Outdoor forced air furnace

I am still in search of a solution to my emergency heat and supplemental heat situation. Just to rehash, I have an old house, and there is not a good place for a wood stove, masonry fireplace or RMH. I have an okay place for a very small RMH, and it may come to that, but a better option is something I could put outside and use to force air inside.

So I found this. http://www.survivalblog.com/2009/01/how_to_build_an_inexpensive_fo.html

It lacks considerable detail in information, so any thoughts on it would be appreciated, but my other question is this. What about building a larger than usual cob oven, only not insulated and add another "story" to it to capture the heat and insulate all around the entire thing?

Have you considered. Or are you able to put it in an attached garage and duct the hot air into the house? The Design you have shown seems to have very small pipes moving the hot air into the house.

There is no garage or basement in which to put it. It would have to be outdoors, though perhaps sheltered.