I just got myself a temp gun in preperation for my new Uro. I've been building and setting up my new cage and have been using the gun to test the temps throughout the enclosure. I love the gun. it's super conveniant and seems pretty accurate, except for one thing. See, i've got a 3 1/2'x2'x2' galvanized steel water trough as my cage. I built at top for it that has the ability to hold 4 lamps if desired. Right now i've got two 100 watt halogen floodlights towards one side. One is over a raised basking site and the other just a a few inches away but facing towards the center of the cage. When i read the temps under those lights it's great. I get what look to be very accurate readings. However it's my cool side that's the problem. I have a 60 watt ceramic heat emitter that i was thinking of using to keep the cool side in the mid to low 80's and also to keep temps adequate at night. When i don't have that light on the temps on the cool side are in the high 70's. So you would think that if i just turned it on (and mind you it's probably around 18" from the surface) i would be able to obtain the temps i want. Yet according to my temp gun, the temps around that ceramic heat emitter range from the high 90's to over 150 degrees! I know this can't be right. I point it right at the surface only a inch above it and i get something like 120 degress, yet the metal surface is still somewhat cool to the touch, not even warm really. It would have been able to burn my hand at those temps. What's going on? I have yet to test it with substrate but i doubt that will make much a difference. Any idea what's going on. I've had this same ceramic bulb running on a 15 gal tank for a kingsnake and the temps were never even close to that hot.
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Help: Temp Gun crazyness
Replies (3)
I find that you need to point it perfect to get the right temp.I usually have to move mine around alot to find the temperature I want.Are you pointing it at the metal trough?It might be reflecting into the bulbs.
Reflecting INTO the bulbs? Hmmm, good point. I was thinking it might have been that the light being reflected from the other bulbs was somehow screwing up the reading but i never htough about the beam or whatever you call it from the gun actually reflecting off the metal back up to the bulb. But then again, i'm getting strange readings in just about any direction i point it on the cool side. Guess i'll do some more testing.
i am not sure i understand exactly what is happening from your description, but you could be trying to temp a surface with a different Emissivity than normal.
very basically, the Emissivity rating of an object is a measurement of how well it can be temped using an infrared thermometer (temp gun).
95% of surfaces shoot easily and reliably. some exotic metals do not. polished or shiny metals can be difficult to measure as well, and i think that may be what you are running into.
if you paint or cover the shiny metal surface, you can temp it reliably. you can do something as simple as putting a piece of black tape over a portion of the surface. just a couple of square inches will do. the tape (or paint) will come to the same temp as the original surface, and your temp gun will shoot it just fine 
like i said, i THINK this is the problem you are having
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robyn@proexotics.com
