Introduction: Build a Zwift Smart Fan Out a Cheap Fan

I built a smart fan for Zwift, from a cheap fan and connected it to the Zwift game. The fan speed adapts based on the power, speed, or heart rate from the Zwift game data or from the bike sensors. 


As a triathlete, at some point, I had to start indoor training to train on some specifics aspect of my physical condition. If you're reading this you may already know that indoor training is strongly synonymous with Zwift training, so I started training with this app, and it didn't take me long before realizing that cooling is central to indoor training. I google "Zwift Fans" and after seeing a few price tags I closed my browser and decided to find another and cheaper solution. The idea of spending 200€+ on a fan was a no-go, and making my own solution instead sounded more appealing to me. So here we are, and even though other great articles are already out there I decided to share the implementation of my DIY Smart Zwift fan with you, and I hope you'll find it useful to make your own as-is or to adapt it to your needs.

Supplies

Before we dive into the tutorial, here are the elements I used for this project along with their prices.

  • Fan with a mechanical switch: 30€
  • Relay board: around 3€
  • ESP8266: 3€ I choose the WeMos D1 Mini but any ESP will do the job
  • Ant+ receiver: 10€ (Optional)

Total: 46€

Step 1: Migrating the Mechanical Switch to an Electronic Commanded Switch

The idea is fairly simple, we have to replace the mechanical switch to control the fan with the ESP. To mimic the push on the buttons we'll be using a 3-channel 5V relay.

Unplug your fan and dismount the switch. You should have something similar to what I have in the following photo. Take a series of photos and even a video of all the connections and cable color before cutting anything.

In my case, the brow cable comes from the wall plug, and then 3 cables (blue, white, red) head to the fan motor. So my common cable is the brown one.

Connect the ESP to the relays and take note of the pin you selected, you'll have to configure it in the next step.

Ok, you can now cut the wire of your mechanical switch, and connect the common cable (brown in my case) to the COM port of 3 relays. Connect the 3 other cables (blue, white, red) to the Normally Open port of each relay, and respect the same order as in your mechanical switch. It will be easier to match the relay and the fan speed. Leave the ground cable untouched.

Step 2: Install and Configure Tasmota to the ESP

Install Tasmota on your ESP, this is step is pretty straightforward, and a ton of tutorials are available out there if you don't know how to proceed. There is a Web install that is super easy to use.

Once Tasmota is installed, find the IP address of your ESP. You'll be presented with the dashboard, head to the Configuration panel, and select Module type Generic (18). Configure 3 relays on 3 different GPIO ports. Match the GPIO to the connections you used earlier. Use the relay_i options and assign a different value from 1 to 3 on the aside dropdown.

Save the configuration and let the ESP reboot

On the main page now you should have 3 Toggle buttons that appeared, each button controls one relay.

Step 3: The Software

The Zwift API is not public anymore, making it difficult to retrieve data in real-time to control the fan. So there are 2 options, using a second Ant+ Stick to retrieve the data from the sensors directly, or using a third-party app.

Ok, let me show you how to set up the third-party app. Login to your Zwift account on the website and head to Account > Connections and scroll down to the end. You should see Consent to sharing your real-time Zwift activities and profile with Zwift GPS and Gold Rush.

  • Click on Opt-in. The page should reload and the icon is now colored.

Lastly, get the code and run the program. You'll find the sources on my GitHub repo at https://github.com/florianpasteur/zwift-smart-fan-controller

Create a JSON configuration file like so:

{
  "fanIP": "192.168.1.127",
  "dataProvider": "zwift",
  "observedData": "power",
  "antConfig": {
    "wheelCircumference": 2.120
  },
  "zwiftConfig": {
    "zwiftID": 1231421,
    "pullingInterval": 2500
  },
  "thresholds": {
    "power": {
      "level1": 0,
      "level2": 10,
      "level3": 20
    },
    "speed": {
      "level1": 0,
      "level2": 20,
      "level3": 30
    },
    "hr": {
      "level1": 70,
      "level2": 120,
      "level3": 150
    }
  }
}

Replace the

  • fanIP by the IP or hostname of the ESP
  • dataProvider leave zwift value. (Use ant value if you want to use the second ant+ stick)
  • observedData choose from power, speed, hr depending on your preference and adjust the corresponding thresholds
  • zwiftID: Your Zwift ID
  • pollingInterval Adjust the polling interval (in ms). Keep a high value to not experience too frequent speed changes.

To run the program use the command

> zwift-smart-fan-controller  --config your-config.json

Step 4: Finish

Put everything back in the case and screw it back to the fan and that's it. You're ready to ride!