When predicting the level of the heat supply system efficiency of the project, it is necessary to determine its basic technical and economic indicators. In order to do this, you need to analyze the entire life cycle of the system, namely: the processes of its design, installation, operation and disassembly. There are centralized heat supply systems in the largest cities of Ukraine today. The equipment and engineering networks of these systems are mostly obsolete, and some fragments require systematic repair or full replacement, depending on which of these measures is economically more justified. In any case, the restoration of the initial (or sufficient for the effective functioning of) the indicators of engineering systems requires considerable investment and labor costs for employees of their housing and communal enterprises and construction and installation organizations. Therefore, the more compact and less extended are the heat supply networks, the less is the probability of their premature failure the less is the cost of their maintenance, associated with physical wear and tear of the plots, equipment and the system as a whole. In addition, reducing the length of the pipeline system makes it possible to reduce the cost of building materials and construction and installation works. At the same time, the design cost also decreases. However, the indicators of heat losses in pipelines of the heat supply system in the process of ex-exploitation are no less important. The size of these losses largely depends on the temperature of the coolant, the method of laying the pipelines and their diameters (or other parameters of the cross-sectional shape), but more from the lengths of the corresponding sections of the system. Obviously, the length of heat networks is one of the key factors determining the overall economy of the heat supply system, but the level of its energy efficiency should be also formed taking into account the specific heat losses. This publication reveals the analysis of the factors, the general principles of optimization of the heat supply system should be formulated, and mathematical foundations for determining the geometric parameters of this system are suggested, taking into account these factors.