Peltier Junction Heats, Doesn't Cool

[Mk]

I have a peltier junction rated at 12V and when ran both sides become hot, what's wrong?

[Physics_wiz]

I suggest that you post this here:
http://www.physicsforums.com/forumdisplay.php?f=102

Might also wanna read the thread called "Newbee question" by me :biggrin:
I became interested in pelteirs myself and I might start using them to cool parts of my computer down.

[russ_watters]

I have a peltier junction rated at 12V and when ran both sides become hot, what's wrong? You need to strap a heat sink to it, otherwise there is nowhere for the heat on the hot side to go except over to the cold side. I bought one a couple of months ago to play with and I got two heat sinks with fans and rubber banded them together with the peltier in the middle.

[Mk]

Ahh, thanks guys. Yeah, I have a heat sink already from my gutted Pentium 2. If I turn down the voltage, can I feel the coolness of one side? How can you tell which side will be hot, and which will be cold?

[russ_watters]

If I turn down the voltage, can I feel the coolness of one side? Without a heat-sink, you'll need to be touching both sides the moment the power is applied to tell the difference. But it should work (with a heatsink) at 5V - I used a computer power supply to run mine for testing.How can you tell which side will be hot, and which will be cold? Unless its marked, you have to turn it on to find out - and trust me, you'll know. It takes less than a second for it to cool 50+ degrees.

[Mk]

Is there a maximum heat output? Can I turn the voltage up past 12V?

[mecj5]

Is there a maximum heat output? Can I turn the voltage up past 12V?

Most put a thermal switch in that cuts out at 150 degrees F. yes you can go past 12 volt NOT ALL but most 12 volt pelter junctions have a absolute max voltage input of 15.2 volts