Abstract: An adsorption chamber is included into a conduit which further includes a blower and at least one heating arrangement; check valves are provided in the conduit which operate in dependence on the pressure conditions prevailing in the respective conduit sections. The blower may be operated in two mutually opposite directions, in one direction propelling the medium to be adsorption treated through the adsorption chamber, in the reversed direction propelling a regeneration medium through the adsorption chamber in counterflow. The adsorption chamber may be filled with two different adsorbents capable of adsorbing moisture in different temperature ranges. Thermostats may be provided for controlling the energization of the heating arrangement.