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Post by Donkey on Dec 8, 2009 17:52:40 GMT -8
Crap... I'm at a loss too.
4 1/4" above should be PLENTY, 2" all 'round is good too.
That leaves the space below the barrel, where flue gasses re-direct into the flue. It can be a funny shape and it's a classic place to mess up. Though it sounds to me like you're careful enough to have gotten this right, or at least close enough.
One more outside possibility. Did you widen the burn tunnel under the heat riser? I did this once as an experiment. widened it suddenly and drastically, it killed the stove very effectively.
It's something that you probably couldn't do on accident.
That's just about the last thing I got.. Higher chimney won't hurt but this thing should be blasting as it is.
I guess I'm stumped.
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Post by jgreen on Dec 9, 2009 14:53:25 GMT -8
Morpho. I'm gonna throw my 2cents out really quickly. I don't have enough internet time right now to reply in the kind of detail I'd like to, or to go back and re-read the rest of this thread. But my understanding is that you've got a stove that isn't drawing strongly enough to keep the flame from climbing up the fuel and then eventually smoking you out. And that you've troubleshooted everything and you don't think there are any constrictions in your stove blocking the flow. If any of that is wrong or if my response has already come up, then excuse my redundancy. I'm not super familiar with this thread. With that said, the first stove that I built had a similar situation. No constrictions anywhere that I could find and it ran fine at times but at other times it would climb the fuel and smoke us out. It didn't seem to have a whole lot of consistency to it either. The smoke outs didn't correspond with wind outside or the height or type of fuel. What we eventually ended up doing (which was our own personal discovery of a principle I've seen donkey writing about) was covering the entire feed area with a piece of sheet steel and leaving just a very small gap for air intake. This stove has a smaller metal barrel surrounding the feed tube (as per the design in the rocket mass heaters book). The picture below shows the metal barrel, but not the sheet metal cover (I don't have a picture of that yet). The sheet metal sits on the rim of the barrel surrounding the feed tube and the gap is created by sliding the shaft of a fireplace poker tool in between the rim and the sheet metal. The fireplace poker tool is used in pushing wood down and jiggling the fire when necessary and it just so happens that by storing it in that location, the right amount of air intake is created for a good draw. So my suggestion, if you haven't already tried is to install a fireproof container (like a barrel) around the actual brick feed tube and control the amount of air allowed to enter into this area. My experience with this particular stove that I built was that with the sheet metal covering most of the opening to the stove, even when the fire creeped up the fuel, the smoke was contained within the small barrel and eventually was pulled into the fire. Since using this setup, the smoke has never come back into the room even if the barrel is full of smoke.  |
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morpho
Junior Member
Posts: 50 
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Post by morpho on Dec 11, 2009 10:15:01 GMT -8
Hi,
Tin foil!
Yes you heard me tin foil.
After some time sitting and pondering and watching the creep etc.
I'm not sure why or what is happening with the air flow but it seemed to be wanting to enter the tube only at the front.
I made a large tin foil wall and placed it at the front of the feed tube. (closest to the heat exchange barrel) This effectively forced the incoming air to have to come in further back in the feed tube. It has helped a lot. Its not perfect but a big difference!
Jgreen:
Yes you are right the feed tube barrel was the trick....I just needed to extend half of what was already there.
I have yet to try the lid on it.
Ok...one step closer to heating without panic.
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hpmer
Full Member
Posts: 240
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Post by hpmer on Dec 11, 2009 16:01:31 GMT -8
Morpho,
You indicated you have two inches between the riser and the barrel. Some barrels have indented ridges running around the sides and Donkey has indicated the ID measurement should be taken from the innermost part of the indent. I wonder if, after factoring the indents into the equation, if you actually have less than the two inches and that is where your restriction lies? I agree there must be a restriction somewhere since you are getting such little heat into the downstream pipe even after a lengthy burn.
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morpho
Junior Member
Posts: 50
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Post by morpho on Dec 12, 2009 18:35:21 GMT -8
Hi hpmer,
The measurement does not include the ridges. (Though I almost made that mistake)
It is running super good now.
I have had 4 burns since I added the baffles and it is humming along very nicely.
I have my feet pressed up against the cob right now as the thermometer outside reads -28
Ahhhh sweet victory!
I would like to thank every person on here who even gave the slightest thought to my problems.
I think it has been a combination of a lot of different advice that made it all come together.
Thank you.
My wife has insisted we put one in the house. (she loves to play with the fire)
After all the trouble, I thought it might not make the cut and would be relegated to a nice idea that just didn't work as I had hoped.
...I have to go....the stove needs some more wood.
Later!
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Post by jgreen on Dec 13, 2009 13:26:41 GMT -8
Sweet. Congrats Morpho. I remember all the tweaking I've done and the sense of satisfaction that comes with getting it right. Glad that its a keeper!
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morpho
Junior Member
Posts: 50
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Post by morpho on Dec 17, 2009 19:30:01 GMT -8
ha!
Thats the funny part. I have to knock the whole thing apart in a few months!
A lot learned though for the final one in the new house.
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morpho
Junior Member
Posts: 50
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Post by morpho on Mar 31, 2010 9:39:57 GMT -8
Well, Winter is over and my little experiment was a success in the end.
I'm kinda sorry to see the temps coming up as I have enjoyed the collecting and burning of wood a lot.
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