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FINISHED: 8" RMH, existing 35ft chimney tie-in

Posts: 17
Location: Detroit, Michigan
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Our 8" RMH is (functionally) finished. The combustion unit's dimensions were reduced proportionally, so that the surface of the barrel is at a more cooking-friendly height. Nearly all materials (excluding the ceramic refractory insulation, perlite, HVAC piping, foil tape, & gasket) were found/salvaged around our nieghborhood in Detroit. Not to mention, these found materials were shuttled by bicycle trailer. It still needs all the finish, detail work... next summer.

3 cleanouts (one at the manifold, one at the 3rd turn in the mass, and one at the base of the chimney for cold-starting as well as debris management. We decided to install a damper at the base of this 35 ft chimney (which was lined with HVAC, to better 'close' the system, so that the chimney's ferocious draw doesn't export all of our precious heat. This was a very, very good idea.

This heater sports an integrated plant bed, to overwinter tender perennials, and, we hope sub-tropicals (now doing research for low-light requiring, winter-able plants

This heater also includes a 'hay box' -- a super insulated container for passively cooking food w/out fire. No, the thermal mass does not feed the insulated box -- just a cosmetic connection.

The heater performs well. The mass reaches 100 degrees f, while 17 outdoors. We haven't been able to burn such fantastic wood yet... just crap and lath. The lath is great, just FAST burning. We haven't needed to cold-start the chimney; not a single smoke-back start. Love that rockety sound! Our issue is our 1903, 3,700 sq ft, un-insulated, super-drafty house... which we are beginning to bite into. Also, our heater draws sooooo much air; you can feel the cold seeping through... so, I am planning on dropping a 6" pipe down the other chimney, to act as fresh air intake. Very curious to see how much this offsets the dragon's hunger for air...

Thanks for everybody who contributes to this forum -- it's proved to be an invaluable resource. Here's to a warm winter!

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Posts: 219
Location: S.W. Missouri, Zone 6B
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A point to consider: It seems more typical to source fresh air intake from a point lower than the firebox, as opposed from a chimney (so as to encourage good drafting; I wonder if it is practical to have such a strong draft you end up wanting to discourage it?). ASTM E1602, among other sources mention this point; by the ASTM standard the CSA of the intake should be at least 12" CSA (which a 4" (12.5" CSA) pipe achieves, but a 3" (7" CSA)does not), made of non-combustible material, and designed in such a manner as to keep coals from falling into it.
greg crawford
Posts: 17
Location: Detroit, Michigan
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Yes Erik, we were thinking to source the fresh air intake from the basement at first... only, at this point in the house-rehab, the basement is suuuuuuuuper drafty, which would just let in all that cold winter air -- which is the case with the house in general. To sidestep the problem, we thought to pipe it in from the chimney. At this point however, it is just a wondersome thought.
Posts: 3241
Location: Southern alps, on the French side of the french /italian border 5000ft elevation
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Greg, my dear Greg.

Don't use that chimney for an air intake. Make a blady bell! You will reduce your draft, and heat more! Thought, it's just a sugestion! It's soo simple. Scavenge a bit of sheet metal, a tube and some rockwool, and you're done! Block the chimney you want to use as a bell, with the sheet metal. In which you will have previously drilled a hole for your tube (6 or 8, i can't remember what you have) Insert the tube, hold it a way or another above the chimney floor, bout 4 inch. Block the front of the fireplace with ametal plate, and send your mass's exhaust pipe into there. Throw some rockwool from the top, of the chimney, so the top metal plate doesn't shed too much heat to the great outdoors. I'm sure you could do another 20 to 30sqft of ISA for your rocket.

You've seen my drawing of a plunger tube before!
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