Hey all you crazy permies! I need to pick some knowledgeable brains, and I know they're hiding in here!
My wife and I have a 1152sf (32x36') stick-frame, truss-roofed, single story above-ground house on a slab (gag, but it's good enough for now) on our little 'stead. It's a pretty open floor plan, save for two bedrooms at the south end of the house. We're heating the place with a 1980s Earth Stove, your standard plate steel, window in front, blower shroud over the back wood stove. Smallish firebox, the sticks need to be 18" or less to fit, and it won't hold a burn overnight unless we make a HUGE mess of coals. Also, since we're using the chimney the previous owners installed, the stove is in the north corner of the house- not a bad placement, but it takes a while for heat to reach the south corner. We're fortunate in that the PO's only drywalled the bedroom walls up to eight feet (the outside walls are 10'), which allows heat to go over them and down into the two enclosed bedrooms... eventually.
I'm considering building a mass heater, and can't decide between a RMH and a Russian Stove. Both of them operate on the idea that one can extract almost all available heat from a small mass of wood, and retain it to radiantly heat one's living space rather than expending it up the chimney. The RMH, as we know, uses the rockety reburn chamber to make a blast furnace effect, and also to provide a workable cooktop, before routing the remaining heat through the cob bench to extract the remainder of the heat prior to its exit from the home. The RS, on the other hand, has no work surface (although some intrepid souls have incorporated small ovens into the flue path), but puts all available heat into the bricks, and routes the flue through an up-and-down zigzag path to extend the time (and space) of the flue inside the domicile, to keep all available heat indoors rather than going up the chimney. It also has a 3-4' horizontal burn chamber to allow the use of long branches rather than requiring the repeated feeding of small bundles of sticks.
The pros and cons, as I've figured them, are as follows:
RMH Pros: Ease of construction, low cost of parts
RMH Cons: Increased work of mixing and forming the cob, the radiant heat source is limited to an outside wall due to the horizontal flue. Also, since RMH are not known to perform well with vertical flues, this obviates its placement anywhere but along an outside wall, where some heat will be lost.
RS Pros: Centralized, fully-radiant heat source, less feeding required, vertical flue allows placement anywhere in the living space.
RS Cons: Expensive (unless one is adept at scavenging bricks, incl. firebrick), labor-intensive construction, takes up valuable center-floor space.
Given these, plus whatever input you may have (and I certainly welcome), which of these would work best? I'm leaning toward the Russian Stove, because I like the idea of keeping the heating mass as close to the center of the house as possible. I also don't relish the idea of sleeping on cob, although with a decent mat I'll try anything.
Nick Lenarz : lets see If this helps you make up your mind !
If you had unlimited money and wanted to hire a Mason to build you A " Russian/Masonary Stove '', he would 1st contract to have the core made for him, likely someplace overseas, Initial price $5,000.oo!
Shipping, - you hope it doesn't come by plane . - ?$? - Trucking - Flatbed tractor-trailer , - ?!? , Unloading, and spotting onsite 2 - 3 hundred ! All before the mason arrives with his trowel ! GREEN ? NO!
One of the reasons why deals with the fact that just like the flue tile in a brick chimney the masonary heater-core can not be cemented-in, they both must be free-floating in there to help in withstanding thermal stress and expansion and contraction !
Properly Built there is no identical problem with The Rocket Stove Mass Heater ! It can easily be built for hundreds, a good Scrounger Should be able to easily build one for 200 or even less with good materials !
The #1 reason to build your thermal mass at bed/bench high, is building over a wood floor, A thermal mass-bench high is a load that a wooden floor can easily take with just a little bracing ! Higher loads should not be a problem on your slab floor !
I have to ask, have you been to www.rocket stoves.com and downloaded your copies- any # ! - of Ianto Evans' Great Book 'Rocket Mass Heaters' there is no other printed material in any language with more specific information on Rocket Stoves ! ( And I don"t make a dime )
Success has a Thousand Fathers , Failure is an Orphan
I"m not sure if I agree with your classification of different types and flue styles of rocket stoves/heaters.
I consider the basic priciples of a rocket stove influencing the combustion feed and riser areas, after that
it depends what you are trying to do, ie. cook/heat water/heat mass or a combination thereof.
Check out the "donkey" links above, also search for "half barrel rocket mass heater" on you tube.
Lot's of ways to do this; just be careful, look at all the previous work, if in doubt stick to the tried and true.
What I would call the "Erica/Ernie" model is proven.
Joe Braxton: I will check those links out tomorrow, and I will be careful- I don't have time for habit-forming when it comes to digital stuff, too much stuff to do IRL! Garden tilling, building an insulated doghouse out of scavenged pallets, making extensions to the goat shed, etc.
Allen Lumley: I'm not sure what the gist of your reply is, unless it's to dissuade me from contracting with a mason to build a masonry stove (something I would most assuredly NEVER do!) or to just shut my yap and build a RMH. I should also be able to build a RMH for less than $100, if I am savvy with my scrounging. I already own Evans' book, and have read it cover-to-cover several times; this is where I found the information (as well as online) about its tendency to run poorly with a vertical flue. If higher loads equals higher thermal output, I should conceivably be able to make it more central to the house, except for that pesky flue thing...
Andor Horvath: I am quite familiar with the Wisner model, and whether due to design or fan base it is indeed widely proven. But again, it heats a SMALL space, primarily through direct bodily contact, i.e., "Butts needing warming go here!" Need I say more? I want to heat more than butts. If it is possible to design a RMH with a vertical flue that will actually do the job, then I will most certainly git-er-dun, but if more experienced heads here say it's a bad idea, I'd love to save myself the agony of more error than trial in my trial-and-error phase of the project. Again, I'll look into the Donkey links as time becomes available.
perhaps I am confusing Ernie and Ianto's work...
with all respect to Ernie and Paul's work here,
I've found the "donkey" board to be the one most
geared to "gear-heads" like me.
horizontal/vertical exhaust stack depends on a couple of things...
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