Hello, I am looking into an open source/hardware solution to replace the Siemens REV11 thermostat at my place. It is controlling a viessman vitorond 100 oil boiler/vitotronic 100 controller, and the only wires connected to the REV11 are l/l1.
Is this possible to be controlled by the Hestia? What is the recommended approach?
From what you say we believe that connecting the 2 wires should start your heating system in which case HestiaPi would be able to support that. Please double check you know what these wires are for and confirm if our assumption applies to you.
Thanks, in the meantime I had to replace the boiler with a gas system (Vaillant VC 306), which now has a two wire ebus system,
with Vaillant extensions probably, and including power (12v ?).
Hmmm… I dont know that.
Do you have a schematic of the wiring so that I understand better?
It is usually located around the terminal block. Take a photo and upload it here.
The thermostat page is here - https://www.vaillant.be/particuliers/produits/multimatic-vrc-700-23424.html
The ebus wiki seems to be only in German (wiki-ebus.org), but there is a GitHub project on ebus binding with openhab here - https://github.com/openhab/openhab1-addons/wiki/eBUS-Binding
I guess we should move this to a new topic.
It’s there any support in OpenHAB 2 ?
apparently yes, and working since February - https://community.openhab.org/t/ebus-and-openhab2/7666/15
Looks compatible but you will still need some sort of adapter to interface HestiaPi with your system.
It seems so. Looks like it will be a bigger project than I expected. Unless I buy a €80 adapter, I’ll have to do my own, there doesn’t seem to be any kit and the hestiapi doesn’t have the hardware for it. I don’t know if I have the time to invest in it right now.
That’s right 
It seems a lot of specialised hardware for only one protocol where HestiaPi’s approach is to address the most people with the least hardware.
I din’t even know about ebus before, but it seems to be the standard in central Europe, with at least the two top brands (Vaillant group and Viessman) using it. I found another interesting blog entry here, which details how to get a Bulex (Vaillant variant) to work with a RPI III with ebusd. I might start with that, if I can find the time. It would be cool to have it with hestiapi.