WO2021214744A1

WO2021214744A1 - High temperature and pressure-free water heaters

Info

Publication number: WO2021214744A1
Application number: PCT/IL2021/050316
Authority: WO
Inventors: Arie SHABTAY; Chen SHABTAY
Original assignee: Shabtay Arie; Shabtay Chen
Priority date: 2020-04-20
Filing date: 2021-03-21
Publication date: 2021-10-28
Also published as: IL274086B

Abstract

The present invention pertains to water heating. Particularly, the present invention pertains to water heaters for heating water with a more efficient use of energy, near- boiling temperature at 1 atmospheric pressure, water and water vapour pressure-free system and a higher yield of consumption of the heated water.

Description

HIGH TEMPERATURE AND PRESSURE-FREE WATER

HEATERS

Technical Field The present invention pertains to water heating. Particularly, the present invention pertains to water heaters for heating water with a more efficient use of energy, near boiling temperature at 1 atmospheric pressure, water and water vapour pressure-free system and a higher yield of consumption of the heated water. Background

The major problems in current water heaters, including electric boilers, sun-heated boilers and heat-exchange boilers, are that they operate as pressure cookers and thus are limited to maximal water temperature of 65°C for safety. Heat-exchange boilers, however, operate at higher temperatures. All three types have a low energy yield up to 30% of the heating energy that is invested in the water. In addition, they all face explosion due to dangerous combination of accumulated steam pressure and malfunction of the thermostat and safety pressure-release valve.

It is, therefore, an object of the present invention to solve these problems of low yield of energy and over-pressure of vapour with a water heater that is more efficient in investing energy in the heating water and lowers vapour pressure at the same time.

WO 2014/003526 describes a low pressure water heater with a configuration that generates stratification of the water in the tank. Incoming cold water is let in at the bottom of the tank, and outgoing hot water is let out by suction from the top of the tank. This configuration is compatible with various water heating systems, such as solar thermal collectors, electrical resistance, heat pump and fuel boiler.

FR 1,503,107 describes a pressureless water heater tank with a single compartment and a single circuit, a cold water inlet valve controlled by a float and a distribution pipe for hot water provided in the water heater. The intake of cold water and outlet of hot water are controlled by valves, where the cold water intake is done at the bottom of the tank. When hot water is drawn or when the water level drops, which causes the float to descend, the valve frees the passage of cold water. The cold water that enters replaces the hot water which has just been drawn, the water rises to its expected level and the float, also rising, presses the surface of the valve against its corresponding seat.

None of the systems in WO 2014/003526 and FR 1,503,107 describes a pressureless water heater that controllably isolates the inlet and outlet of the water tank and enables maintaining a fix selected water temperature of the water in the water tank and maximizing yield of hot water.

Summary

In one aspect, the present invention provides high temperature and pressure-free water heaters for heating water to a high temperature that is higher than the temperature in current standard water heaters. Further, the water heaters of the present invention maintain the heated water at such high temperatures while avoiding accumulation of steam and build-up of high-pressure that may result in explosion. The water heaters of the operation of the water heaters is similar to cooking pots for boiling liquids, including water, on a stove, where the heating temperature is not limited to below the boiling temperature of the liquids, e.g., water. The water, therefore, may be heated close to its boiling temperature.

In still another aspect, the present invention provides water tanks for heating water without build-up of water vapour pressure when heating the water close to near boiling temperature at 1 atmospheric pressure, for example 95°C. Further, such water tanks are isolated from water pressure of water pipe systems in fluid communication with the water tanks. Accordingly, in one embodiment, the present invention provides water heaters for household use such as shower, cooking and hot drinking.

