I was just surfing Woodland Direct and saw this. http://www.woodlanddirect.com/Woodstove-Corner/Circulating-Fans/6-Heat-Reclaimer Has anyone had any experience with one of these? Are they effective? Also- how do they work?- do you need electricity? I'm not sure I'm even interested in purchasing, I was just intrigued by it. I was surprised because I haven't seen these discussed on this forum here at all.