testo 625 Thermohygrometer

A. Product Overview

The Testo 625 is a professional digital temperature and humidity measuring instrument designed for fast and precise indoor climate measurements. It uses a capacitive Testo humidity sensor for relative humidity measurement and an NTC sensor for air temperature measurement.

The instrument measures relative humidity from 0 to 100 percent RH and temperature from minus 20 to plus 60 degrees Celsius. It automatically calculates dew point and wet bulb temperature, helping users evaluate indoor air conditions, condensation risk and thermal comfort.

The Testo 625 also supports Bluetooth 5.0 connectivity with the Testo Smart App. Through the app, users can configure the instrument, view measured values graphically, save readings, manage customers and measuring points, create measurement reports and send reports by email.

An audible alarm warns the user when a configured limit value is exceeded. Timed and point mean calculations are also available for evaluating changing environmental conditions over a selected measurement period.

Key Features

• Measures air temperature and relative humidity
• Calculates dew point temperature
• Calculates wet bulb temperature
• Relative humidity range from 0 to 100 percent RH
• Temperature measuring range from minus 20 to plus 60 degrees Celsius
• Humidity accuracy of 2.5 percent RH from 5 to 95 percent RH
• Temperature accuracy of plus or minus 0.5 degrees Celsius
• Bluetooth 5.0 connectivity
• Compatible with the Testo Smart App
• Audible alarm for limit value violations
• Timed and point mean value calculation
• Graphical measurement display through the app
• Measurement data storage and report generation
• Approximately 100 hours of battery life
• Compact handheld construction
• Supplied with transport bag, calibration protocol and three AA batteries

B. Working Principle

The Testo 625 uses two integrated sensing technologies to measure indoor environmental conditions.

The capacitive humidity sensor detects changes in the electrical capacitance of its sensing element as the moisture content in the surrounding air changes. The instrument converts this change into a relative humidity reading displayed as a percentage.

The NTC temperature sensor measures air temperature by detecting changes in electrical resistance. As the surrounding temperature changes, the resistance of the NTC sensor changes, allowing the instrument to calculate and display the air temperature.

Using the measured temperature and relative humidity values, the Testo 625 automatically calculates:

• Dew point temperature, which indicates the temperature at which moisture begins to condense
• Wet bulb temperature, which helps assess evaporation and thermal conditions
• Timed mean values over a selected measurement period
• Point mean values from multiple individual readings

The measured data can be displayed directly on the instrument or transferred through Bluetooth to the Testo Smart App for graphical analysis, storage and documentation.

C. Why It Is Used

The Testo 625 is used to monitor and evaluate temperature and humidity conditions in indoor spaces, HVAC systems, storage facilities and industrial environments.

Accurate humidity and temperature measurement is important because excessive or insufficient humidity can affect human comfort, stored materials, manufacturing processes and building conditions.

The instrument is commonly used for:

• Assessing indoor air quality and thermal comfort
• Checking temperature and humidity in offices and commercial buildings
• Monitoring storage rooms and warehouses
• Inspecting HVAC systems and air-conditioning installations
• Identifying conditions that may cause condensation
• Evaluating the risk of mould formation
• Monitoring environmental conditions during production
• Checking climate conditions in laboratories
• Verifying temperature and humidity limits
• Recording measurements for inspection and compliance reports

The automatic dew point calculation helps users identify when condensation may form on walls, ducts, machinery or stored products. The audible alarm also allows quick identification of readings that exceed configured limits.

D. Suitable Buyers

The Testo 625 Thermohygrometer is suitable for:

• HVAC technicians
• Air-conditioning service engineers
• Facility management companies
• Building inspection professionals
• Indoor air quality consultants
• Warehouse operators
• Cold storage operators
• Pharmaceutical storage facilities
• Food storage and processing companies
• Laboratories
• Manufacturing plants
• Quality control departments
• Environmental monitoring professionals
• Maintenance engineers
• Safety and compliance teams
• Hospitals and healthcare facilities
• Museums, archives and libraries
• Hotels, offices and commercial buildings
• Educational institutions
• Industrial instrumentation suppliers

Frequently Asked Questions

1. What does the Testo 625 measure?

The Testo 625 measures relative humidity and air temperature. It also calculates dew point temperature and wet bulb temperature.

2. What is the humidity measuring range of the Testo 625?

The relative humidity measuring range is 0 to 100 percent RH.

3. What is the temperature range of the Testo 625?

The NTC temperature sensor has a measuring range from minus 20 to plus 60 degrees Celsius.

4. What is the humidity accuracy of the Testo 625?

The humidity accuracy is 2.5 percent RH within the range of 5 to 95 percent RH.

5. What is the temperature accuracy?

The temperature accuracy is plus or minus 0.5 degrees Celsius.

6. Does the Testo 625 calculate dew point?

Yes. The instrument automatically calculates dew point temperature from the measured air temperature and relative humidity.

7. Does it calculate wet bulb temperature?

Yes. Wet bulb temperature is automatically calculated and displayed.

8. Does the Testo 625 support Bluetooth?

Yes. It supports Bluetooth 5.0 connectivity for communication with the Testo Smart App.

9. What can be done with the Testo Smart App?

The app can be used to configure the instrument, display graphical measurement curves, save data, manage customers and measuring locations, create reports and send reports by email.

10. Does the instrument have an alarm function?

Yes. An audible alarm sounds when a configured measurement limit is exceeded.

11. Can it calculate average readings?

Yes. The Testo 625 supports timed mean value and point mean value calculations.

12. Is the Testo 625 suitable for HVAC applications?

Yes. It is suitable for HVAC inspections, indoor climate assessment, air-conditioning systems and environmental monitoring.

13. Can it be used in warehouses and storage rooms?

Yes. It can be used to confirm that appropriate temperature and humidity conditions are maintained in warehouses, storage rooms and product storage areas.

14. Can the Testo 625 help detect condensation risk?

Yes. Its dew point calculation helps identify conditions in which condensation may occur.

15. Can measurement reports be created?

Yes. Measurement results can be documented through the Testo Smart App and exported as PDF or CSV reports.

16. What type of batteries does it use?

The instrument uses three AA batteries.

17. What is the battery life?

The specified battery life is approximately 100 hours under normal operating conditions.

18. What is included with the Testo 625?

The standard package includes the Testo 625 instrument, transport bag, calibration protocol and three AA batteries.

19. What is the Testo 625 order number?

The order number is 0563 1625.

20. Is the Testo 625 suitable for professional use?

Yes. It is designed for professional HVAC, facility management, storage monitoring, building inspection and indoor environmental measurement applications.