In one embodiment, the water heaters of the present invention reach over 90% yield of the heated water by keeping it at near-boiling temperature at 1 atmospheric pressure and using almost its entire volume for obtaining hot water for different household uses. The high temperature of the water thus enables to distribute it in larger volumes of water for regular use at lower temperatures. Keeping the water at a highly elevated temperature also increases energy yield of the energy which is invested in heating the water. Particularly, the yield of the heated water reaches 91.6% of water use relative to standard water heaters. For example, a relatively small amount of near-boiling temperature at 1 atmospheric pressure of water may be sufficient for a shower for several persons with a much less investment of energy, which is at least three times the efficiency in current water heaters. Another advantage is in reducing the volume of the heated water and, therefore, the volume of the water tanks. This translates to reduction in the amount of materials, easier transportation and installation easier set up and repair, energy saving and lower costs in all aspects of the invention. In view of the above, in one embodiment, the volume of a water tank of the water heater may be three times less the volume of a tank of a standard water heater.

In still another aspect, the water tanks of the present invention are isolated from the municipal water piping and are, therefore, free from water pressure. This is enabled by controlling the inlet and outlet of the water tanks with electric valves for streaming cold water into the tank for heating and out of and into a household water pipe system, respectively.

In one embodiment, the water tanks of the water heater of the present invention are made of relatively light materials such as aluminium, PVC (Polyvinylchloride), Perspex, copper, brass and steel. Further, in another particular embodiment, it is sufficient to make these tanks with thin walls relative to current ones, because they do not need to resist high water vapour pressure despite heating the water to near-boiling temperature at 1 atmospheric pressure.

In still another embodiment, the water heater of the present invention is used in pressure-free water heating solar systems. The water pipes in current solar radiators are made of materials such as copper that resist water pressure flowing from the municipal water pipe system with which they are in fluid communication. Accordingly, every such radiator weighs about 40 Kg. In using the pressure-free water heaters of the present invention in hot water systems that include solar radiators and water tanks and share the same water piping, lighter materials may be used for the pipes of the radiator. In turn, this will reduce their weight and make them more cost- effective and easier for transportation and installation.

In one particular embodiment, the yield of heating the water reaches 91.6% as shown in the following example:

Example 1

In two cylindrical water tanks with the dimensions of height, h, of 120 cm and base radius, r, of 15 cm, their total volume is calculated according to the formula:

Vtotal = 2 · p · G² · 1i

Their total volume is then equal to Vtotal = 2 · p · 15² · 120 = 169.56 liters

Each tank comprises a float located at its top end and extends along a length of 10 cm and takes a volume that can not be occupied by water. The two floats, therefore, occupy a volume, Vfloat = 2 · p · 15² · 10 = 14.13 liters. The net volume in the two tanks that can be fdled with water is then:

Vnet = Vtotal - Vfloat = 169.56 - 14.13 = 155.43 liters.

Now, considering Vtotal as 100% of the tanks volume, Vnet/Vtotal = 169.56/155.43 · 100% = 91.66% and Vfloat/Vtotal = 14.13/169.56 · 100% = 8.33%.

A marginal volume of 2.5 liters may be reduced from the net volume due to immersion of the floats in the water.

The net volume of the tanks is fdled with water that can be elevated to a temperature of 95°C and used to heat a volume of water three times the volume of current water tanks, where the water tanks of the present invention are isolated from the municipal water pipe system and, therefore, are not in pressure-equilibrium with the water in the pipe system. This isolation and the fdling of the water tanks to full capacity prevent liquid pressure and water vapor pressure build-up inside the water tanks. As a result, the water in the tanks can be safely heated to near-boiling temperature at 1 atmospheric pressure and increase the efficiency of different household uses of the hot water. The following exemplifies the higher efficiency of use of hot water with the water heater of the present invention relative to standard water heaters.

Example 2

In a water heating solar radiation system or a heating system based on circulating water, the water temperature is limited to 65°C. Assuming tank volume of 155 liters, about 35-40 liters spending for a shower of a single person in a household and 40°C of the actually consumed water, the total volume of water used equals -

Xstandard = 65· 155/40 ~ 252 liters. Now dividing this actual volume by 30-40 liters per person, we get -

Nmax = 252/35 = ~ 7 and Nmin = 252/40 = ~ 6. That is, the number of users is 6-7.

For water in 95°C and assuming same tank volume of 155 liters and actual temperature of 40°C we get actually consumed total volume of water of -

Xinvention = 95* 155/40 = 368 liters. Dividing this actual volume by 35-40 liters per person, we get -

Nmax = 368/35 ~ 10 and Nmin = ~ 9. That is, the number of users is 9-10.

