GB2179430A - Thermoelectric water heater - Google Patents

Abstract

A thermoelectric water heater includes a passage 2 through which water to be heated can flow at relatively slow rate, an insulated thermoelectric element 3,4 located in intimate contact with the passage 2 to heat the water passing therethrough, and a container 5 for receiving heated water from the passage and also arranged to receive heat through direct contact with the passage. The heater also includes a controller which controls both the electricity and water by means of single rotary lever 21 which acts on an electrical switch and a water valve 24 in the water supply pipe. The passage 2 as shown is a coiled thin metal pipe formed into a flat helix but may take a circular helix, rectangular spiral or other form or may be replaced by a thin metal box or tray compartmented to provide sinuous channels. <IMAGE>

Description

SPECIFICATION Thermoelectric water heater This invention relates to thermoelectric apparatus for providing hot water and/or warm air for public and domestic requirements.

The principal object of the invention is to provide hot water and/or warm air for washing, cleaning, bathing and space-heating in an economical, simple, safe and convenient manner in houses, hotels, restaurants, shops and like premises.

To this end, according to the principal feature of the invention, water to be heated is passed through at least one thin metallic pipe or sinuously-channelled box or tray which is so arranged that the water will flow at a relatively slow rate, an insulated thermoelectric element is placed in intimate contact with the or each pipe, box or tray so as to heat the water passing therethrough, and a container is provided to receive heated water flowing from the or the last pipe, box or tray and which can also receive heat through direct contact with the or the last pipe, box or tray.

The or each pipe may have a zigzag, wavy or other sinuous form, or may be coiled into a spiral or a helix with, for example, a form selected from circularrectilinear, circular, elliptical, oval, triangular, rectangular, quadrilateral, and polygonal. Preferably, the or each pipe is in the form of a flat or circular helix or a spiral, and the turns of the pipe are in contact with or closely adjacent one another.

Preferably, the transverse dimension of the pipe or channel is between substantially 2 and 40 millimeters, typically 10 millimetres. The box or tray may have a thickness of between substantially 3 and 50 millimeters, preferably 5 millimeters.

Various embodiments of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figures 1 to 5 are perspective views showing different forms of thermoelectric heater in accordance with the invention: Figures 6 to 8 are plan views of three forms of pipe which can be employed in the heaters of Figures 1 to 5; Figures 9 to 11 show various forms of tray which can be used as alternatives to the pipes shown in Figures 6 to 8; Figure 12 is a plan view of a switch for controlling the water heater of Figures 1 to 5; Figure 13 is a front elevation of the switch of Figure 12 in combination with a valve for controlling the supply of water; Figure 14 is a side elevation of the valve of Figure 13;; Figures 15 to 17 are diagrammatic representations of three forms of connection between the hot water collector of the water heater and a consumer outlet; Figure 18 is a perspective view on a reduced scale of one form of outer casing for the apparatus of Figures 1 to 5; Figures 19 to 21 are end, side and plan views respectively of an insulated base for a rectangular thermoelectric heater; and Figures 22 and 23 are elevational and plan views respectively of an insulated base for a circular thermoelectric heater.

Figures 1 to 8 of the drawings show various heat transfer means employing a long thin metallic water pipe 2 which can be coiled in the form of a flat helix (Figures 1 and 4), a circular helix (Figures 2 and 3), a rectangular spiral (Figure 5), or may have the sinuous forms of Figures 6 and 7 or the spiral form of Figure 8; Alternatively, a thin metal compartmented box 11 of the kind shown in any one of Figures 9 to 11 can be employed in lieu of the pipes to obtain the heat transferring effects; The water channeis are defined within the box 11 by baffles 12 formed with gaps or holes for the slow flow of water, one surface 1 1a of the box of Figure 11 being corrugated for better radiation. A thermoelectric element 4 enveloped by an insulator 3 forms the thermoelectric section D of Figures 1, 2 and 4.

Each geometrical form of pipe shown in Figures 1 to 8 can be employed alone or in combination with others to fit the thermoelectric elements of Figures 1 tc 5 and 19 to 23.

