I have a non-electric propane heater on pilot for power failure.
Ony problem - without any circulating fans all the hot air shoots to the roof and cooks anything there whilst leaving a few feet down cold. Last time I spent a stimulating three hours in there flapping a piece of cardboard up and down.

Any suggestions for how to keep air circulating automatically for a few hours whilst the mains is off? I was thinking along the lines of a DC fan and 12V battery on trickle charge.