I am now for one day on Home Assistant and I love the system. The reason I opted for Home Assistant was that it is local and does not require to go into the cloud. There is a nice cloud option, though 
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I have a problem in finding the right thermostat for my central heating. My furnace is controlled by 2 wires on/off or open-therm (my current thermostat is just on/off). I noticed that most thermostats require 4 or 5 (c-wire) wires and control 230V. Worse, most of them require an account and connection via Wifi, while I want either Z-Wave or Zigbee.
Question: Is there a Zigbee or Z-Wave thermostat to control a 2 wire, open-therm central heating, not requiring an account? Batteries ok and I am willing to pay for a good quality thermostat. I am not allowed to tinker with the furnace as it is not my own.
Any advice is welcome