Patent application title: SOLAR HEATING SYSTEM FOR A HOT WATER HEATER
James E. Straeter (Rochester, MN, US)
James E. Straeter (Rochester, MN, US)
IPC8 Class: AF24J240FI
Class name: Of fluent medium temperature responsive set point control
Publication date: 2012-08-23
Patent application number: 20120210999
A solar heating system for a hot water heater. The system has at least
one solar heating unit that heats water contained therein and is fluidly
connected to a water storage tank. The water storage tank is enclosed
underneath the surface of the earth and is fluidly connected to the hot
water heater in order to provide hot water to the hot water heater. An
active over-heat protection system for the heating panels that tilts away
from the sun when heating isn't needed. An active system that maintains
proper water temperature in the storage tank during use of hot water and
during reheating of water.
1. A solar heating system for a hot water heater comprising: at least one
solar heating unit having water enclosed therein such that light from the
sun is used to heat the water; said solar heating unit is angled to
create a downward fluid flow path toward a water storage tank that is in
fluid communication with the solar heating unit; said water storage tank
enclosed underneath the surface of the earth; and a hot water heater is
in fluid communication with the water storage tank to receive water
2. The system of claim 1 further comprising a thermo bypass valve disposed between the hot water heater and water storage tank wherein when the temperature of the water is below a threshold temperature the thermo bypass valve redirects water to the water storage tank preventing the water from flowing to the hot water heater and above the threshold temperature forces water to flow to the hot water heater.
3. The system of claim 1 wherein the solar heating unit is operatively connected to a controller that tilts the solar heating unit away from solar rays of the sun when the solar heat unit reaches a predetermined temperature.
4. The system of claim 1 wherein the solar heating unit is movable.
5. The system of claim 1 wherein the solar heating unit has a pipe system that is within a support post that provides a fluid flow path between the solar heating unit and the water storage tank.
6. The system of claim 1 further comprising a cold water supply line fluidly connected to the storage tank and having a valve element that controls cold water added to the storage tank such that water is only added when heating is occurring and water temperature in the tank is above a threshold temperature.
7. The system of claim 1 wherein when circulation of water to the solar heating unit stops air in the water storage tank displaces water located in the solar heating unit thereby draining all water into the storage tank.
BACKGROUND OF THE INVENTION
 This invention relates to a system for supplying hot water to a hot water heater. More specifically, this invention relates to a solar heating system for a hot water system supplying domestic hot water and hot water for space heat.
 With the continuous rising cost of energy, individuals and companies have looked for a way of utilizing natural energy such as wind and solar power in order to supplement current forms of energy to reduce cost. Specifically, companies have begun providing systems that use solar energy in order to provide heat for a home and hot water heaters. An example of this can be seen at www.solarpanelsplus.com wherein heat pipes known as evacuated tube technology is presented in association with a solar heat exchanger in order to provide heat for a hot water heater.
 While such systems are effective at providing additional heat to a hot water heater these systems are very complex and difficult to maintain. Specifically, the system provides an anti-freeze in which the system has to transfer heat via a heat exchanger to the water. The addition of the heat exchanger provides additional cost and maintenance that minimize any cost savings from utilization of the system and presents a risk of water contamination by the anti-freeze liquid.
 Therefore, a principal object of the present invention is to provide a solar heating system for a water heater that is inexpensive to manufacture.
 Another object of the present inventions is to provide a solar heating system for a water heater that is efficient in collecting direct solar energy, flexible in location of the collector and able to supply hot water at maximum temperatures even when solar energy isn't being added to the water reservoir.
 Yet another object of the present invention is to provide a solar heating system for a hot water heater that provides additional water storage capacity.
 These and other objects, features or advantages of the present invention will become apparent from the specification and claims.
