The main innovation provides a significant reduction in energy consumption for heating, namely by more than 60%. Plus, because 100% of the waste air is recycled, the initial investment cost is reduced - there is no need to install an exhaust system or to ensure a forced supply of fresh air when installing these dryers. Furthermore, heat is recovered from the exhaust air and reused. Additional savings come from the greatly reduced requirement for installed power - less than 4 kW compared to 10 - 25 kW for the conventional dryers of this capacity. The extraordinary results of the EVO4 drying technology have been achieved by applying advanced knowledge of air conditioning and heating with heat pumps, and, in particular, the physical properties of substances used as refrigerants in refrigerators and air-conditioned cars. The easy-access machine construction is designed to minimize the time and cost of service and repair.