TEC experts: Whats going on?

Well my non-contact IR thermometer came in the mail today so I decided it was finally time to start playing with the 110watt TEC I got a while ago.

I pulled out an old PS, jumpered it to start and made a little rig where the pelt sits on top of my SLK-900 which sits on top of a Sunon 80mm fan.

I filipped the PS switch and started taking temps. 20°C, thats not too cold. Then it started to jump around mainly staying near room temp. I flipped it over and tried again, this time the centre reached 120°C (I think I found the hot side) but as I moved the sensor beam around the TEC I noticed that the side the black wire attached to was about 80°C and the red about 30°C. I flipped it back over and tried again 2°C, thats ok, but I was hoping for colder. I touched it and it didnt feel cold, it actually felt warm enough that I didnt want to leave my finger there for long. Kind of a 'tingly' feeling.
I kept taking readings and the temps started to rise, I turned it off around the 20°C mark. I then checked the base of the heatsink figuring that it couldnt take the heat which made the TEC heat up. Nope, it was cold.

Anyone explain whats going on / I'm doing wrong?

Alt+0176 = °

the hot side has to be held down with a lotta pressure to dump its heat efficiently

TEC need about 200-300 pound of pressure in order to make good contact. I wouldn't play with the way you are for too long, or you might bust it (120°C is probably near if not over the upper limit).

Ahh, good to know. But why the varying temps across the surface?
My coldplate should be getting here any day now, I'll try again when I can put some pressure on it.

Thanks

Ahh, good to know. But why the varying temps across the surface?

Click to expand...

I would guess that it was due to varying pressure across your heatsink. If it was just sitting there, the weight and stiffness of your wires would have a substantial effect. Try setting something like a big paperweight on it and fire it up for just a second and see what you get.

A pelt might screw with the mind of an IR thermometer quite a bit too. One surface of the pelt is cold, but the other surface which is onlya couple mm away is hot. This has got to cause some sort if issues for the IR sensor.

LOL, The thermometer has issues and screwed up in the mind. ha-ha. That's rich, May have to send it to a therapist or even a support group for deranged thermometers.