Hello, so I decided to make a very large wood stove to heat my shop. The idea behind the project was to use only scrap I had laying around (don’t mind how rough it looks it will get prettied up when it’s done haha) which led to using an old water tank which is 5’ long and 3’ In diameter. For air vents there are 2 2” pieces of pipe on either side of the door. The only chimney it has so far is a 3’ piece of 6” pipe with a dampener in it. I also welded a small piece on channel steel in the stove just below the pipe to try and retain more heat. I wanted to do a burn in it before plumbing the rest of the stove pipe and putting the stove in but I’m having a problem with keeping the stove lit with the door closed. It runs fine with the door open but dies down to only embers with the door closed and both air vents wide open than when opening the door it bellows out smoke until the fire starts up burning again 10 seconds later. Is it just not getting enough air to the back of the stove? If that’s the problem would putting another air vent into the back of the stove help? or putting a pipe from the front of the stove to the back with air holes drilled fix the issue? Thank you in advance everyone. This is the first stove anywhere near this size I’ve made (and out of scrap)
I am no expert, but that is a huge stove, and yet the intakes are sized like the ones on my far smaller old Fisher, a mama bear...
The symptom sounds like lack of air.
But, since you do not have enough chimney rise to create a strong draft, it is hard to blame only the intakes.
And finally, I am pretty sure you will need a substantially larger chimney than that. 6" is only used on mediumish stoves, yours is *much* larger than anything I have seen with 6". I have no idea if you want 8, or even larger, though...
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That's a good looking stove. Obviously, you've diagnosed the problem -- there's just not enough draw.
If you could make an adjustable vent on the front door or on the bottom of the barrel, you could slide the vent open or closed as needed, that might do the trick.
One of the issues might be the large size of the burn chamber. Fresh air has a higher percentage of oxygen (O2), whereas spent air from the fire is full of carbon dioxide (CO2). That extra carbon atom makes it heavier, sinking down and smothering combustion. Your fresh air may be rising above the layer of CO2 that sinks to the bottom of the chamber -- it just floats up over the top and goes right up the chimney. Some sort of baffle at the top of your burn chamber would force the air to mix a bit, or reconfiguring the chimney so it draws from the bottom of the back of your burn chamber rather than the top would draw air right though the burn zone rather than up over the top of the coals.
Short of that, perhaps lighting the fire right at the front of the burn chamber next to the air intake would help. The warm CO2 would rise and go out the chimney, and hopefully not smother the fire that is being fed by the fresh O2-rich air.
Best of luck.
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i have one kinda like that in wood shop, mine has 2 barrels welded together end to end, you need a grate at the bottom so air can come from under what your burning, chimney has to be taller than top of building.
for a grate repurposed cast iron barbque grill grates are ideal. is that aluminum or steel you have lined the barrel with, you dont want to use aluminum inside a wood stove. if aluminum starts to melt and burn the flumes will mess you up. I had a friend die from using plasma cutter on aluminum in his shop.
posted 1 year ago
Thank you everyone for the reply’s. I added a grate that sits about 3” high and added another air vent made from 2x4 steel that runs under the grate until around the middle of the stove. Also made a makeshift baffle to try and force air downwards towards the fire. Last change was another air vent on the door. The stove burns good now especially when I hook a blower onto the 2x4 vent to really heat it up haha
Rocket Mass Heater Plans: Annex 6" L-shaped Bench by Ernie and Erica