Why Does My Temperature Data Logger Show Different Readings Malaysia?

 

You place two temperature meters side by side.

 

One shows:

 

25.2°C

 

The other shows:

 

26.0°C

 

Does this mean one of them is faulty?

 

Not necessarily.

 

Differences between temperature and humidity instruments can occur because of accuracy specifications, sensor position, response time, airflow, direct heat exposure, stabilisation time and calibration condition.

 

This is particularly important when comparing a Benetech GM1365 Temperature & Humidity Data Logger with another thermo-hygrometer or environmental monitoring instrument.

 

Before deciding that your logger is inaccurate, investigate the measurement conditions first.

 

1. Every Instrument Has an Accuracy Specification

 

A digital instrument showing decimal places does not mean every displayed digit represents absolute accuracy.

 

For example:

 

Display Resolution ≠ Measurement Accuracy

 

An instrument may display:

 

25.3°C

 

but its specified accuracy must still be considered.

 

When comparing two instruments, check the manufacturer's accuracy specifications for both.

 

Two correctly operating instruments can show slightly different values and still remain within their respective specifications.

 

2. Resolution and Accuracy Are Different

 

This is one of the most misunderstood concepts in measurement.

 

Resolution

 

The smallest change shown by the display.

 

Accuracy

 

How closely the measurement is expected to represent the actual value under specified conditions.

 

A meter displaying more decimal places is not automatically more accurate.

 

Therefore, don't choose a data logger simply because:

 

“This one shows more digits.”

 

Look at the actual measurement specification.

 

3. Sensor Position Can Change the Reading

 

Even a small difference in position can matter.

 

Imagine:

 

Logger A → On a table

 

Logger B → Near an air-conditioning outlet

 

The readings may differ because they are not measuring exactly the same environment.

 

Other problematic locations include:

 

Near windows

 

Near external walls

 

Direct sunlight

 

Near machinery

 

Near doors

 

Beside heaters

 

Near ventilation outlets

 

Close to cold surfaces

 

Before comparing two instruments, place them as close together as practical under stable conditions.

 

4. Give the Instruments Time to Stabilise

 

Suppose you move a logger from:

 

Air-Conditioned Office

 

to

 

Warm Warehouse

 

The sensor will not necessarily display the final environmental condition instantly.

 

Allow sufficient time for the instrument to stabilise.

 

Comparing readings immediately after moving instruments between environments can produce misleading conclusions.

 

5. Different Sensors Have Different Response Times

 

Two instruments exposed to the same environmental change may respond at different speeds.

 

For example, when moving from a cool room into a warmer area:

 

Meter A → Responds quickly

 

Meter B → Responds more gradually

 

During the transition, their readings may differ.

 

After sufficient stabilisation, the difference may become much smaller.

 

This is why comparison should be performed under stable conditions.

 

6. Airflow Can Affect Measurement

 

Air-conditioning and ventilation can create local differences.

 

A sensor directly exposed to moving air may respond differently from one located behind an object or in a less ventilated position.

 

This is particularly important when investigating:

 

HVAC systems

 

Clean rooms

 

Laboratories

 

Warehouses

 

Equipment rooms

 

The measurement location should represent the environment you actually want to monitor.

 

7. Direct Sunlight Can Cause Problems

 

If a logger is exposed directly to sunlight, the instrument housing itself may absorb heat.

 

The resulting reading may not represent general ambient air temperature.

 

This is particularly important in:

 

Agriculture

 

Greenhouses

 

Warehouses near windows

 

Outdoor-adjacent areas

 

If the objective is to measure ambient air conditions, sensor placement should minimise inappropriate direct radiant heat exposure.

 

8. Don't Hold the Sensor While Comparing

 

Your body generates heat.

 

Holding a small temperature or humidity instrument can influence the local conditions around the sensor.

 

For better comparison:

 

Place Instruments Together → Do Not Hold Them → Allow Stabilisation → Compare

 

This provides a more meaningful result.

 

9. Humidity Comparisons Can Be More Difficult

 

Relative humidity readings can be particularly sensitive to environmental conditions.

 

Humidity can change with:

 

Temperature

 

Airflow

 

Sensor exposure

 

Condensation

 

Movement between rooms

 

Human proximity

 

Therefore, seeing different humidity readings immediately after moving two instruments does not automatically mean one sensor is defective.

 

Allow sufficient stabilisation time.

 

10. Compare Under Stable Conditions

 

A simple preliminary comparison can be performed by placing both instruments:

 

Close together

 

Away from direct sunlight

 

Away from HVAC outlets

 

Away from heat sources

 

In a relatively stable environment

 

Then allow them to stabilise before comparing readings.

 

This is much more meaningful than comparing one instrument in your hand with another instrument mounted on a wall.

 

11. Is Your Reference Instrument Actually Accurate?

 

This is another common mistake.

