Zendher WHR 950

Port of ComfoAir protocol to ESPHome.io firmware originally by @wichers modified by @nyxnyx to be installed as external_components. Modified for the Zehnder WHR 950 by @tieskuh. Also confirmed working for the Zehnder WHR 930.

Configuration

Add to your yaml configuration the definition of external_components:

external_components:
  - source:
      type: git
      url: https://github.com/tieskuh/esphome-comfoair
    components: [comfoair]
    refresh: 0s

and than use it:

uart:
  id: uart_bus
  rx_pin: 22
  tx_pin: 19
  baud_rate: 9600

comfoair:
  name: "WHR 950"
  uart_id: uart_bus
  fan_supply_air_percentage:
    name: "Supply fan"
  fan_exhaust_air_percentage:
    name: "Exhaust fan"
  fan_speed_supply:
    name: "Supply fan speed"
  fan_speed_exhaust:
    name: "Exhaust fan speed"
  is_bypass_valve_open:
    name: "Bypass"
  is_preheating:
    name: "Preheating"
  outside_air_temperature:
    name: "Outside temperature"
  supply_air_temperature:
    name: "Supply temperature"
  return_air_temperature:
    name: "Return temperature"
  exhaust_air_temperature:
    name: "Exhaust temperature"
  is_supply_fan_active:
    name: "Supply fan"
  is_filter_full:
    name: "Filter status"
  bypass_step:
    name: "Bypass valve"
  is_summer_mode:
    name: "Summer mode"

button:
  - platform: template
    name: "Reset filter"
    on_press:
      then:
        - lambda: |-
              id(comfoair_climate)->reset_filter();

Sensors

The following sensors are created:

Hardware

I used the following hardware:

• RS-232 cable with DB9 D-SUB male connector
• M5Stack: https://nl.aliexpress.com/item/1005003299215808.html
• M5Stack RS-232 add-on: https://nl.aliexpress.com/item/1005005933403536.html
• 12v to 5v USB-C adapter: https://nl.aliexpress.com/item/1005004984244010.html

Pin layout:

• RX (receive) = pin 2
• TX (transmit) = pin 3
• GND (ground) = pin 5

(If it doesn't work, try to switch RX and TX. The RX on one end should be the TX on the other end.)

To power the M5Stack, I used a 12v to 5v USB-C adapter and powered the M5Stack via USB-C. There are unused 12v connectors on the WHR's board. I assume you can also connect the 12v of the WHR directly to the 12v of the M5Stack RS-232 addon. Or just use a normal 220v USB adapter.