WO2010082162A2

WO2010082162A2 - Water heater

Info

Publication number: WO2010082162A2
Application number: PCT/IB2010/050128
Authority: WO
Inventors: Gideon Francois Engelbrecht; Daniel Hendrik Booysen
Original assignee: Gideon Francois Engelbrecht; Daniel Hendrik Booysen
Priority date: 2009-01-13
Filing date: 2010-01-13
Publication date: 2010-07-22

Abstract

The invention relates to a water heater (10) and to a water heater installation (500). The water heater includes at least two water chambers (12, 14), each defining a cavity (16, 18) therein and a heating element (24, 26) within each cavity (16, 18). The water heater (10) also includes at least two linking channels (20, 22) linking the two chambers (12, 14) in parallel and a water inlet (28) and a water outlet (30) in fluid flow communication with the chambers (12, 14) wherein one of the heating elements (24) is independently operable in a pre-heating phase when no water flows through the inlet (28) and the outlet (30), and wherein all the heating elements (24, 26) are operable in a full heating phase when water flows through the inlet (28) and the outlet (30).

Description

WATER HEATER

FIELD OF INVENTION

This invention relates to a water heater and to a flow switch for use in such a water heater.

BACKGROUND

The Inventors are aware of conventional water heaters having a water chamber and a heating element therein to heat the water.

In one version, the water heater (or geyser) has a large water chamber to act as a water reservoir to store a large volume of preheated water for use on demand. A disadvantage of this water heater is that it is energy inefficient as it can be wasteful to maintain the large volume water at its pre-heated temperature.

In another version, the water heater is a "flow-through" water heater which does not preheat the water but rather relies on a high-capacity element to heat cold water instantaneously as it flows past the element. A drawback of this is that the heating capacity of the water heater is limited to the capacity of the element.

The Inventors desire a water heater which overcomes or at least alleviates these drawbacks. Further, the Inventors are aware that conduits, such as copper pipes, are commonly used in plumbing applications for conveying water. The Inventors are also aware that in many applications heating elements are provided in such conduits to heat the water as it flows past the element. To eliminate the possibility of the elements being activated without any water flowing in the conduit, the Inventors desire a switch which automatically senses when flow is taking place in such a conduit or pipe, and consequently actuates an electrical contact.

SUMMARY

According to a first aspect of the invention, there is provided a water heater which includes: at least two water chambers, each defining a cavity therein; a heating element within each cavity; at least two linking channels linking the two chambers in parallel; a water inlet and a water outlet in fluid flow communication with the chambers; wherein one of the heating elements is independently operable in a pre-heating phase when no water flows through the inlet and the outlet, and wherein all the heating elements are operable in a full heating phase when water flows through the inlet and the outlet.

The chambers may be orientated in an upright position, once the heater is installed or in use. More specifically, the chambers may be elongate and upright.

In the pre-heating phase, the two cavities defined by the chambers, together with the two linking channels, may define a closed-loop fluid flow path. In the pre-heating phase, water within a first chamber, containing the independently operable element, may heat up and subsequently flow or rise upwardly through the chamber, through the top linking channel and into the second chamber, and the water from said second chamber may then flow downwardly and through the bottom linking channel into the first chamber, thereby causing convection flow of the water around the closed loop fluid flow path.

The inlet may be positioned at a bottom linking channel, and the outlet may be positioned at an upper end of one of the channels.

In the full heating phase, water flowing in from the inlet may flow into the second chamber, and the water in said second chamber may flow up through the chamber and out of the outlet. Water may be drawn from the first chamber, through the lower linking channel, through a Venturi effect.

The water heater may include a pre-heater thermostat to control the independently operable element thereby to maintain the water in the water heater at a pre-set temperature during the pre-heating phase. The pre-heater thermostat may be located in the second chamber.

The water heater may include a safety thermostat operable to interrupt power supply in case a maximum safe temperature is exceeded.

