AU625244B2 - Solar fluid heater assembly incorporating a booster heater and method of installation - Google Patents

Description

PIATENTS ACT 1931 COMPLETE SPECIFICATION

(ORIGINAL)

62524,4 FOP. OFFICE USE.' Application N~umben: Lodged: Clots 1nt, Class Complete Spcification Lodged:, Accepted., Pubilithcd, Priority.- Rel~ftil Art.

44 4 Name of Applic~nt~s): DPETER- JOHN- MORRIS -and GARRY-RODNEY- WHITE 4 Adi.reis of Applicant(s): 4 A~ulInventor(s): both-of Th 2-1;Virginia Avonue, Maddington, Western Australia Australia-, G2.09:,i

APPLICANTS

Address for Service: Ralvin Lord Co., 4 Douro Place, WEST PERTHs 14A Western AUStra]Jia 6005.

Complete Specification for the invention entitled: "SOLAR FLUID HEATER ASSEMBLY INCORPORATING A BOOSTER HEATER AND METHOD OF INSTALLATION" 'The following statement Is a full description of this invention, Including the best method of performing it known to mel us -2 The present invention relates to a booster heater apparatus for a solar fluid heater assembly.

The present invention relates particularly to a gas fuelled booster heater apparatus.

In accordance with one aspect of the present invention there is provided booster heater apparatus for a solar fluid heater assembly comprising: heat exchanger means; first fluid flow means via which fluid is able to flow from fluid storage means of said solar fluid heater assembly to said heat exchanger means; t T second fluid flow means via which said fluid is able to t flow from said heat exchanger means to said fluid storage means; **4 15 burner means to heat said fluid in said heat exchanger means; sensor means arranged such that it is sensitive to the temperature of said fluid in both said fluid storage means 4* and in solar collector means of said solar fluid heater 20 assembly; and, means to activate said burner means when the temperature of o* said fluid sensed by said sensor means indicates that the temperature of said fluid in both said fluid storage means and in said solar collector means has fallen below a selected level, wherein heat is transferred to said fluid in said storage tank by said booster heater apparatus substantially by thermosyphonic action.

In accordance with another aspect of the present invention there is provided a method of heating fluid from a fluid 2astorage means of a solar fluid heater assembly comprising: providing sensor means which is sensitive to the temperature of fluid in both said fluid storage means and in solar collector means of said solar fluid heater assembly; and, activating burner means of a booster heater apparatus to heat said fluid from said fluid storage means and return heated fluid thereto substantially by thermosyphonic action when the temperature of said fluid sensed by said sensor means indicates that the temperature of said fluid in both said fluid storage means and in said solar collector means has fallen below said selected level.

I I 2 6 4 CI -I 1 i 3storage means ot a solar luid neater assembly comprisiEg: sensing the temperature of fluid indicative of the temperature of fluid in said fluid storage mea and in solar collector means of said solar flu* eater assembly; and, activating a booster heater aratus to heat fluid from said fluid storage me nand return heated fluid thereto substantiall yy thermosyphonic action when the temperature of fluid indicative of the temperature of fluid in saifuid storage means and in said solar collector aens falls below said selected level.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a side elevation view of a solar fluid heater 4 i* 4 15 assembly incorporating a booster heater apparatus in accordance with a first embodiment of the present .invention; Figure 2 is a perspective view of the solar fluid heater assembly and booster heater apparatus shown in Figure 1; Figure 3 is a partly cut-away perspective view of the booster heater apparatus shown in Figure i showing the casing; Figure 4 is a sectional end view through the booster heater apparatus and casing as shown in Figure 3; Figure 5 is a perspective view of the heat exchanger and burner housing and the burner control assembly which are located in the casing (partly shown in phantom); Figure 6 is a perspective view of the heat exchanger and

IP

burner located in the heat exchanger and burner housing; Figure 7 is a side elevation view of a length of tube of the heat exchanger, shown in Figure 6, showing the fin arrangement thereon; Figure 8 is a perspective view of the tube and fin arrangement shown in Figure 7; Figure 9 is a sectional end view of the heat exchanger and burner shown in Figure 6; Figure 10 is an elevation view of a solar fluid heater assembly tank having a booster heater apparatus, in accordance with a second embodiment of the present invention, connected thereto; Figure 11 is a perspective view of the booster heater apparatus shown in Figure 15 Figure 12 is a sectional end view of the booster heater apparatus shown in Figure 10 showing the casing; Figure 13 is a partly cut away perspective view of a portion of the casing of the booster heater apparatus shown in Figure 20 Figure 14 is a schematic view of an alternative embodiment of the fluid temperature sensor.

