How to Calibrate Wireless Temperature Sensors

The above video explains the recalibrating process in detail. For more detailed instructions, please see below.

From day one, accuracy is essential. So straight out of the box, your ALTA Wireless Standard Temperature Sensors arrive accurate to +/- 1% (1° C or 1.8° F). Adding calibration provides an even greater accuracy of +/- 0.25° C (± 0.45° F).

If you require greater accuracy or believe the reading for a Temperature Sensor is inaccurate, you can calibrate or set default calibration in iMonnit. However, executing a successful calibration includes some critical considerations.

Things to Consider

Timing

Therefore, it's important to leave the sensor probe at a stabilized temperature until the next Heartbeat after the calibration is saved in iMonnit.

The following message and icon (shown below) will appear until the calibration is applied to the sensor: “Fields waiting to be written to the sensor are not available for edit until the transaction is complete.”

Heartbeat

Although it’s possible to calibrate using the default 2-hour Heartbeat, you may consider setting the Heartbeat of both the gateway and the sensor to the most frequent Heartbeat allowed on your network.

This setting may be advisable to accommodate the time difference between entering the calibration value and the sensor accepting the entered calibration. Also, configuring your sensor to a more frequent Heartbeat allows you to identify temperature fluctuations in smaller increments.

We recommend calibrating your sensor in an environment with a stable, uniform temperature. If you see temperature fluctuations, you may not execute a successful calibration.

Stabilization

As a rule, you should always wait long enough for exposed sensor parts to stabilize to the target temperature. Exposing a sensor lead or probe to a specific temperature will take some time before the sensor hardware's temperature reaches the environment's temperature and stabilizes.

Typically, 90 minutes of stable readings will yield the desired result. The most significant factor leading to unsuccessful calibration results is executing the calibration too quickly. The most common factor resulting in an unsuccessful calibration is calibrating without a stable temperature.

Environment

Because the calibration function is linear, we recommend calibrating the sensor in the temperature range it will monitor.

For example, the calibration may be off if you calibrate at room temperature and place the sensor in a refrigerator or freezer.

In addition, elevation and other environmental factors can affect your calibration results.

Condition

The physical condition of your sensor can also influence calibration. Ensure your sensor (especially the probe) is free of dust, oil, paint, and other materials influencing accuracy.

Access the Temperature Sensor’s Calibrate Tab

If your sensor supports calibration, a tab labeled Calibrate will be visible when viewing the sensor through the iMonnit Online Portal. To view the sensor’s calibrate tab:

• Log into your iMonnit.com account.
• Select Sensors in the left main navigation menu.
• Select the sensor you wish to calibrate.
• Select the Calibrate tab.

Set the Calibration to Default

Before calibrating, you may want to reset the calibration to default if the sensor was previously calibrated.

• Select the Sensor you want to calibrate.
• Select the Calibrate tab.
• Click the Default button to set the calibration to default.

• Allow your sensor to check in and accept the default calibration value.

Enter and Save the Calibration Value

• Select the Sensor you want to calibrate.
• Select the Calibrate tab.
• Enter the observed temperature (the temperature you expect the sensor to report) in the “Actual reading is” field; select Fahrenheit or Celsius corresponding to the configured Scale for that sensor.
• Click the Calibrate button.

• Leave the sensor at the stabilized temperature until the calibration is saved to the sensor.
• The calibration will be applied to the sensor’s subsequent Heartbeat.

Calibrate Using the Ice Bath Method (Leaded Temperature Sensors)

• Combine water with a good number of ice cubes in an adequately sized container; allow 15 minutes or so for the water to become a uniform temperature, and stir.
• Insert the lead into the ice bath (preferably a stirred one). The reading should be close to 0° C (32° F), though this can vary depending on altitude (adjust for altitude).
• As permitted, watch for the stabilization of readings for 90 minutes.
• In the “Actual reading is” field, enter the observed reading value to 0° C (32° F) or the freezing water temperature for your altitude as per the steps above.
• Select the Calibrate button.
• Calibration should be accepted on the next Heartbeat.

After Calibration

To confirm success, we recommend leaving your sensor at the stabilized temperature and observing the readings following the calibration.