Solar hot water heater

A combined solar water heating device and storage tank for low cost solar hot water heaters is disclosed, consisting of an insulated open-topped tank in which is introduced a volume of water at atmospheric pressure to be heated by solar radiation entering through the open top of the tank. A transparent cover extends over the open top of the tank and acts to trap long wavelength reradiation from the heated water, such as to insulate the volume of heated water by preventing radiant heat loss. A pivotal reflector-insulator panel is also positioned over the tank opening which is alternately placed in an open position, in which it allows the entrance of solar radiation which is maximized by a reflectorized undersurface of the panel; and a closed position, in which it serves to insulate the heated water. The position of the pivotal reflector-insulator panel is optionally controlled by a radiation sensor to open and close the panel under varying conditions of solar radiation. The water level within the tank is also varied by a variably positioned float valve, causing additional water to be introduced into the tank as the temperature of the water increases. A channel arrangement is also incorporated interposed between the inlet and outlet to the tank insuring proper heating of the water prior to its withdrawal at the tank outlet.

BACKGROUND DISCUSSION 
This invention concerns a solar heating device and more particularly a 
solar liquid heating device as for providing a hot water supply for home 
plumbing systems or other similar applications. 
The major barrier to the utilization of solar energy to provide a portion 
of the nation's energy requirements has been the capital expense of the 
necessary equipment. Since most solar heating structures require extensive 
and elaborate equipment, the cost of which offsets entirely or to a major 
degree the savings realized by reduced expenditures for purchased energy, 
i.e., oil, gas or electricity. This is particularly so in the 
installations adapted for residential properties, in which the cost of 
equipment must be kept very low in order to provide a reasonable payoff on 
the investment for the solar heating equipment. 
Widespread application of solar heating has been found in providing a water 
supply for residences, business or industrial applications, but even such 
devices have typically included solar heating devices in which water is 
circulated through solar panels installed on the residence roof to a 
separate remote storage tank. The relatively long lines required to convey 
the heated water to a storage tank and the widely spaced location of the 
point of hot water storage has involved relatively extensive installation 
labor and considerable expense for these components. 
It is an object of the present invention to provide a combined solar liquid 
heating device and storage facility such as to provide a self-contained 
unit which may be manufactured and installed at relatively low cost. 
It is a further object of the present invention to provide relatively high 
efficiency for the heating of water or other liquids such as to enable the 
solar heating and storage functions to be combined in a single 
installation. 
SUMMARY OF THE INVENTION 
These and other objects of the present invention, which will become 
apparent upon a reading of the following specification and claims, are 
achieved by the provision of an insulated open-topped water tank into 
which is introduced the water to be heated at ambient atmospheric 
pressure. The tank is installed such as to allow direct solar radiation 
heating on the water disposed within the tank, with a transparent cover 
extending over the tank opening serving to insulate the water and maximize 
the heating effect by trapping the long wavelength reradiation from the 
heated water to increase the efficiency of the heating process. A pivotal 
reflector-insulator panel is mounted to the tank top and positionable in a 
raised or open position, in which the solar radiation is allowed to pass 
into the tank interior, the panel having a reflectorized undersurface 
thereof which increases the radiant energy passing into the tank interior. 
The pivotal reflector-insulator panel is also positionable in a closed 
position, overlying the tank top opening and having an insulating layer 
and conserving the heat energy contained in the water during periods of 
minimal solar radiation. 
The entire assembly is covered with a transparent cover serving as a 
weather shield for the solar heater components. 
The movement of the pivotal reflector-insulator panel is under the control 
of a radiation sensor such as a photovoltaic array sensing the level of 
solar radiation, which controls a motor positioning the panel in the open 
or closed position during periods of high and low solar radiation, 
respectively. 
The efficiency of the solar heating process is enhanced by the use of a 
variably positioned float which controls the valve controlling the water 
level within the storage tank interior, to increase the level of water in 
the tank as the water temperature increases. 
A channel arrangement is also incorporated and serves to control the 
movement of the inlet water to the outlet of the tank such as to insure 
that the water is heated prior to being withdrawn from the tank. 
