1) the expansion tank opened at the highest does not provide security near the boiler, because a rapid and violent overpressure takes time to propagate to the balloon, and by inertia can cause farting.
So considering the price, it is safer to put a safety valve very close to the boiler heat source which can boil water quickly (depending on its mass).
ok I agree but "considering the price", we are not talking about the same thing. I recover, but a thermal safety valve and a prescomano do not react to the same principles (one is thermal the other pressostatic) and the price is not at all the same. I put anyway a prescomano (10 euros) but my question was more about the thermal valve (120 euros !!!)
2) for the greenhouse is there domestic water ??
Or is it just the water that heats the greenhouse in the ground?
Normally the water circuit of the boiler is never connected to sanitary water, because otherwise we drink rot from the boiler and radiators !!
in fact the boiler is the recovery but I do not need the DHW function but in one of the first posts, someone advised me to connect the circuit anyway to be sure that it does not blow up not. so it is connected to the balloon as the heating production pipes.
I tried to send my diagram but I couldn't. I am well aware that by not exchanging only in writing without knowing that we are certain of understanding each other well, this can lead to confusion.
hoping to have been clearer and once again thanking you for taking the time to help the planet and its eco-citizens, I salute you .....!
A+