The report analyzes the work of a pumping unit from the hot water installation of the Faculty of Technics and Technologies - Yambol, Bulgaria, under different load conditions. Simulation stands have been adapted that are suitable for analyzing the performance of motors of different types and depending on how they are put into the pump unit. It was found that when the energy inefficient electric motor is directly started, the maximum efficiency is 79,63% and is achieved at 100% of its load. When using a frequency converter, at 100% of its load, the efficiency is 86,83%. The proposed energy-efficient electric motor, with direct start-up, has the highest efficiency of 86,7%. The obtained results can be used in the modernization of the hot water installation of the Faculty of technics and Technologies - Yambol, in the part “pumping units”.