Barn Addition

hello all
writing from the North East corner of Ohio on the banks of(ok 2.5 miles from) Lake Erie
i'm writing about the addition i'm putting onto my barn in order to facilitate expanding our chicken flock to include a large breeding group of Buckeye Chickens.
the barn sits on a hill sloping down towards the west so i could either dig or fill to add space. i have never checked the degree of slope but it just seemed easier to build up on the downhill.
it is a round locust pole frame with rough mortis and tendon joints.
my intention is to bundle Phragmites and use it as a wall filler instead of straw bales, and not nearly as thick, that will then be covered with earthen plaster
maybe with a little lime on the outer walls
2 large window panes (32x76") will lay long way side by side in the west wall
the north and south walls are curved on a 5' radius
overall the foot print of the barn is 16x27' made of cement block
the addition is 10x25
last summer we replaced the cement sidewalk and driveway at our farm so we had a ready supply of big chunks of the stuff (1st time I moved it)
this we dumped behind the barn after doing some foundation mending and general tuck pointing.
and there it sat for most of 9 months.
last fall with the warm weather I set poles and a roof adding 240+ square feet onto the barn. (new coop)
I know that cold winters like last year are more likely now and to be clear, the barn was sealed up with all hands on board for almost 3 months except for my routine visits.
we have 2 goats and 55 chickens at the moment with a pair of twins coming next month from our new Lamancha named Ann Hydrous Amonia. or just Annie.
their accumulated decomposing bio-mass and spent straw/hay does a decent job keeping the place above deadly cold but not for those kids who decide to enter the world on THE WORST night of the winter.
for that reason I decided that since the floor is getting filled in along the entire length of the barn, why not put a rocket into the floor itself and use that to heat the place?

my thought is to go out across the floor and follow the curve around the north wall (addition faces west)
i'm stuck at 2 places
1. i've seen 25-35' on a 6" system. what is the maximum length in the floor that I can achieve?
2. does there NEED to be a vertical chimney for exhaust? if yes does it NEED to return to the source to get "rewarmed" before going out the chimney?

my thinking goes as follows
1 . most of my heat is intended to go into the wall and floor between rooms using the cement block to catch the radiant heat from the barrel. i want to use the exhaust to heat as much of the room as possible.the stove sits on the south end of the addition, towards where the new door will be, the heat will go away from the door into what will be the coldest part of the room towards the north. this only makes sense. in most benches, the pipes go back on themselves, sort of double heating the same mass. here the heat is always finding cold mass. does not doubling back negatively impact flow?

2. i can put the exhaust outside anywhere i want to as most of it isn't there yet, just some old greenhouse plastic and unused craft store banners (billboard canvas) i would much rather not put any more holes in the roof than i really need to. my other RMH return to the source before rising up over the barrel and along the ceiling until the peak to exhaust outside. i've seen a few pictures of the exhaust port coming directly out the side of a building as simply a Tee connector and not riser.

i mocked up a drawing on sketch-up that shows 2 possible layouts. they are both over 30' but not by much. the red one is slightly longer.
today is about cooking maple syrup and tapping away at this computer
if anyone has any thoughts, i would appreciate them
c

let me try that again

That system will need much higher chimney stack so it can work. bends deduct from the total length you can have. with a system like that you may need 15' or maybe even higher stack. the Y exhaust will not seem to give you any advantage if not completely stall your air flow. exhaust in contact with ground will suck heat and suction power from your system total strength and may cause copious amounts of condensation in your pipes.

i should amend. the chimney can be tall in either case.
red and green.
they are not going in together
they are options as to whether i need to return to the heat source to lift the exhaust or not.
as for the heat getting sucked away, if i put some sort of moisture barrier into the infill but beneath the stove pipe, that should keep the floor's dry and able to radiate
or am i completely off on this?

