We have been dinkin with this thing a few days now. I am getting up to 800 on the barrel top and it is making a wooshing rockety noise (not as loud as some ive heard) but it seems to leave a lot of coals in the batch box. It starts and drafts quite nicely, I'm very exited about that.
My dimensions are as such:
Jtube, 6" wide X 18" long one fire brick high horizontally laid, I'm guessing 4"
riser 6"ID 8"OD 26.5" tall
barrel is 25g at 28" tall
exhaust is 6" around 18' long with little mass as of yet
Heres my questions.
1. Does it take time to "break in"?
2. are the coals normal or should it burn the wood completely?
3. It has a little poof back of smoke thats pretty steady. Ive made some dakota fire pits that didnt do this.
Thanks for the help in advance. I'm comfortable with it right now as its in a green house but I plan to build one in the house eventually and I want to get it dialed in.
Hi Jim; Do you have a builders guide ? They really help.. 700-800 on the barrel top is good, after its all warm and dry it should not puff up... coals should burn themselves down to ash. Sounds to me like your burn tunnel is to low and depending on where you measured your burn tunnel length it could be to long. A 6" system should be apx. 5.5 x 5.5 all the way to the riser. I would also use a taller riser... mine is apx. 50" on an 8" system. I suggest buying the book and reading up before building in the house.
Thanks Thomas! I have Ernie and Ericas "as built Guide" and a few other things I have downloaded. I'm a kenesthetic learner and suffer from "squirell" so I can only read so long. I needed to build something! I'm on board with everyone here as to why these aren't in every wood burning household. I got in a hurry and have limited resources as well but i think it works. I will take your advice and adjust the height of the Jtube tunnel. I am going into to town today to buy some more fire bricks and rebuild it again. I have a 55 gallon barrel maybe I'll redesign that as well I just wanted a smaller footprint as we have only 200 sf in the green house.
Jim ; The other place I can't see is your transition manifold from the barrel to your horizontal pipe.... that should be at least 3x the area of your horizontal pipe ... you also are going to want a cleanout access or two to get the flyash out at the end of season. As you build your mass it is going to take weeks to truly dry out and store heat.... as this drys you will have drafting issues until it is all dry and warm. The dimension part of the core and manifold are critical to a properly functioning dragon.
Yes sir. I was to address the clean out issue today. The picture (dont judge my cob work:) is the 6" elbow. So this little fella should be 18" then down to 6"?
I was thinking about the "breaking in" thing. I am getting a lot of steam, so much water drop were steady, so I figured it wouldn't draft properly until everything was dry and warm.
For the 6" system, your CSA (cross sectional area) is just over 28"sq, so for the manifold you want to allow for more than that to avoid a bottleneck where the exhaust flow makes a turn from flowing down the barrel. Make sure there is at least 3" clearance between the duct and the riser too, to prevent restrictions.
Drying out the system will help with draw, just double check clearances in the manifold first to be sure it's more than enough CSA.
Thanks folks! I just returned from town with a few more bricks in hand and a positive can do attitude! I'll try and get it worked out this evening. My barn cats found a way under the house and tore my insulation down sooooo yeah theres that.