Our
RMH is still not quite complete. We can safely run it, but the bench seat back doesn't go all the way yet (still another 3' to go), and I want more mass around the barrel so there's more battery instead of so much immediate radiant heat.
Some details:
We live in a timber-framed,
straw bale in-fill home in central Vermont. It is designed for passive solar--large windows set low on the south wall, some large windows on the east side, three small windows on the west side, and small inoperable windows on the north side. There are 3' roof overhangs on all sides. The walls average R34 as does the ceiling, while the floor is R26. We're still building, so we're still finding a few gaps that are quickly filled. We're in a snow belt, so we receive lots of snow, and our 1200' of elevation means the snow begins early and stays late. Being on the east-facing slope of a range of hills and mountains is not ideal, but south-facing properties cost 3x as much, and we lacked the budget. We do receive copious light from sunrise to late afternoon during winter, more so in summer.
We survived last winter with a rinky-dink
wood stove. We had planned it would be the emergency backup, but due to construction delays, it became the only heat source. It sucked. Literally. Thank God last year was mild or we may have had to seek
shelter elsewhere. But we made it through and this winter we're looking forward to
enjoying it.
(For a whole series of reasons that I don't feel like detailing here) we have a
wood floor over a crawlspace, so we built a replica of the Bonnie 8". We followed Ernie & Erica's book meticulously, remeasuring regularly, and actually dismantling and rebuilding the J-tube at one point. It is on a raised platform built of bricks (just like the Bonnie 8"). It has 3 easily accessible clean-outs. The mass is composed of a ton or two of rocks from right outside out door. These are mortared into place using the “masonry”
cob recipe in the Wisner's book (mostly sand, a little bit of clay). The
RMH has 3 runs—the first running from the barrel, then looping around behind that, and a third running back above the second run. The mass retains heat for hours, but we hope that by enclosing the rest of the third run and finishing the bench we can have the heat last longer.
Our issue/concern is with the draft we're getting. It seems a bit much. We have difficulty lighting the RMH because the air being sucked down the
feed tube blows out the flame on our paper before it has a chance to light our
kindling. It usually takes 3 tries to get the fire going. We're using itty-bitty twigs which are dry, so it
should light immediately. The only time I've had it light on the first try was when I used a bunch of birch bark that I wrapped around the bundle of twigs. All this extra paper and birch bark is contributing to the excess
ash we're seeing (less than we had last winter with the
wood stove, but still more than expected). I clean the burn tunnel every few fires and get a few cups of ash each time. I'm seeing little to no ash build-up at the first clean-out, which is immediately after the manifold, and no ash further down.
I imagine that a major contributing factor to the excellent draw is the extensive chimney we're running inside our house. After running 3 times through our 10' bench it goes vertical—through the second floor and up to the attic, exiting near the peak of the roof on the leeward side. Single layer pipe whilst inside changes to one section of insulated outside. Properly capped and everything.
Because of the excellent draw we never run the RMH fully open. We always limit airflow after it's lit. Despite having its airflow reduced we still get that roaring rocket and intensive heat.
Is this amount of draw typical? Is this just a feature we need to get used to? Are there any pointers on lighting on the first try? General thoughts?
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