Hello,
I am very new to this forum.
I want to be able to modify parameters from outside but wihout internet connexion.
Because we want to leave the house fiew month we want to suspend internet connexion.
I want to developp a GSM / SMS gateway receiving and interpreting SMS.
This gateway will forwards order to thermostats.
The house has 10 zones so, will have 10 thermostats.
Is it posssible to connect at least 10 captor of temperature and regulate 10 zones with Hestiapi ?
Is it possible to send order to hexiapi by wifi to modify some parameters ?
Is that possible to read temperatures from hexiapi ?
Is that possible to connect relays (10) to hexiapi to be able to controle all different zones ?
Thank you for helping me !
Best regards
Hello and welcome to the club 
Feel free to introduce yourself here
I would advise for your SMS gateway to support MQTT messages over WiFi. Through MQTT you will be able to read and write all values/settings from all 10 HestiaPi individually (Read state at zone number 3) or globally (set heating off on all Zones ). Same applies for the multiple temperature sensors. For the multiple relays, you can use spare Raspberry GPIO pins and drive the 10 relays with these.
Sounds like a great project and I am very confident HestiaPi can support this setup but will require a lot of your time and configuration. Keep us updated
Many thanks for your repsonse.
so if I understand well,
I can use one hestiapi for all 10 zones.
I can modify the settings like reference point by the way of MQTT.
Can I choose the temperature captor ? like one wire 18b20 ?
It’s sound great !
Theoretically yes but DS18B20 has been proven unreliable producing spikes in the values. So if you were to choose DS18B20 you should also develop your algorithm in a way to filter out spikes (ignore, and re-read, reading if it varies more than x% from average value of the last y readings).
I would suggest spending 1-2 USD/GBP/EUR per sensor and get the one we use as it is much more reliable and precise. It will save you a lot of time in debugging in the long run 
In terms of hardware, a solution based on the ESP or NodeMCU should be adequate as they support both DS18B20 and BME and there are ready solutions that support both sensors, WiFi and MQTT or HTTPS which should suffice.