I have wanted an outdoor wood stove for several years now, but price has prevented me from committing. While lamenting this fact to a coworker one day he said "why don't you just build your own?" I was intrigued when he told me it was not that hard and that he had built one of his own, and sold when he said he only spent around $2200.
With that I began to assemble materials. Luckily for me I had access to two tanks already, so that major expense was down. I started with a 250 gallon anhydrous ammonia tank that would be my burn chamber and a 500 gallon propane tank that would be my water jacket. I started by filling the propane tank full of water to flush out any residual gas and then cut the end out of it at the weld. I did the same thing with the anhydrous tank. I laid the two ends on top of each other and used the smaller as a guide to cut hole for my firebox to poke through. I then put the firebox end aside to use as a door later.
After that I prepared the smaller tank to go in the larger by welding feet onto the it so it would stay level. In the pic below I am checking fit.
I also welded ports closed and made sure everything was air tight. I welded the ring of the larger tank on the smaller one. I then slid them together and welded everything. This is the part that took the longest. I plugged all the ports but one, and attached an air hose to that one. I pressurized it and sprayed soapy water over everything to check for leaks. Then I let the air out welded the suspect areas and did it all over again. It felt like it took forever. Here is a pick of it hoisted up as I am looking for leaks.
After the two tanks were together I welded in the ports I would need in the water jacket. A fill port, suction port, return port, and a port for the aquastat.
My next problem was figuring out how to seal the door. My first plan didn't work out though. I put metal strapping on the the inside of the firebox and fire gasket sandwiched between.
It seemed like a good idea but ended up being too close together to get the door in so I had to cut the outside strapping off. To get the rope gasket to stay on I tied it in a circle and slipped it around the inner strapping. To be sure I got a good seal against the gasket I bent some 1/2 inch round stock in to a circle and welded it to my door. Here is a pic of my dad heating it with a rosebud to relieve the stress.
So with the seal in place the door was ready to go on. It took us two tries to get a design that worked for the hinges. Luckily we have lots of scrap metal laying around. Using some parts from a field cultivator and an old combine we built a hinge heavy enough to support this huge door.
Once I got the door on there I used shims to get it to close correctly and then slathered the hinge in good Cat high temp anti-seize. With the door shutting now I built a hinge out of an old piece of a planter and some teeth from a harrow.
After seeing that other people that built these insulated their doors I took the left over piece of the propane tank cut it down a little and then welded it into my door as an air gap.
To finish out the door I added the tube to mount my blower and a cover to keep the rain off of it. You can see in this picture where I patched a hole after a mid-build design change.
The door was finished so the last major item to be tackled was the chimney. I decided to use a 7 inch fire extinguisher that I had as a chimney, so I cut a 12 by 12 hole through my water jacket and then tried to cut a smidgen over 7 inch hole in the fire box. I failed. The fire box hole was too big. We decided to break out the MIG welder because of the thinness of the fire extinguisher. This meant we had to spend four times as long making sure everything was clean, and that there were no drafts in the shop since this weld would need to be perfect. We also ended up wrapping some half inch round stock around the hole to use as filler. This worked pretty good, we only had one spot that was suspect. In order to clean that spot up dad pulled out his Air-Arc and I cut the imperfections out and re-welded. I then rolled the tank over and got inside the firebox and welded it there as well.
I then welded the outer portion back on, but due to a lack of the finer points of machine work, I got the hole off and it didn't fit quite right. I just added some filler and welded the gaps. Then came pressure checks and re-welds.
With all the major things done now all I had to do was a little finish work. I am eventually going to add a taller chimney that will sit next to the unit, but until then I need to add a dampener to this one. I did this by taking the end that I had cut off and welding a nut to it and then welding a bolt to a piece of metal that I inserted into two slots cut in the stack. That way I can screw it up and down to adjust draft.
The last thing I did was add a box to put the aquastat controller in.
With everything done that I could get done in the shop it was time to load it up and take it to the house. Here we are loading it on the trailer.
I will post more as I get it installed.
