WO2013131129A1

WO2013131129A1 - A water heating system

Info

Publication number: WO2013131129A1
Application number: PCT/AU2013/000205
Authority: WO
Inventors: Patrick Pussell; Mark Mason
Original assignee: Dux Manufacturing Limited
Priority date: 2012-03-06
Filing date: 2013-03-05
Publication date: 2013-09-12
Also published as: AU2018200629A1; AU2013230675A1

Abstract

A water heating system (10) including a water storage tank (12), an instantaneous-type water heater (18), a first pump (20), at least one solar panel (30) and a second pump (32). The water storage tank (12) has a mains water (MW) inlet (14) and a heated water (HW) outlet (16). The instantaneous-type water heater (18) has an inlet (18a) and an outlet (18b), with the instantaneous-type water heater outlet (18b) being in fluid communication with the water storage tank (12). The first pump (20) has an inlet (20a) in fluid communication with the water storage tank (20) and an outlet (20b) in fluid communication with the instantaneous-type water heater inlet (18a). The at least one solar panel (30) has an inlet (30a) and an outlet (30b), with the at least one solar panel outlet (30b) being in fluid communication with the water storage tank (12). The second pump (32) has an inlet (32a) in fluid communication with the water tank (12) and an outlet (32b) in fluid communication with the at least one solar panel inlet (30a).

Description

A WATER HEATING SYSTEM

Field of the Invention

[0001] The present invention relates to a water heating system.

[0002] The present invention has been primarily developed for use with gas instantaneous type water heaters and will be described hereinafter with reference to that application. However, the invention is not limited to this particular field of use and can also be used with electrical instantaneous type heaters. In the United States of America, instantaneous type water heaters are known as tank-less heaters.

Background of the Invention

[0003] The Applicant's international PCT patent application NO. PCT/AU2011/000579 (WO 201 1/146962) discloses a water heating system, with reference to Fig. 5, in which heated water can be supplied to a water storage tank from either a gas instantaneous type water heater or a solar panel.

[0004] The water heating system shown in Fig. 5 has a single pump which draws water from the bottom of the water storage tank and pumps it to a first valve. A controller controls the first valve to direct the pumped water to pass through either the gas instantaneous type water heater or through the solar panel for heating, before being returned to the top of the water storage tank. The water heating system also has a second valve which the controller controls to drain water from the solar panel, when the water in the solar panel is sensed to be reaching a temperature where it may freeze and damage the solar panel. The controller controls the pump and the valves in such a way as to always attempt to use solar energy as a preference, in order to minimise purchased energy (e.g. gas), but to switch to gas in order to satisfy a user's heated water demands.

[0005] In the disclosed system, water can be heated by only one of the gas instantaneous type heater or the solar panel at a time. A limitation of the disclosed system is that a user's demands may necessitate the water being heated by the gas heater during periods where available solar energy is not being utilized. Object of the Invention

[0006] It is an object of the present invention to provide a water heating system that overcomes the above limitation.

Summary of the Invention

[0007] Accordingly, the present invention provides a water heating system including:

a water storage tank with a mains water inlet and a heated water outlet;

an instantaneous-type water heater having an inlet and an outlet, the instantaneous-type water heater outlet being in fluid communication with the water storage tank;

a first pump having an inlet in fluid communication with the water storage tank and an outlet in fluid communication with the instantaneous-type water heater inlet;

at least one solar panel having an inlet and an outlet, the at least one solar panel outlet being in fluid communication with the water storage tank; and

a second pump having an inlet in fluid communication with the water tank and an outlet in fluid communication with the at least one solar panel inlet.

[0008] The water heating system preferably includes a controller adapted to energise the first pump only or the second pump only or the first and second pumps, responsive to user demands and/or availability of solar energy.

[0009] The water storage tank preferably includes a first opening that is in fluid

communication with the inlet of the first pump and a second opening that is in fluid communication with the outlet of the at least one solar panel.

