Three different designs for adsorption calorimeters are presented, which use sensors based on the Seebeck effect. The noises of signals with respect to the baseline are evaluated on each one of the builded equipment and the detection limit of the thermal effects is expressed in µWatt. It was determined that the different designs and working conditions affect the baseline noise and the detection limit. Values of the noise in the baseline are between ± 100 µV and ± 0,5 µV and between 887,2 and 24 µWatt. These values allow making measures in the solid-gas interphase with very good precision.