A number of pipes may be made in sections of different sizes, such as those shown at A, B and C in Figures 1 to 5, and the ends of such pipe sections can be connected to one another by metallic joints 1, as shown in Figures 1 and 5, or by electric welding or soldering, whereby the possibility of a short circuit in the thermoelectric element due to leakage of water from the joints of the pipes or boxes is avoided. Thus, a pipe can be extended to any required length.

The thermoelectric elements of Figures 1, 2 and 4 are encased in the insulating material, the section D being of the same geometrical form as the pipe sections to enable the sections A,D,B and C to be fitted one within the other in series; the thermoelectric section D is inserted between two pipe sections A and B, and all of them are then inserted into the pipe section C, as shown in Figure 1. A stout thermoelectric element of sinuous form is covered by an insulator which can be inserted into the pipe section A, as shown in Figure 4. Both high- and low-powered thermoelectric elements without covering insulators or insulating material are employed in the heater of Figure 3 and are loosely inserted one after another into the middle of circular pipe sections A and B or even C.The ends of the thermoelectric elements stand in insulated supports 6 for installation in the back cover 35 or base cover 31 of a metallic box, and all are enveloped by a top cover 30. The base cover is provided with vents 32 for the inflow of air.

The thermoelectric element of Figure 5 has an insulated base 7 provided with vents or holes 9 arranged at the bottoms of channels 10 for the high- and low-powered thermoelectric elements, the positive terminals of which are at either 8B or 8C and the negative terminals 8A of which are joined together. The leads of the elements are connected to a mains supply of electricity (see Figures 19 to 23). The insulated bas6 is fastened to a metal support by two screws which pass through holes 34 in the base 7 (Figure 23). A thermoelectric element with the circular base 7 of Figures 22 and 23 can be employed in lieu of the insulated thermoelectric element or section D and can be inserted into the middle of the curved pipe of the heater shown in Figure 4.

A water container 5 of appropriate geometrical form can be mounted on the outermost pipe section for receiving hot water from the pipe sections and for receiving heat by conduction and radiation from the pipe sections, and even by internal transfer in the case in which the pipes, the container, and thermoelectric elements are covered by a metal cover giving a particular external appearance to the heater. The cyiindrical part of a T-shaped water container can be inserted into the middle of the circular pipe section B and the upper part of the T can just rest on the tops of pipe sections A and B in conductive contact therewith (see Figure 2).By means of such an arrangement, the water in the T-shaped container will be kept hotter than in other containers, and the external appearance of the heater will be cyiindrical. In Figures 1 to 4, the covered water container can be either omitted or installed as required.

Three ways in which the water container can be connected to the pipes and pipe sections are shown in Figures 15 to 17. When the tap 27 is closed, the hot water from the pipe sections will fill the container through a bottom pipe 36, whereby the air in the container will be compressed and forced into a top pipe 28 (which can be extended as required), as the water rises. The hot water can therefore be kept higher in order to avoid an air cushion occupying a greater volume of the container in connection with which all the pipes are soldered or welded. The hot water can flow in at the top of container and be discharged from the bottom, as shown in Figure 16. In this case, the hot water flows through the tap 27 direct from the container 5.In the cases shown in Figures 15 and 17, whether a small water valve 29 is opened or closed, the water does not flow into the container when water is being discharged from the tap 27. In Figure 17, a small water valve with a short rotary lever 33 is installed in the bottom pipe 36 of the container to keep hot water therein as long as required. If the water valve 29 is opened and the tap 27 is closed, the hot water can fill the container. The arrows in Figures 15 to 17 show the path of hot water flowing into the container from the pipe or pipe section.

According to the invention, the electricity and water are both controlled by a single long rotary lever 21 of an electricity-water controller, shown in Figure 13. Both electric switch (Figures 12 and 13) and water valve 24 (Figures 13 and 14) are in connection with the lever 21 when the heater is switched off.

Once the lever is turned clockwise (with reference to Figure 13), the switch and the valve become separated and the cold water passes through the valve 24 to flow into the pipe.

