Simple, smart & efficient : Ecofan Self Powered Woodstove Fan
by Erwan Pianezza, Locronan, Brittany on 07. 3.05
Would you need more than heat during cold winter nights when your ultra efficient woodstove (Rais, Topolino, etc...) is running at full capacity ? Well ecofan won't require more wood but will add efficiency to the heating process as a whole by distributing hot air faster, without asking for plug, batteries or any kind of outsider's energy : Ecofan runs silently by itself when left at the top of the stove, wings powered by a side effect of the heat known as the Peltier effect. The hotter your stove, the faster it spins.
Even though simple in its function, the technology inside this little marvel is more complex than it seems. Here is a sample explanation of the Peltier effect that powers ecofan as temperature on the top of your woodstove climbs to hundreds : at the same temperature, two dissimilar semiconductors (p-type and n-type) connected together establish a static electric potential difference. With the introduction of a temperature difference heat flows across the joined semiconductors which in turn permits electrons to flow. With the electron flow or current comes the ability to power electrical devices such as the fan's motor (source : caframo shop).
Ecofan is high quality : body is molded out ouf black brushed aluminum finish, blades are made of brass. The Canadian producer promises a power to move 150 cubic feet of air per minute (CFM).
Having been looking around stove shops, I found the ecofan in a local chimney retail in Quimper, Brittany : that's a sign, if they've got it here, they've got it everywhere, yes that gadget is available worldwide, just check internet shops or ebay.
There is a woodstove fan around that comes without silicon: http://www.moderntradingpost.com/freebreeze/index.html
The cost is a bit higher (~ $200) but it is a real STIRLING engine.
Could a redesigned one of these be used to vent an attic? Yes, I know they make solar powered ones.