North Pole Alaskan rocket stove

Is the 14' x 14' interior or exterior dimensions? I would think interior, as wall thickness would make the other possibility miniscule inside. Even a 14' interior dimension renders the corner mass placement the only reasonable choice given the buttresses.

If your sketch of the stepped north buttress is accurate, you would probably need to send one or both of the flues through the buttress, where the heat would damage the earthbags' exterior wrapper. You will need to replace some of that material with heat-resistant material at least for the first penetration from the barrel outlet.

Integrating the buttresses with the thermal mass would make sense - let the heat get into those as well as the bench and it will be comfortable to lean up against.

14x14 is the interior dimensions. The northern buttress steps down enough for the flu. If i lime plaster over the bags will that protect them from the heat? Or should I use cement over the bags?for where the heat will touch the bags? Should I just use the that corner of the building as my single mass and have my ducting and clean outs run through it then up through the roof? Or out the side of the house? Near the roof?

Deagen D. : In no particular order, If we build everything into the north wall you are going to promptly dedicate 20-25%
of the total floor plan to Your RMHs build.

If You can accept the placement of Your RMH in the center of your mass We will actually use Less floorspace about 15-20%
and have better radiantheat distribution everywhere else !

You will need to do a soil sediment test, to determine the % of clay in your soil, Google -fu also a test to determine the
workability of your clay. I understand that many skim coats and lime washes have portland cement in them, it is there as a
readily obtainable way to stiffen the mortar/wash mix and make application go better, I personally have a bias against the
high energy costs of cement, and have avoided using it and have
zero experience with it, However we will get you at least a couple of working Recipes.

If you look at the RMH video I showed you earlier, at about 2:00 there is a good look at the long axis of the RMH, mostly the
day bed and lounging side! If we keep the location of the feed tube barrel axis the same and come out of it about 4' then use
an elbow and a short length of pipe and then an elbow we can turn 180 degrees and run along side of the Barrel and feed tube
and have a sitting area and then a day bed.

Given your inside dimensions a diagonal line drawn from the northwest to southeast is ~19' 9.6''~ I propose to install your RMH
some where on that line.probably with the day bed / lounge on the door side and able to see the window !

Assuming that you have no major broken bones to bake at the fire, I am assuming that you will want your dominate/stronger
arm on the inside close to the RMHs feed tube, here the test is your muscle memory, in which hand do you normally hold a drink!
By anticipating things like this we elevate our RMHs build from something you like to something you love!

If we think of the total shape of the RMH less the thermal mass generally we would call that shape a Keyhole, or say its shape
was close to theoutline of a Edison based incandescent light bulb !

The thermal mass in the video is like a big Pork chop kind of wrapped around the keyhole. The bone side of the pork chop clearly
represented by the backrest/spine shown in the video. The meaty part of the pork chop makes up the day bed position in the
video. we will be using a similar layout just a different cut of meat !

I assume you have a plan for visitors using the loft space and a little thought must be given where we run the final vertical stove
pipe up through that space and out thru your roof, but our total budget for elbows is 3 and we Must stick to that, we can move
the location of the RMH around in the House until it is actually built!

Look at the video again , try to think of the questions raised and get back to me ! for the Good of the Crafts Big AL

With a 14' interior dimension, a 6' long daybed would leave only 3 1/2' on each side all around it, NOT counting buttresses on two sides... essentially making it occupy the entire center of the room with barely enough space to move around it and have anything else at all in the room. If you want storage space on this level, you might put in a shallow closet in the NW alcove you identified and move the daybed just out from it, allowing a door/walkway at one side of the daybed. Letting the back of the daybed be against a wall gives much more flexibility in floor arrangement. If the bed is built against the north buttress and incorporates the steps inside it, that part of the impediment will go away. How big of a bed surface were you wanting? Enough for two, or just one? Given the space it seems it should double as sitting area with a back.

As a thought experiment, if the W end of the bed is 3 1/2' from the W wall, that leaves 2' to get between it and the W buttresses into the closet area in the NW corner. A 6' bed leaves 3 1/2' clear to the E wall. If the back incorporates the buttress steps and leaves a useable storage space behind it, it will be 2' or say 2 1/2' from the N wall. Assuming 3' depth including backrest, that leaves 8 1/2' clear to the south wall... not a bad distance for radiant heat to reach.
The bed (centered on the N wall) will have about 2 1/2' x 2 1/2' alcove behind it considering buttress thickness. Maybe the barrel can go in that space (slightly adjusted for clearances etc.) with the feed tube peeking out from behind it, arranged to be convenient to reach from the bed/bench. The 3 1/2' wide alcove left in the NE corner should leave enough space for some indoor wood storage as I don't expect you want to have to go outside more than once a day to get wood. It would only be a couple of feet from the door.

