- First contact
- The settings of the infrared camera
- Points to watch out for
- The image in Flir's image
- Still expensive technology
To detect insulation faults, leaks or invisible water leaks behind a wall or under a heated floor, the thermal imaging camera is the ideal tool. Based on infrared technology, it highlights radiation from more or less hot areas. If its use is simple, the images are sometimes difficult to interpret for a neophyte.
1 Infrared lens
2 Digital camera lens
3 Image storage control
4 Handle and battery compartment
5 USB socket compartment
6 Control Screen
7 Power key and cancel selection
8 Multifunction button (menu, navigation, picture adjustment)
9 Digital camera activation
10 Measuring pointer
11 Minimum and maximum temperatures covered by the objective
The screen The camera (Testo 870-2) has a screen of 160 x 120 pixels. The higher the number of pixels, the better the contrast. Two commands are very solicited: a multifunction to adjust the image and one on the handle to memorize the shots (in Jpeg).
The stability of the image At startup, the camera initializes to stall the image. Then point the device to the surface to be analyzed. The development and measurement of temperatures are automatic. The shooting distance is between 10 cm and 50 m. Depending on the angle, and the distance, the measurements may vary. The further away you are, the less accurate they are. Here, the radiator works perfectly: the hot zone (red) is homogeneous.
Measuring radiation The camera measures the thermal radiation emitted by the materials. The sensor associates the received intensity with a color and each one corresponds to a temperature (of the cold in hot blue in red). The camera only gives an interpretation of the temperatures. It is by no means a thermometer.
The good moment Measure outdoors early in the morning or in the evening, when the sun does not have too much impact on the building. Avoid rain and fog that distorts the data. Indoors, the greater the difference in temperature with the outside, the more the detection of thermal bridges is noticeable, especially during the heating period.
The device offers four different visualizations to select from the menu for better reading comfort.
A "Iron": from dark blue to yellow
B "Gray": black and white
C "Rainbow": from blue to red
"Cold-hot": from blue to red
These four infrared images highlight the hot and cold spots differently. There is no rule, it is the user who chooses the most readable viewing mode according to the situation.
The settings of the infrared camera
The menus The menu, sub-menus and navigation are displayed via the multifunction key. Validation is done by pressing OK. The menu allows you to intervene at any time during the viewing, to modify or refine the settings. the camera is pre-set and ready for operation as soon as it is started.
The aim mode By default, the aiming mode is displayed with a pointer markable in the center of the screen. It indicates the temperature there. For more precision, it is possible to add two additional sliders. One measures the hottest temperature and the other the coldest. These two pointers move automatically to extreme temperatures.
The scale of measurement. The scale on the right of the screen gives the color intensity according to the maximum and minimum temperatures that the camera automatically perceives. To refine the display and obtain more contrast, it is possible to modify the scale of measurement by playing on the minimum and maximum temperatures.
The emissivity. The Testo 870-2 takes into account the thermal radiation of materials that may affect infrared measurements. The "emissivity" function offers different presets according to the materials encountered (wood, concrete, plastic, aluminum, etc.).
Digital clichés. The camera can also take digital images in low definition. The focus is automatic, but the images are of poor quality. Just press the button on the right of the screen or via the interactive menu. These snapshots can help to locate and come in addition to the infrared image.
The good contrast. Locating a pipeline leak through the ground allows you to intervene in the right place to quickly make repairs. Underfloor heating is easy to locate. To bring out the coils, it is necessary to push the heating as much as possible. The "iron" mode has been selected here for better contrast.
Points to watch out for
The roller shutter boxes are often less well isolated areas. This generates heat loss. The blue area in this image shows that at this location, the outside air cools the inner wall.
The camera makes it possible to check energy losses appliances, like here with a refrigerator. The door gasket of the freezer compartment is red: it is still waterproof.
Switches and sockets embedded in a lining or in a wall may be zones of thermal bridges. Losses usually occur through bleeding and poorly insulated sheaths.
Windows or, as here, the front door are to be inspected first. With time, thermal bridges can be created. On this door, the measurement revealed an airtightness defect marked in dark blue on the left of the image. Its disordered hinges are the cause of this loss.
The camera does not film through a window. On the other hand, it allows to see the absence of gas in a double glazing. The windows as well as the polished metal parts reflect the thermal image like a mirror. In this image, the natural ventilation at the top of the window (in dark blue) allows the air to pass correctly.
The image in Flir's image
The E40 Flir camera (rented at Loxam) has the option "PIP" (image in the image). When filming, the thermal image appears in the center of the screen and is superimposed on the digital image. It is a real plus to locate in space. One can, as on the Testo choose in the menu between the four visualizations of the infrared image. In addition, it is possible to focus manually by rotating the lens ring from right to left, as on a conventional camera.
Still expensive technology
With the purchase, a camera costs between 1 500 and 4 500 € and a complete diagnosis carried out by a professional returns to 500 € minimum. Rental is therefore an interesting solution for the individual. At Loxam or Kiloutou, this equipment is rented around 140 € / day or 233 € / weekend. To best interpret infrared images, some manufacturers, such as Testo and Flir, offer training. For their part, Éditions Eyrolles published the "Practical Guide to Building Thermography". This book introduces you to the interpretation of thermal images.