In Figures 1 and 2, there is shown a solar fluid heater assembly 10 comprising a fluid storage tank 12 and a solar collector panel 14. The storage tank 12 and the solar collector panel 14 are connected together in conventional manner such that they are in fluid communication.

Preferably, the fluid is water.

The solar fluid heater assembly 10 may be of conventional 'i 5 form to heat fluid in the solar collector panel 14 and return it to the storage tank 12.

Preferably, the solar fluid heater assembly 10 is mounted on the roof 16 of a building.

However, the solar fluid heater assembly 10 may be provided at any suitable location at which the solar collector panel 14 is exposed to solar radiation.

The storage tank 12 is positioned at a higher level than the solar collector panel 14, as can be seen in Figures 1 and 2. This is readily achieved when the solar fluid heater assembly 10 is mounted on the roof 16 by taking advantage of the slope of the roof 16 itself to have the Sstorage tank 12 positioned at a higher level than the solar collector panel 14.

15 The fluid outlet of the storage tank 12 is connected to the 4,44 fluid inlet of the solar collector panel by a pipe (not shown). The fluid inlet of the solar collector panel 14 is located at the lower part of the solar collector panel 14, i.e. the part of the solar collector panel 14 that is most remote from the storage tank 12. The fluid outlet of the solar collector panel 14 is connected to the storage tank 12 by a pipe 18. The fluid outlet of the solar collector panel 14 is located at the upper part of the solar collector panel 14. This can be seen in Figures 1 and 2.

The solar fluid heater assembly 10 has a booster heater apparatus 20 connected thereto.

The booster heater apparatus 20 comprises a casing 22 divided into two portions 24 and 26 by a partition plate V -6 a at a a a a.

a. a a i 4 4 a 28. The partition plate 28 is provided with a pair of openings 30 and 32 in the form of slots.

A heat exchanger and burner housing 34 and burner control assembly 35 (shown in Figure 5) are located in the first portion 24. The heat exchanger and burner housing 34 is provided with a flue outlet 36 which extends into thQ portion 26 of the casing 22 through the opening 32.

A baffle plate 40 is provided in the portion 26 of the casing 22 and divides the portion 26 into an upper part 42 and a lower part 44. The bottom wall 46 of the portion 26 is provided with a grid 48 comprising openings 50. The top wall 52 of the portion 26 is provided with a cowl 54. The portion 26 is provided with a curved front wall 56. The curved front wall 56 lies adjacent the side of the storage 15 tank 12 when the booster heater apparatus 20 is connected to the solar fluid heater assembly 10. This can be seen in Figures 1 and 2.

The heat exchanger and burner housing 34 encloses a heat exchanger 58 and a gas burner 60. The heat exchanger 58 and burner 60 are shown in Figures 6 to 9.

The heat exchanger 58 comprises a pair of headers 62 and 64 having tubes 66 extending therebetween. Each header 6~2 and 64 is formed by a pair of domes 68 which are connected together at their edges. The tubes 66 extend between inner opposed domes 68 of respective headers 62 and 64.

A fluid return tube 70 extends aleag the side of the heat exchanger 58 and has a branch tube 72 which is connected with the inlet of heat exchanger 58 at the lower part of a aa~aa a a

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a I #aa r 7 the outer dome 68 of the header 64. A fluid flow tube 74 is connected with the outlet of the heat exchanger 58 at the upper part of the outer dome 68 of the header 62.

The outlet of the heat exchanger 58 is thus at a higher level than the inlet.

