FridgeCure

What it does

The practical chamber concept is inspired by Growtutorials' DIY fridge curing guide. That video is a useful reference for chamber layout, fan placement, and water management.

Works locally

The FridgeCure controller operates the fridge and heater over its own private Wi-Fi network, even when the home router or internet is unavailable.

Adapts to the chamber

FridgeCure learns how the fridge and heater affect the chamber, then adjusts when they switch to keep conditions steadier and protect the equipment.

Includes a dashboard

Use the browser dashboard to check current conditions, review recent activity, change settings, and spot sensor or connection problems.

Open the interactive FridgeCure demo to explore the dashboard and settings without a device.

Disclaimer

This is an experimental DIY controller, not a certified appliance safety system. You are responsible for electrical safety, food safety, process suitability, and supervision of your equipment.

Limitations

Because FridgeCure controls humidity by cycling a refrigerator compressor, the required compressor cooldown limits how tightly it can hold the target, allowing humidity to drift while the compressor waits to restart. Commercial curing chambers may provide steadier control through purpose-built systems, including thermoelectric (Peltier) cooling that does not require the same cooldown period. Airflow can also be less even in a converted fridge than in a commercial chamber, although better fan placement and circulation design may improve it.

Safety first

This project combines mains electricity, moisture, refrigeration, and heat. Test the system while you are present before leaving it unattended.

Keep smart plugs, power strips, and mains-voltage adapters outside the fridge.
Never put a mains power strip inside the chamber.
Check the current and wattage rating of every plug and device.
Leave ventilation space around the fridge and keep water away from electronics.

What you need

FridgeCure control parts

These parts replace the off-the-shelf temperature and humidity controllers used in the video. You’ll still need the fridge, heat mat, fan, and the other chamber hardware listed below.

Parts and approximate cost

Part	Quantity	Approximate price
Small fridge	1	20–100 EUR
ESP32 microcontroller (see supported models below)	1	5–15 EUR
SHT41 or SHT31 sensor	1	8–20 EUR
Tasmota smart plug	2	15–25 EUR each
Seedling heat mat	1	20–50 EUR
PC fan	1	5–15 EUR

Pre-flashed plugs are available from suppliers such as Athom's Tasmota range.

Connect the sensor

Disconnect power from the control board before wiring the sensor. Connect VCC to 3V3, GND to GND, SDA to the board's SDA pin, and SCL to its SCL pin. The table shows the default pins for each model. You can use other pins and change the SDA and SCL pin assignments later in Settings.

Board profile	SDA	SCL
ESP32 Dev Module	GPIO 21	GPIO 22
M5Stack ATOM Lite (Grove connector)	GPIO 26	GPIO 32
Seeed Studio XIAO ESP32C6	GPIO 22	GPIO 23

Hang the sensor in free air near the middle of the chamber. Keep it away from the cold wall, heat mat, direct fan outlet, and condensation.

Seeed Studio XIAO ESP32C6 wired to an SHT41 sensor, viewed from above — Example XIAO ESP32C6 and SHT41 wiring.

Underside of a Seeed Studio XIAO ESP32C6 showing the sensor wires soldered to its pins — Example XIAO ESP32C6 and SHT41 wiring.

ESP32 Dev Module connected to an SHT41 sensor cable with female jumper connectors — Example ESP32 Dev Module and SHT41 wiring using jumper connectors.

No installer app required

Install FridgeCure from your browser

FridgeCure is installed directly onto a supported control board. Use a desktop version of Chrome or Microsoft Edge and a USB data cable. Safari and Firefox do not support the type of USB connection this installer needs. Before connecting, the installer guides you through choosing a device name, private Wi-Fi password, optional home Wi-Fi credentials, and sensor type.

Loading the FridgeCure installer…

Before connecting

Connect the control board directly to the computer with a known-good USB data cable.
Select the exact model printed on the board or its packaging. Similar-looking models can require different installation files.
Choose Connect and install and review the initial settings in the setup window.
Select the USB connection for the control board and keep the cable connected until installation and setup both complete.

The installer uses the device name to create separate private Wi-Fi, local hostname, Home Assistant display name, and MQTT topic settings. Those settings remain independent after installation. Use Erase everything before installing only for recovery or a deliberate factory reset.

First start

After installation, FridgeCure restarts with a private Wi-Fi network named after the chosen device, together with the selected password and sensor type.

Power the FridgeCure control board after installation.
Connect a phone or computer to the private Wi-Fi network using the name and password selected during installation. The prefilled values are FridgeCure and fridgecure.
Open http://192.168.4.1.
If you kept the prefilled private Wi-Fi name and password, change them before normal use.

FridgeCure dashboard showing readings, adaptive control ranges, status buttons, and duty history

Connect to home Wi-Fi

Skip these steps if you supplied home Wi-Fi credentials during browser installation.

Open the Wi-Fi settings from the dashboard.
Enter the home network name and password.
Select Connect and wait for the connected status.

You can then use the displayed device IP. If the network supports mDNS, use the local address shown by the installer. For example, a device named Curing Fridge 1 uses http://curing-fridge-1.local.

Configure the Tasmota plugs

Use one plug for the fridge and one for the heat mat. Both plugs should join the private Wi-Fi network named after your FridgeCure device so control continues without the home network.

Note the private Wi-Fi network name and password selected during installation. If you kept the prefilled values, change them first.
For each Tasmota plug, join its temporary setup Wi-Fi and open http://192.168.4.1.
Configure the plug to use the selected private Wi-Fi network name and password.
In FridgeCure, assign the fridge plug under Dehumidifier and the heat-mat plug under Heater.
Use each panel's Toggle button while present to verify the correct physical device switches.

FridgeCure private Wi-Fi settings — Use a unique Wi-Fi name and password.

FridgeCure dehumidifier plug settings — Assign the plug that powers the fridge.

FridgeCure heater plug settings — Assign the plug that powers the heat mat.

Choose cautious starting settings

Good targets depend on the material, chamber, and ambient conditions. As an initial supervised test, 58% RH and 20 °C are reasonable example values—not universal curing advice.

The targets are averages rather than fixed switch points. FridgeCure learns a control band around each target and adjusts it after valid operating cycles. Watch the first cycles and confirm that the fridge reduces humidity, the heater raises temperature, the fan stabilizes readings, and the compressor does not short-cycle.

Optional Home Assistant connection

FridgeCure works without Home Assistant. MQTT discovery can add readings, targets, device activity, and sensor health to an existing Home Assistant installation.

Configure an MQTT broker and the MQTT integration in Home Assistant.
Open Home Assistant in FridgeCure.
Enter the broker address, port, username, and password.
Keep the discovery prefix as homeassistant unless the broker uses another prefix.

FridgeCure Home Assistant and MQTT settings

FridgeCure device controls and sensor readings in Home Assistant

See the Home Assistant MQTT documentation for broker and discovery setup.

Temperature and humidity analysis

The data was recorded from a FridgeCure device in Home Assistant over five hours.

Humidity

59.93%time-weighted mean

Variance: 2.14 pp²
Standard deviation: 1.46 pp
Range: 56.25–62.58%
Middle 90% (P5–P95): 57.83–62.15%

Temperature

18.09 °Ctime-weighted mean

Variance: 0.20 °C²
Standard deviation: 0.45 °C
Range: 17.28–19.01 °C
Middle 90% (P5–P95): 17.38–18.87 °C

pp means percentage points; pp² is the corresponding variance unit.

The stepped lines show recorded sensor states, the dashed lines show the time-weighted means, and the shaded bands show the middle 90% of readings (P5–P95).