BRIEF SUMMARY OF THE INVENTION
 A solar heating system for heating water and delivering it to a point of use. This system utilizes a plurality of heating units that have water enclosed therein such that the light from the sun is used to heat the water. The solar units are connected so that water within the units is urged to drain toward a water storage tank that includes a pump that supplies water to the solar heating units. The water storage tank is completely enclosed underneath the earth and thus insulated by the earth and additionally insulated via convention means. The tank is in fluid communication with a hot water heater in order to provide water to the facility of end-use.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a schematic diagram of a solar heating system;
 FIG. 2 is a perspective view of a solar heating unit; and
 FIG. 3 is a view of the solar panels and mount.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 FIG. 1 shows a solar heating system 10 that utilizes a plurality of solar heating units 12 to harness solar energy from the sun 14 to heat water. The solar heating units 12 are best seen in FIG. 2 and in a preferred embodiment include a double walled vacuum insulation tube 16 that preferably is a glass tube manufactured from a strengthened borosilicate glass. The heating unit additionally includes a black absorption inner layer 18, a center heat transfer fin 20, and a centering tube stopper 22 that utilizes a heat pipe condenser 24. This preferred solar heating unit 12 shown in FIG. 2 is conventional and known in the art as an evacuated tube wherein specifically the area between the inner and outer layers of the doubled wall vacuum insulation tube 16 are evacuated by a vacuum in order to keep heat from escaping into the atmosphere. In sum, the solar heating units 12 are designed to convert the light generated by the sun 14 into thermal energy in the interior of the unit 12.
 The plurality of solar heating units 12 receive and contain water in its interior water manifold 25 shown as a copper header. Specifically, the plurality of solar heating units 12 that preferably are solar panels are fluidly connected to a storage water tank 26 having a recirculation pump 28 that is located underneath the surface of the earth to provide insulation from outside elements and cold. The plurality of solar heating units are angled such that gravity causes water within the units 12 to drain into the water storage tank 26 when recirculation pump 28 is not operating. The recirculation pump 28 pumps water from the interior of the storage water tank 26 to the plurality of solar heating units 12.
 The recirculation pump 28 supplies water to a pipe system 30 that is fluidly connected to manifold 25 and is located in a support post 32 and has insulated pipe covers 34. The solar panels 12 are mounted on the post 32 in such a manner that the panels 12 can be tilted to get an optimal angle to the sun, thereby collecting maximum energy. Alternatively, when overheating of the solar heating units 12 is detected by a sensor or the like a controller 35 pivots the units 12 away from the sun. When the panels 12 are tilted the pivoting point is also the point where insulated pipe covers 34 are attached to support post 32. This communication of pipe and support posts 32 is done such that the tilting of the frame has a common axis with the insulated pipe covers 34 and not stress, force or impairment occurs upon the pipe covers or recirculation pipe when the frame is tilted. Because the pipe system 30 is closed loop, water pressurized by the recirculation pump 28 is directed to the manifold 25 in one solar panel, then to the second solar panel, and finally back to the origination point in the tank 26.
 A hot water supply circuit 38 supplies water to a home and maximizes efficiency. The circuit 38 includes a thermostat 40 that measures the temperature of water coming from the storage tank 26 and supplied to pressure pump 42 that is fluidly connected to pressure switch 44 to supply water within supply water line 46. The thermostat 40 is additionally electrically connected to a battery 48 that is also electrically connected to a solenoid valve 50 that is within a return line 52 where the solenoid valve similarly is electrically connected to the pressure switch 44. The return line 52 has a relief valve 54 that is fluidly connected to the solenoid valve 50 and a thermo valve 56 that provides a fluid flow path between supply line 46 and return line 52. Specifically, if the thermo valve or thermo bypass valve 56 detects that water in the supply line is below a threshold temperature the valve will open to recirculate cold water to a return line 52 to the storage tank 26. If the temperature of the water is above a threshold temperature, the thermo bypass valve 56 closes allowing hot water in the supply line to feed the water to a water heater 58.