[0010] The water storage tank preferably includes an opening that is in fluid communication with the inlet of the first pump and also with the outlet of the at least one solar panel. The opening is preferably connected to the inlet of the first pump and also to the outlet of the at least one solar panel by a pipe-in-pipe fitting. The pipe-in-pipe fitting preferably includes an internal pipe for communication of water into the water storage tank from the at least one solar panel outlet and an external pipe for communication of water from the water storage tank to the first pump inlet, whereby the water is independently communicated through the interior of the internal pipe and communicated in the space between the interior of the external pipe and the exterior of the internal pipe respectively.

[0011] The water heating system preferably includes a valve arrangement in fluid

communication between the second pump outlet and the at least one solar panel inlet, the valve arrangement controllable between allowing water to be pumped from the second pump outlet to the inlet of the at least one solar panel or allowing water to be drained from the at least one solar panel inlet to atmosphere.

[0012] The valve arrangement preferably includes a ball valve with first and second operating states, the first operating state allows or prevents water to be pumped from the second pump outlet to the inlet of the at least one solar panel when open or closed respectively and the second operating state prevents or allows water to be drained from the at least one solar panel inlet to atmosphere when open or closed respectively.

[0013] The valve arrangement preferably includes a first and a second solenoid valve, wherein the first solenoid valve allows or prevents water to be pumped from the second pump outlet to the inlet of the at least one solar panel when open or closed respectively and the second solenoid valve prevents or allows water to be drained from the at least one solar panel inlet to atmosphere when open or closed respectively. The first and second solenoid valves are preferably controllably interlocked such the first valve is open when the second valve is closed and first valve is closed when the second valve is open.

[0014] The water heating system preferably includes a one way valve adapted to only allow fluid communication from the at least one solar panel outlet to the water storage tank.

[0015] The opening is preferably at or near the middle of the tank. The instantaneous-type water heater outlet is preferably in fluid communication at or near the top of the water storage tank. The second pump inlet is preferably in fluid communication at or near the bottom of the water storage tank.

[0016] The water heating system preferably includes a space heating circuit in fluid communication with the water storage tank. In one form, the space heating circuit includes a first heat exchanger in a space to be heated. In another form, the space heating circuit includes a first heat exchanger and a second heat exchanger, wherein the first heat exchanger is in a heat exchange relationship with the second heat exchanger and the second heat exchanger is in a space to be heated. The water heating system preferably includes a third water pump for circulating water through the first heat exchanger. The water heating system preferably includes a fourth pump for circulating fluid through the second heat exchanger.

[0017] The instantaneous-type water heater is preferably energised and de-energised responsive to the first pump being energised and de-energised respectively.

[0018] The water heating system preferably includes a controller adapted to energise the first pump, responsive to the temperature of the water in the water storage tank.

[0019] The water heating system preferably includes a hydronic heating circuit in fluid communication with the water storage tank. The hydronic heating circuit preferably includes at least one hydronic line and a third pump for circulating water through the at least one hydronic line. The water heating system preferably includes an adjustable ball valve, in fluid communication with the third pump, which is adapted for adjusting, most preferably by throttling, the amount of heated water supplied to the at least one hydronic line. The third pump preferably has a maximum flow rate that is 80-85% of the maximum flow rate of the first pump. These relative flow rates can be achieved in a number of ways, including: the third pump having a maximum flow rate that is fixed as a percentage of the maximum flow rate of the first pump; the third pump having a switchable speed control; or the third pump being similar in maximum flow rate to the first pump but throttled down with a ball valve.

[0020] The water heating system preferably includes a tempering valve, in fluid

communication with the ball valve and also main water supply.

