Inventor: Carl Dworman, LLC
See the schematic and photos of my prototype all-polypropylene solar hot water system.
This was first made public when I posted it on http://www.Sol-Y-Agua.com on April 10, 2009 (confirmation of registration with GoDaddy.com available.)
First, we are using a vacuum tube solar panel array that is many times more efficient than the standard flat plate copper solar panels. For example, on a cloudy day, even if the temperature is 15¡C, (59¡F) the output on a standard flat plate copper solar panel will be at best, minimal. In contrast, in the same conditions, the solar vacuum tube system is able to output at least 48¡C (118¡F) even if the ambient temperature is even below freezing! As to a practical application, this is no less than amazing.
To further simplify and improve the design, we use a proprietary roto-molded thermal insulated polyethylene tank the will endure many years of trusted service, not subject to the pitfalls of rust or corrosion.
Second, we integrating both an open loop and closed loop system to create heated domestic hot water. Till now in the industry only an open or closed loop system has been used, but not a combination of both. We are using an all-polypropylene, roto-molded insulated 189 liter (50 gallon) water tank to hold the water as it is continually heated by the water circulating through the vacuum tube solar panel array. The water in the tank is in a closed loop system, meaning that the water in the tank is continually circulated through the solar hot water panel and does not exit to the domestic hot water supply. Running through the tank is a high efficiency conductive coil filled with water supplied by the domestic cold water source. This water exits to the domestic hot water supply after being heated by the water that has been heated in the tank. This is known as an open loop system.
Prior to the water entering the coil within the tank and to the tank itself, the water passes through an optional external solar coil that acts as a booster. Then it passes through a "Y" connection that supplies both the domestic hater water supply and to the closed loop system. The circulation in the closed loop system is accomplished through the natural process of thermal hydronic siphoning: hot water rises, colder water sinks.
This thermal hydronic siphoning process is well known in the solar hot water industry. To accomplish this, the hot water tank must be higher than the top of the solar panel, which is set at an angle approximately the same as the latitude to which is being placed for maximum solar heating efficiency. (If you are in a 14¡ degree latitude, the angle of the solar panel should be set at 14¡ degrees.)
The outlet to the solar panel should be at the top of the panel and should enter into the upper third of the plastic tank. Adjacent to or at the same level to this tank inlet should be the outlet for the domestic hot water supply to the house. After the heated water from the coil exits from the tank, the hot water passes through a mixing valve to reduce the possibility of scalding by ensuring that the resultant domestic hot water to be used is not above 44¡C (111¡ F) unless manually set otherwise. This heated water output can then be passed through an auxiliary in-line hot water heater or an existing hot water heater in the rare event that the domestic water exiting the coil from the tank is below 39¡C (100¡F) due to the possibility of an onset of many rainy days. Since the water tank has the option of such very large capacities, this water is continually being heated and re-heated through the thermal siphoning process; the hot water reserve actually acts as a large battery reserve for excess hot water being continually produced.
Also in the system are a series of drain valves, check valves, on/off by-pass isolating valves, air release valves, temperature/pressure release valves and vacuum breakers which all add to the safety and efficiency of the design.