Given that the interior will not be very warm in any case, I think coming back to the barrel offers a safety feature, and a way to prewarm the chimney for much easier starting. In such extreme heat-sink conditions, I would advise an 8" system. At worst, it will have more power than required and will need to be fired less often; at best, it will give the heating capacity you really need for cold weather. An 8" system is good for up to 50', minus 5' per 90 degree elbow, so you could run it most of the way up & down the length of the addition safely. You could not come close to this with a 6" system.

You do need a vertical chimney that rises several feet above the roof to ensure good draft and avoid smokeback in unfavorable wind directions. The more of the chimney that is inside, the less draft you lose to wind chilling and the more heat you put into the space.

A moisture barrier might help a bit, but you really need insulation below the duct, or you will be sending half the heat down into the ground where it will be lost.

if i could go back, i would do 8" duct. the stove's internal dimension is set for a 6"system. i mean i could tear it down and recut all the brick in the riser if absolutely necessary. that was a lot of work to have to go back and re-do.
i'm not looking to warm this place to the same temp as i keep my house. it's a barn after all. 40-50 F would be great when it gets and stays below freezing

I also note the very long burn tunnel in your photo. Making this extra long will not improve your fire; you want the flame to get to the riser and do its draft-push as soon as you have the initial combustion mixing done. When I have observed a 6" J-tube without barrel, the flames do not reach much farther than the base of the riser in normal conditions. A short burn tunnel lets the maximum amount of heat reach the riser to generate draft and complete combustion.

Bringing the duct back to the barrel allows you to install a bypass with damper so you can have good draft to start the system when it is cold, instead of having to push cold air all through the duct at first.



Assuming those are standard firebrick, you effectively have a 5" diameter combustion core, which will generate even less heat than the 6" system you are talking about. This in turn has less distance it can push the exhaust through the duct. I really think you will be happier long-term with the effect of an 8" system. For one thing, it will probably take half the firing time every day to get a given amount of heat into the space and floor.

i can shorten the length of the burn tunnel easily enough.

here are a couple of posts i did about it on my blogish thing
http://trilliumcenter.org/2016/02/22/heat-for-the-kids/
http://trilliumcenter.org/2016/02/24/what-a-day/

I read your blog posts... sad to see you have completed all the core work at a size that I firmly believe will be too small for your needs. You will definitely not be able to push the exhaust 35-40' through the duct, maybe 20'. I made a demo 6" J-tube with a half-barrel bell and a 5' length of stovepipe for a chimney, and on a 90 degree day it drafted like crazy while leaving only mild heat at the top of the chimney. If yours is not getting a strong draft now, I foresee sorrow later when you have an underground duct run.

I think you could even keep the footprint of your burn tunnel width (shorten its length by several bricks), and add another brick to its height to get a 6"w x 7"h burn tunnel, then a 7" x 7" heat riser would be easy. You actually don't need hard firebrick for the heat riser, the soft firebrick will do an excellent job there and come up to operating temperature almost immediately.

i feel like throwing up

I'm truly sorry to lay such a downer on you, but it could be much worse - you could have the underground work done. The core rework would negate the hours you spent on soft brick finishing, but fireclay mortar is pretty easy to remove so the bricks can be reset. If you eliminate the hard firebrick riser and just reset the soft bricks to a 7" x 7" inside dimension, you should be able to reuse most of what you have done. Saving the clay plaster you put on the outside of the riser and rewetting and reusing it should let you avoid wasting the work and materials of mixing that up the first time.

i've been racking my brain on this thing all night and may have found a smooth spot
the thing to remember here (mostly i'm saying this to myself) is that the goal is NOT to get the barn to a house temperature
it's pretty snug already. my hope is to take the brutality out of the cold when it comes back.
so i have this rocket stove sitting behind my barn based on 6" and i have 3 or 4 more soft brick total. ALL the soft bricks around the riser are cut, recutting them thinner only increases the chance of breaking them
if i could rebuild the thing out of all soft brick I would. i'm curious there too. you say soft brick heats up fastest, which i understand, but it gets cool fastest too. my effort is to insulate the hard brick in the inner core in order to hold the heat to improve flow/vortex/combustion.
or am i coming at this all wrong?

