FIELD: heat transfer from heat transfer agent to heat accumulating medium, for instance, water. SUBSTANCE: invention can find use in solar water heating installations. In compliance with first variant heat exchanger for thermosiphon systems includes collectors, heating elements in the form of heat exchanging tubes which outer diameters are equal to inner diameters of collectors. Heat exchanging tubes are hydraulically coupled to collectors with overlapping of their inner cross-sections with formation of single through conduit for heat transfer agent from inlet to outlet branch pipes. Plane of one butt of each heat exchanging tube is oriented at angle of 90 degrees with reference to its longitudinal axis and plane of opposite butt of each heat exchanging tube is oriented at angle of 45 degrees relative to its longitudinal axis. Each heat exchanging tube oriented with plane of butt at angle of 45 degrees relative to its longitudinal axis is connected in turn first to one and then to another collector. In correspondence with second variant of invention heat exchanger has heating elements in the form of bypass and blocking-bypass heat exchanging tubes. Planes of both butts of each bypass heat exchanging tube are oriented at angle of 90 degrees with regard to its longitudinal axis and planes of both butts of each blocking-bypass heat exchanging tube are oriented at angle of 45 degrees with reference to its longitudinal axis and are parallel one another. Each bypass heat exchanging tube is connected in turn after one blocking-bypass heat exchanging tube to collector without overlapping of its cross-section and each blocking-bypass heat exchanging tube is connected in turn after one bypass heat exchanging tube to collector with overlapping of its inner cross-section. In this case each blocking-bypass heat exchanging tube is developed in collector with one butt in opposition to stream of heat transfer agent and it is developed in collector with its second butt in path of stream of heat transfer agent. EFFECT: both variants enable efficient heat exchanger to be designed thanks to exclusion of stagnant pockets and formation of single through conduit for heat transfer agent.
