Wood burner

FreeBear

Jeepers_Creepers said: Sterling engines are just fab.  Pretty much useless, but absolutely fab :-).

Far from useless. Stirling engines are used by NASA to generate power in quite a few deep space probes. Philips developed a number of (relatively) high powered engines to be used in generator sets among other things. Some modern designs are very good at using waste heat to produce mechanical energy (think micro electrical generation from domestic boilers).

Run in reverse, they can be used as cryogenic coolers.

If you want a real wacky, zero mechanical component device (aside from a pair of check valves), then look up a fluidyne engine - A neat little stirling engine used for pumping water.

They also make for great little toys to get children interested in science and engineering - Not cheap, and not just for children

Apodemus

Petriix said:

... However, stove fans don't actually shift much air at all in practice. They look really good but have minimal effect.

That's certainly not my experience.  Makes a huge difference in my room.  I often turn the fan through 90 degrees to warm the end of the room where my desk is.  Also helps blow the warm air out into the hall if we leave the room door open and the hall is noticeably warmer than before we had the fan.  Again, as mentioned above, experience may differ depending on the specifics of the house, including the air-tightness and insulation.