Fitting for Hot Water Cylinder

Abstract

 The invention relates to a fitting (10) for a 2" or less BSP threaded immersion heater opening in a domestic hot water cylinder which comprises a first channel (18) for receiving an immersion heater, a second channel (20) for the inflow of liquid to the cylinder and, a third channel (22) for the outflow of liquid from the cylinder.

Description

[0001] The present invention relates to a fitting for a hot water cylinder, particularly a domestic hot water cylinder, to enable the connection of an external heating system, particularly a solar powered heating system.

Background to the invention

[0002] It is becoming increasingly common to have solar panels fitted to domestic dwellings to provide a "greener" form of water heating from this renewable source of energy. Once fitted, a solar powered heating system can be expected to provide from between 40% and 70% of the domestic hot water requirement for a single dwelling.

[0003] Most houses in Europe have a hot water boiler and a hot water cylinder with a heat exchange coil to transfer heat from the boiler to the water in the cylinder. To install a solar heating system an additional heat exchanger is required for the solar heating circuit. This is normally achieved by replacing the existing hot water cylinder with a larger twin coil cylinder. The replacement of the existing cylinder is costly and labour intensive, which can cause significant disruption in the household and result in high costs of installation. This inconvenience and cost deters potential customers from choosing to have a solar heating system installed.

[0004] To address this problem, various solutions have been suggested which do not involve the replacement of the existing hot water cylinder. One solution suggested is to insert a heat exchanger into the hot water cylinder via the hot water outlet at the top of the cylinder. However this has the major disadvantages of having too low a heat exchange area typically required for solar heating, and also creates a restriction in the flow of hot water from the tank, thus reducing system performance.

[0005] Another proposed solution feeds water heated from the solar system to the cylinder via the existing hot water exit pipe and draws cold water from the existing cold water feed pipe. However, this system has the major disadvantage of not feeding heated water to the right location in the cylinder.

[0006] Other methods suggested involve inserting a heat exchanger through the immersion heater boss, however, because of lack of space, these methods involve loss of the immersion heater during installation of the solar heat exchanger, which is a major disadvantage.

[0007] GB 2454052 discloses a fitting for a 2¹/₄" BSP threaded immersion heater opening which comprises the immersion heater and the water inlet and outlet ports. However some cylinders do not have a 2¼" BSP threaded opening.

Summary of the invention

[0008] It has been observed that some cylinders, particularly unvented or pressurised cylinders, only have the smaller, e.g. 1³/₄" British Standard Pipe (BSP) opening, which is almost entirely taken up by the cylindrical port from the immersion heater. Introducing additional channels for effective use seems not to be possible in view of the extremely small space available.

[0009] In a first aspect, the present invention relates to a fitting having a 2" (i.e. inch) or less British Standard Pipe connection and for connection to a 2" British Standard Pipe threaded immersion heater opening in a hot water cylinder, particularly a domestic hot water cylinder, wherein the fitting comprises a first channel for receiving an immersion heater, and a second channel for the inflow of liquid to the cylinder.

[0010] British Standard Pipe has been a global standard in the industry for over 100 years. It also has a European equivalent standard BS EN 10226:2004.

[0011] By innovatively designing such a fitting, an external water heating system, e.g. a solar heating system, can be fitted directly to an existing hot water cylinder having a 2" or less BSP threaded immersion heater opening without needing to modify the existing hot water cylinder and without compromising its performance.

[0012] The fitting according to the invention is relatively easy to install and much cheaper than fitting a new cylinder, e.g. a pressurised/unvented cylinder. For example, the opening can be on a side of the cylinder and the fitting is mounted horizontally.

[0013] The connection can be a 2", 1¾", 1½" or 1¼" British Standard pipe fitting. However, a 1¾" fitting is preferred

[0014] The opening is preferably a 1¾" British Standard Pipe (BSP) immersion heater boss. Replacing the existing immersion heater fitting, e.g. 1¾" BSP with the fitting according to the invention allows the opening to be shared by a smaller immersion heater and pipework for the external water heating system.

