The low pressure gravity feed system consists of a vacuum glass tube collector, a storage tank, feeder tank and a flat roof stand. The evacuated glass tubes are filled with water and exposed to the sun, thus heating up the water in the glass tubes.
As the specific gravity of cold water is heavier than hot water, the hot water in the glass tubes starts rising in the insulated water tank and the cold water in the tank sinks into the glass tubes.
As this cycle is repeated, water in the solar water heater is heated. This process is known as Thermosiphon and is based on natural convection.
* Each evacuated tube consists of two glass tubes.
* The outer tube is made of transparent borosilicate glass that is able to resist hail.
* The inner tube (also made of borosilicate glass), is coated with special selective coating (AI-N/AI).
* This coating features exceptional solar heat absorption and minimal heat reflection qualities.
* The air is withdrawn (evacuated) from the space between the two glass tubes to form a vacuum, this process eliminates conductive and convective heat loss.
(Compliments of Solar Ray)