HVAC schools do not teach IR…just saying.
Here John, if you finally want to “get” Anderson, you can use this statement. However, you will have to know what you are talking about in order to do so. That is my challenge to you.
I think you are taking what you want to take from Chuck’s post. Chuck never once said you absolutely do not need accurate temp measurements. He also did not throw in “always” for his protocol. There is a time and a place. What Anderson is talking about is the time it is needed. Do you even know when that time is? If so, then answer Anderson’s and the OPs original question.
OP:
John:
We are not even talking the same subject John.
You are talking Home Inspection and we are talking Electrical - Mechanical Inspections.
We are talking about Thermal Imagers and your talking Thermometers!
No your saying that, not me. There are variables and you must consider them.
What you are missing is that there are inspections when we must have correct measurements and there are some that are not required (if not required, get rid of them). As I have said many times in the past, do not use numbers on your scan if you do not correct them or explain what they are.
The problem (which you created with your sub-standard training) is that Home Inspectors are calling things significant (pointing out uncorrected apparent temps) when they have no idea how far off they are. And you can’t seem to explain how and when they should be corrected.
I am not going to get your students in the middle of this to prove a point to you. But there are hundreds of examples of this all over Home Inspector web sites. Even yours!
This is a scan taken with John’s recommended resolution and sensitivity camera for his students.
The left is set at .95 and the right is set at the emissivity of a copper wire.
11F Delta T on the left, 0F Delta T on the right.
- a blind man can see that this is wrong.
- even without taking the numbers away, we see these scans all over indicating “Overheated Breaker”! Is this “overheated”?
- There is another significant problem with this scan. Anyone wish to venture a guess why this scan should be thrown out and never used (even if it was a significant temperature rise)?
Both targets are the same temp in the right image
But they teach how to measure temperature. You missed the point.
We all know they don’t teach IR.
My question David is why would you set it up for the copper wire? The wire is shielded in Vinyl. Wouldn’t you be closer at .95 then you would be at .78-.79? Just looking for clarity on this.
I never said that Chuck said “absolutely do not need accurate temp measurements” nor did I say “always” was his protocol.
Geesh.
You answer the “time it is needed” question. Teach me.
Telling lies does not support your opinion.
Greg - Before we got sidetracked with John’s thermometer scenario we were talking about placement an adjustment of spot measurement tools in the thermal image.
And as John was trying to point out using someone else’s narrative, there are a lot of places you could put these measurement tools to obtain a particular temperature differential (which determines the condition severity that you should be reporting in an electrical/mechanical inspection). There is a potential for you to put a spot on the wire insulation and put a spot on the circuit breaker connector screw or bus bar or some other metallic object within the panel (or the panel itself).
The point I’m trying to make is that even if you use the same material, as in the scans above (one wire with a high load and one wire with no load made of the same material) and do not properly set the emissivity, the temperature differential you are trying to obtain will be significantly skewed. If you’re going to use the numbers that your thermal camera puts out, they must be corrected properly or you can have significant errors as I’m trying to point out above.
Hypothetically, (to answer your question) you could have your camera set to measure a copper conductor and forget or not change it to measure the insulation on a wire. John seems to think that emissivity doesn’t matter because it’s difficult to acquire sometimes. I’m just trying to point out how significant it can be if you don’t “understand” what you are doing and reporting.
To correctly report a temperature difference between two dissimilar materials you must adjust the thermal scan for each material to generate a proper Delta T.
If you come across a situation where you have no earthly idea what the emissivity is when you’re on site (and you’re too lazy or incompetent to figure it out later) the next best recommendation is probably to set the camera at 1.0 and maybe somebody else can figure it out later down the line.
Of course you can probably take a stab at it and set your camera as close as possible and be closer to actual temperature than to do nothing at all! However, you are using .78-.79 as a copper conductor and there is a possibility that the actual emissivity could be closer to .05 (depending on its condition age and geometry). John is trying to point out this vast potential difference in emissivity saying it is so difficult to “guess”, we should just not worry about it because nobody worries about it using an IR thermometer. “So what difference does it make?” He’s starting to sound like Hillary Clinton!