The water heater may include associated control circuitry. The water heater may also include a display arrangement. More specifically, the display arrangement may include three coloured indictor lights. These lights may respectively indicate that the water heater is powered, that the preheating phase is in progress and that the full heating phase is in progress. - A -

By way of development, the invention extends to a water heater installation, including: a water heater as defined above; and a flow switch operable to sense flow of a liquid in a conduit, the flow switch including: a housing having an inlet and an outlet in flow communication with each other, the housing defining a seat, a portion of which is arcuately curved; a sealing member pivotally mounted between the inlet and the outlet within the housing, the sealing member being operable to pivot about a pivot axis, a free end of the sealing member thus defining a displacement arc, the arcuately curved portion of the seat having a radius of curvature which matches that of the displacement arc of the sealing member, such that the sealing member abuts sealingly against the curved portion of the seat when radially aligned therewith, but permits flow of liquid when the sealing member is angularly displaced past the arcuately curved portion of the seat; and a contacting means connected to the sealing member, the contacting means being operable to actuate an electrical contact in response to the pivoting of the sealing member past a predefined angular threshold.

The flow switch may be operable to switch automatically between the preheating and full heating phases.

The sealing member may be in the form of a plug or a vane.

The arcuately curved portion of the seat may have a constant radius of curvature, which matches that of the displacement arc of the sealing member, such that the sealing member abuts sealingly against the seat when the sealing member is angularly displaced along the arcuately curved portion. The seat may further define a flow-permitting portion, following the arcuately curved portion, having a progressively increasing radius of curvature relative to the displacement arc of the sealing member, such that the sealing member progressively permits increased flow of water as it is angularly displaced through the flow-permitting portion of the seat.

The flow switch may include biasing means operable to bias the sealing member to a closed position wherein the sealing member sealingly abuts a rest position of the arcuately curved portion of the seat.

The biasing means may have a user-adjustable bias.

The bias of the biasing means may be adjusted through the tightening or loosening of a screw. Adjusting the bias may adjust the compliance of the sealing member.

The sealing member may be angularly displaced or displaceable by water pressure exerted on a face of a high pressure side of the sealing member. Accordingly, a pre-defined threshold of water pressure may be required to displace the sealing member past the arcuately curved portion of the seat such that, only once the sealing member has passed the arcuately curved portion and is radially aligned with the flow- permitting portion, may through-flow of water be permitted. Thus, no flow may occur until a pressure threshold sufficient to displace the sealing member past the curved portion of the seat is reached. Adjusting the bias may therefore adjust the pressure threshold.

The contacting means may include a cam shaft fast with the sealing member, the shaft sealingly protruding through an aperture in the housing, to the exterior, and being operable to pivot about the pivot axis. The housing may include an aperture seal situated in the aperture through which the cam shaft extends, preventing leakage of water from the housing.

The cam shaft may include a cam at a distal end thereof, the cam being operable to actuate the electrical contact in response to the pivoting of the cam shaft due to the displacement of the sealing member past a predefined threshold. The predefined threshold may be the position at which the sealing member is displaced past the curved portion of the seat.

The electrical contact may be in the form of a switch.

The biasing means may be in the form of a spring connected to the cam of the contacting means.

According to a second aspect of the invention, there is provided a method of heating water, the method including: pre-heating the water in a pre-heating phase as defined above; and heating the water in a full heating phase as defined above.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings:

Figure 1 shows a schematic cross-sectional view of a water heater in accordance with the invention; Figure 2 shows a schematic cross-sectional view of the water heater of Figure 1, with the heater in a pre-heating phase;

Figure 3 shows a schematic cross-sectional view of the water heater of Figure 1, with the heater in a full heating phase; Figure 4 shows a top plan view of a display arrangement of the water heater of

Figure 1;

Figure 5 shows a front view of a flow switch for use with the water heater of Figure 1;

Figures 6 to 8 show cross-sectional views of the flow switch of Figure 5 in various stages of operation;

Figure 9 shows a schematic circuit diagram of a water heater installation, in accordance with the invention; and

Figures 10 to 12 show graphical test results of the water heater of Figure 1.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

Referring first to Figures 1 to 4, reference numeral 10 refers generally to a water heater, in accordance with the invention. The water heater 10 is described first, and the flow switch aspect is described thereafter.