The actual volume means that the hot water are mixed with cold water to bring it to the acceptable use for showering.

In one embodiment, the water heater of the present invention is comprises a single water tanks that contains or is attached to all the components of the water heater. In still another embodiment, the water heater comprises two water tanks in fluid communication with each other to form a system of communicating vessels. The components of the water heater are located partly in one of the tanks and partly in the other tank. The inlet and outlet electric valves regulate the fluid communication of the water heater with the household water pipe system so that is exposed to external water pressure such as the water pressure of the municipal pipe system only for filling the tanks. In addition, a non-retum valve after the exit point of the tanks disconnects the water heater from other hot water systems such as a water heating solar radiation system. As a result, when the water heater supplies hot water, the other hot water supply system, e.g., water heating solar radiation system, is kept shut, and vice versa. The non-retum valve essentially prevents backflow of water from the solar system to the tanks of the water heater, mixing and lowering of temperature. As a result, the water heater operates with full efficiency while the household may use both hot water sources at the same time. Such parallel configuration may be applied to any water heating system.

In one particular embodiment, the water heater of the present invention may be installed in private and central hot water supply systems. In still another particular embodiment, the water heater of the present invention may be comprise any flash heating apparatus or mechanism for fast heating of water in the water tank(s) of the water heater. The table below proves the advantage of the water heaters of the present invention over current water heaters in different parameters:

The advantages of the water heaters of the present invention are as follows:

- Pressure-free tanks without any risk for pressure explosion;

- Above 90% yield of hot water; - Near boiling temperature limit of 95 °C at 1 atmospheric pressure;

- Use of hot water for cooking and drinking;

- Low weight of tanks, easier transportation and installation;

- Material saving;

- Applicability of a variety of materials; - Fluid communication with a heat dissipating source for circulating heated water in heat exchanger inside the water tank and the heat dissipating source. Such heat dissipating source may be a heating system with water-based heat radiators and a water heating solar radiation system. The following describes particular configurations of the water heater of the present invention, where all of them employ the major principle of pressure-free tanks, which are controlled by inlet and outlet water valves. Brief Description of the Drawings

Fig. 1 schematically illustrates one configuration of the water heater of the present invention.

Figs. 2 schematically illustrates another configuration of the water heater of the present invention.

Fig. 3 schematically illustrates another configuration of the water heater of the present invention.

Figs. 4-5 illustrate the electrical circuits that control the electrical valves of the water heater tanks of the present invention.

Fig. 6 schematically illustrates another configuration of the water heater of the present invention.

Fig. 7 is a flow diagram of the heating water cycle in the water heater of the present invention.

Detailed Description of the Drawings

Fig. 1 illustrates one embodiment of the present invention in which the tank of the water heater is provided as communicating vessels. In this particular case, two tanks are provided which are in fluid communication with each other through upper and lower elastic tubes 18. The left water tank comprises a float 25 connected to a flexible pipe 21, where the flexible pipe is connected to an outlet with water valve 19. Water valve 19 may be used to drain water out of the water tanks to repair or replace damaged or malfunctioning components inside the tanks. The float 25 moves up and meets the top of the left tank as water streams into the tank from the right tank through the upper and lower tubes. The float stops water from streaming in when it reaches the top of the tank. Thus the float regulates water intake to near full capacity while occupying the remaining free volume in the tanks. This way it prevents vapour build-up and maintains the tanks pressure-free. After the water is heated to the desired or near-boiling temperature at 1 atmospheric pressure, it may be released for use through valve 7 and water valve 19 from the bottom of the right and left tanks, respectively. Particularly, water valve 19 is connected to the flexible tube 21 in the left tank, through which the heated water stream down the household piping system and pass through heat supervisor 16, through which cold water are stream from an extemal source 17. Thus the water going out of the tank at near-boiling temperature at 1 atmospheric pressure is mixed with cold water for different uses such as a shower. This way the water in the tanks are uses almost to completion, because the can be maintained at a high temperature, e.g. near-boiling temperature at 1 atmospheric pressure, by closing their inlet and outlet electric valves.

