another option i learned from a wise old-timer at our deer camp is to use a coffee can with charcoal in it, there is a little smell at first, but after that its basically odorless. probably wouldnt do too much for heating the entire blind and keeping it warm, but for warming up the hands, face, etc, it works quite well. somethin to try before goin out and spending a buncha $ on a mr heater and propane.