Temperature sensors (cold chain)

Monitor the temperature of your cold rooms, fridges and freezers from the app. The sensor sends its readings on its own to our MQTT server (Mosquitto) and EzGYM emails you if it goes out of range, when it recovers and if the sensor stops sending (for example, a power cut at night). It is free, up to 30 sensors per account.

Which sensors work

WiFi sensors that let you choose the MQTT server:

  • Shelly H&T, Plus H&T or Plus 1 with the Add-on and a DS18B20 probe.
  • ESP32 or ESP8266 with ESPHome, with DS18B20, DHT22, SHT31 or BME280 probes.
  • Devices running Tasmota (Sonoff, NodeMCU).

{warning} Stock Tuya and Sonoff devices send their data to the manufacturer's cloud and cannot be redirected: flash them with Tasmota or ESPHome.

1. Add the sensor

  1. In the app, go to Menu → Sensors and tap Add sensor.
  2. Enter a name (for example "Freezer room"), choose temperature or humidity and the allowed minimum and maximum (for example -25 and -18 °C).
  3. Alert after: the minutes in a row out of range before alerting, so you don't get an alert every time the door opens. Default: 15.
  4. Save. The app shows the server, port, username, password and topic.

{primary} The password is shown only once. If you lose it, tap New password on the sensor page.

2. Set up the sensor

  • Shelly: in the Shelly app or web UI, Settings → MQTT → Enable. Enter server:port as Server, the app's Username and Password, and the topic the app gave you as MQTT prefix. Save and reboot.
  • ESPHome: the app gives you the mqtt: block ready to paste into the device YAML.
  • Tasmota: the app gives you a line to paste into the console.

Within a few minutes the sensor shows its current temperature.

3. See readings and get alerts

  • Sensors shows each sensor with its current value: green if in range, red if out of range and alerted, yellow if out of range or without data.
  • The sensor page has the chart from 6 hours to 30 days, with the allowed range band, and the settings.
  • Alerts are emailed to people who can see the sensors: when it goes out of range, when it recovers and when it stops sending for longer than the minutes you choose (60 by default).

Readings are kept for 90 days (average, minimum and maximum of each minute).

{info} This is a monitoring tool. Records required by health authorities depend on each location.