Sometimes Good Draft; Sometimes NOT; ?????

So, I've made my design to the book as much as i can; followed all the measurements and what not.
What i found:
• Putting the feed in the front instead of on top ("L" shape instead of "J") worked a lot better. I had a much easier time getting the fire started and keeping it going. The draft was better as well.
• Sometimes, for no apparent reason, i suddenly get a huge amount of smoke, just going everywhere, including out the feed. Maybe just wetish wood, but, wow, too much smoke out the feed.

Thoughts:
• This is a dry run, no mortar, and using a clay/sand or high heat mortar in between all the bricks will tighten it up.
• My heat riser is only a couple inches thick, leaving a 4-5 inches pocket around it. Today I will fix that and shrink the pocket down to 1.5 inches with a much thicker heat riser.

I've never done anything like this before, and no one in my area (Ashland, OR, of all places) has stepped up to help me out that has made one before. Maybe i need to make some more phone calls. If anyone can help mentor me with this, that would be great. It's really cold here and i would love to be able to move into my new home ASAP
...letting the journey mold me and be the richness of life, not the goal i am after, life is good.
Many thanks...

A little ground wind problem maybe, try adding 6 foot exhaust chimney?

Im not a rocket heater professional but I now have one working very well and seeing your photo reminds me of the first ones that I tried that also burnt much better when fed horizontally from the front.
I think you should play more with the design because probably the proportions are not yet right. I tried many designs first and finally literally copied the one in the rocket mass heat book. Test first without the barrel and when you feel the pull and heat coming through the heat riser add the barrel and test again. also what helped in my case was sealing everything and adding a chimney which initially I wasnt using which occasionally cause wind to blow the draft the opposite direction resulting in a dead fire and lots of smoke on certain days. Good luck!

Thanks. I'm somewhat torn about whether to go horizontal or vertical, but i like the clean out solutions with the horizontal. I'm going to install it inside tomorrow, so speak now or forever hold your peace.

Taller chimney=better draft

just saying

peace

Chimney as in exhaust, not heat riser, yes?

Hi,
I also choose horizontal but installed a vertical 'chimney' outside. The horizontal exhaust was easier to realize because of the height of the building and I like the fact that i can hide it in a bench and its easier to clean. This part is about 3 meters in my case. I added a T to the end and a vertical exhaust of about 2 meters outside purely because on some days the wind would blow into it and cause smoke back, now it burns standard good and no! smoke back.

Well, I'm going to have a horizontal exhaust for the mass heater and then vertical to exit the building. What i'm talking about is the feed. On most models, the feed is vertical/top. With the horizontal/front feed, it's easier to get a fire started because you can reach directly into the combustion chamber and make the bulk of the fire inside it instead of at the very beginning of the chamber in the case of the vertical feed. Also, it's way easier to clean out the front feed - you just shovel it out from the front. With the top feed, you have to devise some kind of clean out in the front, or use a shop vac; both of which are extraneous complications in my opinion. I can still put long pieces of wood in there, because the horizontal length of the combustion chamber is two feet; i just have to make sure that i keep pushing it in since i don't have the convenience of the gravity feed as with the vertical/top feed.

I find feeding the wood vertically consumes a lot less because it burns literally everything and produces more heat, somehow. I clean it out with a long spoon but there is never any coal in the feed just almost white ash and some very small coals at the front (pieces that remain once you stop the fire) which are easy to get out. with the horizontal feed there was much more coal and because it filled up really fast I needed to stop the fire and clean out a couple of time a day. Actually the amount of coal I would have to take out of the horizontal feedtube was about as much as I would remove form my traditional fireplace. Vertical if you can get it working is much more efficient and probably safer.

Hmmm. For some reason i just didn't have a very good draw with the vertical feed. Sometimes outright bad. Maybe just because of leaks here and there in the demo version and not the driest wood in the world (it's winter in Oregon).

Yes wet wood is really a problem but I think if you stick to the build in the book and play around with it a little bit you'll get it right, maybe build some wind shelter around it (with enough distance) to make sure that that doesn't cause problems?

Lookng at your picture again I think the coal forming is the problem at a certain point it starts to block the heat riser and that's where your smoke back (and probably bits of fire coming out of the feeder?) starts.