiving electrical energy to heat the water passing through the boiler, and it may also have appropriate control connections, although, as will be described below, the boiler 1 can be controlled by a circuit that can be housed within the boiler casing 4.

[0037] For reference Figure 2 and Figure 3A cross-sectional view shows that boiler 1 includes an inner container 5 and an outer container 6, which share a common first end plate 7. The inner container 5 also includes a fan-shaped inner cylinder 8 (which can be seen more clearly in…). Figure 3 ) and inner end plate 9. The inner container 5 includes seven 2 kW heating element boxes 10a-10g ( Figure 3 (As shown), where only heating element boxes 10a, 10g, and 10d are in Figure 2 The middle part is visible.

[0038] Each of the heating element boxes 10a-10g includes an internal electrical conductor and may additionally have a temperature sensing device (such as a thermistor) to control and limit the internal temperature of the heating element box, but the temperature may be controlled in any of a variety of known ways.

[0039] The first end plate 7 has six threaded holes into which one of the heating element boxes 10a-10f is screwed and sealed. Another central hole 11 in the first end plate 7 has a threaded port 12 extending therefrom to provide a hot water outlet 3.

[0040] refer to Figure 2 The inner end plate 9 (at the end of the inner cylinder 8 relative to the first end plate 7) has six holes formed therein, only two of which (13 and 14) are visible in the figure. These are positioned opposite the distal ends of the respective heating element boxes 10a-10f to guide fluid delivered to the inner container 5 onto the respective heating element boxes 10a-10f. There is also a central hole in the inner end plate 9 through which the heating element box 10g passes.

[0041] The outer container 6 is the exterior of the inner container 5. As previously described, the outer container 6 shares the first end plate 7 with the inner container 5, but additionally includes a fan-shaped outer cylinder 15 and an outer end plate 16. The outer end plate 16 has a threaded central hole 17 for the heating box 10g.

[0042] The inner cylinder 8 and the outer cylinder 15 define a small gap of approximately 2 mm to 3 mm wide between their walls, which defines a water jacket 18 surrounding the inner cylinder 8. The separation between the inner end plate 9 and the outer end plate 16 allows the water jacket 18 to extend on the inner end plate 9. (As from...) Figure 2 As can be seen, the outer cylinder 15 has a hole 19 (in which port 20 is screwed), and port 20 forms a cold water inlet 2.

[0043] On either side of the outer cylinder 15, two ultrasonic transducers 21 and 22 are positioned and housed within the outer casing 4 of the boiler 1, which is filled with thermal insulation material 23. The outer cylinder 15 is formed of copper tubing with a wall thickness between 1 mm and 2 mm. The inner cylinder 8 is formed of copper tubing of similar thickness and defines a water jacket 18 therebetween, which may be approximately 2 mm to 3 mm wide. When the heating element boxes 10a-10g are located within the inner cylinder 8 and the boiler is filled with water, they will have a natural resonant frequency, and the ultrasonic transducers 21 and 22 are tuned to approximately match this frequency to maximize their efficiency in preventing scaling and other deposits from accumulating within the boiler 1. The boiler additionally includes an overtemperature sensor 24, which is triggered when the temperature inside the boiler exceeds a safe operating threshold.

[0044] The cold water inlet 2 (in the form of a threaded port 20) is tangentially guided to the walls of the inner cylinder 8 and the outer cylinder 15. Therefore, in use, the cold water entering the space between the outer cylinder 15 and the inner cylinder 8 is guided circumferentially around the inner cylinder 8, thus spiraling forward as it is drawn downwards and passes through the holes 13, 14 in the inner end plate 9. Then, its journey through the inner cylinder 8 is directly conducted to the outer surface of the heating element boxes 10a-10g before exiting the threaded port 12 to the outlet 3. Therefore, in use, when the heating element boxes 10a-10g are energized and water is conducted from the cold water inlet 2 to the hot water outlet 3 via the boiler 1, the water is first passed around the outside of the inner container 5, thus preheating the water by absorbing heat from the inner container 5, then passes through the holes 13 and 14 into the inner container 5, where it is then heated in a second pass by direct contact with the heating element boxes 10a-10g.

