Movable fans are used instead of rotary fans in order to modernise dryers equipped with movable fans and dryers with non-structural ceiling constructions. The advantage they have over rotary fans is that they have similarly positive drying characteristics to air wall dryers. Unlike rotary fans, movable fans have greater maintenance requirements due to the constantly changing power supplies and columns of fans in a hot, damp climate. Maintenance expenditure is reduced through use of the latest cable carrier and drive systems.