Thanks, Paul. Another question: Ianto says in the book not to burn spruce in these stoves -- do you know why he said that? If we end up back in the Interior of Alaska, spruce is about all we'll have to burn (at least at Tok, where my brothers live). I know it creosotes stovepipe up pretty bad, but am thinking that the combustion chamber on a rocket stove should aleviate that problem.
So Paul asked me, and I thought about it, and then I asked Ernie .... and here come the results:
1) Spruce is pitchy.
It's not the creosote, so much as the characteristics of the burn itself. (You're right, once it gets past the burn chamber, there's not much creosote or smoke left, and with the pipes encased in earthen masonry, there's little chance of it catching fire or doing much damage if it does.)
But within the burn chamber:
Softwoods often burn pitch-first, and then stand on their little foamy charcoal ends. So for a J-tube feed
, the effect is that the fire moves up the wood, chasing the pitch, and the charcoal on the ends doesn't burn down fast enough to keep the fire in the right spot. Smokes back. Burns too quick, and too slow, at the same time.
(I've been thinking about fire lately as a super-speed fungus: it resembles 'brown rot' fungi
, which eat lignin first, leaving checkered brown cellulose. Fire, too, feeds on the complex wood oils and proteins first, and leaves the carbon
for last. Softwoods have proportionally more cellulose, and less lignin, with their spread-out pale growth rings.)
If softwoods is your main fuel, I'd definitely recommend creating an ash pit below the fuel feed, like on Ianto's drawings. That gives the fire a little more room to handle those charcoal ends.
Your AK spruce is generally denser (tighter-grained) than our softwoods, which is good. We get really big-grained spongy "spruce" and "fir," force-grown on tree farms, that are really basically papier-mache masquerading as sticks. They are like cellulose foam. Weird stuff, takes forever to finish burning, but gives little heat. Fruitwood twigs & trimmings work a lot better for us here.
With your dense spruce, it may not be a big problem, if you design your stove to draft well in the first place. Tall heat riser, compact feed tube, maybe a little extra height on your burn tunnel, and cut your wood to fit the feed tube, not stick up above.
If you're going to burn pitchy wood (or any wood, for that matter), season it well.
Like most wood for rocket stoves, it may do better in straight rounds with the bark still on, rather than square splits. 1" to 6" around, you can split some for kindling
but the main fire will be made of circles and a few wedges, not squares. You can mix it with tamarack or well-cured willow, and find a blend that burns well for you.
I would definitely recommened either
1) stick with the dimensions in the book as closely as possible, including 8" diameter pipe,
or if you are able,
2) experiment on your AK property when you get up there, and see if you can adjust the dimensions for optimum function using your fuels and weather patterns.
If you have to build the first season you get there for shelter
, then collect as much local
info as you can ahead of time. Get your brothers up there to monitor weather, storm wind direction, etc. (Or send them the book, and see if they'll play around with it.) Or have a back-up plan for shelter e.g. a woodstove, fireplace, or friend's house.
2) You were talking about Cleanouts:
Yes, you can build them sticking up. Most folks clean them out with a Shop-Vac, except Ianto, who uses his hands. You can also use a rag on a wire cable (thread
it through then pull the rag through after), or a chimney brush on a flexible snake.
Like Paul said, the critical area for ash build-up is near the manifold / barrel area, and of course the burn chamber itself.
Ernie's friend Shannon Dealy build a 10" diameter system into a floor, and he put his cleanouts poining up. (a T-shaped joint with the main pipe, or a 3-way joint sticking up from a corner). He covered them with tile When it's time to clean, he pulls the tile off, pulls the cap on the T-joint, inserts a shop-vac or brush, and then reassembles the whole thing. You don't have to do this often, but it can be very handy in case you get a rat's nest or wad of newspaper
The other note from Shannon's experience
: Beeswax is not an ideal finish for a heated earthen floor - tends to get sticky when warm. Linseed oil or another curing oil might work better; or just sprinkle water
to keep the dust down.
Also, Ernie says, you'll want substantial insulation UNDER the floor.
Mineral insulation like perlite, pumice, or something that can hold your floor stable, would be good. (Synthetic foams can work, but they also break down in certain conditions, and could de-stabilize an earthen floor. You could pour a concrete
slab, and use suitable insulation. But be sure everything's laid right the first time, and expect it to crack - many slabs do.) It also helps if the insulation can drain, and is stable when wet, in case anything leaks.