Brief Description of the Drawings

[0021] Preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings in which:

[0022] Fig.1 is a schematic view of a first embodiment of a water heating system; [0023] Fig. 2 is an enlarged detailed view of a tank wall and associated fitting used in the water heating system shown in Fig. 1 ;

[0024] Fig. 3 is a schematic view of a second embodiment of a water heating system; [0025] Fig. 4 is a schematic view of a third embodiment of a water heating system; [0026] Fig. 5 is a schematic view of a fourth embodiment of a water heating system; and [0027] Fig. 6 is a schematic view of a fifth embodiment of a water heating system; Detailed Description of the Preferred Embodiments

[0028] Fig. 1 shows a first embodiment of a water heating system 10. The system 10 includes a 315 litre water storage tank 12 that, as will be described in more detail below, operates in a dual zone manner with an upper (gas) heated zone 12a and a lower (solar) heated zone 12b.

[0029] The tank 12 is generally cylindrical in construction and includes a side wall 12c. Mains water MW is admitted into the tank 12 via an inlet 14 near the bottom of the tank 12. The tank 12 also includes an outlet 16, near the top of the tank 12, for heated water HW. The outlet 16 is connected to a user controlled outlet device, such as a hot water tap (not shown).

[0030] The system 10 also includes a gas instantaneous type water heater 18, preferably of 4, 5 or 6 Star rating. The gas heater 18 includes an inlet 18a and an outlet 18b. The system 10 also includes a first pump 20, with an inlet 20a and an outlet 20b. As shown in Fig. 2, the tank wall 12c includes an opening 12d through which passes a pipe-in pipe fitting 22. The fitting 22 has an inner piper 22a and an outer pipe 22b. Water flowing through the interior of the inner pipe 22a is independent of the water flowing between the exterior of the inner pipe 22a and the interior of the external pipe 22b. The external pipe 22b acts as a tank outlet and provides water from about the middle of the tank 12 to the inlet 20a of the pump 20. The outlet 20b of the pump 20 communicates water to the inlet 18a of the heater 18. The outlet 18b of the heater provides heated water to an inlet 24 of the tank 12, which is positioned near the top of the tank 12. The upper zone 12a of the tank 12, the heater 18, the first pump 20 and the external pipe 22b together form a gas heating circuit. [0031] The system 10 also includes a solar panel 30 with a solar air bleed 32. The solar panel 30 has an inlet 30a and an outlet 30b. The system 10 also includes a second pump 32 with an inlet 32a and an outlet 32b. The inlet 32a of the pump 32 draws water from near the bottom of the tank 12 via an outlet 34. The outlet 32b of the pump 32 supplies water to a valve arrangement 36. The valve arrangement 36 includes two solenoid gate type valves 38 and 40. The first valve 38 is biased to an open position in the absence of electrical power and closes when energised. The second valve 36b is biased to a closed position in the absence of electrical power and opens when energised. The first valve 38 has an inlet 38a and an outlet 38b. The second valve 40 has an inlet 40a and an outlet 40b. The outlet 38b of the first valve 38 is in fluid communication with the inlet 30a of the solar panel 30. The inlet 30a of the solar panel 30 is also in fluid communication with the inlet 40a of the second valve 40. The system 10 also includes a one-way valve 42 with an inlet 42a and an outlet 42b. The one-way valve 42 only allows water to flow from the outlet 30b of the solar panel 30 and into the tank 12 via the internal pipe 22a of the pipe-in pipe fitting 22. The lower zone 12b of the tank 12, the solar panel 30, the second pump 32, the internal pipe 22a and the one-way valve 42 together form a solar heating circuit.

[0032] The system 10 also includes a controller 44 which receives an indication of the water temperature in the tank 12 and the solar panel 30 via temperature sensors (not shown). The controller 44 is also able to issue control signals to the gas instantaneous heater 18, the first pump 20, the second pump 32, the first valve 38 and the second valve 40. ,

[0033] The operation of the system 10 shall now be described. In response to user demand, the controller 44 energises the gas heater 18 and also the first pump 20. This causes relatively cooler water to be drawn from the middle of the tank 12 through the external pipe 22b of the pipe-in pipe fitting 22 and pumped through the gas heater 18 for heating. The heated water is then pumped to the tank 12 and is available for drawing off by a user at outlet 16.

