equithermal regulator

Equithermal regulation of the temperature in the room consists in setting the temperature of the heated water (by regulating the heat source) based on the outside temperature. At a lower outside temperature, a higher temperature of the supplied heated water is required to achieve a balance between the supplied heat and the heat losses of the room, so that the room temperature remains constant.

For a given room, it is possible to establish a system of so-called equithermal curves (also "heating curves"), which describe the mutual dependence of the temperature of the heated water, the room and the outside temperature.

Based on the desired room temperature, it is possible to select a certain curve and regulate the temperature of the heated water according to the outside temperature. Of course, several basic questions immediately follow from the given description. What does it actually mean "is it possible to establish a system of equithermal curves?"