[0045] Figures 1 to 3 The double-pass arrangement of boiler 1 shown provides a large heat transfer area to the limited volume of water contained within boiler 1.

[0046] For reference Figure 4 and Figure 5 This is shown here. Figures 1 to 3 The alternative boiler shown is typically designated as 25. Boiler 25 has multiple... Figure 2 and Figure 3 The same parts as boiler 1, and similar labels are used to indicate similar parts, which will not be described here.

[0047] exist Figure 4 and Figure 5 In one embodiment, six 2-kilowatt heating element boxes 26a-26f are arranged in a cylindrical pattern in the first end plate 27, wherein only heating element boxes 26a and 26d are in a cylindrical pattern. Figure 4 The middle part is visible.

[0048] In this embodiment, each of the heating element housings 26a-26f has a corresponding inner cylinder 28a-28f, which is coupled to a first end plate 27 at a first end and to a common inner end plate 29 at a second end. As in the previous embodiment, the inner end plate 29 has holes, only two of which (30 and 31) are visible. Figure 4 In the middle, it is positioned opposite to the end of each heating element box 26a-26f.

[0049] Each of the inner cylinders 28a-28f has a hole, of which only two (33 and 34) are visible. Figure 4 In the middle, adjacent to the first end plate 27. These holes connect the interior of each inner cylinder 28a-28f to a central channel 32. The central channel 32 extends the length of the inner cylinders 28a-28f and extends through the inner end plate 29 to a threaded port 35, which forms a hot water outlet 3. (As from...) Figure 5 As can be seen, the six inner cylinders 28a-28f are adjacent to each other and welded together, so that they form a continuous sealing surface to define the central channel 32. The outer cylinder 36 is located outside the inner cylinders 28a-28f, and the outer cylinder 36 defines a space that forms a water jacket 37 when filled with water.

[0050] During use, water enters through cold water inlet 2. Figure 4 and Figure 5 Boiler 25 and spirals downward within water jacket 37, through holes (such as...) Figure 4 Before entering the inner cylinders 28a-28f through the holes 30 and 31 shown, heat energy is extracted from the outward-facing outer surfaces of the inner cylinders 28a-28f. Water is then forced to flow across the surface of the heating element housings 26a-26f and exits at the holes (such as holes 33 and 34) into the central conduit 32. Here, the water travels along the length of the central conduit 32 (contacting the inward-facing outer surfaces of the inner cylinders 28a-28f), thus extracting heat energy from the inward-facing outer surfaces of the inner cylinders 28a-28f as it passes through the boiler 25 in a third pass, and then exits at the hot water outlet 3.

[0051] It should be understood that the same advantages are... Figure 4 and Figure 5 The boiler 25 achieves this, just like with Figure 2 and Figure 3 Boiler 1 is used to achieve this; but utilizing Figure 4 and Figure 5 The boiler 25 allows the water to undergo an additional third pass, resulting in even more efficient heat exchange with the heating element boxes 26a-26f.

[0052] For reference Figure 6 Here, the control is schematically shown. Figure 2 and Figure 3 Boiler 1 or Figure 4 and Figure 5 The boiler 25 contains various components. These components include a processor (control circuit) 38, which is arranged to control the supply of electrical energy along cables 39 to the heating element boxes 10a-10g or 26a-26f. The processor 38 is also connected via wire 40 to the temperature sensors of the internal heating elements 10a-10g or 26a-26f.

[0053] The processor 38 is also connected via wire 41 to the over-temperature sensor 24, and via wire 43 to an optional flow sensor 42. The flow sensor 42 is shown externally to the boiler 1. However, it should be noted that... Figure 6 This is for illustrative purposes only, and the flow sensor 42 and processor 38 may be located inside the outer casing 4 of the boiler 1.

