Heat exchanger

The heat exchanger transfers heat from the transfer-fluid to the water. Heat exchangers are used in closed-loop systems. There are various types of heat exchangers; some are designed for immersion in the storage tank, while others are separate units connected from the outside. The core of external exchangers should have two completely separate tubing systems, one for the heat transfer fluid and the other for potable water. In a solar hot water system, the heat transfer fluid and potable water must be kept separate to make sure that the fluid does not get into the drinkable water. Double-walled exchangers help prevent the possibility of any leaks.

As the solar heated transfer fluid flows through the exchanger, it transfers the heat to its metal tubing, which in turn transfers the heat to the water flowing separately in its own tube on the other side.