WO2010116251A2

WO2010116251A2 - Low-pressure hot water supply unit

Info

Publication number: WO2010116251A2
Application number: PCT/IB2010/000798
Authority: WO
Inventors: Dawid Thirion; Carl John Wesselink
Original assignee: Dawid Thirion; Carl John Wesselink
Priority date: 2009-04-09
Filing date: 2010-04-09
Publication date: 2010-10-14
Also published as: WO2010116251A3

Abstract

A low-pressure hot water supply unit (1 ) is provided comprising a low- pressure water heater including a storage tank (3, 31 ) wherein the water heater has associated with it a low-pressure cold water supply container (4, 21, 52, 41). The unit has an overflow or relief outlet (1 1 ) communicating with the interior of either the cold water supply container thereby enabling overflow from the storage tank to form part of a cold water supply or a separate collection chamber (20, 30) communicating with the storage tank. The low-pressure water heater preferably has a cold water supply container carried on top of the water heater. The water supply container typically has a float controlled valve (5) associated therewith for maintaining a predetermined minimum water level (6) within the cold water supply container. The inlet passage supplying water from the cold water supply container to the lower region of the storage tank of the water heater is preferably configured to form an anti-thermo-siphon loop (8a). The low- pressure water heater may be a solar water heater or a solar assisted water heater.

Description

LOW-PRESSURE HOT WATER SUPPLY UNIT

FIELD OF THE INVENTION

This invention relates to a low-pressure hot water supply unit that includes a low-pressure water heater that may be heated using electrical energy but more particularly, may be heated, or at least partially heated, by solar energy.

BACKGROUND TO THE INVENTION

Low-pressure water heaters are distinctly less costly than high-pressure water heaters, and are, accordingly, a preferred solution in low-cost housing and other cost sensitive applications.

Low-pressure water heaters are, however, accompanied by some significant disadvantages. In the first place, consequent on expansion of water whilst being heated from cold to hot, there is invariably a significant amount of water that is released into an overflow arrangement from which it runs off to waste. Applicant believes that the amount of such overflow water is typically of the order of 4%; a significant amount in an arid country in which water conservation is of prime importance.

Another disadvantage of a low-pressure water heater is that an associated cold water supply is typically at elevated supply pressure and the mixing of hot and cold water in order to achieve an intermediate temperature, such as would be required in the instance of taking a shower, proves to be rather difficult to achieve. OBJECT OF THE INVENTION

It is an object of this invention to provide a low-pressure hot water supply unit that overcomes, at least to some extent, one or more of the disadvantages indicated above.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a low-pressure hot water supply unit comprising a low-pressure water heater including a storage tank wherein the water heater has associated with it a low-pressure cold water supply container, the unit being characterised in that the low-pressure water heater has an overflow or relief outlet communicating with the interior of either the cold water supply container thereby enabling overflow to form part of a cold water supply or a separate collection chamber communicating with the storage tank.

Further features of the invention provide for the low-pressure water heater to have a cold water supply container carried on top of the water heater; for the cold water supply container to have a float controlled valve associated therewith for maintaining a predetermined minimum water level within the cold water supply container; for an inlet passage to communicate between the cold water supply container and a lower region of the interior of the storage tank of the water heater; for the inlet passage supplying water from the cold water supply container to the lower region of the storage tank of the water heater to be configured to form an anti-thermo-siphon loop (or heat trap) to prevent heat loss from the storage tank and consequent heat gain in the cold water supply container; and for the low-pressure water heater to be a solar water heater or a solar assisted water heater.

In one variation of the invention the cold water supply container serves also as a cold water supply reservoir and the interior of the cold water supply container has a cold water outlet associated with its lower region. In this instance the inlet to the passage communicating with the interior of the storage tank of the water heater preferably communicates with an upper region of the cold water supply container.

In another variation of the invention, a cold water supply reservoir is separate from the cold water supply container in which instance the cold water supply reservoir may have its own float controlled inlet valve assembly and a cold water outlet.

In a further variation of the invention the hot water storage tank has two outlets at different heights with an outlet at a lower height being a priority outlet that suffers less from any pressure fluctuations occasioned by water drawn off the higher outlet.

In a still further variation of the invention the cold water supply container may be split into two parts, an elevated expansion chamber, and a cold supply tank, which also acts as the cold water supply container. The expansion chamber may also be a separate chamber.

