The module is composed of 126 couples.To supply heat energy to the hot side of TE modules, a thermo coax electric heater SEI 10/50 is used providing a continuous power of about 150 W. An aluminium heat sink with fins was mounted on the cold side of the TE modules. Thermal grease is used to enhance heat transfer between the surfaces. Two different cooling systems are tested to maintain a constant temperature on the cold side [12,13] (an electric air fan or temperature controlled cold water).Best results were obtained with cold water. Temperature measurements were made with type K thermocouple 10/100 mm to avoid heat shunts and were placed in different parts of the modules. The whole device was enclosed in stone wool for insulation.