Thermal Imaging

Air source, ground source and associated systems for heating homes
Swwils
Posts: 530
Joined: Sat Feb 26, 2022 12:58 pm

Re: Thermal Imaging

#21

Post by Swwils »

The hardware is the same. The firmware unlocks more features.

Google is your friend.

E4, E5, E8 and the xt versions all based on the same 320 x 240 sensor, also some of the Ex0 series too.
Petertc
Posts: 40
Joined: Sun Dec 26, 2021 12:45 pm

Re: Thermal Imaging

#22

Post by Petertc »

I had some thermal imaging pictures done on our previous house about 10 years ago, I was the guy from the company that used to run the other forum.
Some of it was we had one room that always felt cold so thought the builders left the insulation out. But it turned out to be ok.
It was the trickle vents on the windows that got me.
Where the vent was closed the glass was hotter so it looked like we were losing more heat from them, where as with the trickle vent open the glass was colder, so not losing so much heat ?
The other area was the previous boiler copper vent pipe, evening though this had been filled up, there was still a lot of heat transfer through the pipe it's self.
Swwils
Posts: 530
Joined: Sat Feb 26, 2022 12:58 pm

Re: Thermal Imaging

#23

Post by Swwils »

Most general imagers (8-14um) won't get an accurate measurement on glass because the wavelength is not correct, you'll either see a IR reflection or what's behind or near the window as it's allowing this transmission.

You need something narrow and below 8um to get a low penetration and make it act like a solid body for accurate measurement.

Again with copper it has a low emissivity (around 0.65 when oxidised, super low when not) means the T-reflected will indicate like a nearby heatsource.
Oldgreybeard
Posts: 1873
Joined: Thu Sep 09, 2021 3:42 pm
Location: North East Dorset

Re: Thermal Imaging

#24

Post by Oldgreybeard »

@Swwils is right, part of my job for a couple of years was measuring the IR signature of warships, many years ago. The emissivity of the surface at the wavelength of interest is a major contributor to the accuracy of the measurement. In general, cheaper domestic type thermal imaging systems and IR thermometers are calibrated to give a reasonably accurate reading with a surface emissivity at their sensor peak wavelength sensitivity of around 0.9 to 0.95. If the surface emissivity drops below this they start to under-read, below an emissivity of around 0.6 they become effectively useless.

Most surfaces, like walls, the ground, timber, painted surface of any colour (bar being shiny silver, perhaps) will give a reasonably accurate reading, good enough for any normal purpose relating to energy saving measures anyway. There is a table here of typical surface emissivity that is good enough as a guide as to how far out the reading of an IR thermometer may be with different surfaces, lower numbers mean a bigger error. Closer to about 0.9 to 0.95 the more accurate the reading will be: https://www.thermoworks.com/emissivity-table/

There is an easy fix for measuring materials with a low surface emissivity, just stick a bit of thin tape on it and leave it for a while for the temperature to equalise (don't do this in bright sun where the tape surface may warm up from the sun). I use black electrical tape. seems to work well, has a surface emissivity almost perfectly matched for most domestic type IR imager and thermometers (i.e. those without actively cooled bolometer sensor arrays), and comes away afterwards without leaving a mark, usually.
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Swwils
Posts: 530
Joined: Sat Feb 26, 2022 12:58 pm

Re: Thermal Imaging

#25

Post by Swwils »

Yeah you can just use some black electrical tape and most brands have a known emissivity published somewhere.

The survey conditions also make a massive difference.
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