[0054] For reference Figure 7 In operation, at start 44, processor 38 first determines in step 45 whether there is a demand for hot water based on flow sensor 42. If there is no demand for hot water, processor 38 returns to start 44. However, in an alternative embodiment, if no flow sensor is present, the heating element can be maintained at 60°C; in this case, step 45 can be omitted. In the illustrated embodiment, if there is a demand for hot water, processor 38 proceeds to step 46 and determines whether the temperature inside heating element boxes 10a-10g or 26a-26f is higher than 60°C. If this temperature is exceeded, processor proceeds to step 47 and shuts off heating element boxes 10a-10g or 26a-26f, and returns to start 44. However, if in step 46 the heating element temperature is not detected to be higher than 60°C, processor 38 proceeds to step 48 and determines whether an over-temperature value has been exceeded. If it is exceeded, processor 38 proceeds to step 47 and shuts off heating element boxes 10a-10g or 26a-26f, and then returns to start 44. However, if the over-temperature value is not exceeded at step 48, the processor 38 continues to step 49 and opens the heating element boxes 10a-10g or 26a-26f, then returns to start 44 and repeats the process.

[0055] The above describes one process in which the processor 38 controls the energization of the heating element boxes 10a-10g or 26a-26f; however, it will be apparent that any number of other steps could potentially achieve the same overall result. In particular, it should be noted that... Figure 6 The flow sensor 42 is unnecessary; instead, boiler 1 can be maintained at a constant 60°C regardless of whether water flows through the boiler. Figure 7The steps shown are modified accordingly by deleting step 45.

[0056] For reference Figure 8 and Figure 9 Here, an embodiment of a boiler (generally indicated as 50) is shown, which is essentially a double-pass boiler for providing hot water, similar to the previous references. Figure 2 and Figure 3 The boiler that has been disclosed and described. (and) Figure 2 and Figure 3 Common components will not be described here, as they function in the same way. However, in Figure 8 and Figure 9 In one embodiment, a second outer cylinder 51 is located around a first outer cylinder 15 (hereinafter referred to as the first outer cylinder 15 in this embodiment) to define a space 52 between the second outer cylinder 51 and the first outer cylinder 15. The second outer cylinder 51 is coupled to a first end plate 7 at a first end, the first end plate 7 together with the second outer end plate 53 forming a second water jacket 54 surrounding the outer container 6. The second water jacket 54 has a second inlet 55 at a first end and a second outlet 56 at a second end. This separate second water jacket 54 can be used to heat a separate body of water, and this can typically form a boiler in a centrally heated system. Therefore, in Figure 8 and Figure 9 In one embodiment, boiler 1 may function as a combined boiler to heat domestic hot water and water for a central heating system, respectively, in a manner described later.

[0057] For reference Figure 10 and Figure 11 These figures illustrate boiler 57, which is similar to the previous reference. Figure 4 and Figure 5 The boiler described is a three-pass boiler. Similar to previous references. Figure 8 and Figure 9 In the described embodiment, boiler 57 further includes an additional second outer cylinder 58 and a second outer end plate 59, thereby forming a second water jacket 60, such that it is similar to... Figure 4 and Figure 5 The three-pass boiler can also be used to provide domestic hot water and has also been developed for central heating systems.

[0058] For reference Figure 12 Here, the control is schematically shown. Figure 8 and Figure 9 Boiler 50 or Figure 10 and Figure 11 The boiler 57 requires various components. Some of these components are similar to those in previous references. Figure 6The components described include a processor 65 and a flow sensor 42 for determining the time when hot water is drawn through the boiler 50 for sanitary supply.

[0059] Figure 12 The boiler 50 additionally has an outlet 56 connected to a plurality of radiators 62, which in turn are connected to a pump 63. The pump 63 is also connected to the inlet 55 of the boiler 50 via a central heating reflux temperature sensor 64 to complete the reflux of the central heating circuit. The central heating reflux temperature sensor 64 sends a signal along wire 66 to a processor 65 based on the reflux temperature of the water to the boiler 50. The processor 65 also controls the operation of the pump 63 via wire 67, but furthermore, the connection between the processor 65 and the boiler 50 is... Figure 6 The connection between processor 38 and boiler 1 is the same.