regardless
model 3 is attached
that is 10' out and 10 back, i've only shown 10' of rise but 15 is easy enough, it's just through the roof at 10' and will need at least 5' more to clear the peak.
i could even shorten it to 5' out and 5'back

the point is to have a warm soft in the middle of the barn when i need one. enough to keep water back there without it freezing


shortening the fire tunnel is easy enough
insulating around and under the pipe is doable. i could do the entire room. we can get 2" slabs of garage door insulation around here (Styrofoam with fiberglass sheets on both outer surfaces)
that stops any moisture from below
dry mass gives off heats, wet mass takes heat

That looks like it would work to have a warm part of the floor, and take the edge off of the interior temperature. Will the floor remain one space, so that animals can always reach the warm section if they want to?

I think your next step, if you want to keep a nominal 6" system, is to get 30-35' of ducting and elbows so you can lay out the runs and chimney in the open air. If the system can draft in that situation, it will probably work when buried under the floor. (Bare duct sheds heat faster than duct encased in mass.)

I would keep in mind that the combustion core you have (based on my reading of your brick configuration) is actually more equivalent to a 5" diameter system than a 6". Thus your potential rate of heat generation will be less than the common 6" size, and you will have to run it longer to get the same amount of heat.

Soft brick heats up and cools down faster than hard brick, but the riser will not be cooling off until the fire is down to coals and the feed tube and burn tunnel are starting to cool. If you watch the fire and close off the feed according to the burn rate, you can keep the system hot as long as it needs to be. Letting the feed stay wide open as the fire burns down will let a lot of excess air pass through and cool the whole system.

it might not stay as 1 single room, but they will always be able to get to the heat as the mass goes in front of the door between the old part of the barn and the new addition.
not evident in the drawing.

the internal dimension throughout is 6" x 4.5" = 27 sq in
6" duct = 28 sq in
5" duct = 19.6 sq in
it's all prototype for the Magnum Opus anyways

Hm, the riser looked more like 4 1/2" square or 4 1/2" x 5", but I can see now where you have the 6 x 9 bricks you mentioned. Perspective angle makes them look narrower. Anyway, a square channel is not equivalent to its exact equal area in a round channel, as the corners cause some turbulence and drag. It is said by some experts that a square channel is equivalent in flow to a round channel of the same outer diameter, i.e. 6" square = 6" round. So you likely have between 5" and 6" equivalent core size. Anyway, a slightly smaller core than duct just means faster airflow in the core, which is supposed to be better than the opposite.

I've been picking away at my stove.
As the floor comes up around the mass box, I'm getting a sense of what can happen.
I did shorten the firebox like suggested. 7.5 or 9" I can't remember.
Then I put a 7.5'x6" duct out to a 180 deg turn and 7.5'x6" back to just by the stove
90 deg turn towards the roof and at this point, only fir first 5' of the chimney.
it took right off and drew like a champ.
Better than my first one and the bricks aren't really mortared together yet.
The thermal mass will be 22" wide, 20" deep and 8" long
at no point does the ducting come within 4" of the insulation
my intention is to fill the box with cob
wracking my brain to think of what would be the driest material I could fill it with.
as long as the cob is a little on the drier side, it won't take any longer to dry out than bank sand or pea gravel

before building the insulated mass box, i went all the way down to the lowest original soil level I could find and laid in a sheet of heavy black plastic.
on top of this went the 22x48x2" garage door insulation panel
into the bottom of the box went a layer of cement chunks
aside from putting together the duct work, the stove is largely on hold until I can punch the chimney through the roof.
In the mean time, I'll be making Floor Lasagna
After I worked the black plastic most of the way across the room as low as possible, I laid in a layer of flat cement chunks nestled cheek to jowl.
on top of this goes several inches of loose, moist clay.
This gets tamped in place and another layer of cement goes on top
repeat until I fill my 24+" void

It's all a game of moving cement chunks back and forth



i'll fill the mass box eventually.
weather depending

thank you for the advise
you saved my butt

It's great to hear that your revised layout works well. I suspect the shortened burn tunnel had a lot to do with that, as it lets the heat riser see more heat and make a stronger draft.