Figure 1 shows the water heater 10 which includes two water chambers 12, 14, each defining a cavity 16, 18 for the temporary storage of water. Both chambers 12, 14 are elongate and are positioned upright, when installed correctly. The cavities 16, 18 are linked in parallel by two linking channels 20, 22, bringing the water chambers

12, 14 into fluid flow communication with each other. Each chamber 12, 14 has a heating element 24, 26 positioned within its cavity 16, 18. Each heating element 24, 26 may, for example, be a 3 kW, 4 kW or 5 kW immersion element. Example combinations of elements 24, 26 include 4 kW + 3 kW (for a total rating of 7 kW), 4 kW + 4 kW (for a total rating of 8 kW) and 5 kW + 4 kW (for a total rating of 9 kW) and these examples are used for tests in Figures 10 to 12.

A minimum of a 40OkPa relief valve (not shown) is located above the first chamber 12. The water heater 10 may include other valves and/or switching devices for safety, if desired (e.g. vacuum breaker valves, etc). A fluid inlet 28 is positioned in the lower linking channel 22, and a fluid outlet 30 is positioned above the second chamber 14.

The water heater 10 is capable of switching between two phases, a preheating phase (as illustrated in Figure 2) for heating the water before use, and a full heating phase (as illustrated in Figure 3) for heating hot water on demand.

In the pre-heating phase, only the first heating element 24 is activated, while no water flows in through the inlet 28 or out of the outlet 30. With no water flowing in or out of the heater 10, the chamber cavities 16, 18, together with the linking channels 20, 22, define a closed loop fluid flow path. The activated or energised element 24 heats the water in its proximity which causes a convection flow of the water within the closed loop fluid flow path. More specifically, the activated element 24 causes the water near the element 24 to heat up and subsequently rise and flow upwards through the first chamber 12, through the upper linking channel 20, and into the second chamber 14. This then causes the water in the second chamber 14 to be drawn through the lower linking channel 22 into the first chamber 12. The convection flow causes the water to circulate constantly past the activated element 24, thereby constantly heating it. The first chamber 12 also houses a pre-heater thermostat which controls the first heating element 24 in terms of a pre-set temperature.

Water can be drawn from the heater 10 through a tap or other valve which may be connected to the outlet 30. When the tap is opened, a flow switch (described further below) automatically switches the heater 10 to the full heating phase wherein both heating elements 24, 26 are activated, while water flows in from the inlet 28 and out of the outlet 30. The water flowing in from the inlet 28 flows into the second chamber 14, while the water in the second chamber 14 flows out of the outlet 30. Water is drawn from the first chamber 12, through the lower linking channel 22, through the Venturi effect. This effect causes the water flowing up through the second chamber 14 to bifurcate, with some of the water flowing out through the outlet 30 and some flowing through the upper linking channel 20 and into the first chamber 12. Thus, newly heated water is mixed with the preheated water, thereby to provide at least some of the benefits of large volume geysers and flow-through water heaters. (In an alternate configuration, water may flow from the inlet 28 through the chambers 12, 14 in parallel and out of the outlet 30.)

The heater also has a display arrangement which consists of blue, green and red indicator lights 32, 34, 36 (as shown in Figure 4) to indicate the status of the heater 10.

The operation of these lights 32, 34, 36 is as follows. The green light 34 indicates that the heater 10 is on and ready to begin the pre-heating phase automatically.

Pre-heating stage: After the initial start-up, both the blue and green pilot lights 32, 34 are on. It takes roughly two minutes and fifty seconds for the heater 10 to heat the water from ambient tap water temperature up to roughly 50⁰C. When the water temperature reaches 50⁰C, the blue pilot light 32 goes off. The blue light 32, when on, thus indicates that pre-heating is taking place but not yet completed.

Full heating stage: When the water is pre-heated to roughly 50°C, the heater 10 is capable of supplying water at this temperature for 95 seconds at a rate of 5 litres per minute, before the temperature starts to reduce when the pre-heated water becomes depleted. During this stage, both the blue and red pilot lights 32, 36 are on.