The heated water is directed to a utilizing system by means of a pump 
receiving water at the outlet and pressurizing the same for use in the 
utilization system.

DETAILED DESCRIPTION 
In the following detailed description, certain specific terminology will be 
employed for the sake of clarity and a particular embodiment described in 
accordance with the requirements of 35 USC 112, but it is to be understood 
that the same is not intended to be limiting and should not be so 
construed inasmuch as the invention is capable of taking many forms and 
variations within the scope of the appended claims. 
Referring to the drawings and particularly to FIG. 1, the solar hot water 
heating device 10 includes an open-topped insulated tank 12. The storage 
tank may be constructed in a box shape having an outer panel member 14 of 
metal, plastic or other sufficiently durable material, together with an 
insulating layer 16 of a suitable insulating material such as foamed 
plastic, etc. 
The insulated tank 12 includes an internal cavity 18 into which a volume of 
water indicated at 20 is introduced at substantially ambient atmospheric 
pressure. This may be by means including the water supply 22, and level 
control means including a float valve 24 acting so as to maintain a 
predetermined water level within the internal cavity 18. 
Heated water is adapted to be withdrawn via an outlet passage 26 which 
directs water to the inlet pump 28 to pressurize the heated water and 
direct the same to the utilizing system 30 or to the secondary storage 
location. 
The opening above the internal cavity 18 is covered by a sheet 32 which may 
be constructed of a suitable transparent plastic material or glass, such 
as to transmit the relatively short wavelengths of solar radiation while 
trapping the very long wavelength radiation emitted by the heated water 
such as to provide an insulating function for a relatively high efficiency 
solar heating of water 20 within internal cavity 18. 
Movably mounted to the top of the insulated tank 12 is a pivotal 
reflector-insulator panel 34 which extends to completely cover the opening 
over the internal cavity 18 with the pivotal reflector-insulator panel 34 
in the closed or down position. The pivotal reflector-insulator panel 34 
is positionable either in this latter closed or down position, in which it 
overlies the opening above the internal cavity 18 and pivotable to the 
open or up position which opens the interior of the internal cavity 18 to 
receive solar radiation as indicated in FIG. 1. 
The intensity of solar radiation radiating into the water volume 20 is 
increased by the construction of the pivotal reflector-insulator panel 34 
which the surface 38 of a panel member 36 is reflectorized as by the 
provision of an anodized aluminum surface. The panel 36 is covered with an 
insulating panel 40 as of the rigid foam plastic material. 
Thus, in the open position, the pivotal reflector-insulator panel 34 
provides an increase in the solar radiation contributing to the water 
heating process, while in the closed position the internal cavity 18 is 
insulated such as to greatly reduce the loss of heat energy from the 
heated water to the surrounding environment. 
The entire upper part of the solar hot water heating device 10 is enclosed 
by a transparent moldable cover 42 which acts to enclose all of the 
components, including the pivotal reflector-insulator panel 34 throughout 
its extent of movement, to act as a weather shield while allowing the 
entrance of solar radiation. 
Accordingly, it can be seen that a very low cost but efficient solar water 
heating device is provided in that the insulated tank 12 acts both as a 
heating device and at the same time a storage facility to store the hot 
water by virtue of the provision of a movable pivotal reflector-insulator 
panel 34 which maintains the water temperature during periods of low solar 
radiation to thus provide very economical construction. 
It can be seen that this device should be oriented with respect to the sun 
such as to maximize the solar radiation coming from the lefthand side of 
the device as viewed in FIG. 1, i.e., that the lefthand side be south 
facing such that the pivotal reflector-insulator panel 34 does not block 
out the solar radiation in the raised position and indeed increases the 
solar radiant energy entering the device by virtue of the reflectorized 
surface 38. 
Referring to FIG. 2, an arrangement for varying the level of water in the 
internal cavity 18 is provided to match the volume of water to the 
available solar energy, i.e., the water level within the internal cavity 
18 is reduced under low sunlight conditions, while being increased during 
bright sunlight conditions, such as to insure adequate heating of the 
water disposed within internal cavity 18. 
