Floris – Floris Romeijn

Introduction

I bought a new Vaillant ( Hr-ketel ecoTEC plus) central heating boiler a few months back, my old boiler from 2001 still worked, but I rather had it replaced, before it broke. When ordering there was an option to make it connected with the vSMART for about €200 extra. It sounded a bit to much and saw no integration with Home Assistant (HA) directly (at that time). So I tried an alternate way.

eBUS

Vaillant uses a protocol called eBUS for external communication. This protocol is based on UART but at different voltage levels, so be able to use this protocol we need some hardware to do the translation. Although there were some solutions available online, I couldn’t find a tiny and SMD variant. This is why I decided to create my own PCB in KiCAD. My design is based on the following project: https://ebus.github.io/adapter/. My project can be found here: https://gitlab.com/fromeijn/ebuzzz-adapter

This PCB uses a USB to UART converter board with an CP2102, e.g this one. It is electrically isolated so no harmful ground loops or other issues can occur. There are also some helpfull LEDs to show you what is going on.

Home Assistant Integration

To integrate with Home Assistant I used ebusd running on an Raspberry Pi I had laying around. The ebusd has an MQTT client integrated, this is an easy way to hook it up to Home Assistant. To give you an idea how it is hooked up see this drawing below. The eBUS to USB converter board will be connected to the bus with two wires. The position of those wires doesn’t matter.

To install ebusd on Raspberry Pi OS (Raspbian) you use the following documentation from the ebusd repository: https://github.com/john30/ebusd/wiki/1.-Build-and-install

I used it in the following configuration for ebusd, there are some optional parts.

# add custom config for the VRT350 thermostat (only needed if you have VRT350)
cd /home/pi/
git clone https://github.com/john30/ebusd-configuration.git
cd ebusd-configuration/
cp ebusd-2.1.x/en/vaillant/15.370.csv ebusd-2.1.x/en/vaillant/15.350.csv

# you can change the r; at the beginning of the lines by r1; so it will be read out automatically and pushed on MQTT. If you can also poll values via MQTT, see down below for an example.

Edit /etc/default/ebusd

# Without local ebusd-configuration
EBUSD_OPTS="--scanconfig 
--mqtthost=<homeassistant_ip> --mqttport=1883 --mqttuser=<user> --mqttpass=<passwd>"

# With local ebusd-configuration
EBUSD_OPTS="--scanconfig 
--configpath=/home/pi/ebusd-configuration/ebusd-2.1.x/en --mqtthost=<homeassistant_ip> --mqttport=1883 --mqttuser=<user> --mqttpass=<passwd>"

To restart the ebusd

sudo service ebusd restart

In Home Assistant you need to have a MQTT broker setup. In my case I use Mosquitto broker addon, what can be install via the Supervisor. See the documentation of the addon. Also do not forget to add the MQTT integration into your config. I used the MQTT HVAC integration and set is up as follows:

mqtt:
  broker: core-mosquitto
  username: <your-mqtt-user>
  password: <your-mqtt-pass>
  discovery: true

climate:
  - platform: mqtt
    name: CV
    max_temp: 25
    min_temp: 15
    precision: 0.1
    temp_step: 0.5
    modes:
     - auto
     - heat
     - cool
     - 'off'
    mode_state_template: >-
      {% set values = { 'auto':'auto', 'on':'heat',  'night':'cool', 'summer':'off'} %}
      {{ values[value] if value in values.keys() else 'off' }}
    mode_state_topic:  "ebusd/350/Hc1OPMode"
    mode_command_template: >-
      {% set values = { 'auto':'auto', 'heat':'on',  'cool':'night', 'off':'summer'} %}
      {{ values[value] if value in values.keys() else 'auto' }}
    mode_command_topic: "ebusd/350/Hc1OPMode/set"
    temperature_state_topic: "ebusd/350/DisplayedHc1RoomTempDesired"
    temperature_low_state_topic: "ebusd/350/Hc1NightTemp"
    temperature_high_state_topic: "ebusd/350/Hc1DayTemp"
    temperature_low_command_topic: "ebusd/350/Hc1NightTemp/set"
    temperature_high_command_topic: "ebusd/350/Hc1DayTemp/set"
    current_temperature_topic: "ebusd/350/DisplayedRoomTemp"

Tip: Use MQTT Explorer if you are having problems getting MQTT to work between HA and ebusd.

Automations

When having home assistant and ebusd connected we can start automating things and let the computer do stuff for us. I have configured a google calendar in which I can plan my normal heating schedule. But this only is enabled when i’m home, and turns off when I leave the house.

Heater on/off on calendar automation

alias: Heater on/off on calendar
description: ''
trigger:
  - entity_id: calendar.heater
    platform: state
  - entity_id: binary_sensor.people_home
    platform: state
    to: 'on'
condition:
  - condition: state
    entity_id: binary_sensor.people_home
    state: 'on'
  - condition: template
    value_template: '{{ not is_state("climate.heater", "off") }}'
action:
  - choose:
      - conditions:
          - condition: state
            entity_id: calendar.heater
            state: 'on'
        sequence:
          - service: climate.set_hvac_mode
            data:
              hvac_mode: heat
            entity_id: climate.heater
    default:
      - service: climate.set_hvac_mode
        data:
          hvac_mode: cool
        entity_id: climate.heater
mode: single

Heater low when nobody home automation

alias: Heater low when nobody home
description: ''
trigger:
  - entity_id: binary_sensor.people_home
    from: 'on'
    platform: state
    to: 'off'
    for: '00:05:00'
condition: []
action:
  - data:
      hvac_mode: cool
    entity_id: climate.heater
    service: climate.set_hvac_mode
mode: single

Poll WaterPressure from bai over ebus

alias: Poll WaterPressure from bai over ebus
description: ''
trigger:
  - platform: time_pattern
    minutes: /1
condition: []
action:
  - service: mqtt.publish
    data:
      topic: ebusd/bai/WaterPressure/get
mode: single

we also want a sensor to receive this data, add this to your configuration.yaml

sensor:
  - platform: mqtt
    name: "Water Pressure CV"
    state_topic: "ebusd/bai/WaterPressure"
    unit_of_measurement: 'bar'
    value_template: "{{ value.split(';')[0] }}"

Conclusion

With this integration we can control the temperature remotely or automatically. I’ve added presence detection and a google calendar so no energy is wasted which is a big plus for me. This project was fun to get my home automation kick stared and I learned something one the way. Hope this helps some of you as well!

Boards (un)available

Unfortunately I have decided to stop my production of these board. If you want to build your own see https://gitlab.com/fromeijn/ebuzzz-adapter

Author: Floris

Connected Vaillant to Home Assistant