A paper sketch would be good at this point, to fully grasp the space potential. Draw a uniform 1' grid first to help with layout and keep you honest

Another notion: Given the duct run restrictions counting elbows, and the tight space, you might not be able to fit enough 6" duct for good heat transfer. Look at Matthew Walker's "half-barrel bell" concept - it can dramatically increase the heat transfer area and reduce friction losses while fitting under a bench.

Glen : And the last shall be 1st, and the 1st shall be last ! I really like the idea of 1/2 barrels, which Should be do-able in Fairbanks, just a little into the country
that may be a problem ! Why don't You P. M. Him and see if he wants to join this conversation !

With a 14' X 14' cabin the diagonal axis is 19' 9.6''-ish My propose all is to center the mass, otherwise Double D's room will shrink to 10 by 14 with more space
unavailable!

I am missing your entire point about the buttress steps, but perhaps you got a clearer look at the cabins interior than I did !

Deagen find som graph paper and do something to scale, right now we are just eliminating what you cant live with, But, we are running out of time !

For the Good of the Craft ! Big AL

Ok I will make a better sketch and get some good interior pictures next time I go out there so I can take some measurements. I am not opposed to changeling the interior at all to get optimal space and efficiency. As for clay% it's zero. There is no clay on my area it is rare and I had to take a boat on the river just to get a little bit for a small pizza oven I might make later. So my mass will have to be made of mostly stone and cement/lime. I don't know when I'll be out there next but I'll try to get out there tomorrow morning to take some pictures and measurements and make a sketch

Deagen D. : Regular concrete made from Portland cement, all imported, (for you, mostly it comes from So. Korea) starts to fall apart at temperatures above

400dC.

The internal temperatures of the Combustion Core are above 1100dC, you can not use Concrete within the Keyhole footprint of the RMH !

You can do a google search for more information or just search for this information from your neighbors the Cold Climate Housing Research Center, an arm
of the University of Alaska Fairbanks! www.cchrc.org While looking at the cchrc.org site please remember that there is a boat load of steaming crap
out there in U-tube land, I sent you to cchrc.org because I trust them, I know Cold, They KNOW COLD ! !!!

No clay, no RMH footprint, you can buy it as a 50 lb, bag and will probably need 3 bags of 'Fire-clay' probably shipped up from the states ! If, you want to go
that route !

Also, I have to give you some home ork, which requires you to buy the text book, You need to goto rocketstoves.com and download a pdf copy of the
brand-new 3rd Edition of Rocket Mass Heaters, this is a must as we get to the heart of this build ! 4 the craft Big AL

Nice Glenn I checked that half barrel bell idea out and it looks like a great idea if I use 2 10" ducting. I also like how the mass was filled and elevated off the floor with forms. As for not using cement I'm all for it. I know I can use gravel and rocks and sand for most of my mass. Could I cover that in a lime/sand plaster mix?

Using barrels instead of ducting takes up more room and provides less space for mass. However don't the barrel bells get hotter? Is the draft pull better? Does the thermal mass heat up faster when barrel bells are used rather than ducting? I def have more barrels than ducting available.

Deagen Demientieff wrote:Using barrels instead of ducting takes up more room and provides less space for mass. However don't the barrel bells get hotter? Is the draft pull better? Does the thermal mass heat up faster when barrel bells are used rather than ducting? I def have more barrels than ducting available.

Deagen, it's dead simple.

Exchange time and exchange surface.

Mass can accumulate more calories, or BTU's than you think. If a mass heats up at 120C° instead of 60C° it stores twice the power than at 60C°

Let's compare an 8 inch flue, to an55 gallon barrel of equal lengh.

Let's say 20ft long.

8x3.1415926 =25,1327inch. X 12 x20= 9047.78sqin.

A barrel is 22.83 in diameter.

So, 22.83 x3.1415926 = 71.72 in. /2 for a half barrel =35.86inch plus 22.83inch for the base. =58,69" x12 x20 =14085sqin

So it's about 1.55 times the surface of a 8 inch flue. Well, in both case, the whole heat exchange surface is not active, and there's differences between round and half round. But there's differences in the heat exchange surface.

Plus the cross sectional area is different. 8x8x3.1415926 = 201.06 sqin/4 =50,26sqin x12x20 =12063 cubic inch for the 8 flue

Compared to

22,83x22,83 x3.1415926 /4 =409,35 sqin. x12 x20 =98245 cubic inch /2 for a half barrel =49122 cubic inch

So it's about 4.07 times the volume. So gases slow down in there about 4 times.

