SOL-Perpetua™ Solar Water Heating System Installation Instructions and Operating Manual For Series "A" Pumps
Components of a SOL Perpetua™ System - Heat Exchanger
The Heat Exchanger is made of two copper pipes soldered together along their length. The hot working fluid flows through one pipe while potable water flows in the opposite direction through the other pipe. The hot working fluid gives up most of its heat to the potable water.
Potable water circulates by natural convection from the bottom of the tank through the Heat Exchanger and into the top of the tank. In order to fill the storage tank completely with hot water, the Heat Exchanger must be located as low as possible. The tank should be raised about 30 cm (12") to promote convection and to allow sufficient space under the heat exchanger to attach a hose to the drain cock.
The gentle flow of heated water to the top of the storage tank results in stratification, that is, where hot water gathers at the top of the tank. Having some hot water at the top of the tank is more useful than having that same amount of hot water distributed throughout the tank. Hot water going to the point of use is always taken from the top of a storage tank.
The size and shape of the heat exchanger is important to the proper performance of any system of solar water heating. The heat exchanger must have sufficient surface area of metal between the working fluid and the potable water to transfer the heat from the working fluid into the domestic water. The resulting difference between pump inlet and outlet temperatures should be between 17 C (31 F) and 35 C (63 F) depending on the strength of the sun's rays (called insolation) and the temperature of potable water being heated. A high rate of insolation results in a higher difference in temperature. A low incoming water temperature also results in a higher difference in temperature in the system. We try to balance the size of the Bubble Pump, Heat Exchanger, and Space Heater/Drier Module you receive to the area of collector panels you intend to use.
In some jurisdictions a "single wall" heat exchanger can be used when propylene glycol, a non-toxic antifreeze, and water make up the working fluid. Other jurisdictions require a "double wall" heat exchanger even when only pure water is used in the system. BAPL supplies only "double wall" heat exchangers which can be used anywhere.
An adjustable gauge is mounted on the Heat Exchanger so that you can easily monitor the condition of the system. A set of four thermometers is available at extra cost, one for each inlet and outlet of the Heat Exchanger.
A pressure relief valve is mounted on the Heat Exchanger to which is attached a flexible tube, the free end of which you can insert into a container to capture any working fluid that might blow off.