ESPHome Fan Controller

This repo gives you all the keys to build a quiet thermostat-controlled fan for cooling any enclosure (media console, DIY server cabinet...)

The software is ESPHome and works well with Home Assistant. For hardware, I used an ESP8266 and Artic BioniX F140 140mm fans.

This project is based on ESPHome Fan Controller

What do I need ?

To build my DIY server cabinet thermostat-controlled fans, I used:

• ESP8266 (Any board should be compatible)
• LM2596 Buck Converter - to convert 12v down to 3.3v
• 12v Power Adapter and 12v DC Female Jack
• 12v PWM 4-pin Computer Fan - I picked some BioniX F140 from Arctic but you can use any 12V PWM-controllable fan
• DHT 11 temperature and humidity sensor

I also hired someone to design a custom PCB with 3 fan headers and slots for each component, you can find it in /pcb folder and order it on JLCPCB for example. (Thanks shazmeter for letting me share your work !)

⚠️ This is the V1 version of the PCB, there are some modifications to be made in order to be perfect ! The DC Barrel input does not fit the power supply I had, and the FAN1, FAN2 and FAN3 pins are not thick enough to secure the FANs cables. ⚠️

Wiring Diagram

Some important notes:

• connect the fan PWM pin to a PWM GPIO
• turn the knob on the buck converter with a screwdriver to make it output exactly 3.3v. You'll need a multimeter to measure that output.
• ensure the 12v and 3.3v grounds are connected together.
• the unused pin on the fan is the "Tach" pin. This could tell you the RPM of the fan. We won't use this instead opting to measure the input voltage we're sending to the fan.
• you could easily skip the Buck converter and use two power sources 3.3v and 12v.
• the fritzing diagram shows a 4-pin DHT-11, when in fact I have the simpler 3-pin version as shown in the parts list. The 4-pin version might need a pullup resistor, haven't tried it.

You can find the fritzing project in /fritzing-project folder

Installing the software onto the ESP8266

Get this repo

Clone this github repository. From the command line cd into the directory

Review the YAML and read the ESPHome docs.

Review the YAML file.

Ensure the pins are set correctly for the PWM Fan (D8) and the DHT-11 (D1).

Review the instructions for the ESPHome Climate Thermostat, ESPHome PID Climate Thermostat and the DHT-11 sensor.

Change the device name from console-fan to whatever seems appropriate. You might want to change the yaml filename as well.

Note that the DHT11 sensor is setup to average the last 15 readings. Each reading takes place every 1.5 seconds. Without this filter the PID controller reacts to every minor sensor movement. If you have a faster sensor like the BME260 you might need to tweak this filter.

filters:
  - sliding_window_moving_average:
      window_size: 15
      send_every: 15
      send_first_at: 1

Also note that my fans have a max power of 80% applied to the fans to control the noise. You might want to remove this maximum.

- platform: esp8266_pwm
    id: console_fan_speed
    pin: D8
    frequency: "25000 Hz" 
    min_power: 13%
    max_power: 80%

Setup your wifi details

mv secrets-sample.yaml secrets.yaml

Edit your wifi credentials in secrets.yaml. The .gitignore will prevent you accidentally uploading your wifi credentials to github.

Install ESPHome

Install ESPHome according to the instructions on the ESPHome website.

I prefer command-line on Mac: pip3 install esphome

You could use the ESPHome that runs inside Home Assistant.

Install to ESP8266

Connect your ESP8266 via USB to your computer, then upload the Firmware to the ESP8266.

esphome run console-fan.yaml

At this time if you've set the pins right, the sensor should be spitting out values and the PID can control the fan.

Success!

% esphome logs console-fan.yaml
INFO Reading configuration console-fan.yaml...
INFO Starting log output from console-fan.local using esphome API
INFO Successfully connected to console-fan.local
...
[22:54:09][C][mdns:085]:   Hostname: console-fan
[22:54:09][C][homeassistant.text_sensor:023]: Homeassistant Text Sensor 'ha_kp'
[22:54:09][C][homeassistant.text_sensor:024]:   Entity ID: 'input_text.kp'
[22:54:10][C][homeassistant.text_sensor:023]: Homeassistant Text Sensor 'ha_ki'
[22:54:10][C][homeassistant.text_sensor:024]:   Entity ID: 'input_text.ki'
[22:54:10][C][homeassistant.text_sensor:023]: Homeassistant Text Sensor 'ha_kd'
[22:54:10][C][homeassistant.text_sensor:024]:   Entity ID: 'input_text.kd'
[22:54:10][D][dht:048]: Got Temperature=30.0°C Humidity=38.0%
[22:54:10][D][sensor:113]: 'Humidity': Sending state 38.00000 % with 0 decimals of accuracy
[22:54:11][D][dht:048]: Got Temperature=30.0°C Humidity=38.0%
[22:54:11][D][sensor:113]: 'Humidity': Sending state 38.00000 % with 0 decimals of accuracy
[22:54:12][D][dht:048]: Got Temperature=30.0°C Humidity=38.0%
[22:54:12][D][sensor:113]: 'Humidity': Sending state 38.00000 % with 0 decimals of accuracy

Setup Home Assistant

If the above steps worked correctly, the device will be auto-discovered by Home Assistant. You will need to add the device.

Multiple sensors and switches are exposed by the ESPHome software.

You also need to setup the dashboard. I'll explain those two steps below.

Setting up the Home Assistant Dashboard

Here is my full dashboard in Home Assistant.

