Non-Pressurized System
Non-pressurized system are also called straight-in all-glass vacuum tube solar water heaters. Because the vacuum collector and water tank are sealed by sealing rubber ring, they can not withstand pressure.The non-pressure solar water heater normally uses the non-pressure water shutdown, the efficiency is high and the service life is long. The low-pressure gravity system consists of a vacuum glass tube collector, an insulated storage tank and optional stand parts (make up tank).
The water is delivered to the tank on the roof by a pump of some kind or from a water tower, which naturally means there is some pressure and then the evacuated glass tubes are filled with water and exposed to sun, thus heating up the water in the glass tubes. This system is completely compatible with shower pumps and other household pumps to add water pressure in the house. But the tanks and the panels or tubes are not pressurized themselves.
