Virtual thermostat

From eedomus - Documentation

Jump to: navigation, search

The virtual thermostat, also called Heating Zone, is a programming that operates as described below.


The algorithm for the calculation of the power according to the temperatures is: Power (between 0 and 100 % of time) = C x (difference between the setpoint and current inside temperature) + T x (difference between the setpoint and the ouside temperature). The values by default C = 0,6 and T = 0,01 suit generally. They correspond to a heating power of 100W / m2 and an average insulation. They can be adjusted (and T increased until the insulation of the building(ship) Ubat brought back(reported) to the power, until 0,03).

For a 1000 watt heating, a setpoint of 21°C, a current temperature of 20°C, and an outside temperature of 11°C give P = 0,6 * (21 - 20) + 0,01 * (21 - 11) = 0,7. The heating will heat 70% of the time, eg 700W.


The formula is planned to control a ON/OFF relay. The value is limited between 0 and 100 %. A 10 % value will switch on the relay 10 % of time, that is 1 minute (over 10 minutes). Except change in the setpoint , the calculation is realized every 10 minutes on eedomus. The algorithm works off-line.

This duration of cycle is adapted to a gas boiler (it is the default value of certain thermostats), and for electric heating where the cycles could even be slightly shorter. For fuel boilers, or systems of central heating, it is necessary to increase the duration of cycle in 20 or 30 minutes, even more (by a personalized thermostat).

We invite you nevertheless to check the duration of the cycle with your installer/heating engineer/builder.


If the temperature stabilizes under the setpoing, it is recommended to increase the values by default C = 0,8 and T = 0,02 for example. It is also necessary to verify that the local thermostat of every convector is not limited to a too low temperature which would make that it cuts itself.