If water is still demanded after 95 seconds, the heater 10 will supply water at 45°C at a rate of 5 litres per minute as little or no preheated water remains. A higher temperature than 45° C will be available but at the expense of less volume, and vice versa.

With reference now to Figures 5 to 8, reference numeral 100 refers generally to a flow switch in accordance with the invention.

The flow switch 100 includes a housing 120 having an inlet 140 and an outlet 160 in flow communication with each other. The direction of the flow of water through the housing 120 is indicated by arrow 170. A base of the housing 120 accommodates an inwardly facing seat 200, a portion of which is arcuately curved 200.1.

The arcuately curved portion 200.1 has a constant radius of curvature, followed by a flow-permitting portion 200.2.

The flow switch 100 also includes a sealing member 180 (in this example in the form of a circular plug), pivotally mounted within the housing 120 via an arm 185, operable to pivot about a pivot axis 190. The flow-permitting portion 200.2 may have any appropriate profile, such as a progressively increasing radius of curvature relative to the pivot axis 190, but in this example is linear and slopes away from the pivot axis 190 and then terminates completely.

In one embodiment of the invention, the arcuately curved portion 200.1 of the seat 200 extends for about a 12° arc about the pivot axis 190, and the flow- permitting portion 200.2 extends for a further 20° relative to the pivot axis 19. The Inventors believe that the configuration of the seat 200 facilitates mechanical flow control thereby permitting mechanical temperature control.

Typically, the flow switch 100 is installed, in series configuration, with a water carrying conduit or pipe, such as a copper plumbing pipe, upstream or downstream of the water heater 10. In an initial closed position, as shown in Figure 6, the sealing member 180 sealingly abuts the arcuately curved portion 200.1 of the seat 200, thus preventing the flow of water past the sealing member 180. In use, water pressure is exerted on the sealing member 180 due to water in the pipe, for example, by the progressive opening of a tap (or faucet).

The water pressure causes the angular displacement of the sealing member 180 about the pivot axis 190, the sealing member 180 thus defining a displacement arc. The displacement arc of the sealing member 180 matches the radius of curvature of the arcuately curved portion 200.1 of the seat 200, such that the sealing member 180 sealingly abuts the seat 200 as it is displaced along the arcuately curved portion 200.1, not yet permitting water flow (Figure 7). The radius of curvature of the flow-permitting portion 200.2 of the seat 200 deviates progressively further from the displacement arc of the sealing member 180, such that increased flow of water is progressively permitted as the sealing member 180 is displaced along the flow- permitting portion 200.2 (Figure 8). The further the sealing member 180 is displaced, the more water is allowed through the housing 120.

With reference to Figure 5, the flow switch 100 further includes contacting means 220 operable to actuate an electrical contact or relay in response to the pivoting of the sealing member 180. The contacting means 220 includes a cam shaft 210, fast with the sealing member 180, and co-axial with the pivot axis 190. In fact, the cam shaft 210 pivotally mounts the sealing member 180 within the housing 120. The cam shaft 210 pivots about the pivot axis 190 in response to the angular displacement of the sealing member 180. The cam shaft 210 protrudes through an aperture in the housing 120. The aperture is sealed with two O-rings inserted in grooves cut around the cam shaft 210. The contacting means 220 further includes a cam 230 which projects radially from the distal end of the cam shaft 210.

Access to the housing 120 is permitted by means of a removable cap 150 which is operable to engage sealingly with the housing 120.

Rotation of the cam shaft 210 due to the angular displacement of the sealing member 180 past the predefined threshold causes the cam 230 to pivot about the pivot axis 190 and to actuate or close an electrical contact or switch 320. The sealing member 180 is biased to the closed position by a spring 300. The compliance of the spring 300 influences the compliance of the sealing member 180. Therefore, the threshold of water pressure required to displace the sealing member 180 past the arcuately curved portion 200.1 of the seat 200, to allow water to flow and to actuate the switch 320, is adjustable by selecting a spring 300 having an appropriate compliance. The spring 300, by biasing the sealing member 180 towards its closed position, also ensures that the electrical contact or relay is switched off when no water flows.

