DC wrote:OK thank you, in conclusion, I am content to cut the circulator at the level of the control panel but I did not understand why in fact it is necessary to stop the circulation in the circuit of the radiators at this moment ...
Because when a "liquid" circuit is purged of gas, it is done if possible with a stationary circuit so that the bubbles are naturally raised to the high points, where the purgers are (normally!).
If you are not confident (there are sometimes more or less screwed up circuits where gases are stored in places not equipped with traps), nothing prevents you from making a check by redoing a purge for a few days of operation. after the premiere.
Besides, not sure if you understood what you define as "entresol"? On the ground floor? To be clearer, what is the approximate height from the floor of your cellar to the top of your highest radiator upstairs?