Wireless Thermostat Recommendation

Hardware
1

Hi! I am looking for a thermostat and I seem to be having trouble finding something that meets my needs. Maybe any of you can help me.

  1. I want it to be fully locally controlled. No cloud. I already have a Zigbee network, but WiFi is acceptable too.
  2. I am renting and cannot pull wires through walls. The gas heater is in a closet and I would like the thermostat to be outside (for it to measure the actual temp inside my living room). There are dumb RF thermostats that do that: They have a receiver mounted next to the heater and a wireless, battery operated console unit you can move around the house.
  3. The heater is controlled using a dumb on/off dry contact
  4. I want it to still work reliably if the HA server dies (so no DIY software thermostat with a relay and a temp sensor)
  5. I live in the EU, so 230V
2

If you have 230v power near the boiler you can use a smart relay converted to dry contact to start and stop the boiler and a simple temp sensor in the home to get the room temp, then use something like Better Thermostat in ha to automate it.

3

As I said, I would like a solution that doesn’t fail when the HA server dies aka a dedicated thermostat that can work independently. For now, it seems that maybe the Hive ones could work with Z2M? They seem to have this exact receiver-remote configuration that I’m looking for.

4

Sorry, I completely missed your 4th point.
For what is worth in my search for hvac automation I’ve never seen something like you’re describing.