[0060] For reference Figure 13 The diagram schematically illustrates that in Figure 8 and Figure 9 Boiler 50 or Figure 10 and Figure 11 During the operation of boiler 57, by Figure 12 The steps performed by processor 65.

[0061] Starting at step 68, processor 65 determines at step 69 whether there is a demand for hot water by monitoring the signal from flow sensor 42. If there is no demand for hot water, then processor 65 determines at step 70 whether there is a demand for central heating. This can be determined within processor 65, which is part of a central heating controller. Alternatively, processor 65 may receive a separate signal (not shown) indicating whether there is a demand for central heating.

[0062] If there is no demand for central heating (and no demand for hot water) at step 70, then processor 65 shuts off central heating pump 63 at step 79 and then shuts off heating element box at step 80, and then returns to start 68.

[0063] However, if there is a demand for central heating (but no demand for hot water) at step 70, then processor 65 turns on central heating pump 63 at step 71.

[0064] Then, at step 72, the processor 65 determines whether the temperature of the heating element boxes 10a-10g is higher than 60°C. If the temperature of the appropriate heating box is higher than 60°C, the processor 65 proceeds to step 73 and shuts down the heating element boxes 10a-10g, then returns to the start 68.

[0065] Alternatively, if the processor determines at step 72 that the temperature of the heating element boxes 10a-10g is below 60°C, then the processor 65 proceeds to step 74 and determines whether the boiler's over-temperature threshold has been exceeded, as determined by the over-temperature sensor 24. If the over-temperature threshold has not been exceeded at step 74, then the processor proceeds to step 75 and turns on the heating element, then returns to start 68. If the over-temperature threshold has been exceeded at step 74, then the processor 65 proceeds to step 73 and turns off the heating element, then proceeds again to start 68.

[0066] If the processor determines at step 69 that there is a demand for hot water, it proceeds to step 76 to determine if the central heating return is above 50°C. If it is not above 50°C, the processor proceeds to step 77, shuts off the central heating pump, and then proceeds again to step 72.

[0067] Alternatively, if the processor 63 determines at step 76 that the central heating reflux is above 50°C, then the processor proceeds to step 78 and turns on the central heating pump, and then continues to step 72.

[0068] When there is a demand for hot water, the purpose of step 76 (the processor determines whether the central heating return is above 50°C) is that if the central heating return is above 50°C, then the central heating pump 63 should be turned on, because, for example, refer to... Figure 8 This will result in warm water being supplied from the central heating system to the second water jacket 54, which will act to preheat the sanitary supply of cold water as it enters the boiler at the cold water inlet. However, if the central heating return is below 50°C, then the processor 65 shuts off the central heating pump 63 at step 77, thereby ensuring that all the heat generated by the heating element boxes (when they are turned on at step 75) is used to heat the sanitary water flowing through the boiler between the cold water inlet 2 and the hot water outlet 3.

[0069] In this manner, the water in the central heating loop can be used as residual energy storage to be depleted when there is a demand for hot water, while the energy in the central heating system is replenished when there is no demand for hot water. This allows a relatively low-power boiler to satisfactorily supply the demand for instantaneous hot water while also providing an energy source for the central heating system.

[0070] For reference above Figure 12 and Figure 13 An alternative embodiment to the described embodiment, Figure 12The central heating reflux temperature sensor 64 can be omitted, as it is assumed that the temperature of the central heating reflux will always be higher than the temperature of the cold water at the cold water inlet 2, and as domestic water enters the boiler 50, some heat will always be transferred from the central heating reflux to the domestic water. With this arrangement, the flow sensor 42 can also be omitted, where the heating element box is controlled to permanently maintain them at 60°C. Figure 13 Steps 69, 76, 77, 78 and 80 will be omitted, with processor 65 proceeding directly from step 78 to step 72.

[0071] The various embodiments of the invention have been described above by way of example only, and many alternative embodiments falling within the scope of the following claims are possible.