The tubes 66 are each provided with a helical fin 76 which extends along their outer surface. The helical fine 76 are omitted from the tubes 66 in Figure 6 for clarity.

However, a portion of a tube 66 with the fin 76 thereon is shown in Figures 7 and 8.

The burner 60 is elongate and extends longitudinally beneath the tubes 66. The burner 60 is provided with a plurality of paired flame nozzles 78. Each pair of flame S nozzles 78 is spaced substantially 450 from the vertical.

This can be seen in Figure 9, along with the general disposition of the tubes 66 and burner The fluid flow tube 74 and fluid return tube 70 extend through the heat exchanger and burner housing 34 and the casing 22.

The fluid flow tube 74 then extends upwardly and into the storage tank 12 at an end thereof. The fluid return tube then extends downwardly and connects with the pipe 18.

I it. Fluid is able to flow from the heat exchanger 58 to the storage tank 12 in the fluid flow tube 74, whilst fluid is able to flow form the storage tank 12 and return to the heat exchanger 58 in the fluid return tube The fluid return tube 70 terminates in a socket The burner 60 extends through the heat exchanger and burner S8 housing 34 and connects with a gas line 82. The gas line 82 is provided with a test access point 84. The burnor is provided with an air inlet 86 adjacent the main jet 88.

An interuptor screw 90 with a lock nut 92 are provided in the burner 60 such that the burner flame can be adjusted.

The burner control assembly 35 comprises a gas control valve 94, thermostat 96, thermocouple 98 and a pilot gas line 100 which connect into a housing 102.

The gas control valve 94 controls the gas flow from a gas main line 103.

The thermostat 96 is connected with temperature sensors 104 which are located in the fluid return tube 70 adjacent the branch tube 72.

J*a* The pilot gas line 100 leads to a pilot light (not shown) f 15 inside the heat exchanger and burner housing 34. The pilot light ignites the gas at the flame nozzles 78 when gas Sflows to the burner 60. The thermocouple 98 terminates adjacent the pilot light. The thermocouple 98 is provided such that the main gas flow to the burner 60 is turned off 1 20 if the pilot light is extinguished.

A pilot light access port 106 is provided in the heat exchanger and burner housing 34 to enable the pilot light to be lit. A door 108 is provided in the casing 22 to enable access to the pilot light access port 106.

Similarly, a door 110 is provided in the casing 22 to enable access to the burner control as'sembly The manner of use and operation of the present invention will now be described.

The booster heater apparatus 20 is connected to the solar fluid beater assembly 10 as hereinbofore described.

The gas control valve 94 is adjusted to provide proper gas flow and the pilot light is lit. The interuptor screw is adjusted to provide the proper burner flames and is locked in place by the lock nut 92. The thermostat: 96 is adjusted such that when the temperature sensed by the sensors 104 drops below a selected level, the booster heater apparatus 20 will come into operation, i.e. when the temperature sensed by the sensors 104 is above the selected level, the booster heater apparatus 20 will remain inoperative.

The fluid return tube 70 (inside which the sensors 104 are located) is connected to the pipe 18 in which heated fluid flows from the solar collector panel 14 to the storage tank 12. Thus, the fluid ret'rn tube 70 is in fluid comm~unication with the fluid in the pipe 18 and thereby 4,44 with the fluid in the storage tank 12 and the solar Ott collector panel 14. Thus, the sensors 104 are sensitive to the temperature of the fluid in both the storage tank 12 and the fluid in the solar collector panel 14.

Accordingly, if the temperature of the fluid in the pipe 18 (which will be indicative of the temperature in the solar Iloilocollector panel 14 and the storage tank 12) is above the selected level, the thermostat 96 will prevent the booster heater apparatus 20 from coming into operation.

Thus, when the tL. rature of the fluid in the storage tank 12 is above the -xced level, this will be sensed by the 4 4. *4 4444 4444 *4 *44 4 44*4 4 4444 *44, 4 4*44 4444 4444 10 sensors 1,04 (since the fluid return tube 70 is in fluid communication with the pipe 18 which is in fluid communication with the storage tank 12) and the thermostat 96 will prevent the booster heater apparatus 20 from coming into operation. This will be the case even if the temperature of the fluid in the pipe 18 (and the solar collector panel 14) is below the selected level.