 

A customer says:

 

“My GM1365 is wrong because my other meter says 25°C.”

 

But how do we know the other meter is correct?

 

If neither instrument has a known calibration status, comparing them only tells you:

 

The two instruments are different.

 

It does not establish which one is closer to the reference value.

 

12. What Is a Better Way to Verify Accuracy?

 

For measurements that matter, comparison should be made against an appropriate reference under controlled conditions.

 

Calibration provides a more formal approach.

 

A calibration process can help determine:

 

Reference Value

 

vs

 

Instrument Indication

 

and establish the observed measurement error under the calibration conditions.

 

This is much more meaningful than comparing two unknown meters.

 

13. When Should You Consider Calibration?

 

Calibration becomes particularly important when measurements are used for:

 

QA/QC

 

Laboratory monitoring

 

Food storage records

 

Customer requirements

 

Environmental documentation

 

Controlled processes

 

Audit requirements

 

The required calibration points and traceability should follow the application and quality system.

 

14. What If the Logger Was Dropped?

 

Physical shock can potentially affect an instrument.

 

If a logger has:

 

Been dropped

 

Been exposed to water beyond its intended protection

 

Experienced extreme conditions

 

Been stored improperly

 

Suffered physical damage

 

and the readings suddenly become suspicious, inspection or calibration may be appropriate.

 

15. What If the Humidity Sensor Gets Wet?

 

Condensation or inappropriate moisture exposure can affect humidity measurements.

 

If a logger is moved rapidly between very different temperature environments, condensation may occur under certain conditions.

 

Follow the manufacturer's operating and environmental limitations.

 

If the sensor continues to behave abnormally after returning to appropriate conditions, further inspection may be required.

 

16. Data Logger Placement Can Create “False Problems”

 

Imagine a warehouse has three loggers.

 

Logger A → 27°C

 

Logger B → 28°C

 

Logger C → 31°C

 

The immediate reaction might be:

 

“Logger C is inaccurate.”

 

But then you discover Logger C is mounted near the roof under a metal structure receiving substantial heat.

 

The logger may actually be showing a genuine local hot spot.

 

This is exactly why data loggers are useful.

 

Different readings can reveal real environmental differences.

 

17. Use Multiple Loggers to Find Environmental Differences

 

Instead of assuming different readings are errors, investigate the pattern.

 

For example:

 

Loading Door → Logger A

 

Centre Warehouse → Logger B

 

Upper Rack → Logger C

 

Lower Rack → Logger D

 

If Logger C repeatedly records higher temperatures during the afternoon, the result may indicate a real environmental pattern rather than instrument failure.

 

18. GM1365 for Temperature & Humidity Trend Monitoring

 

The Benetech GM1365 is useful because it does not only provide one current measurement.

 

It records environmental conditions over time.

 

This allows users to distinguish between:

 

Random Reading Difference

 

and

 

Repeated Environmental Pattern

 

A repeated trend can be much more informative than comparing two displays for a few seconds.

 

Troubleshooting Checklist

 

If your GM1365 or another temperature data logger appears to show a different reading, check:

 

1. Are both instruments measuring at the same location?

 

2. Have both instruments stabilised?

 

3. Are they exposed to the same airflow?

 

4. Is either instrument in direct sunlight?

 

5. Is one near a heat or cooling source?

 

6. What are the accuracy specifications?

 

7. What is the calibration status?

 

8. Is the reference instrument itself trustworthy?

 

9. Has either instrument been damaged?

 

10. Does the difference remain consistent over time?

 

Only after checking these factors should you conclude that the logger may require inspection or calibration.

 

Different Reading Does Not Automatically Mean Faulty

 

Remember:

 

Instrument A ≠ Instrument B

 

does not automatically mean:

 

Instrument A = Faulty

 

or

 

Instrument B = Faulty

 

The difference must be evaluated against:

 

Specification + Environment + Placement + Stabilisation + Calibration

 

This is the correct measurement approach.

 

Looking for Temperature & Humidity Logger Calibration in Malaysia?

 

MTM Precision supplies the Benetech GM1365 Temperature & Humidity Data Logger and a wide range of environmental measuring instruments in Malaysia.

 

If your logger readings appear inconsistent, send us:

 

Instrument Model + Application + Reading Difference + Comparison Instrument + Calibration Requirement

 

We can help determine whether the issue is likely related to application, placement, instrument specification or whether further calibration/inspection should be considered.

 

Contact MTM Precision

 

MTM Precision Sdn Bhd

No. 29-1 & 29-2, Jalan Bandar 18,

Pusat Bandar Puchong,

47160 Puchong, Selangor, Malaysia.

 

Website: www.mtmpre.com.my

WhatsApp: +6016-660 7346

Email: mtmpre@yahoo.com

 

Different Reading? → Check Placement → Stabilise → Compare Specifications → Verify Calibration — MTM Precision Malaysia