Let's go through them section by section.

The Primary Controls

By clicking the thermostat you can turn on/off the thermostat and fan and adjust the target temperature which will be persisted to flash on the ESP8266.

type: entities
title: Console Fan
entities:
  - entity: sensor.fan_speed_pwm_voltage
  - entity: climate.console_fan_thermostat
  - entity: sensor.contact_sensor_1_temperature
    name: Room Temperature
  - entity: sensor.openweathermap_temperature
    name: Outside temperature
  - entity: number.console_fan_kp
  - entity: number.console_fan_ki
  - entity: number.console_fan_kd

• The Fan Speed (PWM Voltage) is the % of voltage being sent out via PWM to the fan controller. At 100% it will be sending 12v, at 50% it will be sending 6v.

• The Console Fan Thermostat is a controllable thermostat, by clicking it you can alter the target temperature and turn the fan on/off.

• The Room and Outside temperatures are from other sensors in my house for reference.

• The kp, ki and kd inputs are exposed from the device. Your ESP8266 will be automatically receiving changes to these values to control the behavior of the PID controller. While you could tune these from the config.yaml it requires a compile, upload and reboot cycle each time. This is inconvenient and best to tweak in real-time. We want to expose these 3 parameters to a Home Assistant dashboard.

The Graphs

Add the fan speed and the thermostat to two separate graphs. I've also added my room temperature from a separate device for comparison.

type: vertical-stack
title: 3 hr
cards:
  - type: history-graph
    entities:
      - entity: sensor.fan_speed_pwm_voltage
    hours_to_show: 3
    refresh_interval: 0
  - type: history-graph
    entities:
      - entity: climate.console_fan_thermostat
        name: ' '
      - entity: sensor.contact_sensor_1_temperature
        name: room
    hours_to_show: 3
    refresh_interval: 0

Helpful Details - More Sensors and Switches

This Lovelace YAML exposes various sensors and switches from the ESP8266.

type: entities
entities:
  - entity: sensor.console_fan_ip_address
  - entity: sensor.console_fan_wifi_strength
  - entity: sensor.console_fan_uptime
  - entity: sensor.humidity
    name: console fan humidity
  - entity: switch.console_fan_autotune
  - entity: switch.console_fan_ESP8266_restart

• console_fan_autotune is a switch which starts the PID tuning process. I ended up abandoning this approach and manually tuning the PID.

• console_fan_ESP8266_restart restarts the ESP8266 remotely.

Configuring the PID Parameters

The thermostat is controlled using a standard Process Control system called a PID.

In our system the goal of the PID control is to set the fan voltage (speed) to bring the temperature measured by the sensor to a target temperature (30degC).

Search the internet and you'll find many resources for setting up a PID Controller. There are a lot of resources for fast response systems like cruise control systems but not many for dealing with slow response cooling systems like this one.

The ESPHome PID Climate system that we're using here has some resources to explain how to tune the parameters. However, its autotune system didn't spit out useful results for me and I will explain how to manually get the right parameters. Your system will be different to mine and so your parameters will need to be slightly different. For instance, your cabinet will be a different size, I have two fans, you may only have one, etc.

There are only two parameters you will need to adjust: the kp and ki parameters. The kd parameter is not useful for us.

In my system the goal of tuning was to minimise aggressive changes to the fan (my wife complained she could hear the fan turning on and off). I don't mind the system drifting up to 2degC away from the target temporarily while it slowly reacts. A 7% drift (2degC/30degC) on some control systems could blow up a Nuclear plant or cause a Cruise Control system to crash into another car. But in our system a 7% short temperature drift is a fine tradeoff for quiet fans.

Setting the kp (gain) parameter - how aggressively to cool?

KP is the main Gain. How aggressively will the fan respond to a small change in temperarature? Do you want the fan to go to 100% power in response to a 0.1degC change in temperature? In general my goal was to have the fan at 50% in response to a 1degC change in temperature, thus could normally stave off any further temperature rises, but if it the temperature did keep rising the fan will then climb to 100% power.

Using lower gain (0.1) (my preferred setting):

• takes longer to cool down
• is more likely to under react to fast temperature changes.
• 2deg sharp spikes can occur before the system reacts
• It can takes up to 10 minutes to fully close a 0.5degC gap.
• but, it is much less likely to oscillate around the target temperature and cause the fan to turn on and off constantly.

Using higher gain (1.0):

• responds quickly to changes in temperature
• but, is more likely to oscillate and make the fan swing from 0% to 100% and back again as it tries to control the temperature. This means you can hear the fan trying to adjust.

Setting the ki parameter - how long to adjust an offset?

ki: 0.0009

The ki parameter adjusts for temperature offset. Try setting ki to 0. Set your system initially with kp=0.1, ki=0 and kd=0. You'll find that the system operates with a constant delta/offset to the target temperature. The ki parameter adjusts for this.

1/ki is the seconds it should attempt to correct an offset. So 0.03 will adjust in 30seconds. 0.0009 will close a small temperature delta in 20 minutes. See a good description here https://blog.opticontrols.com/archives/344

Higher numbers like 0.03 will respond much quicker, but it also will cause a lot of noise and oscillation in the fan speed.

Setting the kd parameter - predicting a change

The kd (D in PID) is meant to pre-react and backoff early. Small parameters can help overshoot but does create some fan noise and oscillation. The interwebs says that most (70%) of process controllers don't use the D and just a PI controller.

Tell me

I'm keen to hear what PID parameters works for your fan.