Fresh air box with air filter, heating coil, and sound-absorbing inner lining. The heating coil features a closed tubular jacket heating element made of stainless steel with a low surface temperature for heating the outside air to the specified setpoint temperature. Simple operation is facilitated via a control element, which includes a 10 m cable. Filter monitoring is possible through a pressure differential switch (accessory). It has a large-surface M5 filter for long maintenance intervals. The flat housing is made of galvanized sheet steel, thermally and acoustically insulated on all sides with 30 mm mineral wool. For service purposes, the cover can be easily opened via two safety screw locks. The unit has protection class IP 44. It includes a low-noise and powerful radial fan in a spiral casing. The EC motor/impeller unit made of galvanized sheet steel is accessible for service purposes. It is driven by a maintenance-free, energy-saving EC external rotor motor in IP 54, with sealed, low-noise ball bearings that have long-term lubrication. Operation of an EC exhaust fan as required via remote control is possible.