Originally Posted by STANIMAL
Just use an electric heater ?
1500 watt electric is about 5000 btu. The pictured heater is probably 50000 - 75000 btu. The difference is huge.
There are vented propane furnaces/heaters but I don't know of any that are portable (it is a good idea, though).
I have a Kerosun vented kerosene heater, but I don't run it much - the floor stays so cold it somehow doesn't seem worth it. I use the Halogen worklights for light and heat - right on the hands, where it counts (or stay inside near the woodstove).