[0015] In a second aspect, the invention provides a method of installing an additional water heating facility to a hot water cylinder comprising an opening comprising the step of installing a fitting according to the invention and connecting the fitting to an external water heating system.

[0016] An immersion heater is fed through the first channel and secured in place, e.g. by being threaded or by being secured by a flange, so that the immersion heater is received in the first channel. Optionally an immersion heater is integrally formed with the fitting and is not separately removable therefrom. Suitable immersion heaters are comprised of a stainless steel copper or copper-nickel alloy U-tube, e.g. 8 mm in diameter, brazed into a flange or threaded plug, with an electric resistor element inside. However, preferably the immersion heater is feedable through the first channel as this allows it to be fitted once the fitting is connected to the cylinder so that it makes it easier to feed any pipework associated with the fitting in through the opening.

[0017] It has been found that the immersion heater can be made to take up less space if the cross-section of the first opening is non-circular. In this case it is not possible for the immersion heater to be threaded into the first opening and must instead be securable by a connecting means, such as a series of bolts. A particularly efficient shape of cross-section of first channel is one with opposing curved and substantially parallel sides, e.g. substantially an annular section, as it can effectively wrap itself around other circular openings which may be present.

[0018] More space for the channels can be achieved by allowing the fitting to protrude from the exterior of the hot water cylinder. Therefore, in a preferred embodiment, the outermost point of the fitting protrudes by at least 2 cm, preferably at least 3 cm, preferably from 3 to 6 cm, or from 3 to 5 cm, from the exterior of the hot water cylinder when fitted.

[0019] The external heating system is typically based on heating a flow of water, e.g. by a solar panel. Such an external heating system may be an "open" circuit or a "closed" circuit. In an open circuit the water in the heating system and inside the hot water cylinder are in communication. In a closed system the water in the heating system is not in communication with the water inside the water cylinder.

[0020] A closed system has the benefit that the liquid within it can contain additives, e.g. anti-freeze, to prevent damage to a solar panel during freezing conditions. Because of this advantage, an open circuit typically exchanges heat with a closed circuit via an external heat exchanger, the closed circuit flowing through the solar panel itself or the open circuit includes a solar panel specifically adapted to be freeze tolerant.

[0021] The outflow of liquid from the cylinder to the external heating system may be achieved via a third channel in the fitting. For a closed system a third channel would become essential. For an open system the outflow of liquid could be achieved via a third channel or optionally could be drawn from another location, for example by drawing water from the drain fitting at the bottom of a domestic hot water cylinder or from the cold feed at the bottom of the domestic hot water cylinder.

[0022] The fitting may also comprise a further channel in the fitting for a pocket for a temperature probe. Such temperature probes are desirable e.g. when the cylinder is pressurised and has a hard outer casing and the existing immersion heater is located towards the bottom of the cylinder on the side, which is to be replaced with a fitting according to the invention. For traditional vented cylinders a temperature probe may be fitted to its exterior metal casing to provide an accurate reading.

[0023] When a third channel is present, both the second and third channels may pass through the fitting as two separate channels.

[0024] However, the inventors have discovered that, if the second and third channels are concentrically arranged, significant space savings in the fitting can be achieved. Surprisingly, any loss in thermodynamic efficiency has been found to be minimal.

[0025] Thus, in another aspect, the invention relates to a fitting for an opening in a hot water cylinder, which comprises a first channel for receiving an immersion heater, a second channel for the inflow of liquid to the cylinder and a third channel for the outflow of liquid from the cylinder, wherein the second and third channels are concentrically arranged.

[0026] Each of the first, second, third channel and optional further channel are preferably in the form of a bore, passing through the fitting from the exterior to the interior of the cylinder when fitted.

[0027] It is also preferred that, when fitted, the second and/or third channels enter the cylinder substantially normal to the cylinder exterior and exit the fitting deviated from normal, preferably substantially tangentially to the cylinder exterior. However, if the first channel is relatively small (e.g. 1" BSP) then there may be space for the second and third channels to exit the cylinder closer to normal to the cylinder exterior.

