ComfoAir

Port of the ComfoAir protocol to ESPHome.io firmware, which is supported by external_components.

Add the following definition of external_components to your yaml configuration:

external_components:
  - source:
      type: git
      url: https://github.com/wichers/esphome-comfoair
    components: [comfoair]

and then use it:

uart:
  - id: uart_bus
    rx_pin: 3
    tx_pin: 1
    baud_rate: 9600
  # Optional: second UART for a ComfoSense / CCEase display
  # - id: uart_proxy
  #   rx_pin: 16
  #   tx_pin: 17
  #   baud_rate: 9600

comfoair:
  name: "ComfoAir 350"
  uart_id: uart_bus
  # Optional: proxy display traffic (requires uart_proxy above)
  # proxy_uart: uart_proxy
  # Optional: status LEDs as GPIO binary outputs (not HA switch entities)
  # Define under output: then reference here, e.g. red_led: red_led_gpio
  # red_led: red_led_gpio      # high fan
  # green_led: green_led_gpio  # low/medium/auto
  # blue_led: blue_led_gpio    # filter full
  type:
    name: "type"
  size:
    name: "size"
  size_select:
    name: "unit_size"
  intake_fan_speed:
    name: "intake_fan_speed"
  exhaust_fan_speed:
    name: "exhaust_fan_speed"
  intake_fan_speed_rpm:
    name: "intake_fan_speed_rpm"
  exhaust_fan_speed_rpm:
    name: "exhaust_fan_speed_rpm"
  ventilation_level:
    name: "ventilation_level"
  bypass_present:
    name: "bypass_present"
  bypass_valve:
    name: "bypass_valve"
  bypass_valve_open:
    name: "bypass_valve_open"
  preheating_state:
    name: "preheating_state"
  outside_air_temperature:
    name: "outside_air_temperature"
  supply_air_temperature:
    name: "supply_air_temperature"
  return_air_temperature:
    name: "return_air_temperature"
  exhaust_air_temperature:
    name: "exhaust_air_temperature"
  enthalpy_temperature:
    name: "enthalpy_temperature"
  ewt_temperature:
    name: "ewt_temperature"
  reheating_temperature:
    name: "reheating_temperature"
  kitchen_hood_temperature:
    name: "kitchen_hood_temperature"
  return_air_level:
    name: "return_air_level"
  supply_air_level:
    name: "supply_air_level"
  supply_fan_active:
    name: "supply_fan_active"
  filter_status:
    name: "filter_status"
  error_status:
    name: "error_status"
  filter_reset:
    name: "filter_reset"
  error_reset:
    name: "error_reset"
  # Service / PC test mode (default false). When true, auto-creates test
  # entities (test_mode switch, self_test, flaps, fans, relays).
  # enable_test_mode: true
  enthalpy_present:
    name: "enthalpy_present"
  ewt_present:
    name: "ewt_present"
  options_present:
    name: "options_present"
  fireplace_present:
    name: "fireplace_present"
  kitchen_hood_present:
    name: "kitchen_hood_present"
  postheating_present:
    name: "postheating_present"
  postheating_pwm_mode_present:
    name: "postheating_pwm_mode_present"
  preheating_present:
    name: "preheating_present"
  bypass_factor:
    name: "bypass_factor"
  bypass_step:
    name: "bypass_step"
  bypass_correction:
    name: "bypass_correction"
  bypass_open_hours:
    name: "bypass_open_hours"
  preheating_hours:
    name: "preheating_hours"
  level0_hours:
    name: "level0_hours"
  level1_hours:
    name: "level1_hours"
  level2_hours:
    name: "level2_hours"
  level3_hours:
    name: "level3_hours"
  preheating_valve:
    name: "preheating_valve"
  frost_protection_active:
    name: "frost_protection_active"
  frost_protection_hours:
    name: "frost_protection_hours"
  frost_protection_minutes:
    name: "frost_protection_minutes"
  frost_protection_level:
    name: "frost_protection_level"
  filter_hours:
    name: "filter_hours"
  motor_current_bypass:
    name: "motor_current_bypass"
  motor_current_preheating:
    name: "motor_current_preheating"
  summer_mode:
    name: "summer_mode"
  p10_active:
    name: "p10_active"
  p11_active:
    name: "p11_active"
  p12_active:
    name: "p12_active"
  p13_active:
    name: "p13_active"
  p14_active:
    name: "p14_active"
  p15_active:
    name: "p15_active"
  p16_active:
    name: "p16_active"
  p17_active:
    name: "p17_active"
  p18_active:
    name: "p18_active"
  p19_active:
    name: "p19_active"
  p90_active:
    name: "p90_active"
  p91_active:
    name: "p91_active"
  p92_active:
    name: "p92_active"
  p93_active:
    name: "p93_active"
  p94_active:
    name: "p94_active"
  p95_active:
    name: "p95_active"
  p96_active:
    name: "p96_active"
  p97_active:
    name: "p97_active"
  bathroom_switch_on_delay_minutes:
    name: "bathroom_switch_on_delay_minutes"
  bathroom_switch_off_delay_minutes:
    name: "bathroom_switch_off_delay_minutes"
  l1_switch_off_delay_minutes:
    name: "l1_switch_off_delay_minutes"
  boost_ventilation_minutes:
    name: "boost_ventilation_minutes"
  filter_warning_weeks:
    name: "filter_warning_weeks"
  rf_high_time_short_minutes:
    name: "rf_high_time_short_minutes"
  rf_high_time_long_minutes:
    name: "rf_high_time_long_minutes"
  extractor_hood_switch_off_delay_minutes:
    name: "extractor_hood_switch_off_delay_minutes"

