coaledsweat wrote:I wouldn't say they are popular, especially with the neighbors. They aren't very efficient and consume a lot more than they are worth. If you have troubles, your going to be out there freezing too. A homes heat source should be in it, the losses will heat your house, not the neighborhood. They are also pretty expensive for what you wind up with if you ask me.
How about this idea.
I saw it years ago in the Upper Peninsula of Michigan. It was designed to burn wood pallets, but I think the concept could be easily modified to burn coal.
This gentleman's "outdoor boiler" was the size of a small shed - about 8'w x 8'h x 10'd as I recall. As I said, his version was designed to burn pallets (which the owner had plentiful free access to from his workplace) so it had a large firebox (3-4"w x 5'h x 8'd), and the firebox was surrounded (encased) by 18" to 24" of sand. Copper water pipes ran through the sand. The purpose of the sand was to trap and hold heat. The water tubes absorbed the heat from the sand and brought it into the house, similar to the standard outside boiler. But the owner told me that he would fire the thing once a day, usually when he got home from work with about 8-10 pallets in the back of his pickup. He wouldn't bust them down or anything, he pushed them in whole (hence the need for the large firebox), sprayed a little bit of diesel fuel on the ends of a couple of them to light them, and then closed it up and walked away. The fire would burn hot for an hour or two and go out, but the sand absorbed enough heat to last the whole night and the next day until he fired it again. I know there was some baffling in the firebox with some dampers to allow a direct draft/vent when you first lit the fire. Once it was established, you closed the dampers and the smoke/exhaust had to travel through the baffles which allowed for more heat to be absorbed. I remember that the owner said he had some issues with creosote build-up in the chimney because the smoke was relatively cool by the time it reached the chimney - he said that he just kept the dampers open once a month and let a good chimney fire burn it out.
Now I was thinking that if I burned coal instead of pallets, I could build something similar, but not as big.
I wish that I could remember where I saw this boiler. But alas... it was years ago when I was in college, and all I can remember is that it was in the U.P. somewhere along the Lake Superior shoreline! (Dang Sometimers' Disease...
) Hmm... seems like there was 2 seperate water loops - one that was in direct contact with the firebox and distributed the heat more completely through the sand, and the second that brought the heat into the house.