Good sport Manet!
I will answer anyway and you will follow up as soon as you have the opportunity!
I appreciate our civilized discussion which shows that it is possible to bring our arguments without killing each other!
In fact, if I understood correctly, the external probe allows water to be sent at the most precise temperature possible to have the right atmosphere.
Why send water at 70 ° if 45 ° is enough?
This is also what I understand from this way of proceeding, I do not know if you have followed the discussion I had on adaptive thermostats with Dédé, but I believe that the regulation of the temperature of the circulating water can be managed by this kind of thermostat, if this thermostat adapts to the house according to the time it takes to make the temperature correction, it can very well manage this same temperature of the circulating water by what it can read referring to the time of the temperature drop!
This is why I launched this sentence taken up by Dédé "Why keep it simple when you can make it complicated", now the marketing of boiler salesmen must make people believe in innovation in their products, I can hardly imagine a competitor saying that 'it works without this probe, it will be quickly planted by others!
A little anecdote here on the types of electric heaters, while for you the hot air convectors which are low-end for you, some here claim that it is superior to our electric baseboard heaters to boost their sales, which is not the case in reality but we use the fact that in Europe it is what is the most sold for its ridiculous price at home while here the low end is this famous plinth whose only real problem is the thermostat that controls it!
Unfortunately too often the arguments of a supposed technological advancement to boost sales outweigh the logic to the detriment of consumers!
We see this on many products in your home while here we are rather conservative because a heating system must be forgotten and must not become a burden for the user.
Stepping behind sometimes can strengthen friendship.
Criticism is good if added to some compliments.
Alain