Designed for high-efficiency wood stoves, these ingenious stovetop fans are completely silent and cost nothing to operate. Based on a phenomenon known as the Seebeck effect, Ecofans use thermocouple technology to generate an electrical current by exploiting the temperature difference between the stovetop and the ambient air. The fan speed varies with the temperature difference (greater difference, greater speed), quietly moving warm air from the stovetop. Made largely from anodized aluminum, they are an efficient way to disperse heat.