Simultaneously, the switch is closed to connect the thermoelectric element with the mains. As soon as a cyiindrical tip of the lever 21 touches the switch, the movable part 26 of the switch and its movable cover 13 are driven anticlockwise, as shown in Figures 12 and 13, and a metal bearing 14 with a small inner spring 15 is pushed into a hole by the convex tip of the movable part 26 to make contact with the middle copper terminal 16B to which the positive lead from the electric mains is connected and fastened by a screw 17. Simultaneously, the conductive bearing 14 is rolled into the interspace between the middle and left-hand copper terminals 16B, 16A to connect them so that thermoelectric element is energised.A fuse can also be connected between the middle and the right-hand terminals 16B, 16C, through which the electric current flows from the positive lead of the mains. According to the invention, the lever 21 of the water valve 24 can be turned further clockwise to let more water flow into the pipe as required. On the other hand, the movable part 26 of the switch cannot be turned any further anticlockwise; the switch can only be returned to the original switched-off position by a clockwise movement of the movable part 26 and cover 13 when the lever 21 is turned anticlockwise. At the same time, the bearing 14 is returned to the interspace between the middle and the right-hand terminals 16B, 16C to cut off the electric current at once, and the water is charged as well.

The switch cover 13 has two holes 18 for screws which attach it to the moXable part 26 of the switch for movement therewith. The movable part 26 is loosely attached to a switch base 25 by an axial screw which passes through a central hole 20 in the part 26. The base 25 has holes 19 for the mounting of the switch on a supporting wall, preferably the heater cover, in such a position that the lever 21 can connect the water valve 24 and the switch. The wall may be between 10 and 40 millimeters thick. The rotary lever 21 is suppprted by a spindle 37 which is attached to the valve by a nut 22. The ends 23 of the water valve 24 may be available in a range of sizes for connection to the pipes so that a larger size can be changed to a smaller one in order to limit the cold water flow rate in the pipe of the heater, as required.

The present electricity-water controller arrangement is preferable for the safe use of electricity, since it avoids the possibility of a short circuit due to the splashing of water drops onto the switch, and for convenience of use in applications which coincide with the requirements of the invention.

Claims (12)

1. A thermoelectric water heater comprising at least one thin metal pipe or sinuously-channelled box or tray through which water to be heated can flow at a reiatively slow rate, an insulated thermoelectric element located in intimate contact with the or each pipe, box or tray to heat the water passing therethrough, and a container for receiving heated water from the or the last pipe, box or tray and also arranged to receive heat through direct contact with the or the last pipe, box or tray.

2. A water heater according to Claim 1, wherein the or each pipe has the form of a flat helix, a circular helix or a spiral the turns or lengths of which are in contact with or closely adjacent one another.

3. A heater according to Claim 1 or Claim 2, wherein the transverse dimension of the or each pipe or channel is between substantially 2 and 40 millimeters.

4. A heater according to Claim 3, wherein the transverse dimension of the or each pipe or channel is 10 millimeters.

5. A heater according to Claim 1, Claim 3 or Claim 4, wherein the sinuous channel in the or each box or tray is constituted by the interspaces between a plurality of metal pieces formed with gaps or holes for the passage of water and arranged between opposite surfaces of the box or tray, and wherein one said surface is corrugated for the transference of heat and the other surface is blackened.

6. A heater according to Claim 5, wherein the thickness of the or each box or tray is between substantially 3 and 50 millimeters.

7. A heater according to Claim 6, wherein the thickness of the or each box or tray is 5 millimeters.

8. A heater according to Claim 5, wherein the gaps or holes in the metal pieces are between substantially 2 and 10 millimeters wide.

9. A heater according to any one of the preceding claims, wherein it includes an electricity-water controller with a single rotary lever which operates an electric switch and a water valve to control both the electricity and the water.

10. A heater according to Claim 9, wherein the switch has an insulated movable cover and a metal bearing is installed in the insulated movable part to act as a main active electrical conductor for the switch.

11. A heater according to any of the preceding claims, wherein it further includes an insulated base with vents for the inflow of air.

12. A thermoelectric water heater substantially as herein described with reference to, and as shown in, the accompanying drawings.