[0034] If sufficient solar energy is available, the controller 44 can also energise the second pump 32 to withdraw water from the bottom of the tank 12 at the outlet 34 and pump it through the first valve 38 and into the solar panel 30 for heating. The heated water then is then pumped from the solar panel 30, through the one-way valve 42, and is returned to the tank 12 via the internal pipe 22a of the pipe-in pipe fitting 22. [0035] Importantly, the gas heating circuit and the solar heating circuit can be operated independently of one another. This advantageously means that available solar energy is still able to be collected and utilised notwithstanding that the user demands of the system 10 necessitate gas heating. This ensures that available solar energy is not wasted.

[0036] If the controller 44 senses that the water in the solar panel 30 is close to freezing then it de-energises the second pump 32 and energises the first valve 38 and the second valve 40. This closes the first valve 38 and opens the second valve 40, and allows the water in the solar panel 30 to drain to atmosphere through the outlet 40b.

[0037] The system 10 utilizes an additional pump to that described with reference to Fig. 5 of the Applicant's previously mentioned PCT application. However, the additional cost of this component is offset due to the fact that the valve arrangement 36 comprises a pair of solenoid valves 38 and 40, which are more robust and less expensive than the motorized ball valves required for the earlier system. The valves 38 and 40 are also very energy efficient, as they are only energized during the draining of the solar panel 30 and therefore do not consume any energy during their predominant operating state.

[0038] The pipe-in pipe fitting 22 advantageously allows the gas circuit and the solar circuit to communicate with the water tank 12 via a single opening 12d. This advantageously requires only one hole to be made in the tank, which minimizes leak risks and stress fracture risks.

[0039] Fig. 3 shows a second embodiment of water heating system 50. The system 50 is similar to that of the system 10 previously described and like features are indicated with like reference numerals. The system 50 includes a third pump 52 which has an inlet 52a and an outlet 52b. The system 50 also includes a first heat exchanger 54 with an inlet 54a and an outlet 54b. The inlet 52a of the pump 52 is in fluid communication with the heated water outlet 16 of the water tank 12. The outlet 52b of the pump 52 is in fluid communication with the inlet 54a of the heat exchanger 54. The outlet 54b of the heat exchanger 54 is in fluid communication with an inlet 56 of the tank 12.

[0040] In operation, the controller 44 energizes the third pump 52 thereby causing heated water from the top of the tank 12 to circulate through the first heat exchanger 54. The heat exchanger 54 can be positioned in a space to be heated, such as a room, and hereby provide a space heating circuit which utilizes gas and/or solar energy as its heating source.

[0041] In a further variation, the system 50 can include a closed hydronic heating circuit 56 comprising a fourth pump 58, a second heat exchanger 60 and a space heater such as a radiator 62 within a room 64. The second heat exchanger 60 is positioned in a heat exchange relationship with the first heat exchanger 54. The controller 44 energizes the third pump 52 and the fourth pump 58. The energizing of the third pump 52 causes heated water to be circulated through the first exchanger 54 as described above. This heat is then transferred to the second heat exchanger 60 whereafter it is circulated by the fourth pump 58 through the radiator 62. Again, this provides a space heater that is gas and/or solar powered.

[0042] Fig. 4 shows a third embodiment of water heating system 70. The system 70 is similar to that of the systems 10 and 50 previously described and like features are indicated with like reference numerals. However, in the system 50, the controller 44 receives an indication of the water temperature in the tank 12 via temperature sensors 44a, 44b and 44c and receives an indication of the water temperature in the solar panels 30 via a temperature sensor 44d. The controller 44 is able to issue control signals to the first pump 20. The gas heater 18 has an internal controller which turns it on when the first pump 20 is turned on and turns it off when the pump 20 is turned off.

