Python script for reading Remeha Tzerra central heating boiler data and send the data as mqtt messages.

To use this script you need:

• a RS232 to TCP converter like this one
• a ttl to RS232 converter like this one.

Put the ip-address of the RS232 to TCP converter in settings.py.

Connect the PC output of the heater to the ttl to RS232 converter using a RJ10/4P4C connector, for instance a cut in half telephone handset cable. Connect the ttl converter to the RS232 to TCP converter.

(Instead of these two convertors you can use an ESP8266 and the WifiTelnetToSerial example sketch in the Arduino IDE)

You will need the Eclipse Paho MQTT Python client library, use pip for installation: pip3 install paho-mqtt

The script returns the current running values of the heater. All values are sent as an mqtt message to your mqtt broker. In settings.py you can set the brokers address, the topic and some other mqtt stuff.

The script is meant to run every minute (or 5) as a cronjob e.g.

* * * * * /usr/bin/python3 /home/pi/tzerra2mqtt/tzerra2mqtt.py > /home/pi/tzerra2mqtt/cronlog.txt

If you use Home Assistant, you can run set_hass_autodiscovery.py once to add the sensor entities to HA automatically. *** THIS IS OUTDATED because of changes in Home Assistants mqtt model. ***

https://community.home-assistant.io/t/rehema-tzerra-central-heating-interface/267366