When the temperature of the fluid in the pipe 18 (and the solar collector panel 14) is above the selected level, this will be sensed by the sensors 104 (since the fluid return tube 70 is in fluid communication with the pipe 18 which is in fluid communication with the solar collector panel 14) and the thermostat will, once again, prevent the booster heater apparatus 20 from coming into operation. This will 15 be the case even if the temperature of the fluid in the storage tank 12 is below the selected level.

Thus, the booster heater apparatus 20 will remain inoperative if the temperature of the fluid in the storage tank 12 is above the selected level even though the solar collector panel 14 may not be functioning, eg., at night or under overcast conditions. similarly, the booster heater apparatus 20 will remain inoperative if the temperature of the fluid in the pipe 18 and (solar collector panel 14) is above the selected level, (i.c when the solar collector panel 14 is functioning) even though the temperature of the fluid in the storage tank 12 may be below the selected level, eg. when the solar collector panel 14 has just started to function in the morning.

Ir ^gsgjgt'^gg^^aasafi^B^*:^^ t-w 11 it! 4444 4cr 4.4.

4444 f 44 44 4 44 4*it *4*4c 444 4** 4444 4444Q i 4 4) .444, 4 4u Thus, the booster heater apparatus 20 is brought into operation only when necessary, and thereby does not use fuel unnecessarily.

When there is sufficient solar energy to heat the fluid in the solar collector panel 14, tte booster heater apparatus remains inoperative. Fluid to be heated flows from the storage tank 12 to the solar collector panel 14 by the pipe previously described. The fluid is heated in the solar collector panel 14 and then returns to the storage tank 12 via the pipe 18. Fluid will also be contained in the fluid return tube 70, fluid flow tube 74, branch tube 72, tubes 66 and the headers 62 and 64.

When the sensors 104 sense that the temperature of the fluid has fallen below the selected level, v =l ane- 15 that the temperature of -both the fluid in\the storage tank 12 and the solar collector panel 14 has fallen below the selected level. The thermostat will then activate the burner control assembly 35. Gas will then flow to the burner 60 via the gas line 82. The gas will be ignited at 20 the flame nozzles 78 by the pilot light.

The flames 112 (shown in Figure 9) will then heat the tube 66, causing the fluid therein to be heated.

Heating of the tubes 66 by the flames 112 of the burner causes a thermosyphonic flow of fluid through the booster heater apparatus 20. The fluid flows downwardly from the storage tank 12 in the fluid return tube 70 and into the branch tube 72 and enters the header 64 at the lower part thereof. The fluid is distributed through the tubes 66 in 12which it is heated. The heated fluid then oxits from the fluid flow tube 74 which is connected to tho header 62.

The heated fluid then flows upwardly in the fluid flow tube 74 and into the storage tank 12.

The inlet of the branch tube 72 into the header 64 is positioned at a lower level than the outlet of the fluid flow tube 74 from the header 62. Similarly, the outlet of the fluid return tube 70 from the pipe 18 is positioned at lower level than the inlet of the fluid flow tube 74 into the storage tank 12. This arrangement assists the thormosyphonic flow of fluid through the booster heater apparatus To further assist the thermosyphonic flow of fluid through the booster heater apparatus 20, the heat exchanger 58 may be positioned at a slight angle in the heat exchanger and burner housing 34 such that the header 64 is at a slightly lower level than the header 62.

This will increase the vertical separation between the fluid inlet and fluid outlet of the heat exchanger 58.

When the sensors 104 sense that the temperature of the fluid hasle 1-mleeow-the selected level indicating that the temperature of the fluid in the storage tank 12 andthe solar collector panel 14 has ft-en=bealowtho selected level) the thermostat 96 will operate to deactivate the burner 60. Gas flow along the gas line 82 will then cease and only the pilot light will remain ignited.

