Smart freezer monitoring: TEMP-1 with Home Assistant

Estimated reading time: 7 minutes

If the freezer breaks down unnoticed, food worth several hundred euros can be lost. Smart temperature monitoring is therefore a real game changer - and this is where the Apollo Temp 1 sensor into play. In combination with Home Assistant turns your freezer into a networked safety system that alerts you immediately in the event of a problem.

In this article, I will show you step by step how to set up the Apollo Temp 1 sensor, integrate it into Home Assistant and use it reliably for alerts and automation.

Funnily enough, I have to say that I bought the wrong sensor myself. The ESP32 board is correct, but there is the food sensor and the temperature sensor and I bought the food sensor instead of the temperature sensor. The latter should be more accurate for the purpose of the refrigerator or freezer. You can buy the sensor directly from Apollo Automation. But be smarter than me and use an EU retailer to save yourself high customs and shipping fees. All specifications for the Apollo TEMP-1 temperature sensor you can read on the link.

For detailed instructions and explanations of all configuration options, I recommend watching the YouTube video linked below. This video goes into detail about each individual setting, providing you with comprehensive instructions on how to set everything up correctly. Any code from the video can be found in this article, so you can use it directly without having to type it out.

Why the Apollo Temp 1 is ideal for the freezer

The sensor is optimized for smart home use and offers the following advantages:

• connects via 2.4 GHz WLAN
• is automatically generated by ESPHome recognized
• continuously transmits temperature values
• Ideal for freezers and refrigerators
• Energy-saving and very reliable
• Modern, compact and can be used without additional hardware

This makes it significantly more stable and reliable than many Bluetooth variants

Requirements

You will need the following for the setup:

• Apollo Temp 1 sensor
• Home Assistant with activated ESPHome integration
• Smartphone for the initial WLAN setup
• Access to your home's 2.4 GHz WLAN

Setup step by step

1. connect to the hotspot of the sensor

After switching on, the Apollo Temp 1 starts in the Access point mode.
You will find a WLAN with the name on your smartphone:

Apollo TEMP1 Hotspot

Connect to it. The configuration portal will then open automatically (if not, open the browser and 192.168.4.1 enter).

There you enter:

• yours 2.4 GHz WLAN
• the password

The sensor now connects to your network and restarts.

2. the device appears automatically in ESPHome

As soon as the sensor is in the WLAN, Home Assistant recognizes it via the ESPHome integration.

You will then see the hint:

"New ESPHome device found: Apollo Temp 1"

Here you click on Install.

The firmware is installed automatically (OTA).
After completion, the device appears completely in ESPHome.

3. add to Home Assistant

Once the firmware has been successfully installed, the sensor appears in the area:

Settings → Devices & services → ESPHome

There you can simply click on Add click.

Home Assistant automatically creates the following sensors:

• Temperature
• Status
• WLAN signal
• Battery voltage / supply

This completes the technical setup.

Important setting: Set sample type to "Food"

You will find the option in the device settings:

Select sample

To obtain measured values in the freezer, you must set the sensor to :

Food

set. But that depends on which sensor you have. In my case, it is also the food sensor in the video, even if I use it for a different purpose.

This ensures that the measurement logic and calibration is optimized for food and frozen food tracking.

Set up three important temperature helpers

You need three Statistics helpereach of which is the Median (or average) of a certain period of time:

1. 30-minute average / median
2. 24-hour average / median
3. 7-day average / median

How to create the helpers

1. Settings → Devices & services → Helpers
2. Add helper
3. Type: Statistics
4. Source: sensor.apollo_temp1_temperature
5. Select period
6. Aggregation method: Median or Mean value (Mean)

Designations such as:

• sensor.freezer_temperature_30_min
• sensor.freezer_temperature_24_hours
• sensor.freezer_temperature_7_days

are assigned automatically or you can define them yourself.

Example: Setting up temperature warnings in Home Assistant

You should create an automation so that you are informed immediately in an emergency.

Example:

• Trigger:
  Temperature of the Apollo Temp 1 rises above -15 °C
• Condition:
  Temperature remains longer than 3-5 minutes above (prevents false door-opening alarms)
• Action:
  Mobile notification such as:
  "⚠️ Freezer is getting too warm! Please check."

Of course, you can also configure alarm sounds, light signals or push messages to multiple devices.

Automation 1: Door open? (30-minute trend)

This automated system reliably detects whether the door is open.
The average of the last 30 minutes only increases significantly if there really is a problem.

Functional principle

• Short-term door openings cause no alarm.
• A real rise in temperature over several minutes triggers the warning.
• Ideal for households with children or frequent access.

Automation (example)

alias: Freezer door open?
triggers:
  - entity_id: sensor.freezer_temperature_30_min
    above: -7
    trigger: numeric_state
conditions: []
actions:
  - data:
      title: Freezer warning
      message: >
        The 30-minute average is set to {{
        states('sensor.freezer_temperature_30_min') }} °C.
        The door may be open.
    action: notify.smartphones

Explanation

• Trigger: Average over -7 °C → unusually warm
• Action: Instant push message
• Benefit: Detection within a few minutes, but without false alarms

Automation 2: Freezer defrosting (24h / 7d trend)

This automation analyzes two important trend lines:

• 24-hour median
• 7-day median

When both If the engine speed exceeds critical values, there could be an insidious defect - such as loss of coolant or weak compression.

Automation (example)

alias: Freezer defrosting (24h / 7d trend)
description: ""
triggers:
  - value_template: |
      {{ states('sensor.freezer_temperature_24_hour') > -10 or
         states('sensor.freezer_temperature_7_days') > -12 }}
    trigger: template
actions:
  - data:
      title: "Freezer: defrost warning"
      message: >
        24h average: {{ states('sensor.freezer_temperature_24_h')
        }} °C 7d average: {{
        states('sensor.freezer_temperature_7_days') }} °C The
        freezer seems to be defrosting!
    action: notify.smartphones

Explanation

• 24h > -10 °C → clear daily trend
• 7 days > -12 °C → Long-term trend also rising
• Warning: The device loses power → Intervene at an early stage!

This method is much more reliable than a pure temperature limit.

Other useful automations

• Battery/voltage warningbefore the power supply weakens
• WLAN signal weak → Display message
• Create long-term statistics via history/graphs
• Temperature logging for weeks and months

This means you always have control over your freezer.

Advantages of the WLAN version compared to Bluetooth

• Significantly greater range
• No proxy devices required
• More stable connections
• Top integration thanks to ESPHome
• OTA updates directly in Home Assistant

WLAN has a clear advantage, especially in kitchens or basements.

YouTube video implementation

Conclusion

The Apollo Temp 1 sensor offers a Solid, stable and really smart solutionto monitor a freezer. Thanks to Wi-Fi connectivity, ESPHome integration and Home Assistant automations, you get a reliable early warning system that informs you in good time and prevents food loss.

Useful links

Apollo Temp 1 manufacturer page
https://apolloautomation.com/products/temp-1

ESPHome - Documentation
https://esphome.io/

Statistics helper - Home Assistant
https://www.home-assistant.io/integrations/statistics/

Automations - Home Assistant
https://www.home-assistant.io/docs/automation/

ESPHome integration - Home Assistant
https://www.home-assistant.io/integrations/esphome/

Forum: Home Assistant Community
https://community.home-assistant.io/

Interested, but lack time or knowledge?

No problem. Contact me and we will discuss your requirements. No matter if business or private.