The sensor defined here is a full list of sensors - if you remove a sensor from the yaml definition it will not be monitored.

Original controller (proxy UART)

Classic ComfoAir RS232 is point-to-point: you cannot put the unit, the wall controller (CCEase / ComfoSense / similar), and the ESP on the same UART as peers. Instead this component can sit between them as a bus bridge:

[CCEase / ComfoSense]  ←→  ESP (proxy_uart)  ←→  ComfoAir unit (uart_id)

Behaviour

• Display commands are forwarded to the unit; unit replies to those transactions are mirrored back to the display.
• ESPHome polls and HA control share the unit UART via short bus ownership (display vs ESP), so the two masters do not TX at once.
• Replies to ESP-initiated polls are not fed to the display (avoids confusing the controller).

Configuration

Use two UARTs at 9600 baud. Example (ESP32 pin numbers — change to match your board):

uart:
  - id: uart_bus
    rx_pin: 16
    tx_pin: 17
    baud_rate: 9600
  - id: uart_proxy
    rx_pin: 18
    tx_pin: 19
    baud_rate: 9600

comfoair:
  name: "ComfoAir"
  uart_id: uart_bus
  proxy_uart: uart_proxy
  # … sensors …

Wiring notes

• Unit link (uart_bus): ESP TX → unit RX, ESP RX → unit TX, common GND. Level-shift if needed (unit is often 5 V TTL / RS232 adapter).
• Controller link (uart_proxy): ESP TX → display RX, ESP RX → display TX, common GND. Same levels as the original wall-controller cable.
• Do not Y-cable the display and ESP onto the unit’s single port.
• ESP8266 only has one usable hardware UART for this in practice; prefer ESP32 (or a board with two free UARTs) when keeping the original controller.
• On boot, logs should include Display proxy UART: enabled under the ComfoAir config dump.

Warning: The size_select entity exposes the ComfoAir unit size (large/small) for installer configuration. Changing this setting should be done sparingly and only when you know the correct unit size for your installation.

For visualization: Checkout https://github.com/wichers/lovelace-comfoair and follow the instructions.

Compatibility

This is a list of models that are known to work, feel free to add yours if you tested it successfully:

• Zehnder WHR 930
• Zehnder WHR 950
• Zehnder ComfoAir 160
• Zehnder ComfoAir 200
• Zehnder ComfoAir 500
• Zehnder Comfoair 550
• Zehnder ComfoD 300
• Zehnder ComfoD 350
• Zehnder ComfoD 450
• Zehnder ComfoD 550

Incompatible

• Zehnder ComfoAir Q350 (CAN)
• Zehnder ComfoAir Q450 (CAN)
• Zehnder ComfoAir Q600 (CAN)

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