... optional: 100L,150L,200L,240L,300L,400L,500L18, working temperature: 90 degree19, cold resistance: -38 degree20, easy installation and best ... Series connection and parallel connection can be chose to compose a collective hot water system. Characteristics of the heat pipe: ... capacity. The heat pipe starts to work fast at low degree. 2. Thermal conductivity working fluid and metal material commonly ...