In order that the above and other features of the invention may be more fully understood an embodiment of each of the two variations of the invention indicated above will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Figure 1 is a schematic illustration of a low-pressure hot water supply unit according to one variation of the invention; Figure 2 is a schematic three-dimensional illustration of a preferred type of water heater to which the invention may be applied;

Figure 3 is a schematic illustration similar to Figure 1 but illustrating an embodiment of the second variation of the invention;

Figure 4 is a schematic illustration similar to Figure 1 but illustrating further variations of the invention and,

Figure 5 is a similar schematic illustration illustrating an embodiment of the invention that includes a separate expansion chamber.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In the embodiment of the invention illustrated in Figure 1 , a low-pressure hot water supply unit, generally indicated by numeral (1 ), comprises a low- pressure water heater (2) including a hot water storage tank (3) and, mounted above it, a cold water supply container (4) that, in this embodiment of the invention, also serves as the low-pressure cold water supply reservoir. The cold water supply container is fitted with a float controlled valve (5) that, when connected to a mains water supply, maintains the level (6) of the water in the cold water supply container at a predetermined minimum level. The content of the cold water supply container is therefore at atmospheric pressure.

The interior of the cold water supply container supplies the inlet end (7) of an inlet passage (8) that communicates between the cold water supply container and a lower region of the interior of the hot water storage tank of the water heater. The inlet end (7) of the inlet passage is located in an elevated submerged region of the cold water supply container so that warmer water that may be present in the container is fed to the hot water storage tank rather than cooler water in a lower region thereof. The inlet passage is preferably configured at an anti-thermo-siphon loop or heat trap (8a), as illustrated.

The cold water supply container also has a cold water outlet (9) associated with its lower region so that cold water may be drawn from it after it has been connected, for use, to an outlet supply circuit (10).

As provided by this invention, the storage tank of the low-pressure water heater has an overflow and relief outlet (11 ) communicating with the interior of the cold water supply container that, in this embodiment of the invention, is serving also as the low-pressure cold water supply reservoir. The upper end of the overflow outlet (11 ) terminates in an upper region of the cold water supply container so that any hot water expelled from the hot water storage tank is delivered to an upper region of the cold water supply container to minimise thermal mixing in the cold water supply container.

In order to minimise loss of heat from the interior of the hot water storage tank it may be that the overflow and relief outlet terminates above the normal water level in the cold water supply container, as indicated by dotted lines (1 1a). In this manner at least some loss of heat by convection may be eliminated.

The hot water storage tank has, in this particular embodiment, a hot water outlet (12) communicating, in the normal manner, with an upper region of the hot water storage tank.

Thus, hot water can be drawn off from the hot water storage tank at almost the same low pressure as cold water can be drawn off from the cold water supply container and the two flows of water can be mixed in order, for example, to provide an intermediate temperature of water for a shower. As hot water is drawn off from the hot water storage tank cold water replaces it by flowing through the inlet passage (8). Water drawn from the cold water supply container either to replenish the content of the hot water storage tank or directly by way of the cold water outlet (9) is replaced by supply water consequent on the action of the float controlled valve (5).

It will be understood that it is, of course, irrelevant to the invention as to the type of heating mechanism that is associated with the water heater but simply for the sake of completeness, the low-pressure water heater is preferably a solar water heater or a solar assisted water heater. One preferred form of solar water heater is illustrated in Figure 2 and has a bank of vacuum tubes (13) that are used to absorb solar energy and transfer it directly or indirectly to water in the storage tank of the water heater.

As indicated above, and as illustrated in Figure 3, the cold water reservoir (20) that serves to receive water from the overflow and relief outlet may be separate from the cold water supply container (21 ) and could, as illustrated, be mounted next to the water heater; typically at one end thereof. In this instance the cold water reservoir has its own water supply and float controlled valve (22). Figure 3 also illustrates a tempering valve (23) being employed to effect an initial mix of cold and hot water that can then be mixed in the normal course of events for example, for use in a shower (24).

This variation of the invention is particularly appropriate to application of the invention in situations in which it is desired to make the hot water generated, for example of a solar water heater, over a day available for use without becoming diluted with cold water. In order to achieve this a main control valve (25) is provided in the main cold water supply pipe (26) so that flow of cold water to the water heater can be interrupted whenever it is required to use the hot water generated. This would typically be after a day of sunlight and can be achieved using a manually operable valve but is preferably achieved using a solenoid operated valve fitted to the cold supply pipe. Such a solenoid operated valve is preferably operated by a photocell device that ensures that the cold water supply container and storage tank are only filled during sunlight hours. This arrangement prevents cold water from entering the hot water storage tank when there is no sunlight to heat the water and also prevents any mixing of cold and hot water thereby ensuring the availability of hot water, for several intermittent usages.

