In the integral collector storage solar system shown in Figure
5 at right, the hot water storage system is the collector. Cold
water flows progressively through the collector where it is
heated by the sun. Hot water is drawn from the top, which is
the hottest, and replacement water flows into the bottom.
This system is simple because pumps and controllers are not
required. On demand, cold water from the house flows into
the collector and hot water from the collector flows to a
standard hot water auxiliary tank within the house. A flushtype
freeze protection valve is installed in the top plumbing
near the collector. As temperatures near freezing, this valve
opens to allow relatively warm water to flow through the
collector to prevent freezing. In south Florida and certain
areas of central Florida, the thermal mass of the large water
volume within the ICS collector provides a means of freeze
protection