[0028] Because space is at a premium, the second and/or third channels are preferably less than 20 mm in diameter, e.g. 8 to 15 mm, allowing them to be ½" BSP, ⅜" BSP or ¼" BSP threaded. However, the channels do not need to be threaded and could, for example, comprise short protruding pipe for further connections to be added. If present, the further channel will typically be smaller in diameter than the second and/or third channels, e.g. from 5 to 12 mm in diameter.

[0029] The fitting may be made of metal, e.g. brass, with the channels being threaded for further connections as appropriate. However, it may be preferable for the fitting to be made from a thermally insulating material, e.g. plastics or ceramic, especially if the outflow of liquid passes through the fitting via a third channel where undesirable heat transfer between the inflow and outflow or between the outflow and hot water in the top of the tank may take place. Any plastics used must be capable of withstanding a working temperature of 85°C comfortably and thermoset plastics such as polyester or polyphenolic plastics are currently favoured. A combination of materials may be used if desired, e.g. a metal body with plastic-lined channels.

[0030] It is highly preferable that the inflow of heated water and the outflow of cold water are positioned at a particular location within the cylinder. Therefore, the fitting is preferably combined with pipework directing the inflow of heated water to the cylinder and also the outflow of cold water from the cylinder. However, any pipework must be feedable through the opening, e.g. 1¾" BSP, e.g. by confining the pipework and immersion heater to a notional cylinder having the same diameter as the very small opening. This constraint on the pipework restricts how it may be arranged to provide inflow and outflow of liquid to particular locations in the cylinder.

[0031] Thus, in a preferred embodiment, the immersion heater and/or the pipework extend beyond a notional cylinder having the same diameter as the opening, e.g. 1¾" BSP, to occupy a notional cylinder having a greater diameter than that of the opening. As such an arrangement would not be possible to fit in through the opening, it is preferred that the immersion heater be removable. Thus, with the immersion heater removed, the pipework can be inserted through the opening. Once fitted, the immersion heater can then be inserted.

[0032] In a preferred embodiment, the pipework deviates from the direction normal to the exterior of the cylinder to provide physical distance between the pipework and the immersion heater. However it is also possible for the immersion heater to deviate away from normal.

[0033] In an open system, a pipe is connected to the internal entry of the second and third channels, the pipes arranged to deliver and extract respectively, water at the optimum positions in the cylinder. It is generally agreed that outflow from the cylinder should be taken from the bottom of the cylinder (e.g. by postioning a pipe at the bottom or by drawing water from the drain fitting or the cold feed as discussed above) and inflow to the cylinder should be at one-quarter to one-third of the height of the cylinder from the base of the cylinder.

[0034] In a closed system, the pipework connects the entry of the second channel to the entry of the third channel and typically includes a heat exchanger form. Heat is then exchanged with the water in the cylinder during flow of heated water.

[0035] The heat exchanger, if present, is preferably a folding heat exchanger, as described in GB 0905541.9.

[0036] It is generally considered that an open system is more thermodynamically efficient, and can operate with a lower temperature difference than is possible with a closed system. However an open system suffers from the drawback of requiring an external heat exchanger or freeze tolerant solar collector, as discussed above. The fitting of the present invention works equally well with both an open and closed arrangement, and the factors dictating which one is preferable would be determined by the particular circumstances of the installation. In general a closed system is considered to be the better solution.

[0037] The fitting can be directly threaded into the opening in the cylinder. However, in order to prevent the need for excessive rotation when fitting, the fitting preferably comprises a removable adapter. The adapter is designed to be threaded into the opening of the hot water cylinder and is adapted to mate with the fitting to provide a secure connection therewith without significant rotation, (i.e. by less than 60°, preferably less than 30°, more preferably less than 20°).

