⚙️ How the SHT31 sensor works
The SHT31 sensor is a precision electronic device that continuously measures relative humidity (RH%) inside the incubator. Its function is to detect the percentage of water vapor present in the air through a capacitive humidity-sensing element, transmit the data to the control unit in real time via an I2C digital protocol, ensuring accuracy of ±2%, and allow the system to activate or deactivate the humidifier while maintaining optimal target values. The sensor is protected by a case that shields it from direct condensation but allows the gas exchange necessary for measurement.
📋 Exploded view reference: This component corresponds to number 14 in the exploded view diagrams of FIEM incubators. Useful for identification during maintenance.
With prolonged use (thousands of hours in a humid environment), the sensing element can become contaminated with mineral deposits from water, lose calibration due to aging of the electronic components, or be permanently damaged by direct condensation or extreme humidity changes. When the sensor fails, the control unit continues to function but receives completely incorrect data, making it impossible to maintain the correct humidity.
🔍 When to replace this part
This component should be replaced if you notice one or more of these symptoms:
- ✓ Locked reading: display always shows 0%, 99% or a fixed value that never changes
- ✓ Clearly incorrect values: sensor indicates 30% when water is overflowing, or 80% when the tank is dry
- ✓ Unstable readings: values that jump continuously (40%-60%-35%-70% in a few seconds)
- ✓ Slow or no response: You add water but the sensor takes hours to detect the change
- ✓ Sensor error: ECU shows "ERR" or "SENS" on the display
- ✓ Disastrous hatching: chicks dehydrated (humidity too low) or drowned in the shell (humidity too high)
⚠️ What are you risking?
If you continue to use a faulty sensor, you're incubating completely in the dark about the real parameters: chicks dying of dehydration in the final days because the actual humidity is 35% but the sensor indicates 55%, embryos drowning in the shell because the humidity has skyrocketed to 85% but the sensor is stuck at 60%, hatching rates plummeting from 80-85% to 30-40% without any clear reason, and a huge waste of fertile eggs and time. The sensor costs €42.50, but a lost brood is easily worth €200-300 in eggs, time, and electricity.
✅ Compatibility verified
This sensor is compatible with all FIEM incubators equipped with ML or LCD digital control units. Check your control unit for the humidity sensor connector.
⚠️ Important note: NOT compatible with older analog control units or mechanical thermostats. The sensor requires an I2C digital connector, which is only available on ML and LCD control units. If in doubt, please send us photos of your control unit on WhatsApp before ordering.
🔧 Assembly in 4 simple steps
Estimated time: 10-15 minutes | Tools needed: Small Phillips screwdriver
- Disconnect power and access the control unit
Wait 5 minutes for the capacitors to discharge. Open the control panel by removing the retaining screws. Locate the old SHT31 sensor: it is connected to the control unit with a thin 4-wire cable and is usually located on the top of the incubator near the humidity tray. - Remove the old sensor
Gently disconnect the sensor connector from the control unit (some have a small clip that you need to press). Unscrew the screws holding the sensor case to the frame. Remove the entire old sensor. Note the exact position so you can reinstall the identical new one. - Install the new SHT31 sensor
Place the new sensor in the same position as the old one, - Initial testing and calibration
Close the control panel. Reconnect the power and turn on the incubator. Verify that the display shows the humidity reading immediately (it may take 1-2 minutes to stabilize). The initial reading should be consistent with the ambient humidity (typically 40-60%). If available in the menu, perform an automatic calibration following the instructions in the manual. Leave the incubator on for 2-3 hours, checking that the readings are stable and responsive to changes (add/remove water and verify that the sensor detects the change).
🛡️ How to make it last longer
With minimal maintenance you can significantly extend the life of the SHT31 sensor:
- ✓ Every 3 months: check the case for dust or white deposits (limescale); clean gently with very low pressure compressed air
- ✓ Every 6 months: Compare sensor readings to a reference hygrometer to verify accuracy is still within ±3-4%. To calibrate, see Wet Bulb Hygrometer or Hair Hygrometer.
- ✓ During use: use distilled or demineralized water to reduce limescale deposits.
- ✓ ⚠️ DO NOT: never touch the white sensitive element with your fingers (skin oils will contaminate it), do not clean with water or liquid detergents, do not expose to direct condensation or splashes
📌 Signs of wear: If you notice that the readings are becoming progressively less accurate (error >5%), or that the sensor is taking longer and longer to respond to changes, it means that the element is aging and it is a good idea to plan for preventative replacement.
🔗 Spare parts frequently purchased together
🔗 Temperature probe (LCD T. PROBE)
If you replace the humidity sensor, also evaluate the condition of the temperature probe. Often, the two sensors age together, and replacing both ensures optimal accuracy across all parameters.
Price: see product sheet
🔗 Replacement control unit (if the problem persists)
If the problems persist after replacing the sensor, the ECU itself may be faulty. Contact us for a complete diagnosis.
Price: see product sheet
📞 Warranty and assistance
✅ 2-year FIEM warranty
Covers manufacturing defects and malfunctions not caused by misuse. If problems arise within 24 months of purchase, the part will be repaired or replaced free of charge.
🔄 Returns within 14 days
If for any reason you change your mind (returns cost money, so make an informed purchase), you can return the product intact and in its original packaging within 14 days of purchase.
📞 Technical assistance included
Free technical support for the life of the product via WhatsApp, email, or phone. Having questions about assembly or calibration? I'll guide you step-by-step, even via video calls if necessary.
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