The invention relates to a solar water heater particularly for domestic use.
Prior Art;
A standard commercially available 100 LPD domestic solar water heater contains mainly a flat plate collector having an absorber of 2 m2 surface, an insulated storage tank and insulated piping which interconnects both the collector and storage tank, containing water required to be heated. The absorber receives solar energy, absorbs heat and transfers it to water, circulation of water takes place on thermosyphon principle. The collector is insulated on all sides, except on the top where it is covered with a transparent cover (usually a glass sheet) to allow the solar radiation to fall on the absorber surface. The absorber panel consists of copper riser tubes, bonded with copper fins, which are joined to the headers, both at the top and bottom. The insulated storage tank is usually made of stainless steel and is fitted with nipples (five nos) one each for the inlet of cold water, inlet hot water from the collector, outlet of hot water from the collector, drain and the utility.
The collector box and the insulated storage water tank are installed on mild steel structure, and collector is oriented at an inclination depending upon the latitude of the place to receive maximum possible solar energy during the year or a particular season.
The collector riser tubes and headers are kept always filled with water from the storage tank placed above the collector. The absorber fin receives thermal energy from solar radiation and transmits the same to the water in the riser tubes. Consequently the temperature of the water in riser tubes increases and the density decreases. As the water in the collector inlet line is colder and hence more dense, it pushes the water in the absorber panel to the storage tank and replaces it with relatively colder water. Thus continuous circulation of water between the collector and storage tank takes so long as the solar energy is available to effect raise in temperature of water. The system provides 100 litres of hot water per day in the range of 60 to 85°C depending on the intensity of solar radiation.
There are disadvantages associated with the present system of domestic solar water heater.
Disadvantages of the Prior Art;
One of the main disadvantages with the present system of domestic solar water heater is the formation of scale inside the riser tubes thereby choking of the tubes and deterioration in the performance of the system.
Another disadvantages with the present system of domestic solar heater is that it is bulky and expensive.
Another disadvantage with the present system of domestic solar heater is that it is expensive to maintain.
The Invented Domestic Solar Water Heating System:
Therefore, the main object of the present invention of a solar water heater for domestic use is the elimination of scale formation inside riser tubes, with the use of heatpipe principle. The collector and the storage tank are together mounted on a single framed structure with no interconnecting piping between them resulting in a compact system.
Another object of the present invention of a solar water heater is that it delivers 10-15% more output on normal sunny day compared to the existing system.
Yet another object of the present invention of a solar water heater is that it is 25% less expensive.
Still another object of the present invention of a solar water heater is that scaling of the raiser and header tubes is eliminated, as the water is not circulated through the collector panel. Hence, the invention has longer life and can be effectively used to heat any type of water, whether soft or hard.
Further object of the present invention of a solar water heater is that it is easy to assemble and practically little maintenance is required.
According to the present invention there is provided a domestic solar water heater comprising a solar flat plate collector with plurality of heat pipe having absorber fins, the condenser part of said heat pipes are projecting out of said solar flat plate collector and immersed in the storage tank and said collector box together with said storage tank are installed on a single rectangular framed structure wherein the and are selectively coated absorber fins welded to copper riser heatpipes and is evacuated and filled with the required quantity of working fluid and converted to work as heat pipe.
Description of the Novel System;
The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to non-limiting exemplary embodiments of the invention represented in the accompanying drawings.

Figure 1 - an isometric sectional view diagram of domestic solar water heater. The system consists essentially of the solar flat plate collector (1) which is an insulated collector box and is fitted with heat pipe (2) absorber fins (3) and PUF insulated (5) storage water tank (4) as shown in Fig.l. The construction of the collector box with top glazing (6) which is a glass cover and insulated with moulded PUF insulation (5) and its area is less by 33% in comparison to the existing standard collector. However, absorber panel is constituted of heat pipe (2) welded to absorber fins (3). The condenser part (7) of the heatpipes and are projected outside the collector box (1) and are immersed in water in the PUF insulated (5) storage tank (4). The collector Box (1) together with the storage tank (4) are installed on a single framed structure (12).
The heat pipe fins are selectively coated copper absorber fins (3) and welded to copper riser pipes (2). The riser pipe (2) is evacuated and filled with the required quantity of working fluid (water in this case) and converted to heat pipe (2). The fin (3) absorbs solar radiation and transmits heat to the working fluid inside the heat pipe (2). The working fluid gets vaporized and rises to the condenser (7) immersed in the storage tank (4). The vapor, in turn, transmits heat to water in the tank and in the process gets condensed. Thus, the water in the insulated storage tank is heated up.
The storage tank is provided with eleven nipples, eight for inserting the heatpipes into tank, one each for coal water inlet (8), hot water outlet (9) to utility, and vent (10). The water is drawn from the hot water outlet (9), at the same time cold water fills up the storage tank (4) from the cold water reservoir. The vent (10) is provided for removing entrapped air in the initial filling. The tank is provided with a outer cover (11).
The system is very compact and uses a solar collector having a typical 1.5 sq.m absorption area for a 100 LPD domestic solar heater. The collector (1) and the storage tank (4) are together mounted on a single framed structure (12) with no interconnecting piping between them.
The solar heater delivers about 10-15% more output on a normal sunny day when compared to the existing system and is 25% less expensive than the present systems. Scaling of the riser and header tubes is eliminated, as the water is not circulated through the collector panel. Hence, the invention has resulted hi longer life of collector panel and is free from water corrosion and can be effectively used to heat any type of water, whether soft or hard. The system is easy to assemble and practically no maintenance is required.
The invention described herein above is in relation to non - limiting embodiments and as defined by the accompanying claims.

WE CLAIM;
1. A compact domestic solar heater comprising a solar flat plate
collector (1); and a hot-water storage tank (4) installed above the
solar flat plate collector (1), and having atleast one cold water inlet
(8) disposed in a diagonally-opposed relationship with a hot water
outlet (9), characterized in that a plurality of dual-acting riser
pipes configured and interposed in the hot-water storage tank (4),
such that the plurality of dual-acting riser pipes establish a heat
flow-connection between the solar flat plate collector (1) and the
storage tank (4), and in that a first portion of the plurality of dual-
acting riser pipes projecting out of the solar flat plate collector (1)
having absorber fins (3) and filled with a working fluid act as heat
pipes (2), and a second portion of the plurality of dual-acting riser
pipes immersed in the storage tank (4) act as condenser pipes (7).
2. A Compact domestic Solar water Heater as claimed in claim 1
wherein the flat plate collector (1) is provided with thermal PUF
insulation.
3. A Compact domestic Solar water Heater as claimed in claim 1
wherein the collector box (1) is provided with top glazing which is a
glass cover.
4. A Compact domestic Solar water Heater as claimed in claims 1 to 3
wherein the area of the collector (1) is less by 33% from the
existing standard collector.
5. A Compact domestic Solar water Heater as claimed in claim 1
wherein the storage tank (4) is provided with atleast eleven nipples,
and wherein atleast eight nipples are utilized for inserting the
heatpipes (2) into the tank (4) and one nipple each respectively for cold water inlet (8), hot water outlet (9), and for a Vent (10).
6. A Compact domestic Solar water Heater as herein described and illustrated in the accompanying drawings.