Thermodynamic analysis of an ideal heat pump’s working processes described by the Carnot cycle has been made. The study shows how the coefficients of performance, costs per unit, and the available low-grade heat factor correlate with the heat source and heat consumer temperatures in any combinations within the absolute temperature field. Boundary conditions have been introduced for efficient performance of ideal heat pumps. Promising for solving practical tasks are four fields where the heat source and consumer temperatures are combined in the interval of 260–380 K.