Quick answer: The testo 872 records apparent surface-temperature patterns. To compare images meaningfully, document emissivity, reflected radiation, palette scale and distance; a thermogram cannot directly detect water behind a wall.
What makes the testo 872 different
The testo 872 belongs to the 865–872 family and has model-/firmware-specific manuals; some older firmware versions have distinct instructions. The official documentation offers separate manuals for different firmware ranges. For related guidance, see Assess Condensation and Mould Risk with the testo 608-H1.
Prepare and carry out the measurement
- Check model generation, lens and firmware manual, and allow camera/environment stabilization as specified.
- Set emissivity and reflected-temperature assumptions appropriate to the inspected surface; avoid polished targets.
- Capture overview and close-up images with repeatable distance, focus and temperature scale.
- Corroborate a suspected anomaly using suitable temperature, humidity or moisture tests and document conditions.
Model-specific use and interpretation
Check firmware before following menu screenshots, adjust emissivity/reflected temperature for the target and save matched views of affected and unaffected surfaces. Keep scale and inspection conditions comparable.
The colours on a thermal image represent a selected rendering of radiometric temperatures. Colour contrast alone is not a defect category. Apparent surface temperature patterns can be due to material, geometry, reflection, sunlight or airflow.
The associated humidity or condensation interpretation depends on measured indoor air conditions, not thermal colours alone. For the air-side calculation behind this interpretation, see why condensation forms on one wall.
Worked example (hypothetical)
Hypothetical wall comparison: two painted surfaces show apparent temperatures of 14 °C and 18 °C under matched emissivity/scale settings. The 4 °C contrast identifies an area for investigation; it does not prove failed insulation or concealed dampness.
Interpretation limits and safe follow-up
- Shiny surfaces may reflect a hot or cold object that is not the target itself.
- A thermal bridge, air movement or damp material can show overlapping patterns; corroborate with appropriate independent measurements.
- Electrical and high-temperature assets must be examined from approved safe positions by competent personnel.
- If inspecting an older model, verify its own manual instead of adopting instructions from later 868s, 871s or 872s models.
Firmware-specific instructions on the 872
Testo publishes separate testo 872 manuals for different firmware generations. Check the installed firmware before following menu screenshots or transferring recorded data. Record emissivity, reflected apparent temperature, scene conditions and measurement distance, then repeat images on comparable surfaces. Humidity interpretation requires independent air-temperature and RH values. For a comparable Testo imager, see the testo 868 thermal camera setup guide.
Interpretation: A 3 °C apparent surface difference does not by itself establish moisture, failed insulation or a threshold exceedance.
Limits and safety
Follow the exact instrument manual and the equipment manufacturer’s acceptance criteria. The example is not field evidence, a legal limit or a commissioning target. Work on energized electrical equipment, combustion systems, charged refrigerant circuits or hot surfaces requires qualified personnel and the site’s approved protective procedures.