In the particular configuration of the water heater in Fig. 1, electric valve 2, which is located close to the top of the right tank, is the inlet for cold water for heating. Electric valve 2 essentially regulates the water pressure applied by externally connected water pipe system to the water heater, and when it is shut, it isolates the tanks of the water heater from such external pressure. The cold water enters the right tank through float 3, which is connected to the electric valve 2, and the two tanks fill until the float 25 in the left tank reaches the top of the tank. When the inlet electric valve 2, outlet valves 19 and 7 and outlet electric valve 13 are closed, the water tank(s) are disconnected from the water piping system and are not subject to water pressure from outside. Further, when the tanks are nearly completely filled, there is no build-up of vapour pressure in the tanks as the water is heated, and therefore, the temperature of the water in the tanks can be elevated to near-boiling temperature at 1 atmospheric pressure without external water pressure or a risk of uncontrolled internal water vapour pressure and therefore a need for a pressure-release valve.

An economic and cost-effective way to heat the water may be heat-exchange, using external heat-emitting sources. Such may be water or any liquid-based heat-radiators or ovens. These are connected to the right tank with inlet 10 and flow through a heat exchanger 5. Heat exchanger 5 is configured in a spiral shape to increase the volume- to-surface ratio, thereby increasing the efficiency of heat exchange between the water/liquid that flows in the spiral heat exchanger and the water in the tanks. An air release valve 27 is connected to the heat exchanger to release air bubbles, which are caught in the hot water/liquid in the heat exchanger. The water/liquid circulates in the spiral heat exchanger 5 and leaves the tank volume through outlet 11 back to the oven or radiators.

A magnesium anode 22 attracts hard precipitates in the hot water and prevents their accumulation on the tanks floor. To supervise the temperature, a thermostat 23 is located in the right tank to keep the water at the desired temperature. An electric heater 24 is installed in the right tank for flash heating or complementing the heating by the heat exchanger to the desired temperature and according to the temperature limit, which is set by the thermostat 23. A drainage outlet is made at the top end of both tanks to drain the water from the top of the tank and expose the float for repair in cases of damage, disconnection, tearing or malfunction. For safety, a floating switch 30 is installed at the top of the tank to regulate power to the electric heater and turn it on only when the tank is filled with water and turn it off to prevent heating when the tank is empty. This switch is activated when the float reaches the top of the tank and closes an electric circuit. Alternatively, a volume sensor may be installed in the float and signal the switch to turn on when reaching a certain level of water and turn it off below this predefined level.

To obtain maximal consumption of the heated water, pump 15 is set after heat supervisor 16 to pump all of the water in the tanks. When pump 15 is open, electric valves 2 and 13 are shut, where electric valve 13 controls the water flow from the water tank of an auxiliary water heating system such as a solar radiation system, into the household water pipe system. This disconnection maintains near boiling water temperature at 1 atmospheric pressure of the heated water of the present invention, prevents flow of water from the solar radiation system to the household hot water pipe system. Non-return valve 14 prevents backflow of water from the water tank of the water heating solar radiation system to the water tank(s) of the water heater of the present invention and mixing of water from the two sources in the household hot water pipe system. This is advantageous, because the heating temperature of the water of the water heating solar radiation system is limited to prevent increase in vapour pressure build-up and for safety reasons. Mixing it with the heated water from the water heater of the present invention will reduce water temperature and decrease the yield of heated water. Non-retum valve 14 is located after the pump 15 and connected to the other hot water supply system, e.g., water heating solar radiation system. This way valve 14 prevents backflow of water from the water heating solar radiation system to the tanks of the water heater and lowering of water temperature of the water heater. The tanks are thermally insulated to maintain water temperature inside and increase water yield for a longer period of time. For example, users in a household may shower one after the other with longer time gaps between them, while the high temperature in the water heater tanks are maintained. Accordingly, the tanks of the water heater comprise an insulating cover 1 and insulating walls 4. Flange 9 and sealing rubber ring 8 thermally seal the tanks at the bottom. Drainage outlet pipe 26 at the top of the tanks is used to evacuate water from the tanks and expose the float for repair in case it is damaged, broken, tom off of the flexible pipe or malfunctions for any reason. The tanks are fixed in place with a geometric locking 20 to enable easier installation.

