Environmental Engineering Reference
In-Depth Information
cylinder is installed at a higher level than the collector. As cold water is heavier
than warm water, it sinks down from the storage cylinder to the collector. Here the
water is heated by the sun and then rises to the top until it reaches the storage cyl-
inder again. If no more solar radiation is available, the cycle stops until the sun
starts it up again.
Figure 6.9
Left: Demonstration model of a gravity system. Right: Gravity system in Spain.
Figure 6.10
Solar gravity system (thermo-syphon system).
If properly designed, this kind of solar system can cover almost all the hot water
needs of a family living in a warm, sunny southern climate. It is only during some
of the sun-starved weeks of the year that the water will not completely reach desired
temperatures. Either this is accepted in those countries or a supplemental heater, for