The casing 22 provides a flue way system for the burner -13- GO. Air is drawn into the lower part 44 of the casing 22 through the openings 50 of the grid 48. The air flows through the opening 30 and into the portion 24 of the caning 22 in which the heat exchanger 58 and burner 60 are located.

The flue gases produced by the burner 60 then pass from the heat exchanger and burner housing 34 via the flue outlet 36 and into the upper part 42 of the %jasing 22. The flue gases then exit via the cowl 54.

The flow path created by the casing 22 is shown by arrows in Figures 3 and 4.

p The cowl 54 is an anti-downdraft cowl and operates to 4 4 re-direct wind out of and away from the cowl 54 regardless of the direction from which the wind strikes the cowl 54.

This action creates a suction which draws flue gases through the flue way and out through the cowl 54.

In Figure 10 there is shown a second embodiment of a booster heater apparatus 120 connected to the fluid storage o tank 122 of a solar fluid heater assembly which is of essentially the same form as the solar fluid heater assembly 10, and accordingly, will not again be herein described.

The booster heater apparatus 120 is positioned a an end of the storage tank 122.

The booster heater apparatus 120 comprises a casing 124 divided into two portions 126 and 128 by a partition plate 130. The partition plate 130 is provided with openings 132 and 134 in the form of slots.

w1 14 A heat exchanger and burner housing 136 and burner control assembly (not shown) are located in the first portion 126t and are of essentially the same form as the heat exchanger and burner housing 34 and the burner control assembly 35 of the first embodiment of the booter hoater apparaitus and accordingly, will not again be heroin described. The heat exchanger and burner housing 136 is provided with a flue outlet 138 which extends into the portion 128, of the casing 124 through the opening 134.

A U-shaped baffle plate 140 is provided in the portion 128 of the casing 124 and divides the portion 128 into two parts 142 and 144.

The upper ends of the portion 128 are provided with air intake openings 146 and 148. The top wall 150 of the portion 128 is provided with a cowl 1,52.

The cowl 152 is of similar type to the cowl 54 of the booster heater apparatus The lower portion of the casing 124 is positioned below the roof 154, as shown in Figure 11.

The heat exchanger and burner housing 136 enclose a heat exchanger (not shown) and a burner (not shown) of the same form as the heat exchanger 58 and burner 60 of the booster heater apparatus A fluid return tube 156 and a fluid flow tube 158 extend from the heat exchanger inside the heat exchanger and burner housing 136.

The fluid return tube 156 and the fluid flow tube 158 FL1.74, connect with a connector assembly 160 for connection with 15 the storage tank 122. The connector assembly 160 comprises a tube 162 which connects with the fluid return tube 156 and a tube 164 which connects with the fluid flow tube 158 and surrounds the tube 164. The end portion of the tube 162 is curved and can be turned such that its inlet 166 is positioned at the desired level in the storage tank 122 such that fluid may be drawn thereinto from a desired level in the storage tank 122. In this way, the temperature of the fluid drawn from the storage tank 122 can be controlled.

The booster heater apparatus 120 is provided with a pair of .4 :sensors 168 and 170 connected to a thermostat 172. This is shown schematically in Figure 14.

The sensor 168 is connected to the outlet pipe 174 from the 15 solar collector panel 176 which extends into the storage tank 122. The sensor 170 is connected to the fluid return tube 156.

.1 The thermostat 172 functions in an analogous manner to the *4 thermostat 96 of the booster heater apparatus Thus if either of the sensors 168 and 170 sense a temperature abovee t selected level (of the thermostat 172) the booster heater apparatus 120 will remain inoperative. However, once the sensors 168 and 170 both sense the temperature as having fallen below the selected 1o level, the booster heater apparatus will come into operation, as previously described with reference to the booster heater apparatus The sensor 168 is sensitive to the temperature of the fluid pkLr4 i I: i' i 16in the outlet pipe 174 (which is indicative of the fluid temperature in the solar collector panel 176) and the sensor 170 is sensitive to the temperature of the fluid in the fluid return tube 156 (which is indicative of the fluid temperature inside the storage tank 122).