Fig. 2 schematically illustrates another configuration of the water heater of the present invention. As in the configuration in Fig. 1, the water heater is provided as a pair of communicating vessels, in which the left tank comprises the float and flexible pipe, which is connected to the outlet of the tanks and into the hot water pipe system of a household. The right tank comprises a cold water injecting tube 29, which is connected to the float 25 and extends downwards inside the tank to fill the two tanks with cold water from bottom to top until the float meets the top of the right tank. Cold water pipe system 28 connects to the inlet electric valve 2 at the top of the left tank. Here too, the water heater and the water heating solar radiation system are connected in parallel to the hot water pipe system of the household. Electric valve 13 regulates the water flow of hot water from these two sources, namely the water tank and the auxiliary water heating system, and prevents water backflow from the water heating solar radiation system to the tanks of the water heater. Although not shown in Fig. 2 all other components of the water heater as shown in Fig. 1 are installed in the water heater configuration in Fig. 2. This includes the magnesium anode, thermostat, electric heater and spiral heat exchanger with its corresponding inlet and outlet. Heat supervisor 17 is also installed after the exit of the hot water from the right tank to reduce water temperature to an acceptable degree. The geometric locking 20 is located at the bottom of the right tank.

Fig. 3 schematically illustrates a third configuration of the water heater comprising a single tank. Fig. 3 shows the essential components of the water heater similarly to the Fig. 2, but also comprises all other components, which are illustrated in the configuration in Fig. 1. The configuration in Fig. 3 is advantageous in placing all components of the water heater in a single water tank, but its principle operation and structure are the same as the configurations in Figs. 1 and 2. Further, the single tank water heater in Fig. 3 comprises all of the components of the water heater in Fig. 1, particularly the magnesium anode, thermostat, electric heater and spiral heat exchanger with its corresponding inlet and outlet in the right tank. Heat supervisor 17 is also installed after the exit of the hot water from the tank to reduce water temperature to an acceptable degree. Floating switch 30 is installed at the top of the tank to regulate power to the electric heater and turn it on only when the tank is filled with water and turn it off to prevent heating when the tank is empty. This switch is activated when the float reaches the top of the tank and closes an electric circuit. Alternatively, a volume sensor may be installed in the float and signal the switch to turn on when reaching a certain level of water and turn it off below this predefined level.

Fig. 6 illustrates another single water tank heater of the present invention. All of the components of the heater are the same as that in Fig. 5. Further, the water heater in Fig. 6 comprises all of the components which are shown in the water heater in Fig. 1. The water heater in Fig. 6 comprises an external float 3 that supervises water level in the tank. Electric valve 2 regulates inflow of cold water from an external source 28. The cold water flows through float 3 and downstream into the water tank through pipe 29. When the water filling the tank reaches the level of the float 3, the float blocks the cold water inlet into the tank and the water inflow stops. Pipe 32 connects the float 3 to the bottom of the water tank. Thus pipe 32 and the water tank form a system of communicating vessels, which are in fluid communication with each other in a closed water circulation. As a result, the position of the float 3 in pipe 32 is always the same as the water level in the tank. This enables the float 3 to block water inflow when the water is levelled with the entry point of pipe 32, which brings float 3 to block the horizontal pipe through which the cold water stream into the tank. Electric valve 2 actively controls the flow of water even when the tank is partly filled or drained out.