Of course, in this arrangement it is necessary that the hot water outlet (27) either communicate with the bottom of the storage tank or be a perforated tube so that water at any level in the storage tank can enter the tube along its length and thus be withdrawn.

Referring now to Figure 4, an arrangement similar to that illustrated in Figure 3 is illustrated wherein the separate cold water reservoir (30) is mounted on top of the hot water storage tank (31) adjacent to the cold water supply container (32) and, indeed, the cold water reservoir and cold water supply container may be a single container with a dividing wall. The cold water reservoir has its own water inlet (33) and float controlled valve (34) for maintaining the water level and the cold water reservoir and cold water supply container are interconnected by means of a communication passage (35) in the upper region thereof. It will be quite apparent how the hot water supply unit functions from the foregoing.

Figure 4 also illustrates a variation in which the hot water storage tank has two outlets, a first one (36), a priority outlet, that is located at a somewhat lower level than a second outlet (37), the difference in height being typically of the order of 50 mm. This arrangement is such that the lower level priority outlet (36) may be connected to supply a shower (38), for example, whilst the higher level outlet (37) can be connected to an outlet tap (39), for example supplying a kitchen sink, wash hand basin or the like. This arrangement enables a person taking a shower, for example, to enjoy priority by having an uninterrupted supply of hot water that may otherwise be interfered with if the outlet tap were supplied from the same level in the hot water storage tank. As an alternative to the arrangement described above, mixing of the hot water and cold water can also be minimized by providing a separate chamber (40), as illustrated in Figure 4, for receiving any overflow from the hot water storage tank consequent on expansion. This separate chamber may take the form of a separate container, as illustrated for reasons of simplicity in Figure 4, but may also assume the form of a heat insulated compartment within in the cold water supply container (41).

It will be understood that numerous variations may be made to the embodiments of the invention described above without departing from the scope hereof.

Claims

CLAIMS:

1. A low-pressure hot water supply unit (1) comprising a low-pressure water heater including a storage tank (3, 31) wherein the water heater has associated with it a low-pressure cold water supply container (4,

21 , 52, 41 ) the unit being characterised in that the low-pressure water heater has an overflow or relief outlet (1 1) communicating with the interior of either the cold water supply container thereby enabling overflow to form part of a cold water supply or a separate collection chamber (20, 30) communicating with the storage tank.

2. A low-pressure hot water supply unit as claimed in claim 1 in which the low-pressure water heater has a cold water supply container carried on top of the water heater.

3. A low-pressure hot water supply unit as claimed in either one of claims 1 or 2 in which the cold water supply container has a float controlled valve (5) associated therewith for maintaining a predetermined minimum water level (6) within the cold water supply container.

4. A low-pressure hot water supply unit as claimed in any one of the preceding claims in which an inlet passage (8) communicates between the cold water supply container and a lower region of the interior of the storage tank of the water heater.

5. A low-pressure hot water supply unit as claimed in any one of the preceding claims in which the inlet passage supplying water from the cold water supply container to the lower region of the storage tank of the water heater is configured to form an anti-thermo-siphon loop (8a).

6. A low-pressure hot water supply unit as claimed in any one of the preceding claims in which the low-pressure water heater is a solar water heater or a solar assisted water heater.

7. A low-pressure hot water supply unit as claimed in any one of the preceding claims in which the cold water supply container (4) serves also as a cold water supply reservoir and the interior of the cold water supply container has a cold water outlet associated with its lower region.

8. A low-pressure hot water supply unit as claimed in claim 7 in which the inlet to the passage communicating with the interior of the storage tank of the water heater communicates with an upper region of the cold water supply container.

9. A low-pressure hot water supply unit as claimed in any one of claims 1 to 6 in which a cold water supply reservoir (20, 30) is separate from the cold water supply container in which instance the cold water supply reservoir may have its own float controlled inlet valve assembly (22, 34) and a cold water outlet.

10. A low-pressure hot water supply unit as claimed in any one of the preceding claims in which the hot water storage tank has two outlets at different heights with an outlet (36) at a lower height being a priority outlet that suffers less from any pressure fluctuations occasioned by water drawn off the higher outlet (37).