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testo 635-2 - Temperature and moisture meter

0563 6352
  • Optional sensors for moisture / temperature / pressure dew point / absolute pressure measurements
  • 2 plug-in and 3 wireless sensors
  • Super-size memory for up to 10,000 readings
  • USB cable, PC software for logging and archiving measuring data
  • The testo 635-2 temperature and moisture meter measures the temperature and moisture of different types of materials, surfaces, and environments, with a wide range of optional sensors.
    The testo 635-2 temperature and moisture meter can be used to carry out different measurements in the field of air conditioning. A wide range of optional sensors and probes provide information on:
    • Relative humidity
    • Material moisture
    • Material compensation moisture
    • Pressure dew point in compressed air systems
    • HTC value
    • Air temperature
    • Surface temperature
    • Core temperature
    • Absolute pressure
    Capacity for 2 connectable sensors and 3 temperature / moisture wireless sensors, whose measurements can be picked up by a wireless module (optional) over a distance of up to 65 feet. The results are presented on an easy to read display.

    Rugged. Practical. Easy to use.

    The testo 635-2 temperature and moisture meter can display min/max/avg values, and calculate the dew point difference between the indoor air and the surface of the wall. This allows you to analyze moisture levels at ceilings and walls. Individually configured characteristic curves ensure 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 poor lighting, and a rugged case protects the meter against impact.

    Saving, transferring, printing out data – easy as pie

    Save measuring sites and allocate measuring data to the relevant site. Create individual profiles to perform parallel long term / material moisture measurements. Save up to 10,000 readings (individual measurements and series) to your meter. There’s also a USB cable and software for transferring your data comfortably to your PC.
    And last but by no means least, the turbo printer (optional) provides you with on the spot printouts.

    testo 635-2 temperature and moisture meter, PC software, USB data cable, calibration protocol, and batteries

    PLEASE NOTE: sensor required (not in scope of supply).

    Temperature - NTC

    Measuring range
    -40° to 302 °F / -40 to +150 °C
    ±0.5 % of mv (Remaining Range)
    ±0.4 °F (-13.0° to 166.8 °F) / ±0.2 °C (-25 to +74.9 °C)
    ±0.7 °F (167° to 211.8 °F) / ±0.4 °C (+75 to +99.9 °C)
    ±0.7 °F (-40° to -13.2 °F) / ±0.4 °C (-40 to -25.1 °C)
    0.1 °F / 0.1 °C

    Temperature - Type K TC

    Measuring range
    -328° to 2498 °F / -200 to +1370 °C
    ±0.5 °F (-76° to +140 °F) / ±0.3 °C (-60 to +60 °C)
    ±(0.4 °F + 0.5 % of mv) (Remaining Range) / ±(0.2 °C + 0.5 % of mv) (Remaining Range)
    0.1 °F / 0.1 °C

    Humidity - Capacitive

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

    Air Probes

    Dewpoint Pressure Probe

    Humidity probes

    Immersion / Penetration Probe

    Pressure Probe Accessories

  • Pressure Probe Accessories
    Absolutdrucksonde 2000 hPa
    Absolute pressure probe 29 psi
      0638 1835
    • RFID Probe

      Surface probes


      Additional Accessories


      Country Specific RFID Handles

      Humidity RFID Probe

      Printer and accessories

      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

      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

      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