This arrangement includes float valve means varying the water level in 
correspondence with the temperature of the water and includes float 
support means consisting of a bimetal lever arm 44 consisting of a pair of 
elements 46 and 48, with the lower element 46 having a relatively large 
coefficient of expansion and the upper element 48 having a relatively 
small coefficient of thermal expansion. Thus, as the temperature 
increases, the bimetal lever arm 44 will tend to arch upwardly and as the 
temperature decreases it will have a tendency to arch toward the bottom or 
downwardly as viewed in FIG. 2. This varies the relative position of float 
50 with respect to its support within the internal cavity 18. 
The float 50 is mounted on the end of the bimetal lever arm 44 by means of 
a mounting rod 52 extending upwardly from the end of the bimetal lever arm 
44. 
The bimetal lever arm 44 in turn acts to control the action of a valve 54 
having an inlet 56 from the water supply, acting to allow water to enter 
the internal cavity 18 via valve outlet 58. 
Thus, as the temperature of the water in internal cavity 18 increases, 
additional water inflow passes into the internal cavity 18 of the device. 
This adapts the heater to varying conditions of solar radiation, i.e., 
when relatively low levels of solar radiation are present, the water 
volume is maintained at a low level such that it may be heated by 
adequately high temperatures, whereas if the solar radiation level is 
high, the volume of water is increased to thus increase the adaptability 
of the device to varying conditions while insuring adequately hot water. 
FIG. 3 depicts another refinement which automatically adapts the solar hot 
water heating device 10 to conditions of solar radiation above or below 
the minimum level required for heating by causing the pivotal 
reflector-insulator panel 34 to be raised to its first or second position 
depending on the intensity of solar radiation present. In this system, a 
photovoltaic array 60 is provided which comprises means generating an 
electrical signal corresponding to the intensity of solar radiation 
impinging thereon and is positioned within the transparent moldable cover 
42. 
A control circuit 62 is responsive to the voltage level generated in the 
photovoltaic array 60 to generate a corresponding electrical signal which 
is applied to a suitably sized DC motor 64, which in turn drives a pulley 
68 and lifting line 66, such as to cause the pivotal reflector-insulator 
panel 34 to assume either the open or closed position depending on the 
intensity level of the solar radiation. 
Under a predetermined minimum condition, the control circuits 62 cause the 
motor 64 to lower the pivotal reflector-insulator panel 34 to a closed 
position, maintaining the heat energy which is stored within the water 
disposed in internal cavity 18. 
Above a predetermined minimum of solar radiation, corresponding to a net 
heating effect on the contained water, the control circuit 62 causes the 
motor 64 to wind up lifting line 66 and open the pivotal 
reflector-insulator panel 34 to the open position maintaining it in this 
position as long as the solar radiation level is at or above the 
predetermined minimum corresponding to a net heating effect on the 
contained water. 
Accordingly, an automated opening and closing mechanism is provided which 
allows the unattended operation of the device as would be required in 
remote locations such as roof top installations of the device. 
It can be appreciated that the change in density of water at greater or 
lesser temperatures may lead to the gravitation of the entering cold water 
towards the outlet such that the cold water passes out of the insulated 
tank 12 and, even though hot water has been generated in the system, it is 
not available to the hot water using system. 
Accordingly, a channel or baffle arrangement is depicted in FIG. 4 and is 
provided within the interior of internal cavity 18 on the insulated tank 
12. This includes guide channels 70 and 72 which are interposed between 
the inlet 56 and the outlet passage 26 which constrains the inflow over 
the first guide channel 70 and around the second guide channel 72 insuring 
adequate warming effects prior to passage out through the outlet passage 
26. 
Accordingly, it can be appreciated that a relatively economically 
constructed solar hot water heating device has been provided in which both 
storage and heating are carried out in the same apparatus. At the same 
time, this device operates with a high degree of efficiency while 
employing only simple components and which adapts the device to widely 
varying solar radiation intensity levels, insuring that hot water will be 
developed under minimum radiation conditions and that the hot water will 
be maintained at an elevated temperature within the storage tank.