Using thermal imagers in the summer
Too many thermographers leave their imagers in the case during the summer. This comes, in part, from the way we used to work when imagers were not nearly as sensitive and our understanding of how to use them was limited to winter work.
Get the darned thing out and use it! In most places, on most mornings, you can get successful "winter" images; if not, keep the home closed up for the night and add a bit of heat in the morning before you arrive.
Once the day warms, heat flow and thermal patterns will reverse. On days when the sun is intense, direct solar loading will make exterior work impossible during the daytime and even interior work will require patience and understanding of how the sun affects things. But it is not impossible by any means!
A few hours after sunset if the evening is warm and the AC on, imaging can be spectacular from both inside and outside.
With a blower door and the building depressurized, air leakage will nearly always be detectable. The image below of a house in the Bay area on a warm early afternoon shows poorly placed figberglass batts in a cathedral ceiling.
Want to learn more? My colleague, Matt Schwoegler, will be presenting a (paid) webinar on July 6 on Warm Weather Thermography. See http://www.thesnellgroup.com/Content/thermal-solutions-conference.aspx for details. You can also see his recent excellent article in the May/June issue of Home Energy Magazine.
I'd encourage all readers to take their imagers to every single job. If you don't get good images, think about why you didn't and, when possible, modify your protocols so the next time you have a better chance.
John
The Snell Group
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Replies to This Discussion
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Permalink Reply by Michael Stuart on -
I've got a few inspections in two weeks time. With my Ti32 and a blower door, I am good to go. (Sometimes I really don't even need the blower door. It's all about having the right training, and the right tools at your disposal.
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Permalink Reply by Davide Lanzoni on -
If my memory is good, RESNET talk of a deltaT of only 3°F for conducting an infrared inspection with blower door: it happens many times and its' about a 100 mK NETD. here are some image with my Ti32. infiltration may be warm or hot, but you can see it almost always
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Permalink Reply by John Snell on -
The 3F delta is for locating air leakage under RESNET. For locating insulation issues, an 18F delta is required. I agree we can often get by with less of a difference if we understand the conditions, know what we are doing and have a more sensitive imager—I favor something around 50mK, which is much more than 2X the sensitivity of a 100mK system. As always, Davide, very nice images!
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Permalink Reply by John Snell on
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Typically there are several reasons "hot work" is not as easy as working with cooler temperatures, and Matt will discuss these in his webinar next week. First, the delta-temperature (inside to outside) is usually not as great. Second, the sun loads the walls. While this may help, often is just confuses things. Finally, as materials cool quickly after a sunny day, differences in thermal capacitance reveal themselves; again, this may help but is often confusing. The attached image shows an exterior in the summer on a clear evening with AC running. The cement board siding has cooled quickly. The 3.5" FG batt insulation is in place. Is it working or only working poorly is it an issue of seeing cooling siding/still warm framing
or a combination of the factors? I find getting good results from summer thermography typically requires experience and skill, patience and a sensitive imaging system. -
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Permalink Reply by Tyson Pischel on -
I have been setting up to inspect about 200 attics that are most likely completely out of compliance with ours(and any) reputable program specs. While testing a couple of remote camera configurations, I made a pass through the attic with my IR camera. As my attic was done correctly, The baffles (as shown on the left) were easy to spot. -
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