Wes Khan

John,
I have already asked an expert (Matt Walker) about using return ducts and he said they had luck with return ducts near the ceiling above the RMH. That's also my end goal. Once I have something that doesn't throw smoke everywhere.

Jason Speaks wrote: I used an electric heater and got the pipe really warm, so to create a draft through the system. Also you need to crack a window when you first start so to draw fresh air into your system. If you don't you will experience negative pressure and you will get back flow. I have been burning for 4 years now. I really don't think the 30 ft chimney will affect the system if it has a straight up run. You just need it warmed up enough to push up a cold chimney.

I stuck a lard candle in the exhaust to warm it up on the first test burn, but then decided to cold start an entire batch full of wood. Boy, was that a mistake. Lol. That's what's got me on the idea of cobbing the bottom section.
I'm in the process of redoing the exhaust. It's going to be closer to the barrel for more heat exchange. Hopefully.

John,
Thanks for the reply. That's very helpful. Is that another chimney in the middle of your house? If so, why did you not use that instead of running class A? My chimney is covered by wood and vinyl siding to match the house. I need to find a contractor or someone to come out and help me understand how it's built, and where to make the cuts.

Hello all,
I am in the process of building a 6 inch system batch box. My prototype which was outside worked wonderfully, but because this is a basement build, I am having draft issues. The exhaust is a plunger style inside of an open bell bench. Currently running at about 45 degrees outside to the window. My question is, would it be possible to tap into my prefab fireplace chimney? It is on the second floor right above the rmh. The main issue I see is that it's an 8 inch chimney compared to my 6 inch RMH. I'm worried I won't be able to produce enough heat to push all that cold air up and out 3 stories. (The house is 2 stories with a very high roof, so basically 3 stories to the top of the chimney).
I was stubborn and tried dry stacking the bricks, then cobbing the inside and outside. It worked in my prototype, so I was hopeful! It's very leaky because my cob cracked while drying (way too fast).
Something I noticed is the firebox has draft during the coaling stage, even when the exhaust is blocked off. Does this mean it's being pulled up the riser and then exiting into the room in the cracks in the mass? None of my CO alarms have gone off, so far. Should I start over or is it possible to cob over the whole mass to make it more air tight? I know I need to solve the chimney issues first. Let me know!