The regeneration period in BVA model dryers with zero air loss heater, starts by reducing the pressure inside the chamber to zero by opening the exhaust valve. Then, atmospheric air flow is provided to the chamber by means of a blower or vacuum pump and the heaters are activated simultaneously. By increasing the temperature in the chamber to 170 ° C, the water held by the adsorption material is evaporated quickly and thrown into the atmosphere from the exhaust valve. Then, the heaters are deactivated and atmospheric air flow is continued into the chamber and the bed is cooled. The ambient air temperature is very important for the cooling process to be efficient. Special series dryers called blower purge (BP) or closed-loop (BVL) should be used in high ambient temperature and high relative humidity.