The sensors 168 and 170 and the thermostat 172 will thus function in the same manner as the sensors 104 and the thermostat 96 of the booster heater apparatus 20. Indeed, the sensors 168 and 170 and the thermostat 172 can be used i 10 in the booster heater apparatus 20 instead of the sensors HI 104 and the thermostat 96; and, vice versa, the sensors 104 and the thermostat 96 can be used in the booster heater apparatus 120 instead of the sensors 168 and 170 and j thermostat 172.

A door 178 is provided in the casing 124 to enable access to the pilot light access port (not shown) of the heat exchanger and burner housing 136. Similarly, a door 180 is *provided in the casing 124 to enable access to the burner j rcr tcontrol assembly.

The booster heater apparatus 120 functions in essentially the same manner as the booster heater apparatus 20 to provide heating when necessary.

The casing 124 provides a flue way system for the burner located in the heat exchanger and burner housing 136.

Air is drawn into the outer part 144 of the portion 128 through the openings 146 and 148. The air flows through the opening 132 and into the portion 126 of the casing 124 in which the heat exchanger (not shown) and burner (not shown) are located. The flue gases produced by the burner j 4/k I: 16a then pass from the heat exchanger and burner housing 136 via the opening 134 and into the inner part 142 of the casing 124. The flue gases then exit via the cowl 152.

The flow path created by the casing 124 is shown by the arrows in Figure 13.

The openings 146 and 148 are arranged such that air is rrrr r itrr ItIL r rr x rrr r cr*r rllP b

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cttF ~LI1: t tI I *I EI 4 -17 drawn into the outer part 144 of the portion 128 regardless of the direction from which the wind strikes the casing 124.

modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention.

is9 9425

Claims (2)

1. Booster heater apparatus for a solar fluid heater assembly comprising: heat exchanger means; first fluid flow means via which fluid is able to flow from fluid storage means of said solar fluid later assembly to said heat exchanger means; second fluid flow means via which said fluid is able to flow from said heat exchanger means to said fluid storage means; burner means to heat said fluid in said heat exchanger means; sensor means arranged such that it is sensitive to the temperature of said fluid in both said fluid storage means and in solar collector means of said solar fluid heater assembly; and,

