Steel cooling fan spins on high heat source of wood stove

As a child, I always walked down to a friend's house down the dirt road to play at their hobby farm. They built a beautiful log cabin and even used a wood fire oven to heat the first and second floors. No furnace. His father was an arborist professor at the University of Minnesota.

I remember seeing something which I am not able to find online. From what I recall, it was an all steel fan blade with a 1/4" plate holding it. As soon as you placed it on the hot stove, it spun. I guess its purpose was to circulate heat off the stove and into the room. I'm sure there was more to it.

Does anyone know what I'm talking about?

I've always been interested in making wood fireplaces and stoves more efficient at spreading heat in a room through either this type of fan along with long finned heat sinks to radiate the heat.

That was likely a stirling engine fan. They use a heat differential to turn the motor... the hotter the surface, the faster they turn. They are available online and can be good DIY projects if you have the tools and time.

Yeah. They are a good way to distribute the heat away from the stove.

This is a fancy, high-tech version.


A simple fan blade (with heat tolerant bearings) could also be utilized.
I would imagine that the more pitch the blades had, the better it would work.
Hot air rises, and as it passes the blades, it starts to push them around.
The greater the heat rise, the faster the blade should turn.

The photo above is from http://www.chimneysweeponline.com/ecofan.htm who sells that model.
The motor is designed to generate electricity from 2 dissimilar semiconductors (Seebeck Effect).
Once heated, they put out enough electricity to run the fan.

As illustrated here (also from the chimneysweeponline site:

These fans use a thermocouple to power the fan. They are also now available for gas stoves.

A thermocouple uses the heating of dissimilar metals to create an electrical current, which powers the fan.