craig offret

I think Glen is right on target with the 50% scale down on heat.

I took the bricks apart this morning in the daylight for analysis and I don't think I'm as impressed as I was initially, except for the burned board on the deck.

I fired it up without the tank and i can't get any flame in the riser, it seems like a large majority of the heat is being dissipated in the burn chamber.

Plus I couldn't get the tank hot enough to melt the stickers off the side. I think this configuration might work if I was trying to heat a 6x8' bathroom or something

Wood so far has been 1x2" kiln dried fir so it burns and feeds itself real well as it is smooth a couple 18" sticks are about all that fits in the feed tube, Im sure things will change when I try to put split alder in there. I was really trying to make a dragon heater and send the fire out the riser to bells, its challenging to put a refractory top on the bells as its so non structural an delicate. I went with the tank as it was a pretty easy solution.

For now I'm pretty versitile as nothing is cast into place. Im going down to the cabin tomorrow to set it up I am set up to put in some type of mass but I haven't decided yet, for now I know I can capture heat for mass around the burn chamber but not much else, I can imagine how terrible the tank will look if I try to wrap it in concrete or brick. Im going to try to make some castable refractory from all the dust I collected from the bricks.

I just hope it puts out 25k btu or better or Im going to have to Scale up to 4" I burned it out on the porch for 3 hours I had to add sticks every hour or so. I think I have the arrangements of feed, burn, riser correct the fire runs as its supposed to. After the cool down I can see the sweeping 90 Upward has seen the highest heat as the bricks are in that area are discolored the most. I could never get it hot enough to burn the paint off the lower half of the tank. I might do it manually with a bonfire.

I am only heating a 16 x 16 cabin with it, I was thinking of putting the exhaust through 2 masonry bells... Dragon heater style. I just wish I could do something with the tank to dress it up a bit.

for now I think I will wrap the burn chamber in bricks for thermal mass storage. my goal is to exhaust cold air

I am really happy with the zero smoke output though, and zero ash.. it is quite impressive as this is my first rocket project..

The trial burn on the porch went well, it only fits a couple 1x2s in the feed chamber at a time, it heated the tank hot enough to burn the paint off after a couple reloads of wood, it gets pretty hot and there is zero smoke when its running right, I tried to open the front and load up the horizontal chamber and it smoked for a bit, If I just keep putting the 1x2s down the feed inlet and let them consume it runs smokeless, the exhaust isn't really that hot, maybe 90-100 degrees maybe. the fire bricks hold the heat in pretty well.

I used a 7 gallon air tank as the drum, I offset the riser opening to one side to make room for an exhaust out the bottom. This saved quite a bit of effort trying to seat the bottom of the drum on the bricks, the square opening to slip over the riser is pretty tight so there isn't any real exhaust leak to speak of.

I used insulated fire bricks they are lightweight and very easy to cut and shape, so the entire Utube and riser are cut out of the bricks, I think it took less than 10 to make the firebox


The input tube is 6" long 2.25 x 2" opening

The horizontal burn chamber 9" long 2.25 x 2.75

The Riser 21" long 2.5 x 2.75

The exhaust 3" diameter

I have researched these heaters for a long time, I got so much info from this forum.

I Really wanted to make a very small version of the rocket heater, I really am not to fond of having a 55g drum in my living room i think it looks kind of janky.

Using zero's fact based formulas I scaled down the size of my heater to less than 3"