The SparkFun COM-10080 is a thermoelectric unit with both a heat / cold functional module.

Thermoelectric coolers (TEC or Peltier) create a temperature differential on each side. One side gets hot and the other side gets cool. Therefore, they can be used to either warm something up or cool something down, depending on which side you use. The Thermal Tape listed below works very well to attach heat sinks to the hot side.

This Peltier works very well as long as you remove the heat from the hot side. After turning on the device, the hot side will heat quickly, the cold side will cool quickly. If you do not remove the heat from the hot side (with a heat sink or other device), the Peltier will quickly reach stasis and do nothing. We recommend using an old computer CPU heatsink or other block of metal to pull heat from the hot side. We were able to use a computer power supply and CPU heatsink to make the cold side so uncomfortable we could not hold our finger to it.

Features:

• 40 x 40 x 3.6mm
• lmax - 7A
• Umax - 15.4V
• Qcmax - 62.2W
• Tmax - 69C
• 1.7 Ohm resistance
• 127 thermocouples

Learn about TECs (Tom's Wiki)

Learn about thermoelectric effect (Wikipedia)

Example Arduino code to control a Mosfet for power