[0038] Once the adapter is threaded in, the fitting can be securely connected to the adapter without significant rotation e.g. by providing the adaptor and fitting with aligned spaced apart holes or with a thread locking ring. This enables a more accurate placement of any connected pipework within the cylinder and in fact may be highly desirable particularly if the pipework is curved or bent to reach the right part of the cylinder without colliding with any pre-existing pipework in the cylinder.

[0039] The invention also relates to a fitting according to the invention connected to a hot water cylinder. The invention also relates to such a fitting with its second and third channel exits fitted to an external heating system, preferably a solar heating system.

[0040] The invention will now be described, by way of illustration, with reference to the following figures, in which:

Figure 1A is an underside view of a fitting according to the invention;

Figure 1B is a side view of the fitting shown in Figure 1 A;

Figure 2A is an underside view of an adapter for the fitting shown in Figures 1A and 1B;

Figure 2B is a side view of the adapter shown in Figure 2A;

Figure 3 is a schematic representation of a domestic hot water cylinder comprising a fitting according to the invention with liquid flowing from an external heating system in a closed arrangement;

Figure 4 is a schematic representation of a domestic hot water cylinder comprising a fitting according to the invention with liquid flowing from an external heating system in an open arrangement where the liquid outflow passes through the fitting;

Figure 5 is a schematic representation of a domestic hot water cylinder comprising a fitting according to the invention with liquid flowing from an external heating system in an open arrangement where the liquid outflow is taken from the bottom of the cylinder.

Figure 6A is a representation of a fitting according to the invention with two attached pipes, intended for insertion into a hot water cylinder near its top;

Figure 6B is a representation of a variant of the fitting and pipework shown in Figure 5A, for insertion into a cylinder at the side;

Figure 6C is a representation of a variant of the fitting and pipework shown in Figure 5A for insertion into a cylinder at the bottom;

Figure 7A is a representation of a domestic hot water cylinder with the immersion heater fitting removed and an adapter for connection to a fitting according to the invention, screwed into its place;

Figure 7B is a representation of a fitting according to the invention with two attached pipes partially inserted into the cylinder; and

Figure 7C is a representation of a fitting according to the invention in contact with an adapter.

Figure 8 is a representation of a fitting according to the invention with connected pipework in a closed arrangement.

Figure 9 is a representation of a close-up view of the fitting shown in Figure 8.

Figure 10 is a representation of another fitting according to the invention with connected pipework in a closed arrangement for fitting the side of a hot water cylinder.

Figure 11A is a perspective view of another fitting according to the invention.

Figure 11B is a perspective view of the underside of the fitting shown in Figure 11A.

Figure 11C is a plan view of the underside of the fitting shown in Figure 11A.

[0041] Figures 1A and 1B show a fitting 10 according to the invention. The fitting 10 is made of brass and comprises a cylindrical body 12, a wider flange position 14 and a narrower cylindrical portion 16 at its base.

[0042] Passing through the fitting, from top to bottom, is first channel 18. Second and third channels 20, 22 enter the fitting at its base and deviate at right angles half way into the fitting to exit the fitting from its side. Thus, when fitted to a hot water cylinder, the second and third channels will enter the cylinder normal to the cylinder exterior and exit the fitting tangentially to the cylinder exterior.

[0043] Flange 14 has six axially spaced holes 24 which are for connecting the fitting to the adapter shown in figures 2A and 2B.

[0044] Figures 2A and 2B show an adapter 30 comprising a flange 32 and a cylindrical portion 34 1¾" BSP threaded on its exterior. The flange 32 comprises numerous holes 36 for connection with the fitting 10.

[0045] During installation, the existing 1¾" BSP immersion heater fitting is removed from a domestic hot water cylinder. The threaded portion 34 of the adapter shown in Figures 2A and 2B is then screwed into its place. The fitting 10, together with any connected pipework as desired is brought into contact with the adapter, the pipework being positioned as desired inside the cylinder. Cylindrical portion 16 fits snugly into the adapter. Minimal rotation of the fitting 10 is necessary in order to align one of the holes 24 with one of the holes 36 in order that they may be bolted together so that flanges 32 and 14 fit snugly together.

