The assignment of this paper was thermodynamic calculation of heat losses through the tube wall and analysis of results for cases with different selected parameters. Introduction describes physical processes of heat exchange, the basic forms and complex form or overall heat transfer. The thermodynamic calculation is based on heat transfer through the tube wall. It was necessary to describe the procedure of calculating the characteristic physical quantities used. After displaying the results in diagrams, it was necessary to analyze and compare them. In conclusion it was found that the type of tube material in contact with the fluid has no significant effect on heat losses, but that the type of fluid which flows through the tube has an impact. Also, the addition of at least 10 mm thick insulation compared to the case without insulation greatly reduces heat losses. It was found that the insulation thickness of 20 mm is sufficient for significantly reducing heat losses through the tube wall and for increasing the thickness of insulation, the cost justification needs to be determined by economic analysis.