Referring now to Figure 9, reference 500 generally indicates a schematic circuit diagram of a water heater installation, in accordance with the invention. In the circuit diagram 500, the following legend is used:

CB: circuit breaker,

P_L: pilot light 32, 34, 36, Fs: flow switch 100,

N/C: normally closed,

R_L A: relay coil,

Th: thermostat,

N/O: normally open, E_L: element, and R_L: relay coil CN18.

The circuit diagram 500 is largely self-explanatory. It is worth mentioning that CB 40 A need only be installed when the water heater 10 and associated controller are spaced further than 1 m apart from each other.

The Inventors believe that the water heater 10, as exemplified, heats water in an energy efficient way, which can be very useful in places where there are energy deficiencies or restrictions. Further, the heater 10 is capable of supplying hot water for a prolonged period, combining the benefits of large water geysers while having energy efficiency comparable to that of flow-through water heaters.

The Inventors further believe that the flow switch 100, as exemplified, provides a simple, cost effective means of sensing the flow of liquid in a conduit or pipe and consequently actuating an electrical contact or switch. The Inventors believe further that the flow switch can be used effectively with tankless hot water geysers for sensing water flow and actuating heating elements. The Inventors also believe that the arcuately curved portion of the seat facilitates mechanical temperature control when the flow switch is used in conjunction with a tankless hot water geyser.

Tests

Tests were conducted and are the result of comprehensive in-practice experiments. The test parameters were designed to establish the efficaciousness of the product in terms of not only its effectiveness (functionality/performance) but also its efficiency (energy saving). Figures 10 and 11 reflect the effectiveness and Figure 12 depicts the energy efficiency. The concept was initially developed from a point-of-use instantaneous flow water heater perspective under semi-whole-house conditions serving two separate bathrooms - divided by one wall - comprising of one shower, one bath tub and two hand wash basins.

The empirical test parameters comprised the testing of two independent variables relative to temperature. The general accepted comfort zones of 5 litres at 40°C over 60 s were used as central values. Figures 11 and 12 reflect the test results in terms of temperature over volume and time over temperature respectively. The dependent variables are time at 60 s and volume at 5 litres. The performance curves in respect of both tests confirmed a strong correlation of inefficiency in respect of an 8kW and 9 kW configurations towards the lower end of a performance continuum.

The water heater 10 was installed parallel to an existing storage geyser with equal pipe lengths ensuring similar conditions for conducting the comparative energy efficiency analyses.

The power consumption was measured independently for each geyser over consecutive periods of thirty days with no variation in frequency of usage. The tests were purposefully conducted under low flow conditions which are normatively not considered advantageous for optimal performance of instantaneous water heaters.

The water pressure for the test was kept purposefully at a constant rather low 50 kPa to represent the utmost lowest pressure in respect of the normatively pressure range spectrum.

Inlet water temperature was measured at 25°C at an ambient air temperature of 28°C. The effective energy efficiency in respect of a 7 kW in comparison with a conventional storage geyser amounts to a saving of 70, 2%.

Claims

1. A water heater which includes: at least two water chambers, each defining a cavity therein; a heating element within each cavity; at least two linking channels linking the two chambers in parallel; a water inlet and a water outlet in fluid flow communication with the chambers; wherein one of the heating elements is independently operable in a pre-heating phase when no water flows through the inlet and the outlet, and wherein all the heating elements are operable in a full heating phase when water flows through the inlet and the outlet.

2. A water heater as claimed in claim 1, in which the chambers are orientated in an upright position, in use.

3. A water heater as claimed in claim 1 or claim 2, in which, in the preheating phase, the two cavities defined by the chambers, together with the two linking channels, define a closed-loop fluid flow path.

4. A water heater as claimed in claim 3, in which, in the pre-heating phase, water within a first chamber, containing the independently operable element, heats up and subsequently flows or rises upwardly through the chamber, through the top linking channel and into the second chamber, and the water from said second chamber then flows downwardly and through the bottom linking channel into the first chamber, thereby causing convection flow of the water around the closed-loop fluid flow path.

5. A water heater as claimed in any of the preceding claims, in which the inlet is positioned at a bottom linking channel, and in which the outlet is positioned at an upper end of one of the channels.

