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testo 635-2 - Temperature and moisture meter

0563 6352
$1 081.00 $1 189.10
  • Dual Probe Measurement 
  • Measurement of air moisture, material equilibrium moisture, pressure dew point 
  • U - Value probe connection 
  • Internal Memory 10,000 Readings 
  • The Testo 635-2 is an instrument designed for measuring air moisture, material equilibrium moisture and pressure dewpoint in compressed air systems. Moisture characteristics can be recorded in the instrument memory and analysed and displayed in graphics or tables. Precision probes up to -60°C tpd are available to check pressure dewpoint in compressed air systems. 

    Key Features

    • Instrument memory for up to 10,000 readings
    • PC software for analysis, filing and documentation of measurement data
    • Measurement of air moisture, material equilibrium moisture, pressure dew point
    • Protection class IP54
    • Direct display of material moisture due to freely settable characteristics curves (based on equilibrium humidity)
    • Storage of single measurements or measurement series by measurement location
    • Fast access to the most important functions via user profiles
    • U-value probe connection option

    Rugged, practical, easy to use

    In addition to all the other measurements, the testo 635-2 temperature and moisture meter can also display min, max and mean values and calculate the dew point difference between the indoor air and the surface of the wall. This allows you to analyze levels of moisture at ceilings and walls. Individually configured characteristic curves ensure that the material moisture content is displayed reliably.   

    Both the meter and the menu guide are simple and comfortable to use. A backlit display allows you to read the measurements in the dark or poor lighting and a strong protective case protects the meter effectively against any accidental knocks and bumps.

    Saving, transferring and printing out data

    Save measuring sites and allocate the measuring data to the relevant site. Create individual user profiles to perform parallel long-term and material moisture measurements. Save up to 10,000 readings – individual measurements and measurement series – to your meter. The USB cable in the scope of supply can be used to connect your moisture meter to your PC or laptop and the software allows you to log and archive your measuring data comfortably and easily. 

    testo 635-2 temperature and moisture meter incl. download code for PC software, USB data cable, calibration protocol, batteries. PLEASE NOTE: a sensor (not in scope of supply) is required to operate the meter.

    Temperature - NTC

    Measuring range
    -40 to +150 °C
    ±0.4 °C (-40 to -25.1 °C)
    ±0.4 °C (+75 to +99.9 °C)
    ±0.5 % of mv (Remaining Range)
    ±0.2 °C (-25 to +74.9 °C)
    0.1 °C

    Temperature - TC Type K (NiCr-Ni)

    Measuring range
    -200 to +1370 °C
    ±(0.2 °C + 0.5 % of mv) (Remaining Range)
    ±0.3 °C (-60 to +60 °C)
    0.1 °C

    Humidity - Capacitive

    Measuring range
    0 to +100 %RH
    See probe data
    0.1 %RH

    Localising mould

    Damp ceilings and walls may be a result of structural damage. In most cases, however, it is a sign of improper ventilation. Once the mould appears inside a house, the tenant assumes that moisture has come in from outside. Numerous disputes have erupted because of the issue of who is liable for the mould damage. However, it is difficult to find out who or what has caused the mould: the tenant or faulty structural design?

    Testo 635-2 is ideal for measuring moisture in ceilings and walls. Using the optional attachment temperature/moisture probe and optional surface temperature probe, the testo 635 automatically calculates the dew point distance. It provides initial information about whether mould is being caused by condensation, or from moisture ingress due to structural damage or faulty insulation.

    The supplied PC software can be used to document and analyse the measurement data.

    testo 635-2

    Measuring material moisture

    Monitoring the moisture in construction materials and different timber is an important part of everyday work in the most diverse areas. For many users, measuring the material moisture as quickly and as non-destructively as possible is crucial.

    Whether it is used to assess the screed drying process, further processing, or the combustibility of wood, our testo 635-2 hygrometer can be used to examine the moisture content in many different construction materials and types of wood.

    testo 635-2

    Monitoring drying processes

    Whether freshly laid screed, or monitored drying of moisture damage, timely determination of the required moisture level will save time and therefore money.

    Screeds are laid in the in interior works stage, generally after plastering. The flooring and painting and decorating then follow. The drying behaviour is therefore a significant factor in the works schedule, primarily because the laying of flooring depends on this.

    The moisture measurement establishes readiness for flooring; liability for the flooring is thus transferred to the respective trade installing the flooring. An important part of this work is therefore documentation and assurance in the testing for readiness for flooring.

    What is the extent of moisture damage and what consequences can be expected in terms of time and costs? These questions have to be answered in order to decide which auxiliary tools and materials are to be used to speed up the drying process.

    The t 635-2 and attachment scatter field probe can be used to measure the moisture in the construction material.

    Using a thin moisture probe combined with the testo 635-2 the moisture of construction materials can be determined by means of an equilibrium moisture measurement. To do this, the probe has to be inserted in a borehole in the material being measured and sealed. The relevant material characteristic can be manually entered into the device or via software. After several hours, equilibrium with the material has taken place and the testo 635-2 displays the material moisture.

    testo 635-2

    Monitoring production and storage conditions

    Our temperature/humidity measuring instruments are used around the world in production, storage and server rooms, museums, archives, cold storage warehouses, containers and sales counters.

    Manufacturers, carriers, or dealers of sensitive products must ensure that specified temperature or humidity values are observed during production and storage. The testo 635 offers the option of performing spot measurements in relevant places.

    The temperature/humidity measuring instrument testo 635-2 offers the user a wide range of humidity/moisture probes. It provides the option of measuring humidity, material moisture and U-value (for the thermal assessment of structural components). In addition to the standard probes, up to three radio probes can be connected to the device in parallel. Measurement results can be analysed, stored and documented using the supplied PC software.

    testo 635-2

    U-value measurement in old buildings

    When redeveloping or renovating old buildings, it is crucial to be able to determine quickly if heat is being lost through the windows and walls. Only then can energy costs be reduced and redevelopment measures carried out efficiently.

    When assessing thermal transmission, e.g. in old buildings in need of renovation, the U-value is one of the most important values. It enables thermal assessment and monitoring of the installed material.

    3 temperature values are required for calculating the U-value:

    • Outside temperature
    • Surface temperature of the internal wall
    • Indoor air temperature


    A radio probe is needed to determine the U-value; this is placed in position outside. It transmits the readings to the measuring instrument inside. To measure the surface temperature the three wires of the U-value probe are attached to the wall with plasticine. The air temperature is recorded by a sensor located on the probe plug. The measuring instrument testo 635-2 automatically calculates the U-value from the three values and shows this on the display. The advantage: there is no need for manual calculation; the result is quick and accurate.

    testo 635-2

    Measuring wood moisture quickly and non-destructively

    The testo 635-2 uses the optional attachment scatter field probe (item no.: 0636 6160) to quickly and non-destructively examine the material moisture in timber. Characteristic curves are available for measuring wood moisture in soft and hard woods, and chipboard. These characteristic curves were developed in cooperation with the LPI institute.

    The measurement results are calculated up to a depth of 5 cm and can be recorded at the touch of a button. The readings are displayed in percent by weight in comparison to the dry mass of the material.

    Measurement data can be stored and documented using PC software.

    testo 635-2