Re burn tubes in a barrel stove???

[thoner7]

I'm wondering if it's ever been done. From what I can tell, the re-burn tubes and a baffle of some kind are needed and that's all.

It may not last forever but I'm wondering if two lengths of black pipe with 1/4" holes drilled in them, inserted at the top of the barrel, would work? Then with 2 elbows and another length of pipe, run those on the outside of the barrel back towards the front. Air gets pulled in the 2nd tube, heating up, before getting shot into the barrel and burning.

A simple piece of crimp together stove pipe would act as the baffle and rest just above the tubes.

Do I understand the engineering behind this design correctly? Would something like this work??

 

[Riddlefiddle]

It just might work.

 

[begreen]

Might also get too hot for that thin metal.

 

[blades]

your sorta close, except that in the reburn area by the tubes it is going to be around 1100 so the piece of sheet metal isn't going to last long. Generally on top of the tubes you would place apx 1/2" insulation board with a rating around 2000. This extends completely across the top of the burn chamber with apx a 1" gap (minimum) opposite your exhaust port. You need to mount the tubes low enough to accommodate the board and still leave a chamber above for the exhaust gases to flow through. most units will have a baffle extending down a couple or more inches in front of the exhaust port using the exhaust flow as a reference for what is front and back. Baffle extends about 2/3 of the way across this area, sides are open and the baffle needs to be about an 1" short of the boards or perhaps a bit more. ( basically a flame arrestor)
Black pipe might not be able to withstand the temps and droop. 1/2" dia pipe 1/8" holes for the tubes generally fed from a single intake manifold. Prior to the epa stoves out now the 2nd air was controllable with some sort of simple damper on it just as the main combustion air is controlled. likely not a lot of info on this on the net from the 90's and early 2000's due to the huge hacking that went on a number of years ago. A lot of conversions/ add ons were taking place back then. Mostly on conventional wood stoves where the typical top plate of the stove would be 3/16" -5/16" thick .

 

[bholler]

I'm wondering if it's ever been done. From what I can tell, the re-burn tubes and a baffle of some kind are needed and that's all.

It may not last forever but I'm wondering if two lengths of black pipe with 1/4" holes drilled in them, inserted at the top of the barrel, would work? Then with 2 elbows and another length of pipe, run those on the outside of the barrel back towards the front. Air gets pulled in the 2nd tube, heating up, before getting shot into the barrel and burning.

A simple piece of crimp together stove pipe would act as the baffle and rest just above the tubes.

Do I understand the engineering behind this design correctly? Would something like this work??

If you do accomplish secondary combustion I am afraid you would quickly burn through the thin sheet metal of the barrel. Why not start with something more durable

 

[thoner7]

If I could find something more substantial I would use it but untill then I'll use a barrel. I was hoping to find a ~70 gallon propane tank to cut up but no luck.

It's only a shop stove and won't be used very often.

 

[EatenByLimestone]

Craigslist often has lots of old stoves for cheap.

 

[bholler]

If I could find something more substantial I would use it but untill then I'll use a barrel. I was hoping to find a ~70 gallon propane tank to cut up but no luck.

It's only a shop stove and won't be used very often.

Why not find a stove?

 

[Corey]

your sorta close, except that in the reburn area by the tubes it is going to be around 1100 so the piece of sheet metal isn't going to last long. Generally on top of the tubes you would place apx 1/2" insulation board with a rating around 2000. This extends completely across the top of the burn chamber with apx a 1" gap (minimum) opposite your exhaust port. You need to mount the tubes low enough to accommodate the board and still leave a chamber above for the exhaust gases to flow through. most units will have a baffle extending down a couple or more inches in front of the exhaust port using the exhaust flow as a reference for what is front and back. Baffle extends about 2/3 of the way across this area, sides are open and the baffle needs to be about an 1" short of the boards or perhaps a bit more. ( basically a flame arrestor)
Black pipe might not be able to withstand the temps and droop. 1/2" dia pipe 1/8" holes for the tubes generally fed from a single intake manifold. Prior to the epa stoves out now the 2nd air was controllable with some sort of simple damper on it just as the main combustion air is controlled. likely not a lot of info on this on the net from the 90's and early 2000's due to the huge hacking that went on a number of years ago. A lot of conversions/ add ons were taking place back then. Mostly on conventional wood stoves where the typical top plate of the stove would be 3/16" -5/16" thick .

Pretty much this. The idea is to create an insulated 'firebox', build a lot of heat, then inject hot oxygen/air into that mix. Problem with a barrel stove is that it's pretty much guesswork as there is no 'production model' to start from. So how much air, where to inject, how to build firebox, etc - you have to come up with all that. For DIY, I'd strongly recommend valves/gates for the various air inlets - that way you can 'tune' for maximum efficiency. ...and use stainless steel for the burn tubes - even thin wall stuff will last for ever.

But that brings up the next issue... inside a barrel, you have no idea what is actually happening and if you open up the door to look, you automatically kill what ever combustion was going on. So now you need a glass door, too!

 

[electrathon]

Coming from someone who likes barrel stoves, I personally do not think this is a good idea. If you do it, make sure you are using a heavy walled barrel (there are a lot of different thicknesses of them),