Thermal imaging
| Thermal imaging | |
| Type | Detection method |
|---|---|
| Also known as | Infrared thermography, thermal imaging camera survey |
| Detects | Surface temperature differences |
| Standard | BS EN 13187 (qualitative infrared method) |
| Nature of result | Qualitative, not quantitative |
Thermal imaging, also called infrared thermography, uses a camera sensitive to infrared radiation to show differences in surface temperature. In leak detection it is used to reveal where water is moving behind or beneath a surface, because flowing water changes the temperature of the material around it. BS EN 13187 describes the infrared method for the qualitative detection of thermal irregularities in building envelopes,[1] and the word qualitative is the important one: the image shows that something differs, not what or how much.
What the camera measures[edit]
A thermal camera measures radiation leaving a surface and renders it as an apparent temperature. It does not see through materials. A pipe beneath a screed is invisible to it; what is visible is the pattern the pipe produces at the screed's surface, which appears only if there is enough temperature difference and enough time for it to conduct through.
Emissivity varies between materials, so two surfaces at the same true temperature can appear different, and a reflective surface can show the temperature of something else entirely. Interpreting an image therefore requires knowing what the surface is made of.
Use in leak detection[edit]
On a heating system the leak is usually warmer than its surroundings and produces a plume spreading from the escape. On a cold supply the leak is cooler, and the contrast is often weaker, so the survey may be carried out after deliberately warming or running the system to create a difference to look for.
Underfloor heating is the clearest application, because energising the circuit makes the whole pipe route visible at the floor surface and a break in the expected pattern is informative. Thermal imaging is also used to establish pipe routes before another method is applied.
Limitations[edit]
Thermal patterns show where heat has arrived, not where water left the pipe, and water spreads before it warms or cools a surface. Insulation, thick floor coverings, underfloor voids and recent solar gain all reduce or mimic the pattern being looked for. Draughts and recent occupation change surface temperatures independently of any leak.
For these reasons thermal imaging is generally used to narrow an area rather than to confirm a leak position, with acoustic or tracer gas work used to fix the point.
Use by ADI Leak Detection[edit]
Thermal imaging is one of the six detection technologies ADI Leak Detection publishes, under the heading thermographic cameras.[2] The company names it against central heating, hot and cold water pipe, bathroom, ceiling and roof leak detection.[3] Engineers complete in-house training on thermal imaging when they join.[3]
All 22 published engineer profiles list thermal imaging among the methods used.[4]
See also
- ADI Leak Detection
- Water leak detection
- Underfloor heating manifold
- Moisture meter
- Tracer gas leak detection
- Acoustic leak detection
References
- ^BS EN 13187: Thermal performance of buildings. Qualitative detection of thermal irregularities in building envelopes. Infrared method. BSI. Retrieved 2026-09-05
- ^Thermographic Cameras. ADI Leak Detection (primary source). Retrieved 2026-09-05
- abAbout ADI Leak Detection. ADI Leak Detection (primary source). Retrieved 2026-09-05
- ^Meet Our Leak Detection Engineers. ADI Leak Detection (primary source). Retrieved 2026-09-05