John I took the level one class it would have been very interesting to see what your fireplace image looked like standing right in front of it and then to one side or the other at an angle. Would also like to see the image taken at
E level 95 and then dropped to about E level 80 for comparison. Probally just me but I would have taken that big pic and those two large glass plates off of the front of the fireplace and shot a pic with them removed just for comparison.
Perhaps I am wrong here but I left class with the understanding that the image can be effected by the E setting, by the angle taken and especially any glass present. I am not doubting that you found water in the wall I am sure that you did. I went to a home that had a chimney flashing leak that was found by another inspector with a moisture meter and I check the same wall with my moisture meter and detected a high level of moisture also; but the camera did not show the moisture and I am not sure as to why. My thinking was I did not have my setting correct as this was before my training and was not even my inspection I just had excess to a vacant home with a known problem. We could all do some learning here if everyone did not get so defensive just my thoughts.
I took the same class with Scott Wood.
Yes, we were instructed on how to use the camera, but Scott said
in a normal residential setting, the e-setting is not going to make
much difference temp reading and no change in the actual
image of the camera. By looking at your image only, you can
\see the moisture areas and that is all you really need.
He recommended that you delete all the setting off of your
cameral screen when you process the pictures of the
moisture spots you find. They are not needed.
Your moisture is verified by the moisture meter anyway.
The emission of radiation (e-setting) helps the camera
give you data and temperature, but we don’t need to
know the temperature. If it’s a wet spot, then it’s wet spot.
Who cares?
Verify it and move on.
Charley,
No offence here, just a normal discussion on my part.
Here is a message I got from Scott Wood. You can
contact him to confim any questions you may have.
Love these type of discusions much has been learned by me over the years with these post’s thanks.
We do not always have to agree but is sure does add much information.
You have no idea how many times I have had this same
debate. Oh… well.
Yes but this time it is helping me because I am now needing to lern a new product.
So you see it was far from wasted and I expect others have been looking in too.
Thanks… cookie
Yes, I do agree.
John,
Continue posting your thermal information as I am also learning this new technology on an everyday basis.
Thank you.
If all materials have acclimated to a common temperature wet or dry there will not be anything for the camera to detect.
Try wetting half of anything porous (sheetrock) or place a block of wood end grain in to a little water for wicking purposes, place object in a cabinet or closet, where no outside effects can take place, for lets say 4 hours. Without moving the test object see how much moisture you can detect with the camera.
Thermal loading of the moisture and materials acclimating back up or down to the surrounding temp at different rates is where the anomalies we see come into play.
Yes, same here…really appreciate the info. Many of us are learning about thermal imaging.
Thanks, guys. 
If
Yes I totally agree with this statement now after my training but before training did not realize this was a big factor. Yes the moisture that the camera did not detect as you stated was because there was no temp difference the home was vacant no A/C on no heat on everything was the same temp.
We are in a bad time of the year to my thinking for these cameras where we go into a home with cool temps at night and the heat is off every thing is the same temp. Outside ambient 50 degrees, Attic 50 degrees, inside ambient 50 degrees. What I have been doing since the weather has been changing is to run the heat when I first arrive and bring the indoor temp above75 degrees before I even attemp to use the camera. Was a lot easier when the attic temp was 140 degrees and the inside temp was 70 degrees.
Exactly.
The the temp difference of moisture is best seen by the IR camera
when it is in a state of evaporation, thus lowing the observed temp
from the surrounding area.
Wind blowing in the room, such as an AC duct, can sometime
help this affect.
Knowing how to see the subtle variations of the image helps too. Not all
moisture stands out like a vivid spot. You sometimes can only
see a slight shadow affect in the cameras display.
Yes… you hit the nail on the head.
Your training has caused you to understand the limitations of the IR
camera in conditions where all the surrounding temp are the same.
If you manipulate the temp from the inside and outside then your are
creating a greater DELTA “T” affect. This is what makes the camera
work at its best.
This was one of the field test they gave us during our Building Science
course in order to show the students how to overcome a low DALTA “T”
and make the camera work in real world conditions.
Good post.