Ebus thermostat controls with modulation

Configuration
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I have the following setup for heating my home: I have a Vaillant boiler with thermostat VRC700 with a control unit VR70. This thermostat is not placed inside the heated rooms, but in a separate technical room. Which makes it not possible to use the builtin temperature sensor of the thermostat to regulate the heating.

My question now is: would it be possible to use the ebus port to send out the actual temperature of the rooms (coming from my knx sensors in each room) to the installation. Is there anybody who has attempted such a thing yet?
Another way might be to have my own thermostat implementation which runs on my raspberry pi and send out the instructions to the ebus port like any other thermostat would do.

Thanks!

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Have you figured this out? I have only one VRC700 but several other temperature sensors and Homematic thermostats in each room. It would be nice to be able to send room temperature of different rooms that currently need heat (I have actuators that close the valves for rooms that don’t)

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I did figure out on home to communicate with my heater/thermostat with ebusd.

Unfortunately, I was not able to just send the actual temperature to the thermostat. This because the VRC700 was configured to just take the outside temperature into account in combination with the temperature of the returning water. Every time I manually set the “actualRoomTemperature” register to the temperature reading from my sensor, the thermostat overwrites it by “None”. I do think this is because of the configuration of the thermostat.

What I did provide is a python script which does two things:

  • it reads the “desired day/night temperature” from homeassistant and compares this with the actual room temperature
  • every hour and a half, it checks the actual room temperature with the desired temperature and modifies the thermostat settings accordingly. It could be possible that I want to have 21°C, the thermostat in the boiler is set to 21°C, but the actual room temperature is 22°C because of too much sunshine. In that case my script will try to adjust the thermostat setting to make sure I get the 21° requested in home assistant. In that case it will monitor the actual roomtemperature and set the thermostat to 20° for example.
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have you worked more on this? i would love to just attach a central placed sensor instead, but there is no instructions on how to do that