 Water heater 58 can be a conventional water heater that heats water using electricity or the like as is known in the art. The water heater can include a mixing valve 60 that mixes in cold water to the water supplied by water heater 58 such that if the water in the storage tank 26 exceeds a predetermined temperature the mixing valve 60 supplies cold water to ensure an individual using the water is not scalded when using a faucet 62 fluidly connected to the water heater 58.
 In operation, during the day when solar energy is available the recirculation pump 28 circulates water into the plurality of solar heating units 12. The water within the plurality of solar heating units absorbs the energy that is transferred from the sun 14 through the solar heating units in order to heat the water. Because the plurality of solar heating units is angled the heated water flows back into the water storage tank 26 at night when the recirculation pump ceases.
 Additionally, when the water in tank 26 gets to a maximum temperature the standard system controller 35 shuts off power to the recirculation pump 28. All of the liquid in panels 12 drain back to reservoir 26 leaving panels 12 exposed to the sun with no water to absorb the heat that is still collected. A controller monitors the panel 12 temperature and should it rise to a certain threshold temperature an electric actuator tilts the panels to a vertical position thereby significantly reducing the solar energy absorbed by the panels and limiting the temperature in the panels to a safe level. This tilting in order to shield the panels contrasts to conventional systems that may be roof mounted or not but which possess no system to limit solar energy uptake. Such systems often have a way to dump heated liquid into a cool down circuit. Those systems use energy to lose energy, have moving parts and a complex radiator system to lose heat. Simply tilting the panels away from the sun's rays is efficient, uses no energy save the tilt process itself and has no moving parts.
 When the water in the tank 26 has been heated the water can be supplied to the water heater 58. The circuit 38 ensures that water is constantly supplied to the water heater 58 in an efficient manner. When the faucet 62 is turned on pressure drops and the pump 42 begins to operate so that an operating pressure is available at the faucet 62. At this time the thermostat 40 is set so that it is closed when the temperature in the water tank 26 is above the predetermined temperature that is required to close thermo bypass valve 56. Thus, when the faucet 62 is opened in the house, pressure drops in the water heater 58 and supply line 46 that closes pressure switch 44 as well as an internal pressure switch in pump 42. This causes the variable speed pump 42 to run and maintain operating pressure but not cut off pressure. When the switch 44 closes in response to a reduced pressure, the solenoid valve 50 opens if the thermostat 40 is closed.
 So in an embodiment when the water temperature in the tank 26 is above the threshold temperature of thermo bypass valve 56, when the faucet 62 is opened, pressure drops and the pump 42 starts so that operating pressure is available to the faucet 62. The solenoid valve 50 is activated because thermostat 40 is closed as a result of the water being above the threshold temperature. In an embodiment such as when water has not been used overnight and cold water is presented in the supply line 46 is below the threshold temperature, the thermo bypass valve 56 opens allowing water to pass through to the return line 52. The cold water in the return line 52 passes through the relief valve 54 and through the open solenoid valve 50 to the tank 26. Thus, pressure at the faucet 62 is able to be regulated by the relief valve 54 as reduced from normal operating pressure, allowing the line from the water heater 58 to the faucet 62 to fill with hot water while at the same time supply line 46 fills with hot water. Consequently, a majority of the cold water is purged from the supply line 46 and returned to the tank 26 because the relief valve 54 maintains only reduced pressure at the faucet 62.
 Once the water in the supply line 46 is above the predetermined temperature the thermo valve 56 closes and no water returns to the storage tank 26 via the return line 52. At the same time the full pressure of the pump 42 is realized at the faucet 62. The fact that some cold water has been put into the water heater 58 is insignificant because water in the storage tank 26 is potentially hotter than the temperature that hot water heaters normally run. Thus, the cool water helps prevents scalding. In addition, the mixing valve 60 can be utilized to add additional cold water again to prevent over heating or scalding as a result of raised temperatures at the water storage tank 26.