If the flue gases have 1.55 times the surface to exchange the heat, and more than four times the time to exchange it. You bet it's more efficient at transfering heat into the mass. Even if there's less of it to store the heat. It will heat up far more. Andfurthermore, since the half barrels can be used as a bell, gases stagnate in thoses, so exchange time is even more increased!

Get it?

Hth.

Max.

" Max" : I know where you are going, but I got lost on the journey there, THE Inside Surface Area is sometimes just an extension of the units CSA, but sometimes
its like the other side of the coin! I Always say you don't know the subject ,if you cant explain it to your grandmother ! Give ME a little time to review CSAs and to
attempt to get my head around this, and Lets see If I can get It right !

For the Good of the Craft ! Big AL

Ok so idk when I'm going back out there to the earthbag house might not be for another week. I can use barrels but I need to use something natural to take up most of the mass rock or silt or gravel with sand?. I can order a clay plaster from American clay or somewhere to give it a nice finish if I can't use lime. I'm doin a lime/sand plaster over the bags so if like to do that over the rmh if I can to match it but not for the bulk of the rmh.

allen lumley wrote:" Max" : I know where you are going, but I got lost on the journey there, THE Inside Surface Area is sometimes just an extension of the units CSA, but sometimes
its like the other side of the coin! I Always say you don't know the subject ,if you cant explain it to your grandmother ! Give ME a little time to review CSAs and to
attempt to get my head around this, and Lets see If I can get It right !

For the Good of the Craft ! Big AL

Internal surface area (ISA) and cross sectional area (CSA) are not related (much!)

We know so far, that a 6 inch batch box can whistand a single bell made of mass; of 6m² ISA (64 sqft) , the floor is not accounted for, if the bottom of the intake and exhaust are at three inches or more from the floor. You reduce that to 5m², if you have a metal bell.

If you have a double bell, you reduce the total isa by 15%, and by 35% if you have a triple bell.

A 6 inch J tube can whistand 3m² ISA aproximately, on top of the 1.8m² from the barrel. That's suposedely an absolute maximum with a good drafting chimney.


I should say CSA and ISA are loosely related. You need the first one, in conjunction with the type of core, to decide the second.

Deagen Demientieff wrote:Using barrels instead of ducting takes up more room and provides less space for mass. However don't the barrel bells get hotter? Is the draft pull better? Does the thermal mass heat up faster when barrel bells are used rather than ducting? I def have more barrels than ducting available.

Well, i didn't adress that.

The answer is yes, if the barrels are used as a bell. A taller bell has less friction than the half barrel system (invented by Matthew Walker) But the half barrel system has less friction than an eight inch flue for example. All due to the boundary layer and laminar flow.

For example, if we were making a cubic bell of the same volume as the half barrel 20ft long bell described earlier.

For 49122cubic inches, we have a bell of 36.62 inches per side. (root of three or third root?)

That means, not accounting for the floor, we have 36.62x36.62 =1341sqin X5 for the four walls and ceiling, =6705sqin or 46.53sqft of ISA, for 36.62 inches of travel.

Compared to the 14085sqin of the half barrel system described earlier, but traveling 20ft in that case.

You double the height of the bell, and you're nearly at the same square footage as the half barrels.

In the case of that 36in cubic bell, we're at about 2/3 of the surface of the 8 inch flue, but for only 1/7 aproximately of the travel. And most of it is friction of gases on gases. Not gases on stalling gases stuck to a pipe wall.

So, as long as you haven't exceded the maximum isa (which is given by the condensation point) where all the gases stall in the bell; a bell lets the draft pass better than an horizontal flue.

About Matt's half barrel system, there's also a trick, down low intake and exhaust of the bell, but at the same end, for less travel That's called a dead end bell. And can also be done with a brick bell or else. As long as the floor surface area is 4x the CSA.

Deagen Demientieff, how goes the project? Our Fairbanks RMH is coming along with some design adjustments. We are using a front feed with fresh air supply and a sealable door.

the building has come to a halt for winter. Im renting a cabin now and i go out to the earthbag house occasionaly to check on it. Cant wait to start back up in may! This is a really fun and rewarding hobby! Linda? thats a good looking rmh with a batch box. Are you currently living with it? Its been a warm winter so far.

Hey Deagen,
We are using the heater as we continue to add mass. It is a crazy warm winter, so it is hard to compare energy costs with last year...no complaints.
It will be cool to see your project continue in May.
Some of my middle school students said they saw good clay by the new Tanana recreation area this summer? I ordered some extra clay from Oregon to continue with my bench.
Take care, Linda

THis is just great linda !! Would you like to meet for coffee?