India, Aug. 13 -- Every Indian home runs a fan for most of the year, and almost all of them still spin exposed metal blades a few feet above head height. It is a compromise households have simply accepted. Bladeless fans change that equation by moving air through an enclosed impeller or blower instead of open rotating blades.

Bladeless fans in India now span a genuine range, from tower fans around Rs.4,500 to ceiling-mounted systems that double as lighting fixtures. The category has moved from curiosity to a real choice, and the price of entry has fallen sharply.

But buying one is harder than it looks. Several fans marketed as bladeless are simply tower-shaped housings with conventional blades hidden inside. The right bladeless fan for ...