Figs. 4 and 5 show the electric circuitry of the electric components of the water heater. Element 200 is the switch that controls the operation of the electric pump 15 and inlet and outlet electric valves 2 and 13, respectively. Switch 200 closes and opens the electric circuits of the pump 15 and electric valves 2 and 13. Coil 210 represents the circuit of the electric pump 15 that operates with a power of 100 Watts. Resistor 220 represents the circuit of inlet electric valve 2 for incoming cold water into the tank(s). Resistor 230 represents the circuit of the hot water outgoing from electric water valve 13 to the hot water piping of the household. The electrical circuits of the pump, inlet electric valve and outlet electric valve are connected in parallel so that pump and valves are controlled simultaneously with a single switch. This means that when the switch 200 closes, pump 15 pumps water from the water tank(s) of the water heater while inlet valve 2 shuts and blocks inflow of cold water and valve 13 also shuts and prevents outflow of hot water from other water heating systems, e.g. solar radiation system. When switch 200 opens, then the pump 15 (coil 210) shuts down, inlet valve 2 opens for streaming cold water into the water tank(s), and valve 13 opens to let hot water from other water heating systems to flow into the hot water pipe system of the household. This electrical configuration isolates the hot water in the tank(s) of the water heater from other sources of water, cold and hot. Such isolation keeps the hot water in these tank(s) at near-boiling temperature at 1 atmospheric pressure for a prolonged period of time, which increases its yield and extends the period of time it can be used at such temperature.

Switch 300 closes circuits of the following electric components that are connected to each other in series: Element 310 represents the floating switch 30 at the top of the tank when it is filled with water or passes a selected water level. Switch 320 controls the closing and disconnecting of the electric circuits of the flash heater 24. This heater operates in a power of 2.5 KW. Resistor 330 controls the thermostat 23. All circuits operate on a potential of 220 Volts. When switch 300 closes an electric circuit, this means that the water has reached full or a selected capacity of the tank and float switch 30 may close an electric circle to heat the water with flash heater 24. Thermostat 23 is also activated and controls the water temperature.

Fig. 7 is a flow chart of the operation of the water heater. The first step 500 is letting cold water enter the tank(s) through the float by opening electric valve 2. Then hot water from a heat dissipating source such as a radiator is let in the spiral heat exchanger 5 in step 510. Water drainage from the top of the tank takes place in step 505 when float 25 that stops incoming cold water malfunctions. After closing electric valve 2 of incoming cold water and keeping electric water valve 13 and water valve 19 closed, the water is heated according to the heat of the hot water that flow through the heat exchanger in step 515. The hot water in the heat exchanger circulates through inlet 10 and outlet 11, in step 520 and the water temperature in the tank(s) is determined by the temperature of the heat dissipating source, e.g. heating radiator, water heating solar radiation system radiator, i.e. step 530. Flash heater 24 may be used to heat the water to near-boiling temperature at 1 atmospheric pressure, e.g. 95°C, in step 525 in addition to the heat exchanger or by itself. Thus, hot water exits through outlet valve 7 for drinking and cooking in step 540. This is made possible, since the water in the tank(s) of the water heater operates similarly to regular pots on a stove or water kettles and thus may be directly used for consumption of beverages and foods. Both routes of heating, with and without the heat exchanger and/or the flash heater, lead to the next step 545 for outgoing water for different household uses, e.g. shower, cleaning. The tank(s) may be completely drained from top to bottom since they are completely fdled and do not allow build-up of vapour pressure. Further, they are controlled by inlet and outlet electric valves 2 and 13 and water valve 19 and, therefore, isolated from external water piping that might alternate their temperature and pressure. In step 550, hot water are let out through one-way valve and their temperature is controlled and reduced to acceptable degree for household uses with heat supervisor 16. In the last step 555, the water enters the household pipe system and flow through to the building faucets.

Claims

1. A pressure-free water heater comprising: one or more water tanks; an inlet electric valve at top of at least one of said water tanks; an outlet valve at bottom of at least one of said water tanks; a float for controlling water volume in every one of said water tanks; a flexible pipe connected to a float in one of said water tanks; a thermostat; a heat exchanger; a heat supervisor located at bottom exit of said water tank(s); an electric pump located after said heat supervisor; a second electric valve located after said electric pump and between an auxiliary water heating system and a household water pipe system; a cover at top of said water tanks; and a flange at bottom of said water tanks, wherein an electrical switch controls electrical circuits of said electric pump, inlet electric valve and second electric valve, said electrical circuits are connected together in parallel, wherein when said switch closes, said valves close and isolate said water tanks and said pump pumps water from said water tanks, wherein when said switch opens said valves open and said pump shuts, wherein said inlet electric valve at top of said water tank(s) and said second electric valve control input of cold water into said tank(s) and output of hot water off said tank(s), wherein said pressure-free water heater is configured to obtain above 90% yield of hot water in said water tank(s).