[0043] The system 70 also includes a ball valve 72, with an inlet 72a and an outlet 72b, a tempering valve 74, with an inlet 74a and an outlet 74b, and a room thermostat 75. The outlet 52b of the third pump 52 is in fluid communication with the inlet 72a of the ball valve 72. The outlet 72b of the ball valve 72 is in fluid communication with the inlet 74a of the tempering valve 74. The outlet 74b of the tempering valve 74 is in fluid communication with the inlet 14 of the tank 12, via a hydronic heating line 78, in which is provided a pair of one way valves 76. The tempering valve 74 is also in fluid communication with the mains (cold) water supply MW.

[0044] In operation, the gas heater 18 is turned on and off responsive to the first pump 20 being turned on and off by the controller 44. The first pump 20 is turned on and off, responsive to the temperature sensors 44a to d, particularly sensors 44b and 44c which indicate the condition of the water in the upper heated water zone 12a of the tank 12. [0045] The hydronic circuit is independently controlled by the room thermostat 75. More particularly, the amount of heated water that is supplied to the hydronic line 78 from the heated water zone 12a is controlled by throttling the ball valve 72. At maximum water temperature, the volume flow rate of the heated water supplied to the hydronic line 78 is about 80-85% of the maximum volume flow rate of the first pump 20 associated with the gas heater 18. The 20- 15% balance of the maximum output of the first pump 20 and the gas heater 18 is reserved for maintaining the temperature of the heated water zone 12a.

[0046] Colder mains water MW can also be mixed into the heated water being supplied to the hydronic line 78, in order to adjust the temperature of same, via the tempering valve 74.

[0047] The system 70 advantageously allows for control of the heater 18 to be simplified to only heating energisation responsive to water flow therethrough. The system 70 also advantageously allows the heat supplied to the hydronic circuit to be adjusted, via throttling of the ball valve 72, so as to not exhaust the energy capacity of the gas heater 18.

[0048] Fig. 5 shows a fourth embodiment of water heating system 90. The system 90 is similar to system 10 previously described and like features are indicated with like reference numerals. However, in the system 90, the fitting 22 is not utilised and instead a pair of openings 12d and 12e are made in the tank wall 12c. The opening 12d is an outlet for the gas heating circuit and the opening 12e is an inlet for the solar circuit. Further, the (dual solenoid gate type valves) valve arrangement 36 is replaced by a single ball valve 92. The ball valve 92 has two operating states, one providing fluid communication from the outlet 32b of the pump 32 to the inlet 30a of the solar panel 30 and another providing fluid communication the inlet 30a to atmosphere (for draining).

[0049] Fig. 6 shows a fifth embodiment of water heating system 100. The system 100 is similar to system 70 previously described and like features are indicated with like reference numerals. However, in the system 100, the fitting 22 is not again utilised and replaced by the pair of openings 12d and 12e in the tank wall 12c. The opening 12d is an outlet for the gas heating circuit and the opening 12e is an inlet for the solar circuit. [0050] Although the invention has been described with reference to preferred embodiments, it will be appreciated by those persons skilled in the art that the invention can be embodied in many other forms.

Claims

1. A water heating system including:

a water storage tank with a mains water inlet and a heated water outlet;

2. The system as claimed in claim 1 , wherein the water heating system includes a controller adapted to energise the first pump only or the second pump only or the first and second pumps, responsive to user demands and/or availability of solar energy.

3. The, system as claimed in claim 1 or 2, wherein the water storage tank includes a first opening that is in fluid communication with the inlet of the first pump and a second opening that is in fluid communication with the outlet of the at least one solar panel.

4. The system as claimed in claim 1 or 2, wherein the water storage tank includes an opening that is in fluid communication with the inlet of the first pump and also with the outlet of the at least one solar panel.

5. The system as claimed in claim 4, wherein the opening is connected to the inlet of the first pump and also to the outlet of the at least one solar panel by a pipe-in-pipe fitting.

