The model number and serial number of this product can be found on the bottom of the unit. CADR**:. Room size. 205 sq ft (19 m2). Air changes per hour (ACH)**Support for Blueair Classic family air purifiers. Browse Classic FAQ, product manuals and more, and get in touch with our US-based Customer Experience team. Before using Blueair Classic 200 series, please read this user manual carefully. The Blueair 205 and 280i air purifiers are electrical appliances. Blueair Classic 500/600 Series. Feel right at home. Blueair Classic 205 Our air purifier replacement filters use a revolutionary combination.