The units of the RPL series, suitable for horizontal installation, are equipped with a crosscurrent heat recovery unit with aluminium plates for effective heat exchange, aeraulic by-pass with the free-cooling function, and synthetic filters in both internal air intake and external air emission. The recovery unit can be equipped with a post-heating system with water coil or electric resistor, suitable also for the antifreeze function. Double suction centrifugal fans or plug fans with phase cutting device paired with AC motor. Some sizes come with radial fans with EC motor and speed regulator.