6. The system as claimed in claim 5, wherein the pipe-in-pipe fitting includes an internal pipe for communication of water into the water storage tank from the at least one solar panel outlet and an external pipe for communication of water from the water storage tank to the first pump inlet, whereby the water is independently communicated through the interior of the internal pipe and communicated in the space between the interior of the external pipe and the exterior of the internal pipe respectively.

7. The system as claimed in any one of the preceding claims, wherein the water heating system includes a valve arrangement in fluid communication between the second pump outlet and the at least one solar panel inlet, the valve arrangement controllable between allowing water to be pumped from the second pump outlet to the inlet of the at least one solar panel or allowing water to be drained from the at least one solar panel inlet to atmosphere.

8. The system as claimed in claim 7, wherein the valve arrangement includes a ball valve with first and second operating states, the first operating state allows or prevents water to be pumped from the second pump outlet to the inlet of the at least one solar panel when open or closed respectively and the second operating state prevents or allows water to be drained from the at least one solar panel inlet to atmosphere when open or closed respectively.

9. The system as claimed in claim 7, wherein the valve arrangement includes a first and a second solenoid valve, wherein the first solenoid valve allows or prevents water to be pumped from the second pump outlet to the inlet of the at least one solar panel when open or closed respectively and the second solenoid valve prevents or allows water to be drained from the at least one solar panel inlet to atmosphere when open or closed respectively.

10. The system as claimed in claim 9, wherein the first and second solenoid valves are controllably interlocked such the first valve is open when the second valve is closed and first valve is closed when the second valve is open.

11. The system as claimed in any one of the preceding claims, wherein the water heating system includes a one way valve adapted to only allow fluid communication from the at least one solar panel outlet to the water storage tank.

12. The system as claimed in any one of claims 3 to 11, wherein the opening or openings is/are at or near the middle of the tank.

13. The system as claimed in claim 12, wherein the instantaneous-type water heater outlet is in fluid communication at or near the top of the water storage tank.

14. The system as claimed in claim 13, wherein the second pump inlet is in fluid

communication at or near the bottom of the water storage tank.

15. The system as claimed in any one of the preceding claims , wherein the water heating system includes a space heating circuit in fluid communication with the water storage tank.

16. The system as claimed in claim 15, wherein the space heating circuit includes a first heat exchanger in a space to be heated.

17. The system as claimed in claim 15 wherein the space heating circuit includes a first heat exchanger and a second heat exchanger, wherein the first heat exchanger is in a heat exchange relationship with the second heat exchangei and the second heat exchanger is in a space to be heated.

18. The system as claimed in claim 16 or 17, wherein the water heating system includes a third water pump for circulating water through the first heat exchanger.

19. The system as claimed in claim 17, wherein the water heating system includes a fourth pump for circulating fluid through the second heat exchanger.

20. The system as claimed in any one of the preceding claims, wherein the instantaneous-type water heater is energised and de-energised responsive to the first pump being energised and de- energised respectively.

21. The system as claimed in claim 1 , wherein the water heating system includes a controller adapted to energise the first pump, responsive to the temperature of the water in the water storage tank.

22. The system as claimed in any one of the preceding claims, wherein the water heating system includes a hydronic heating circuit in fluid communication with the water storage tank.

23. The system as claimed in claim 22,=wherein the hydronic heating circuit includes at least one hydronic line and a third pump for circulating water through the at least one hydronic line.

24. The system as claimed in claim 23, wherein the water heating system includes an adjustable ball valve, in fluid communication with the third pump, which is adapted for adjusting the amount of heated water supplied to the at least one hydronic line.

25. The system as claimed in claim 24, wherein the third pump has a maximum flow rate that is 80-85% of the maximum flow rate of the first pump.

26. The system as claimed in claim 22, 23 or 24 wherein the water heating system includes a tempering valve, in fluid communication with the ball valve and also mains water supply.