If thermal runaway is displayed

If (Thermal Runaway)/Thermal Dip is displayed

During a roast, the Kaffelogic Nano 7 may display the message "Thermal Runaway" and stop the roast. In most cases, this is not a malfunction, but rather the result of the safety device successfully activating when it detects an abnormal condition during the roast.

Main causes of occurrence (important)

This error occurs when the following conditions occur simultaneously during roasting, causing heat to accumulate at the bottom of the roasting chamber.

The three most common causes are:

  • The temperature rate of rise (ROR) became too high suddenly
  • The beans are not circulating properly and are stuck at the bottom (Bean Lock)
  • The air (hot air) flow is weak (low fan airflow)

The most important of these is the ROR (Rate of Rise)

In actual testing and operation, in many cases, "too high ROR" itself is the direct cause of shutdown. If the temperature rises rapidly in a short period of time during roasting, heat concentrates at the bottom of the roasting chamber, and the temperature sensor detects an abnormal rate of rise. This results in a Thermal Runaway/Thermal Dip, which activates a safety shutdown. This is particularly likely to occur when editing a custom profile in Studio, so caution is required.

What to do when an error appears

  1. Press the ▶ (Start/Cooling) button on the main unit
  2. Wait until the cooling cycle is complete

    *Since the roasting process is stopped midway, the beans at this stage will be unevenly roasted and are generally not recommended for drinking.

Points to improve when roasting

Be aware of ROR (rate of rise of temperature)

  • Prevent ROR from rising too much
  • Avoid sudden increases in heater output
  • Check whether the ROR curve is smooth and not sharp.

* In the image below, we refer to the profile where thermal runaway actually occurred.

  • ❌ Example of a profile prone to thermal runaway
  • ✅ Examples of stable profiles

A comparison of the two is provided in the images.

[❌Example of a profile prone to thermal runaway]

Example 1: Sudden increase in ROR

Ideally, the ROR (green line) should decrease gradually as the roast progresses. However, in this profile example, the ROR exceeds 100°C/min about three minutes into the roast. This results in excessive heating, and at 3:30 the safety device trips, stopping the roast and causing a thermal runaway error.

Example 2: ROR rises again

Ideally, the ROR should decrease gradually as the roasting time progresses, but in this profile, the ROR begins to rise again around the 3 minute mark. The actual temperature also rose by approximately 50°C in the 1 minute between 3:00 and 4:00, and at 4:20 it was determined to be thermal runaway, triggering the safety device.

[✅Easy-to-stabilize profile]

Please check the ROR value (green line). After roasting begins, the rate of temperature increase gradually decreases over time. *After about 3:00, it took just under two minutes to raise the roasting temperature by +50°C.

By designing the ROR to gradually decrease in this way, it is possible to prevent thermal runaway from occurring.

Check items if the error occurs repeatedly

Please check the following in order from top to bottom.

① Installation environment of the main unit

  • Is it installed on a hard, level surface?

  • Are the intake and exhaust ports unblocked?

② Cleaning the chaff collector

  • Empty the chaff before each roast

  • Clean the mesh holes in the lid with a brush

If oil or fine particles become clogged, the airflow will decrease more than it appears.

③ Check the firmware

  • Please update to version 7.17.10 or later.
  • *The latest firmware reduces the occurrence rate of this error.

Other improvements

  • Reduce the roast amount (e.g. 120g → 100g / 90g)
  • Increase fan speed
  • Immediately after starting roasting, make sure the beans are properly stirred.

👉 Please be aware that this is particularly likely to occur under the following conditions:

  • Light roast
  • high density beans
  • Large beans (e.g. Kenya AA)

⚠ In rare cases, smoke or burning may occur.

Although it is very rare, beans that accumulate at the bottom may smoke or catch fire.

In that case:

  1. Turn off the power at the wall switch
  2. Cover the top of the chaff collector with a pot lid or similar.
  3. If possible, take the fire outside and let it extinguish naturally.

*If the problem persists, be sure to contact official support.

Possibilities other than Bean Lock

The same error may occur in the following cases:

  • Deterioration or failure of the heater element
  • Temperature rise is weak in empty roasting test
  • An error occurs even under standard conditions (120g, Classic profile)

In this case, part replacement may be necessary.

Please contact support with the following information ready:

  • Roasting log (saved data) Please send us 10 to 20 logs of past roasts by email.
  • Usage Profile
  • Roasted amount (g)
  • Timing of error occurrence