6. A water heater as claimed in any of the preceding claims, in which, in the full heating phase, water flowing in from the inlet flows into the second chamber, and the water in said second chamber flows up through the chamber and out of the outlet.

7. A water heater as claimed in claim 6, in which water is drawn from the first chamber, through the lower linking channel, through a Venturi effect.

8. A water heater as claimed in any of the preceding claims, which includes a pre-heater thermostat to control the independently operable element thereby to maintain the water in the water heater at a pre-set temperature during the pre-heating phase.

9. A water heater as claimed in any of the preceding claims, which includes a safety thermostat operable to interrupt power supply in case a maximum safe temperature is exceeded.

10. A water heater as claimed in any of the preceding claims, which includes a display arrangement operable to indicate respectively that the water heater is powered, that the preheating phase is in progress and that the full heating phase is in progress.

11. A water heater installation, including: a water heater as claimed in any of the preceding claims; and a flow switch operable to sense flow of water in a conduit, the flow switch including: a housing having an inlet and an outlet in flow communication with each other, the housing defining a seat, a portion of which is arcuately curved; a sealing member pivotally mounted between the inlet and the outlet within the housing, the sealing member being operable to pivot about a pivot axis, a free end of the sealing member thus defining a displacement arc, the arcuately curved portion of the seat having a radius of curvature which matches that of the displacement arc of the sealing member, such that the sealing member abuts sealingly against the curved portion of the seat when radially aligned therewith, but permits flow of liquid when the sealing member is angularly displaced past the arcuately curved portion of the seat; and a contacting means connected to the sealing member, the contacting means being operable to actuate an electrical contact in response to the pivoting of the sealing member past a predefined angular threshold.

12. A water heater installation as claimed in claim 11, in which the flow switch is operable to switch automatically between the preheating and full heating phases.

13. A water heater installation as claimed in claim 11 or claim 12, in which the sealing member is in the form of a plug.

14. A water heater installation as claimed in any of claims 11 to 13 inclusive, in which the arcuately curved portion of the seat has a constant radius of curvature, which matches that of the displacement arc of the sealing member, such that the sealing member abuts sealingly against the seat when the sealing member is angularly displaced along the arcuately curved portion.

15. A water heater installation as claimed in any of claims 11 to 14 inclusive, in which the seat further defines a flow-permitting portion, following the arcuately curved portion, having a progressively increasing radius of curvature relative to the displacement arc of the sealing member, such that the sealing member progressively permits increased flow of water as it is angularly displaced through the flow-permitting portion of the seat.

16. A water heater installation as claimed in claim 15, in which the flow switch includes biasing means operable to bias the sealing member to a closed position wherein the sealing member sealingly abuts a rest position of the arcuately curved portion of the seat.

17. A water heater installation as claimed in claim 16, in which the biasing means includes a user-adjustable bias.

18. A water heater installation as claimed in claim 17, in which adjusting the bias adjusts the compliance of the sealing member.

19. A water heater installation as claimed in any of claims 11 to 18 inclusive, in which the sealing member is angularly displaced or displaceable by water pressure exerted on a face of a high pressure side of the sealing member.

20. A water heater installation as claimed in claim 19, in which a pre-defined threshold of water pressure is required to displace the sealing member past the arcuately curved portion of the seat such that, only once the sealing member has passed the arcuately curved portion and is radially aligned with the flow-permitting portion, is through-flow of water be permitted.

21. A water heater installation as claimed in any of claims 11 to 20 inclusive, in which the contacting means may include a cam shaft fast with the sealing member, the shaft sealingly protruding through an aperture in the housing, to the exterior, and being operable to pivot about the pivot axis.

22. A water heater installation as claimed in claim 21, in which the cam shaft includes a cam at a distal end thereof, the cam being operable to actuate the electrical contact in response to the pivoting of the cam shaft due to the displacement of the sealing member past a predefined threshold.

23. A method of heating water, the method including operating a water heater as claimed in any of claims 1 to 10 inclusive, thereby to: pre-heat the water in a pre-heating phase; and heat the water in a full heating phase.