airfilter

⚠️ This is a WIP! Some images are missing, but the firmware works fine.

I've modified my IKEA Förnuftig to work with Home Assistant. After some soldering you can control the filter via MQTT and also (!) manual with the knob (as originally intended). I use an ESP32 NodeMCU but an ESP8266 NodeMCU should also work fine.

Via Home Assistant discovery the air filter will show up as a fan-entity with three preset modes 1, 2 and 3. You can also control the fan via the percentage slider.

Table of contents

• Features
• What you need
• How to
  • Flashing
  • Teardown
  • Soldering and wiring
• MQTT
• Home Assistant
• Questions
• Credits

Features

• Control the air filter via MQTT
• Control the air filter manual (as originally intended)
• Home Assistant discovery
  • Support for preset modes
  • Support for percentage control

What you need

• ESP32 NodeMCU
• 74C14 or 74HC14 Inverter
• 24V to 5V DC/DC-Converter
• Some Jumper Cables
• Superglue
• Soldering iron
• Tiny wires

How to

Flashing

Connect the ESP32 NodeMCU via USB to your PC. On Windows you need some additional drivers. On Linux everything should work out of the box. Start the Arduino IDE and open the sketch file located at firmware/airfilter/airfilter.ino.

Change the WiFi and MQTT settings at the top of the file. Then select your NodeMCU (Tools -> Port) and configure all settings as shown in the screenshot below. Afterwards press flash.

Teardown

Unplug the air filter. Remove the blend and the filter. Then unscrew the two phillips screws at the top and remove the plastic part. Unplug both cables and unscrew the circuit board. You also have to remove the knob before removing the board.

Fortunately IKEA has made a product with a lot of space for us - nice. So we can unscrew the six triangle screws and the two phillips screws at the bottom. If you don't have a triangle screwdriver: A slot screwdriver will work as well. Then remove the two plastic parts. There are clipped, so make sure not to break anything. (wip, screw image)

Soldering and wiring

Warning: This step can not be undone!

The knob must not have an effect on the fan speed directly, so we have to cut the circuit path. I've done this with a small cutter. (wip, img cutting)

The internal DC/DC-Converter is sadly not powerful enough to power up the ESP32 (sometimes it works, sometimes not). So we have to use our own Converter to power up the ESP. Just solder the GND and VIN pins of the DC/DC-Converter to the 24V output pin on the circuit board. Connect the GND and VOUT pins of the DC/DC-Converter to the VIN and GND pins of the ESP.

Connecting the inverter is the hardest part because it's tiny. I've soldered the pins as shown below and then superglued the converter onto the board. Not great, but good enough.

Wiring

This is the fan control CPU. Please mention the origination.

(wip, img knob connections)

Final

Caution: DO NOT USE THIS PHOTO AS REFERENCE! The wiring on this photo looks different from the wiring image because this project was learning by doing. So some GND and VCC wires are connected differently.

Now we can connect all cables through the hole and place the ESP into the perfect fitting space. I also let the usb cable connected for future firmware updates.

MQTT

Additional info: If you turn off the fan by turning the knob to 0 or by sending the off payload, the selected preset mode will not change.

On and off

airfilter/<hostname>/state

Returns the state on or off, while off represents knob position 0.

airfilter/<hostname>/set

Turn the fan on or off by sending on or off as payload.

Presets

airfilter/<hostname>/preset/state

Returns the current selected preset mode (1, 2 or 3). This equals the knob position. Please also notice the Additional info.

airfilter/<hostname>/preset/set

By sending the payload 0, 1, 2 or 3 the fan speed will change like setting the knob to these positions. 0 will turn off the fan.

Speed / Percentage

airfilter/<hostname>/speed/state

Returns the current speed (0, 1, 2 or 3). This equals the knob position.

airfilter/<hostname>/speed/set

By sending the payload 0, 1, 2 or 3 the fan speed will change like setting the knob to these positions. 0 will turn off the fan. Analog to /preset/set.

Home Assistant

Automatic via MQTT discovery (default and recommended)

If you have not disabled MQTT discovery in your Home Assistant instance as well as in the Arduino sketch (homeAssistantMqttDiscovery). The Fan will show up automatically as a fan entity.

Manually via config

You can also set up the fan entity manually by adding the following yaml to your Home Assistant configuration.yaml:

fan:
  - platform: mqtt
    name: "<hostname> Airfilter"
    state_topic: "airfilter/<hostname>/state"
    command_topic: "airfilter/<hostname>/set"
    preset_mode_state_topic: "airfilter/<hostname>/preset/state"
    preset_mode_command_topic: "airfilter/<hostname>/preset/set"
    preset_modes:
       -  "1"
       -  "2"
       -  "3"
    payload_on: "on"
    payload_off: "off"
    percentage_state_topic: "airfilter/<hostname>/speed/state"
    percentage_command_topic: "airfilter/<hostname>/speed/set"    
    speed_range_min: 1
    speed_range_max: 3

Questions

Just open an issue :)

Credits

Created and maintained by Lukas Schulte-Tickmann / Schluggi.