The space for H ?

Hi again I am having a crappy day my 8" stove is not drafting squat after about 2 min. I built the stove to the specks in the book 7" sq 12.5" burn channel I used a 40gal gas WH tank for the insulation cover around the heat riser about 41" in length & 16" in diameter, filled with 1/2" crushed garnet just for the testing. I then placed the 55gal barrel over it @ 21" if everything is perfect I will have a 2.5" in between the barrels is this to much? The base is like a inverted cone the sides go out and around a 8"x3' with a 5' a 90 and another 3' going up flu pipe. Or should I say why is it not acting like a good dragon.


David

David; I know that you just built your rmh . I had trouble with drafting when i first fired mine, I ended up using an electric fan to (force the issue) after 20 mins the first time and maybe 5-10 minutes for the next few days to get it going. Just blow down the feed tube. All of the cob has to dry out or the cold moist air seems to want to back up and stop drafting. you might try adding more chimney to help with the draft.

Thanks Thomas.
I still dont have a answer to my question is 2.5" around the inner tank to the outer barrel too much???

David; No, 2.5 is not to much, as little as 1.5 and over 5" if you want it. Its all experimental whatever works with your stove. Try adding extra pipe on your exit, see if the extra height will help you.

David Marin : I am having a little trouble following the flow of your ideas and your unique nomenclature for parts of your build, over and over we have found
that by asking new members to go to rocketstoves.com to download a PDF Copy $15. of I. Evans' great book 'Rocket Mass Heaters" that a lot of confusion,
time and money are saved in ironing out the very common problems found in a first build. My recommendation here as you say you have the book is to help us
help you, pictures might help, but a common language is the first step !

With over 100,000 Rocket Mass Heaters RMHs, made world wide, most have been made following "The Book ", and 95% of all the first builds (that Worked )
were made following " The Book "! ( I do not make a dime off of recommending this great short cut )

Thomas Rubino makes a good recommendation, I just want to make it a little stronger ! When the barrel goes on the vertical chimney should go up, as you
should be testing outdoors, the recommendation should be for the top of your vertical chimney to be 4' - 5' above any other near object !

By coming immediately off of the bottom off your barrel with a vertical chimney, you create a test bed that allows you to measure and test the Rocket Burners
performance without the horizontal piping, If you have a healthy Rocket/Dragon before you put on your barrel, and still have a healthy Rocket / Dragon after,
then your Rocket burner part is complete. If you had a good 'draft' before,and you lose the roar of the Rocket after putting on the Barrel and the Vertical
Chimney, then you should be concerned with how smooth your walls are and the gaps at the Heat Riser and also at the Manifold just before you attach your
chimney ! I hope that this is timely, and helps, for the good of the Crafts ! Big AL !