First, you should know that the tempi.fi sensors are pre-calibrated at the factory and for most usages, you do not need to re-calibrate them.
However, if you need accuracy better than 2 degrees or 5% relative humidity, we recommend that you do calibrate your sensors. During the calibration process, you should not need to to make adjustments of more than a few degrees or 5% humidity. If you do, please try to follow the instructions again. If the required adjustment is still large, please contact us at firstname.lastname@example.org, in rare cases, the sensor may be defective.
Option 1: Use a reference sensor for temperature & humidity
The easiest way to calibrate the sensor is to use a reference sensor that has already been calibrated. Choose a location where the temperature and humidity will remain constant for at least an hour. Place both sensors in the same location for about 45 minutes. After 45 minutes, open the tempi.fi app and go to the settings for the sensor you want to calibrate. Adjust the calibration values until the temperature and humidity matches the reference sensor.
Option 2: Use ice water to calibrate the temperature
- Place the sensor in a plastic zip lock bag with NO HOLES. Remove all the air from the bag.
- Fill a large glass half way with ice cubes or ice shavings
- Place the sensor in the glass on top of the ice with the logo facing up. Keep the ends of the bag outside of the glass just in the case the bag doesn’t seal properly. NOTE: The sensor is not waterproof. You are responsible for making sure the sensor stays dry or it will be ruined.
- Fill the rest of the glass with ice then with water so the sensor is submerged in water trapped between ice cubes or ice shavings.
- Place the glass in the refrigerator for approximately 60 minutes
- Check the chart. If the temperature has remained constant (within approximately +/- 0.1°) for about 10 minutes, you are ready for the next step. If not, leave the glass in the refrigerator until it has remained constant for about 10 minutes.
- Go to the app settings for the sensor and adjust the temperature calibration value until it reads 32°F or 0°C
- You are done calibrating the temperature
Option 3: Use the ‘salt method’ to calibrate the relative humidity
- Measure 1/2 cup of table salt and place it into a small coffee mug
- Measure 1/4 cup of water and pour it on top of the salt in the mug
- Stir the solution until all the salt is moist
- Place the cup and the sensor in the bag and seal the bag (don’t put the sensor in the cup, make sure the bag is air tight)
- Place the bag in a dark area where the temperature is relatively constant (+/- 5 degrees) and there is no airflow; e.g. a kitchen or bathroom cabinet
- Wait 24 hours and check the chart. If the humidity has remained constant (+/- 0.5%) for about 10 minutes, you are ready for the next step. If not, check back. This may take several days to stabilize.
- Go to the app settings for the sensor and adjust the humidity calibration value until it reads 75%
- You are done calibrating the humidity
Option 4: Use a hygrometer calibration kit
Use a highly rated hygrometer calibration kit that costs ~$8 on Amazon.
NOTE: After calibrating the sensor, all historic readings will automatically adjust accordingly.