The answer is to take the necessary steps to adjust the emissivity of the material or take the time to determine the actual emissivity of the target with the exception.
If you’re not going to do this stuff, then why do anything at all? Besides the fact that you might be wrong and kill somebody, why invest your money in a thermal imager if you’re not going to use it for its intended purpose? An infrared thermometer is a lot cheaper and nobody expects you to obtain a corrected temperature measurement. You still need to consider emissivity and spot size ratio and temperature reflect (none of which you may be able to correct for) but you must consider them.
Just like John thinks his own training is close enough to be teaching you guys, close enough doesn’t cut it when you have someone paying you to do a specific job.
You sure can’t read very good John!
When did I say that you taught anybody how to set the emissivity? Or at what setting? I’m saying you don’t teach people how to do it right!
We are discussing Delta T. You know, the difference between two objects?!
We also discussing how camera adjustments affect the outcome of those calculations.
If you have an object with an emissivity of .97 in you use .63 because it’s “close enough”, do you have any idea how close you are to the actual temperature? If you are scanning and oil filled transformer, a 5°F error factor may be catastrophic to your analysis!
So why don’t you “teach us” for a change, in an open forum just how you would go about setting emissivity during an electrical inspection.
anyone figure out what’s wrong with my thermal scans above?
John? I didn’t think so…
both targets are the same temp in image on the right, and the targets should be on both the loaded conductors, instead of one loaded and one unloaded. There is no way to determine the difference between the two loaded conductors.
That is because of the emissivity setting .05 for polished copper.
We are compairing a loaded conductor vs. an un-loaded conductor of the same material. If we want to check load imbalance, we would put them on L1 and L2.
hint: spot size ratio.
Thank you or the reply to my question David. Yes the emissivity will change for different materials and I do change it for different materials. That is also why the image is also wrong and should not be used. The shot is from below and not from the side which changes the aspect of the image. We really don’t know the emissivity of the material we are imaging. If we really want to be accurate a lab would need to be set up to accurately determine the emissivity.
You state that John says a lot, but I have never said any of the things you have stated. Never.
Is that all you have? Instead of teaching us something of value you come out with wild ideas that have to basis in reality.
When your camera is set to a high emissivity then you should only be measuring materials with a high emissivity. Where do you come up with all these other wild rants that have no proof?
Your talking to all of us like we don’t know anything. Please stop speaking down to us. We are not a stupid as you portray.
You continue to take the position that all of us are doing it wrong and you are the only one who knows some of these basic principles like it is some kind of deep science. We all know that high reflection materials cannot be measured the same way as material with high emissivity. What else is new?
I have never said that .97 materials should be measured at .63 emissivity.
Never. Is that all you have?
You are the one accusing, so the burden of proof is upon you. When did you
develop this phobia about me?
Every time you lie, you just prove the point that you cannot be trusted.
Good post. These are basic principles that we teach in our class as well.
What is really funny is the fact that you show the same image with a .95 setting and then at a .05 setting. Then you try to teach us this profound concept that the temperature readings are different. Oh I am so shocked.!!!
Duhhhh. … ROTFLMAO
Do you really think we are all that stupid and don’t already know this?
Mr Evans gave a logical and well stated case for allowing some room for tolerance because we don’t know the exact emissivity of most materials in the field.
Now you show exaggerated images with extreme settings at opposite ends of the adjustment scale and try to warn us to never do this. No one is recommending such extreme settings but you portray them like all of us are complete idiots. Do you really know anyone who is doing this?
I can “spot” it ](*,)
If he is using this in his training he should be thrown out along with the image…if it is used for training purposes all the people that received training on it should get their money back. WOW is all I can say to this one.