 Alternatively, in an embodiment where the temperature of the water in the storage tank 26 is below the threshold temperature of the thermo valve 56 the thermostat 40 is open and the solenoid valve 50 closes. This eliminates any return water and causes the full pressure of the pump 42 to be present at faucet 62. In this case any cold water in the supply line 46 goes to the hot water heater 58 from tank 26 and the hot water heater 58 acts in a normal fashion as is known in the art.
 Once the sun 14 goes down the recirculation pump 28 stops recirculating water. This occurs by either a timer on the pump or alternatively a sensor that detects the presence of light from the sun. Because the plurality of solar heating units 12 are angled the water from within the solar heating units 12 drain into the water storage tank 26. The system of draining water back when there is no heat from the sun saves the energy that exists in the water normally residing in the pipe system 30 as well as manifold or header 25 from being lost overnight. The next day when solar energy is available there is no wasted time and energy heating cold liquid. Additionally, no freeze damage or pipe plugging can occur since there is no water in the lines above ground. Furthermore, the fact that water is directly heated, and not heated indirectly by means of heat transfer from an anti-freeze solution means that the system saves one step that otherwise would contribute to lowering the over all efficiency of the system.
 Thus, presented is a solar heating system 10 that directly heats water and does not use anti-freeze or transfer heat via a heat exchanger to the water. The system 10 presents a drain back system that is both simplistic and economical. The plurality of solar heating units 12 are tilted slightly in order to drain water to one end such that when the recirculation pump 28 shuts off, the water drains back into the water storage tank 26. Because the water storage tank 26 is buried underneath the earth the tank is well insulated and maintains the temperature of the water heated therein. Thus, by locating the water tank 26 in the ground prevents freezing of the water even if the water is not heated for stretches of time. Due to insulation surrounding the water pipe in support post 32 and insulated pipe covers 34, the water effectively is shielded from cold and therefore loses very little, if any, energy enroute to and from the solar heating units which add energy in the form of heat to the water as it travels through the manifold(s) 25 in the solar heating units 12. The very short distance the water travels and the fact that it travels the entire route in insulated pipes makes the system extremely efficient in harnessing solar energy.
 The system 10 also minimizes the pipe length from the water storage tank 26 to the solar heating units 12. By minimizing the distance that the fluid has to move, minimizes the parasitic energy lost from traveling this distance. In addition, because the water storage tank 26 is placed in the ground the system can be located anywhere a user desires in order to maximize exposure to the sun, maximizing efficiency during the heating process. In addition, by draining the fluid back into the tank 26 at night there is no heat loss overnight to the atmosphere, and the next morning the solar heating units 12 merely need to be reheated.
 The delivery of the hot water to the house is done with the pump 42 and located at the tank 26. If the water in the ground is cool because no hot water has been used for some time, the system sends most of the water back to the tank 26 via a return line. Once the water supply to the house is hot the thermo bypass valve 46 shuts off and only very hot water is sent into the hot water heater 44. Because the system 10 supplies the hot water heater 44 the original hot water heater 44 becomes an extra supply tank that has conventional heat backup.
 In addition, as compared to the prior art, in the prior art when hot water is used then cold water replaces the hot water in a solar tank thereby immediately reducing the temperature of the solar tank water supply. In the present system 10 no cold water goes in unless the sun is up and heat is available. Thus, unless the solar tank is depleted of water there is only hot water supplied to the house.
 Thus presented is a system 10 that uses a drain back system incorporated with evacuated tubes and direct water heat to drive water to a ground mounted storage tank 26 located close to the solar heating units and in the ground. The solar heating units 12 are mounted on a tilt capable stand to get the best angle to the sun 14 such that only hot water is delivered to the house when the solar heated water is available. Therefore, at the very least all of the stated objectives have been met.
 It will be appreciated by those skilled in the art that other various modifications could be made to the device without departing from the spirit and scope of this invention. All such modifications and changes fall within the scope of the claims and are intended to be covered thereby.
Patent applications by James E. Straeter, Rochester, MN US