I have jut received my HestiaPI kit.
I live in Italy, so the power line is 220 Volts, but the boiler is controlled by 2 wire where is present a 24volts dc tension.
My old thermostatan just close the contact to give the command to switch on the boiler.
I believe that may be a more flexible that HetiaPI board export the two contact of the relè. Decoupling the power supply of the HestiaPI and the way who control the device all become more flexible.
Thank you for your work