How can I know which side of the TEC is Cold and hot side?

For the standard P&N TEC modules, the default cold side will printing Model No. and lot Number.

When the hot and cold sides of TEC is unknown, connect the red wire to the positive pole of the power supply and the black to the negative, and touch the surfaces of both sides. The side which feels cold will be the cold side whilst the other for heat dissipation. Important reminder: the time cannot exceed 5 seconds; otherwise the TEC will burn out. For example: 4V power is good enough to test 127 pairs of TEC.

Please note that all thermoelectric module/ peltier module provide by P&N Technology, the polarity can be changed. When change module's polarity, the cold side and hot side of TEC will also change.

Please feel free to consult us if you need assistance when test or assemble a TEC module.  We have professional Thermoelectric engineers here to support you!