Abstract: A ventilator having a housing containing a plurality of electric fan units, each of which is mounted in an air channel provided in the housing for directing air through the ventilator. Within the housing, the air channels are formed by cowlings which surround the individual fan unit. The ventilator also includes a filter element mounted on the housing to filter air moved through the ventilator channels by the fan units. The ventilator further includes a controller featuring a plurality of switches and an electrical network for electrically connecting the fan units to a source of electrical power such as a wall socket. The switches of the controller are manually operable to permit selective activation of the fan units so that multiple modes of ventilator operation may be selected. In accordance with the multiple modes of operation, air may be filtered and moved through the ventilator either in a first direction or a second direction or in both a first direction and a second direction and circulated.