An oversized fan in a small bedroom feels like a wind tunnel; an undersized fan in a living room does nothing at all. Sizing is straightforward.
Match blade span to room width
Bedrooms under 3.5m generally suit 40 to 46 inch fans. Living and dining areas typically need 52 to 60 inches. Long rectangular living rooms often work better with two smaller fans than one large one.
Mind the ceiling height
Blades should sit at least 2.3m above the floor. In flats with false ceilings, confirm the finished height before choosing a downrod.
Why DC motors
DC motors draw a fraction of the power of AC motors, run more quietly and offer six or more speeds with reverse mode for the rainy season.