2. The water heater according to claim 1, further comprising a flash heater.

3. The water heater according to claim 1, further comprising a magnesium anode.

4. The water heater according to claim 1, further comprising an outlet valve at bottom of one of said water tanks for outflow of hot water from said water tank for consumption in beverages and foods.

5. The water heater according to claim 2, further comprising a float switch, wherein an electrical switch controls said float switch, thermostat and a switch of said flash heater in a single electrical circuit, wherein a resistor of said thermostat, float switch and switch of said flash heater are connected in series to each other, wherein when said water tanks are fdled to capacity said float switch closes, said water is heated when said electrical switch, float switch and switch of said flash heater close, said water is heated to a temperature set by said thermostat.

6. The water heater according to claim 5, wherein said temperature of said water is near-boiling temperature at 1 atmospheric pressure.

7. The water heater according to claim 6, wherein said temperature is 95°C.

8. The water heater according to claim 1, wherein said heat exchanger has a spiral configuration.

9. The water heater according to claim 1, wherein said heat exchanger comprises an inlet for inflow of heated water from a heat dissipating source and an outlet for outflow of said heated water, wherein said heat exchanger is in fluid communication with said heat dissipating source, wherein said heated water circulates through said heat dissipating source and said heat exchanger.

10. The water heater according to claim 9, wherein said heat dissipating source is a heating system comprising water-based radiators.

11. The water heater according to claim 9, wherein said heat dissipating source is a water heating solar radiation system.

12. The water heater according to claim 1, wherein said heat exchanger comprises an air outlet valve.

13. The water heater according to claim 1, further comprising a float safety electric switch at top of said water tanks.

14. The water heater according to claim 1, further comprising a drainage outlet at top of said water tanks for water drainage for repair of malfunction of said float.

15. The water heater according to claim 1, wherein walls and said top cover of said water tanks are thermally insulating.

16. The water heater according to claim 1, further comprising a rubber seal between said flange and bottom of said water tanks.

17. The water heater according to claim 1, wherein said water heater is in fluid communication with said household water pipe system in parallel with a water heating solar radiation system.

18. The water heater according to claim 17, further comprising a non-retum valve located after said water pump and connected to said household hot water pipe system, said non-retum valve is configured to prevent water backflow from said water heating solar radiation system into said water tanks.

19. The water heater according to claim 1, further comprising a geometric locking for securing said tanks in fixed position.

20. The water heater according to claim 1, wherein said float is an external float, said external float is located between said inlet electric valve and a top opening of said water tank, said external float comprising a pipe extending into said water tank for streaming inflow of cold water and an a pipe extending from said float externally to said tank and in fluid communication with top and bottom of said tank, wherein said externally extending pipe and tank form a system of communicating vessels, wherein water circulates between said tank and said externally extending pipe.

21. The water heater according to claim 1, wherein said tanks are made of light materials selected from aluminium, copper, brass and steel, PVC (Polyvinylchloride) and Perspex.

22. The water heater according to any one of claims 1-21, comprising two water tanks, said water tanks are in fluid communication with each other through upper and lower flexible tubes, said water tanks forming a system of communicating vessels.

23. The water heater according to any one of claims 1-22, wherein said inlet and outlet electric valves regulate external water pressure on said water tanks by a water pipe system in fluid communication with said water tanks, wherein said water tanks are fdled with water to near full capacity thus preventing water vapour build-up inside said tanks and maintaining them pressure -free.

24. The water heater according to any one of the preceding claims, wherein said water heaters are used for water heating solar radiation systems.

25. The water heater according to any one of the preceding claims, said water heater is configured to be installed in private and central hot water supply systems.