[0046] Figure 3 shows a conventional domestic hot water cylinder 14 with a cold water feed 42 and a hot water outlet 44 and a heating coil 46. The cylinder also comprises a fitting 10 according to the invention. Inserted into the fitting is an immersion heater 48 and two pipes 50, 52 are connected to the second and third openings in the fitting 10. The pipes 50, 52 lead to a heat exchanger 54. The entry from the second channel is therefore connected to the entry to the third channel via the heat exchanger 34. Liquid from a solar heating system (not shown) is fed to and from the heat exchanger 54 via pipes 50 and 52 through inlet 56 and outlet 58.

[0047] Figure 4 shows a similar arrangement as shown in Figure 3, and the same numbering has been used where the same equipment is present. The cylinder in Figure 4 has a pipe 62 connected to the second channel and a pipe 60 connected to the third channel. Heated liquid from a solar heating system (not shown) flows in through inlet 56 and into the internal of the cylinder via the exit of pipe 62 at the ideal location for heated water. Cold liquid from the cylinder enters pipe 60 at the base of the cylinder and is fed out through outlet stream 58 to be heated by the external solar heating system.

[0048] Figure 5 shows a similar arrangement as shown in Figures 3 and 4, and the same numbering has been used where the same equipment is present. The cylinder in

[0049] Figure 5 has a pipe 62 connected to the second channel. Heated liquid from a solar heating system (not shown) flows in through inlet 56 and into the internal of the cylinder via the exit of pipe 62 at the ideal location for heated water. Cold liquid from the cylinder enters pipe 60 at the base of the cylinder, which connected to the feed or drain fitting of the cylinder, to be heated by the external solar heating system.

[0050] Figure 6A shows a representation of the fitting 10 according to the invention with pipes 60 and 62 connected to it, as used in the illustration of Figure 4. Figure 6B shows a variant of the arrangement shown in Figure 6A, for use where the 1¾" BSP opening in the cylinder is partly at the side of the cylinder. Figure 6C is a further variant of the arrangement shown in Figure 6A which is intended for use when the 1¾" BSP opening is at the base of the cylinder. It can therefore be seen that the fitting according to the present invention allows for precise placement of optimal heated and cold liquid regardless of the location of the 1¾" BSP opening.

[0051] Figure 7A shows a domestic hot water cylinder which has had its 1¾" BSP immersion heater fitting removed and replaced with an adapter 30 as shown in Figures 2A and 2B. The surface of the flange can be seen to be flush with the exterior of the cylinder and holes 36 ready to receive the fitting 10. Figure 7B shows a fitting according to the invention connected to pipes 60 and 62 partially fed into the opening provided by the adapter. At this point the exact positioning of the pipes can be arranged before final connection of the adapter to the fitting. Figure 7C shows the fitting 10, fully inserted into the cylinder, in contact with the adapter 30. The fitting can be seen to protrude from the exterior of the cylinder and the 1¾" BSP opening of the first channel for insertion of an immersion heater can be clearly seen. The fitting may now be bolted to the adapter and an immersion heater inserted into the first channel and screwed in place. Once an external water heating system, e.g. a solar heating system, has been installed, it can be connected to the second and third channels to complete the installation.

[0052] Figures 8 and 9 show a fitting 70 according to the invention with pipes 72, 74 connected to it. Pipe 74 is made from copper and deviates away from the direction normal to the surface of the cylinder to which the adapter 70 is to be fitted. Pipe 72 is made from flexible stainless steel and is wrapped around pipe 74. The pipes 72, 74 are connected together providing a closed arrangement. An alternative arrangement is to have a length of stainless steel flexible tube with solid tube ends (also made from stainless steel) welded on, eliminating the need for a copper tube. The stainless steel ends would be long enough to position the flexible tube in the correct part of the cylinder and joined to the fitting with compression fittings.

[0053] Pipe 72 enters the fitting 70 and exits the fitting as cold water outlet 76. Pipe 74 enters the fitting and exits the fitting as hot fluid inlet 78.

