In the source of heat energy for centralized heat supply systems, the joint production (cogeneration) of heat and electricity in one energy conversion unit is most often implemented. In most cases, the cogeneration technologies are based on steam turbine installations. Combined heat and power (CHP) generation is undoubtedly a method where the energy of the fuel input for both products is used more efficiently, in contrast to the production of the same amounts of energy by the split production method. To increase the efficiency of cogeneration plants a low potential heat source can be used. For this purpose, in this paper, based on simulation modelling, a comparative analysis of the operation of a combined heat and power steam turbine plant with a heat pump plant with a low-potential heat source will be carried out. In the study, the mains water that is fed for preheating is used as the low-potential heat source.