2 reasons for insulation:
1) Permafrost is cold.
2) it's what holds the tundra up.
In tundra country, putting a lot of heat into the ground destabilizes the ground, and your foundations, without necessarily warming your house.
If you're planning to get down below the permafrost for your bermed house... and Ernie says in places it's 20 feet deep, depends where you are ... then you just have to worry about the heat loss. And seasonal flooding...
Thinking about this project
, I'm reminded that permaculture
is about appropriate design for your place: bioregion, site, personal space. Designing a house on paper, to be built "somewhere" in future, is an iffy proposition. Features that work well in one region, don't necessarily work in others. You might need several designs, to handle things as basic as sun angles, let alone humidity or permafrost contingencies.
It would be worth looking into northern European and Arctic cultures, to see what they tend to do about building in that circumstance. I personally don't know anyone living in cob
/ with an earthen floor in those regions. Flemming Abrahamsson does rocket and masonry stoves in Denmark, and he's an architect who could consult on your design if you're interested.
Also, if you're digging down more than a couple of feet, air-exchange is an issue.
Our building code in the lower 48 likes fresh air to enter the building lower than the stove's air intake. I think on the grounds that hot air rises, and you don't want smoke filling your house or running backwards up the fresh air intake.
Igloos are built with an air-trap in the entry, like a sink's U-trap, so warmed air stays inside the highly insulative snow block dome. They are heated with minimal fire, traditionally mostly with oil lamps as I understand it. And of course body heat.
Ernie suggests an air intake, possibly sunk into the floor itself for a little pre-warming, that opens near the stove mouth and can be closed when not in use.
Ernie thinks it's fine to build with cob
up North, and he's lived in Alaska so he'd know better than I would. But he says to take appropriate precautions. I asked him to go into detail:
1) Insulation. Lots of it.
2) Air supply: bring in a pipe from outside at floor level. You can plumb this through the bench / floor to pre-warm the air if you want.
3) Sink the stove into the floor and make sure your heat riser is plenty tall. You DON'T want smokeback in a sunken, enclosed space.
4) Earth berming is good, gets the house out of the wind, but DRAINAGE is an issue.
5) You want surface drainage to be away from your house, in 3 levels:
a) below-ground drainage of the foundations that drains to daylight in a frost-safe way. Foundations and floor pad should be at least 2 feet below floor level. And allow enough floor thickness to encase your pipes in cob
above and below.
b) drainage away from the house around the berms
c) a third ring of drainage, for surface water, beyond the berms. Water flows across the top of permafrost in the spring (or any thaw), and will try to "float" a house that's not protected. Most houses don't float so good, they just crack.
I hope this is useful. Ernie knows a fair amount about the Artic as well as rocket stoves, so I figured I'd put it all down.
My own personal note:
If you have never built a house before, you may be surprised at what's involved. I'd encourage you to practice now, wherever you are - create a well-drained patio, build a cob bench or tipi-pad on it, put in a pizza oven
. Build a rocket stove
mock-up, even just the brick firebox, and use it for canning season so you get the hang of feeding it. (It also takes some time to get it going once it's cold - if your Alaska dream home is a vacation retreat, you may want a more conventional fireplace that's easier to start when cold.)
You may find that there are designs from northern Europe for houses that work beautifully with a central chimney, masonry-stove, or set of fireplaces. Rooms can radiate off this feature, with a sculpted "fireplace" or mural on the cob surface that faces into each room. Check out the Masonry Heaters
Association for some inspiration; they have conventional, modern, and funky stoves all built along traditional European lines (vertical masonry mass).
If building your stove into the floor makes too many drainage and insulation problems, here's another design consideration: Your heat doesn't need to be in the exact center of your house. A curved, heated mass will radiate heat toward the inside of the curve - you can create a bench along a curved wall, that will warm things in the center of the room beautifully. Or place the radiant heat barrel near the center, and build the stove into one wall - a "hot wall" that can be shared by a living space and bedroom or bathroom, for example.
I also like the phrase "Build your barn first" - get some practice, and don't sweat the details. Build a single-room workspace that will ultimately be the toolshed, or potting shed, but will keep you warm and dry while you observe local conditions and get ready to build your "real" house. Modern equivalent is living in the garage while building the main house.
Good luck, and have fun.
Ernie and I would love to get up to Alaska together one of these days. If you want to keep in touch, email us: questions@ErnieAndErica.info