Claims

1. An electric boiler comprising a plurality of elongated heating elements and a plurality of inner containers, the plurality of inner containers being thermally conductive, each heating element being concentrically arranged within an associated inner container, each inner container generally surrounding its associated heating element to define an inner channel around its associated heating element, each inner container having an inlet and an outlet for water flow and arranged such that water received at the inlet of the inner container flows along the inner channel near a surface of the associated heating element to the outlet of the inner container, the electric boiler further comprising an outer container in which the inner containers are generally located, the outer container defining an outer channel extending around at least a portion of the inner containers, the outer container having an inlet for water flow and a plurality of outlets, wherein each outer container outlet is connected to or forms a corresponding inner container inlet, and wherein the outer container is arranged such that water received at the inlet of the outer container flows along the outer channel near a surface of the inner container to the outlet of the outer container; The plurality of inner containers are arranged side-by-side in a cylindrical pattern and connected to each other to define a central channel within the electric boiler, wherein the inner containers are aligned with the longitudinal axis of the electric boiler and arranged such that the outlet of the inner container is located at or toward a first end of the electric boiler, and the inlet of the inner container is located at or toward a second end of the electric boiler opposite to the first end. The electric boiler is arranged such that water enters through the outer container at or toward the first end of the electric boiler and travels along the outer channel in a first longitudinal direction to exit the outer channel at or toward the second end of the electric boiler through the outlet of the outer container, and enters the inner container through the respective inner container inlet; then the water travels along the respective inner channel to exit via the respective outlet of the inner container to enter the central channel and travels along the central channel toward the second end of the electric boiler.

2. The electric boiler according to claim 1, wherein the inner container and the outer container share a common heat-conducting wall.

3. The electric boiler according to claim 1 or 2, wherein the outer container comprises at least two end portions and a cylindrical portion therein wherein the plurality of inner containers are located, the cylindrical portion extending between the at least two end portions, wherein each heating element is fixed at a suitable position in one of the two end portions.

4. The electric boiler according to claim 1 or 2, wherein the outer container inlet is arranged to tangentially guide water into the outer channel such that as the water travels along the outer channel to the outer container outlet, the water swirls around the plurality of inner containers.

5. The electric boiler according to claim 1 or 2 further includes one or more ultrasonic transducers, said one or more transducers being arranged to remove or break down any scale or similar accumulations of solid material within the electric boiler.

6. The electric boiler according to claim 1 or 2, wherein the outer container is a first outer container, the electric boiler further comprising a second outer container therein where the first outer container is located, wherein the first outer container and the second outer container share a common heat-conducting wall, the second outer container having an inlet and an outlet and defining a second outer container channel, the second outer container channel being arranged to deliver water near the common heat-conducting wall from the inlet of the second outer container to the outlet, wherein the channel of the second outer container is fluidly isolated from the channel of the first outer container and the channel of the inner container.

7. A central heating and hot water system comprising an electric boiler according to claim 6, the electric boiler further comprising a first inlet connected to a domestic water source and a first outlet arranged to supply domestic water heated once by the electric boiler, the electric boiler further comprising a second inlet and a second outlet connected to a central heating circuit, wherein the electric boiler is configured such that domestic water to be heated enters through the first inlet of the electric boiler before being received and passed through a first outer container channel and an inner container channel, and then exits the electric boiler through the first outlet of the electric boiler, and such that water to be heated from the central heating and hot water system enters through the second inlet of the electric boiler and passes through a channel of the second outer container, and then exits the electric boiler through the second outlet of the electric boiler to recirculate around the central heating and hot water system.

8. The central heating and hot water system of claim 7, further comprising a pump, a temperature sensor, a flow or pressure sensor, and a controller, the pump for circulating water around the central heating system, the temperature sensor for detecting the temperature of water returning to the electric boiler through the second inlet, the flow or pressure sensor for detecting the flow of domestic water through the electric boiler, and the controller arranged to control the pump at least in part based on signals received from the temperature sensor and the flow or pressure sensor, wherein the pump is activated when it detects that the temperature of the centrally heated water drawn from the electric boiler and returned to the electric boiler is higher than a predetermined temperature, and wherein the pump is deactivated when the temperature of the water returning from the central heating system to the electric boiler is lower than a predetermined temperature.

Images