- Detector without sensors
- You want to insulate your attic at € 1?
- And for an individual?
- The main settings
- Elements of measurement
- Infrared thermometer
Become indispensable for professionals who realize the thermal balance of a housing, a thermal camera is a precision tool, expensive to buy, which is now available for rent.
Initially applied to military aiming systems, thermovision (or thermal imaging) has many variations in the civilian world: site surveillance, maritime navigation, night driving... In short, all the circumstances where the lack of lighting, the presence smoke or opaque obstructions greatly disrupt vision.
Detector without sensors
Thermovision is also used in the industry to detect gas leaks and more generally, to control the temperature of pipes or the heating of electrical components (transformers...) or mechanical (bearings, bearings...). But this technology is also unparalleled in identifying thermal bridges. Especially since the measurement without contact is added the ability to capture still images or even make small films, thanks to thermal diagnostic cameras that combine the functions of a thermometer and a camera. The collected images are then analyzed using specific software.
You want to insulate your attic at € 1?
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And for an individual?
Given its price (€ 2,000 and more), the purchase of such equipment makes no sense for an individual. However, its rental (€ 170 for 24 hours) is not lacking interest especially when planning to undertake major renovation work, or in case of doubt about the performance of outdoor insulation announced, a veranda, woodwork... The choice of measurement mode depends on the context: for a small item or a specific point, choose the "spot" measurement; otherwise, opt for the mini or maxi zone. Except for focus, the Digital Camera mode offers no adjustment. And the image quality is very poor! Opt instead for Infrared or Image in Picture (PiP). Become indispensable for the professionals who realize the thermal balance of a housing, this tool of precision, expensive with the purchase, is today available to the hiring. A thermal camera is also used to detect the passage of non-metallic pipes (thus undetectable by a metal detector) in an opaque wall or a slab: heating tubes or sanitary distribution in PER (crosslinked polyethylene), evacuations in PVC... It also facilitates the detection of leaks or infiltrations, while their manifestations are not yet visible (around a roof window, behind a lining or a buried wall...). This device responds even better than temperature differences are important. This is why, in the case of losses through the walls (or joinery) of a building, it is better to operate during the heating period. The values collected will be all the more significant.
The main settings
The model used here (Flir i50) only captures still images on a MicroSD card (or USB flash drive). Three display modes are available: Digital camera, Infrared or PiP (Picture in Picture). In Digital Camera mode, the image is in color, with no indication of temperature. This appears only in Infrared and PiP modes. In Infrared mode, the body's thermal radiation occupies the entire screen, optionally in three color palettes: from black to white ("Gray" type), from dark blue to light yellow ("Iron" type) and from green to red (type "Rainbow"). In PiP mode, the thermal image appears in the center of the screen.
Elements of measurement
Distinct from the thermal image, the measurement zone is reduced either to the central point of the "spot" measurement or to a square of 1.5 cm side. In both cases, a laser pointer is used to accurately locate the controlled area. The square only shows the minimum or maximum value of the area. If, for example, thermal bridges are sought, the minimum value will be used from the inside of a heated space to find out where the cold is coming from; and the maximum value if one proceeds from the outside to know where the calories come out. Although the device itself defines the measuring range, other values can be entered. The contrast of the thermal image is then modified. Which can make it more meaningful.
As soon as you turn it on and after automatic initialization, everything in front of the lens appears on the screen. Attention: the minimum focusing distance is 40 cm.
Except for focus, the Digital Camera mode offers no adjustment. And the image quality is very poor! Opt instead for Infrared or Image in Picture (PiP).
The choice of measurement mode depends on the context: for a small element or a specific point, choose the "spot" measurement; otherwise, opt for the mini or maxi zone.
To materialize the radiation, you do not need to use the "Gray" monochrome palette. Choose the "Iron" palette or the "Rainbow" palette, which are much more readable.
The Infrared mode is all the more readable with a large temperature difference, as above (24-46° C) on a roof window. When it is low (21-32° C), prefer the mode PiP (image in the image) for better readability (bottom).
By combining the Infrared and "Iron" modes (left) or PiP and "Rainbow" (right), the image displayed on the screen becomes much more meaningful.
The manual mode (M) makes it possible to refine the display of the measurements. It is thus possible to vary the minima and maxima of the measured temperatures, together or independently.
If the specialists take into account various parameters, an individual can use the default values for the atmospheric temperature and the emissivity of the materials.
The profiles of aluminum joinery are to be considered first: they are certainly lacking the polyamide bars breaking the famous thermal bridges that can only be eliminated by replacing the joinery.
A double glazing may not be as insulating as one imagines... Here, the surface temperature is 18.7° C against 20° C and more for the surrounding surfaces (including a radiator at 27.4° C).
On the back of this garage door in full sun, the "spot" measurement shows a thermal bridge at the location of the (yet plastic) fasteners of the reflective insulation: 27 instead of 20 at 23.7° C.
Sometimes there are thermal bridges around the wall outlets, embedded in an insulation doubling complex... This is not the case here.
Much cheaper than diagnostic cameras, infrared thermometers also perform an instantaneous temperature reading. Some may also memorize their measurements (Ryobi Doc).
To refine the detection of temperature deviations, the sensitivity of a thermometer can sometimes be adjusted from 0.5 to 3 or 5° C. The color of the pointer (LED) changes from green to red (Black & Decker Doc).