4question

According to the operation mode, the solar water heating system can be divided into natural circulation system, direct current system and active circulation system. It can be divided into direct system and indirect system according to whether there is heat exchanger. The direct system directly heats the water supply in the collector, the indirect system indirectly heats the water supply by using the heat exchanger, and the indirect system is also an active circulating system
circulatory system

Natural circulation system is a kind of hot water circulating by natural convection formed by the density difference caused by the temperature gradient inside the heat transfer working medium. Its structure is simple without additional pressure. However, to ensure the thermosiphon head, the water storage tank shall be placed above the collector. This is a common and widely used solar water heating system.

The solar water heating system has the advantages of simple system structure, safe and reliable operation, no auxiliary energy and convenient management
The disadvantage is that the heat storage tank must be placed above the collector before heat exchange. This natural circulation mode is not suitable for large-scale solar water heating system. In large-scale systems, it is necessary to place the hot water storage tank above the collector, which will bring many problems in building layout and load design.