For moderate potential hot spring, the surface water temperature between 60-80ºC has been also suggested to use in drying process as shown the system descriptions in Figure 5. The geothermal drying room is developed to dry the agricultural products in a well-insulated room. Mae Jan hot spring, Chiang Rai, Thailand as shown in Figure 6(b) is also used to test the heating performance of drying system. The descriptions and photographs of the testing unit are shown in Table 3 and Figure 8, respectively. Finally, the testing results of prototype will be used to predict the guidelines of the geothermal drying room in Thailand.