Here I'll try and go through how I built the stove portion, bear with me as this is like the second page I have authored in about 8 years ;-)
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I Had an old 60 gal electric hot water tank that I cut a section from to make a snow plow blade for my riding lawn tractor. The tank itself is about 20" diameter and just under 5ft in length. First thing was to shorten it to an overall length of about 26"and patch missing section. The tank had a concave bottom so I cut that end off first with a torch, shortened the body, flipped the end around and welded it back in place so it was now convex.
The top of the tank is what I wanted to use for the door end, it has 2 threaded fittings in it and I wanted to use those holes for air vents if needed. To facilitate working inside the shell without having to work through the door I decided to remove the entire front bell end.
The way these tanks are built, they form and weld a large tube first then press the ends inside and weld those in place. There's usually about 1/2" of overlapping material of which I take advantage of. To allow easier alignment later for reassembly, where the tank wall and end bell overlap, I drilled 2 1/8" holes about 1/4" away from the factory weld. To do the majority of the cutting I used a cutoff wheel on a die grinder to cut through only the outer layer where the tube and end bell overlap, cutting right next to the weld holding the end on. If cut in this manner you can pop the bell in and out to make any future design changes easier.
While the front bell was off I marked out a doorway then welded on some rudimentary hinges. The hinges are extended out a bit, this allows the door with an inch and a half of refractory to open on a wider arc.
I added two 2" extensions to the inside of the air vent holes to act as forms and support for the refractory, then I cut out the door with the die grinder. The pre-made hinges assure a nice straight fit of the door.
The shell the had some anchors welded inside the circumference and to both end bells to it to help retain the refractory material, I did some calculations on the thickness of the ceramic cloth insulation and overall refractory thickness I wanted and made the anchors out of 1/4" soft steel rod in a sort of "V" shape, so that the top of the anchor was even with the top of the refractory. I did this so if I needed to add another layer of refractory I could weld on more anchors to the tops of the existing ones. A chimney hole was cut in the back and a short stack of a 6" diameter was welded on, then just in front of the chimney I drilled a 1/2" hole and welded a small pipe inside to poke the nozzle through.
The shell was then was lined with a ceramic cloth to allow for different expansion and contraction rates of the refractory (high temp cement) and shell from the hot/cold cycles. The refractory was obtained from a local boiler repair shop and unfortunately is one of the more expensive aspects of this project but was a necessity as I wanted to be able to have this stove indoors and not have a shell temp of 1800°+ F to get burnt on.. Before lining the shell with refractory I cut a couple of holes for the necessary plumbing and a form was made for the inside diameter to retain the refractory. I had to cut some cheap laminate material to go between the anchors to cover the ceramic cloth insulation from completely collapsing while tamping in the refractory.
Tamping in the refractory was an adventure all in itself, but once done it looked pretty sharp. The refractory I used you have to tamp in place, which basically means you pound it till it stays. I started with the back and laid in a 1 1/2" layer and let it set for a day, then I rolled a form out of sheet metal that just sat inside against the tops of the anchors. Where the form overlapped itself I screwed in one sheet metal screw to keep it from collapsing while tamping. If you choose to duplicate my efforts you should consult the supplier for specific instruction on how to apply the refractory as different brands will have different instructions. There's also a pour able version which I would consider if I were to do this again.
After the refractory was semi-set I brought it outside and built a small fire in it to help the refractory cure. Once cured enough I removed the forms and fitted the inside of the tank with 50 feet of 1/2" copper tubing (the length of which I have determined is not enough) and plumbed the ends through the afore mentioned holes.
I am still deciding on how much storage water to use, I have another 50 gal hot water tank that had rusted a pinhole out and I braised it up, Brass is more then adequate as I don't intend to run any pressure beyond 20 psi if I decide to seal the system. I'm not sure if I want to try and use the tank as heat storage or go with a smaller tank capacity with less reserve and a faster warm up.
For circulation I am running a 1/25 HP Taco radiant heating circulation pump, so far with only the 50 ft of copper its more then enough, as a matter of fact to regulate the temps I have a gate valve before the stove to slow the flow down so its got time to pickup the heat. Hence the determination of not enough copper tube.
I think this should cover it for the stove body. If I've missed any details that you would like to see here, drop me a line and I'll do my best to accommodate.