[0054] Cold fluid outlet 76 and hot fluid inlet 78 can be seen to exit the fitting 70 deviated from normal to the eventual cylinder exterior.

[0055] In use the fitting is fitted to a cylinder whose 1¾" opening is located near the top of the cylinder. The length of pipes 72, 74 is designed such that when fitted they extend close to the base of the cylinder.

[0056] Figure 10 shows a variant of the fitting shown in Figures 8 and 9 but designed for cylinders whose 1¾" opening is at or near the base of the cylinder. Fitting 82 is connected to pipework 84 which is in a closed arrangement with one pipe spiralling around the other, in the same manner as in Figure 8 only with rigid pipes. Also shown is a temperature probe 86 which passes through fitting 82 to the exterior. An alternative arrangement is where the spiralling pipe is made from flexible stainless steel.

[0057] Figures 11A to C show a further fitting 100 according to the invention. The fitting comprises first channel 102, second channel 104 and third channel 106. The second channel 104 and third channel 106 are arranged concentrically. It can also be seen that the first channel 102 is non-circular and is substantially an annular section. The first channel 102 fits snugly around the concentric second 104 and third channels 106 and makes efficient use of space.

[0058] The fitting 100 also has five circumferentially evenly spaced holes 108 passing through the body. These are for attachment to a suitable adapter (not shown).

[0059] The fitting also has four fitting holes 110, for securing the immersion heater (not shown) into the first channel 102 without rotation.

Claims

1. A fitting having a 2" or less BSP connection and for connection to a 2" or less BSP threaded immersion heater opening in a hot water cylinder, which comprises a first channel for receiving an immersion heater, a second channel for the inflow of liquid to the cylinder, and a third channel for the outflow of liquid from the cylinder with pipework connected to the second and third channels directing the inflow of liquid and the outflow of liquid within the cylinder

2. A fitting according to claim 1, wherein the connection is a 1¾" BSP for connection to a 1¾" BSP threaded immersion heater opening.

3. A fitting according to claim 1 or claim 2, wherein the first channel is non-circular.

4. A fitting according to claim 3, wherein the cross-section of the first channel is substantially an annular section.

5. A fitting according to any one of the preceding claims, wherein the second and/or third channels are less than 20 mm in diameter.

6. A fitting according to any one of the preceding claims, wherein the second and third channels are arranged concentrically.

7. A fitting according to any one of the preceding claims, which, when fitted, the second and/or third channels enter the cylinder substantially normal to the cylinder exterior and exit the fitting deviated from normal, preferably substantially tangentially to the cylinder exterior..

8. A fitting according to any one of the preceding claims, wherein a first pipe is connected to the second channel for feeding inflow of liquid to a particular region of the cylinder and a second pipe is connected to the third channel for outflow of liquid from a different region of the cylinder.

9. A fitting according to any one of claims 1 to 7, wherein the pipework connects the entry from the second channel to the entry from the third channel.

10. A fitting according to any one of the preceding claims, wherein the immersion heater and/or pipework extend beyond a notional cylinder having the same diameter of the opening to occupy a notional cylinder having a greater diameter than that of the opening.

11. A fitting according to any one of the preceding claims, wherein the pipework within the cylinder is directed away from the direction normal to the exterior of the cylinder to provide physical separation between the pipework and the immersion heater.

12. A fitting according to any one of the preceding claims in combination with a removable adapter, the adapter being adapted to fit into the opening in the cylinder, and being adapted to mate with the fitting to provide a secure connection therewith without significant rotation of the fitting.

13. A fitting according to any one of the preceding claims, fitted to a domestic hot water cylinder, preferably an unvented pressurised cylinder.

14. A fitting according to any one of the preceding claims, which is connected to an external solar heating system.

15. A method of installing an additional water heating facility to a hot water cylinder comprising an opening, comprising the step of installing a fitting according to any one of claims 1 to 14 and connecting the fitting to an external water heating system.

Drawing