Equithermal regulation. What it is? How does it work?

In this article, we want to briefly outline the concept of equithermal regulation and how this function works. Equithermal regulation (ER) is a method of boiler control, in which the temperature of the heat carrier is regulated depending on the outside air temperature. The outside temperature sensor constantly monitors changes in the weather, and the controller, in accordance with preset dependencies, regulates the water temperature in the heating system (and thus the air temperature in the building) so that constant thermal comfort is ensured at all times.

By complementing this system with a room regulator or thermostatic radiator valves, you can create a reliable, economical and pleasant way to heat your home and increase thermal comfort. On many sites, ER is described as a simple linear function of the dependence of the coolant temperature on the ambient temperature. In fact, ER is a more complex function. First, the dependence is not on the ambient temperature, but on the weather, i.e. additionally, at least air humidity and sun exposure must be taken into account. Secondly, regarding the wall of the room that you are heating, it is necessary to take into account its thermal conductivity, area and, possibly, heat capacity. Thirdly, with regard to the internal space, it is necessary to take into account the heat transfer of the radiator, the volume of the room and even the number of people (living entities) who are there at the same time, and all kinds of installations, as a result of which heat is generated, all this may be important. To build a mathematical model that would adequately describe the ER function, it is necessary to carry out experimental studies, for example, a full factorial experiment (FFE), i.e. without confirmation of repeatability, it is necessary to carry out 2^8 = 256 experiments. Even if we assume that some of the factors turned out to be insignificant and discard them, and assume that there are only 4 factors left, then the number of experiments is reduced to 16, and with the need to repeat the experiment many times at each point and check the adequacy of the model at the zero point of the experiment, you get at least 51. If we assume that the dependences are linear, then the model can be simplified to a linear equation, but the outdoor sensor must take into account significant weather factors, then the response of the function consists of several linear dependences. ER is a method that is ideal for enthusiastic scientists... To implement ER, a complex system is needed, which creates additional redundancy for the entire system and complexity for the user when setting it up. The most applicable is a room temperature sensor, which controls the heating of water exclusively depending on the set room temperature, other factors lose their significance.