44. means to activate said burner means when the temperature of said fluid sensed by said sensor means indicates that the toot temperature of said fluid in both said fluid storage means and in said solar collector means has fallen below a 44 44selected level, wherein heat is transferred to said fluid in said storage tank by said booster heater apparatus j substantially by thermosyphonic action. 2. Booster heater apparatus according to claim 1, wherein said first flow means is arranged to be connected to a pipe which extends from said solar collector means to said fluid storage means in which fluid is able to flow from said solar collector panel to said fluid storage means and said T-A~q+ sensor means is positioned in said first flow means. w3. Booster heater apparatus according to claim 1, wherein -19- 1| ango Q- o A-!t14A--rto r aiLgo 1"as 4 1 4-eedd-eeeend-£4thd--5&ew j(I jamasne said sensor moans comprises a first sensor and a second sensor, said first sensor arranged to sense the temperature of said fluid flowing from said solar collector moans of said solar fluid heater assembly in a pipe and said second sensor is arranged to sense the temperature of said fluid flowing from said fluid storage means in zaid aanaundfluid flow means. 4. Booster heater apparatus according to any one of claims 1 to 3, wherein said means to activate said burner means comprises thermostat means, gas valve means and pilot light rr, *re.-.a+cokuje. s4ak A <sed by means such that when said sensor means' naea that the temperature of said fluid indicativ ofthe-tempeozratueoo- 15 sid=a in said fluid storage means and in said solar collector means a asQbelow said selected level said thermostat causes said gas valve means to allow gas to flow o to said burner means which then is ignite by said pilot light means, r I 5. Booster heater apparatus according to any one of claims 1 to 4, wherein said heat exchanger means and said burner means are provided in a housing having flue outlet means. S'm 6. Booster heater apparatus according to claim 5, wherein said housing is provided in a casing comprising openings and first and second portions, said first portion being divided into first and second separate parts by baffle plate means such that said casing forms a flue way to enable air to enter said casing and flue gases to exit i& therefrom via an outlet means. 7. Booster heater apparatus according to claim 6, wherein said housing is Provided in said second portion of said casing and said flue outlet means opens into said second part of said first portion of said casing and said openings comprise at least one first opening into said first part of said first portion and at least one second opening between said first part and said second portion of said casing such that air is able to enter said first part of said first portion via said at last one first opening and flow into said second portion of said casing Via said at least one second opening and flue gases are able to exit from said housing via said flue outlet means and flow through said second part of said first portion and exit via said outlet Q means* 8. Booster heater apparatus according to claim 6 or 7, wherein said outlet means comprises an anti-downdraught cowl. 4444 9. Booster heater apparatus according to any one of claims 6 to 8, wherein said first and second parts of said first portion of said casing are formed by a substantially flat plate baffle Nand said at least one first opening is provided at the lower part of said casing. Heater booster apparatus according to any one of claims 6 to 8, wherein said first and second parts of said first portion of said casing are formed by a substantially U-shaped plate baffle and said at least one first opening is provided at the upper part of said casing. 11. Booster heater apparatus according to any one of claims 1 to 8 and 10, wherein said first fluid flow means 21 and said second fluid flow means are connectable to said fluid storage means by connector assembly means. 12. Booster heater apparatus according to claim 11, wherein said connector assembly means comprises a first tube connectable to said first fluid flow means and arranged to extend into said fluid storage means and a second tube connectable to said second fluid flow means and arranged to extend into said fluid storage means, said second tube surrounding said first tube. 13. Booster heater apparatus according to claim 12, wherein the end portion of said first tube arranged to extend into said fluid storage means is curved and is r rotatable such that fluid may be drawn thereinto from a '4a, b desired level in said fluid storage means. 15 14. Booster heater apparatus according to any one of the preceding claims wherein said heat exchanger means comprises a fluid inlet and a fluid outlet and said inlet is located at a lower level than said outlet to assist said thermosyphonic action. 15. Booster heater apparatus according to any one of the preceding claims wherein said heat exchanger means 4 444 comprises a pair of headers having finne' tubes extending therebetween and said burner means is provided beneath said u:id.tubes, said first fluid flow means being connected '.o a lower part of a first said header and said second fluid flow means being connected to an upper part of a second said header. 16. Booster heater apparatus according to any one of Ll claims 1 to 9, 14 or 15, wherein said casing is provided Iq II '...u.r.BCT.mr-rT 22- with a curved wall such that said heater booster apparatus is arranged to bo mounted with said curved wall adjacent said fluid storage means. 17. Booster heater apparatus according to any one of claims 1 to 8 or 10 to 15, wherein said heater booster apparatus is arranged to be mounted beside an end of said fluid storage means and said casing is arranged to be positioned partly beneath a roof on which said solar fluid heater assembly is mounted j 10 18. Booster heater apparatus according to any one of f %claims 1 to 9, or 14 to 16, wherein the inlet of said first C Iflow means is positioned at a lower level than the outlet of said second flow means to aid said thermosyphonic action. 19. A method of heating fluid from a fluid storage means of a solar fluid heater assembly comprising: providing sensor means which is sensitive to the temperature of fluid in both said fluid storage means and in solar collector means of s 4 ,id solar fluid heater assembly; and, activating burner means of a booster heater apparatus to heat said fluid from said fluid storage means and return heated fluid thereto substantially by thermosyphonic action when the temperature of said fluid sensed by said sensor means indicates that the temperature of said fluid in both said fluid storage means and in said solar collector means has fallen below said selected level. ,rr.s 20. Booster heater apparatus substantially as hereinbefore 23- described with reference to Figure 1I to 9 or Figures 10 to 14 of the accompanying drawings. 21. A method of heating fluid from a fluid storage means of a solar fluid heater assembly substantially as hereinbefore described with reference to the accompanying drawings. 10 DATED APRIL 2 1992 I MORRIS WHITE PTY LTD By their Patent Attorneys KELVIN LORD AND COMPANY PERTH, WESTERN AUSTRALIA i t