testo 635-1 - Thermohygromete

  • Dual Probe Measurement 

  • Measurement of air moisture, material equilibrium moisture, pressure dew point 

  • U - Value probe connection 

  • Protection class IP54 

Product Description

Robust, practical and easy to handle

In addition to readings, the Testo 635-1 temperature and humidity measuring instrument also displays min., max. and mean values.

When the pressure dew point probe is attached, it can measure the pressure dew point in compressed air. If a humidity probe is attached to the measuring instrument, it can also measure the dew point and water content of indoor air along with the psychrometric temperature, in addition to air humidity and air temperature.

The measuring instrument also calculates the dew point distance between indoor air and wall surface. In the event of mould in the home, this means you get an initial indication of whether mould has been caused by incorrect use of ventilation or by moisture ingress. You can find out more about the measurement of mould in the home with the testo 635-1 in the “Applications” tab.

The temperature and humidity measuring instrument is really easy to use and the menu guidance is user-friendly. The display with its illumination function means the readings are easily legible even when visibility is poor. A solid housing reliably protects the measuring instrument from impacts.

Documentation of measurement data with the Testo 635-1 temperature and humidity measuring instrument

Would you like to document your readings quickly and in a verifiable way? The optional Testo fast printer enables you to print out measurement data such as air humidity or temperature really easily at any time.

Use the practical cyclical printing function on the Testo 635-1. It not only enables the printout of individual readings, but also of whole series of measurements on the Testo fast printer at freely adjustable intervals (for example once a minute). 


Delivery Scope

testo 635-1 temperature and humidity measuring instrument, including calibration protocol and batteries.

Caution: The instrument can only be commissioned with a probe. These are available separately.

More Information
Warranty 2 Years
Technical Data
Temperature - NTC

Measuring range

-40 to +150 °C


±0.2 °C (-25 to +74.9 °C)

±0.4 °C (-40 to -25.1 °C)

±0.4 °C (+75 to +99.9 °C)

±0.5 % of mv (Remaining Range)


0.1 °C

Temperature - TC Type K (NiCr-Ni)

Measuring range

-200 to +1370 °C


±0.3 °C (-60 to +60 °C)

±(0.2 °C + 0.5 % of mv) (Remaining Range)


0.1 °C

Humidity - Capacitive

Measuring range

0 to +100 %RH


See probe data


0.1 %RH

Absolute Pressure

Measuring range

0 to 2000 hPa


See probe data


0.1 hPa

General technical data


428 g


220 x 74 x 46 mm

Operating temperature

-20 to +50 °C

Product-/housing material

ABS / TPE / Metal

Battery type

Alkali manganese, mignon, type AA

Battery life

200 h

Storage temperature

-30 to +70 °C