The mass box sounds fine. The rest of the floor where you put concrete chunks down is good for solidity, though I think you would be better putting just gravel or stone in rather than any clay/soil. Cobbing in the mass box would probably be the best use of the clay you have now. You wouldn't want to put it in anywhere while it is frozen anyway, and just mixing it with enough water to make it moldable will be sufficient. I have recently used hot water to mix up cob from frozen clay brought in from outside, and it makes it much more pleasant to work with.

the floor is moving along in fits and starts
I've been at a bunch of other stuff and not focusing on the coop addition.
the other day some folks came around and helped move a bunch of dirt and sand into the addition
and voila
by the next evening, the floor was within 1/2" of final finished level.
the thermal battery needs filled up, but the chimney for the rocket stove is built and ready to get taped and buried.

I'm wondering about the next bit.
has anyone ever tried mixing hydrated lime (mason's lime) into their cob floor mix?
the reading on this site talk about going above and beyond what I'm thinking
I don't really care to do the original morocco system.
this is a barn and a prototype for when we do the house
I figure the house will never have as abusive a treatment as the barn floor under the chickens
I mixed 2 scoops of lime with a big lump of cob. when I did this outside, it has seemed to resist the water a lot better
Don't get me wrong, cement this is not and never will be. I'm just hoping it stays together a bit better and far cheaper than linseed oil and turpentine.
if it fails terribly, well, it's still the floor in the chicken coop so they won't care

The Ashtabula Local Food Council has been putting on a series of tours around the county and we got on the list.
This gave me more than enough incentive to get the place cleaned up and the projects, if not finished, then, at least, into a condition that won't hurt anyone.
First and foremost, this meant filling the box around the horizontal chimney in the insulated box that runs in front of the door into the old barn.
It has been filling with all the hay wood chips nannie berries and chicken crap that has leaked out of the barn through the door.
Little goaty pants Viann hammered several of the HVAC ducts flat flat.
They were stacked in the addition, behind the door, leaning against the riser barrel, for months, as in all spring and summer
She found them early on and reveled in the sounds they made when she jumped on them.
kids...

So the box was filled with 50% unscreened bank sand and 50% local yellow clay. (the stuff from under the pond across the street)
I didn't add any lime or organic material.
Also, with the recent rains, the sand and clay were already slightly moist so I didn't need to get it any wetter.
I just tamped it in around the pipes as I filled the box.
With it's being down in the ground and only exposed to the air on 1 face, I figured to keep it as dry as I could.
It will take a while to dry, so I'm not in a hurry to cover it up.
Between this drying and the lime in the rest of the floor curing, I won't be doing any more for a while.

I had a little bit of sand and clay left over, once I had the box filled, so I tamped the last load in and around the fire box.
Rather than mortaring the bricks together, I filled the fire box brick and wedged them in place with wooden shims in order to keep the box from collapsing.
I have a small galvanized metal can with a tight lid for the firebox cover.
Once it is time to finish the floor, the first thing will be setting the can in place, with the bottom removed, over the firebox.
Time will tell on all that.
For now, I can content myself with building out the coop fixtures.
The hens are already colonizing 2 buckets at the back of the room as nests.
They were laying behind the stack of windows.
So I know that at least some of them prefer this room to the existing nesting area.
Which is fine for now.

making progress

yesterday I ran the chimney up through the roof and put the cap on.
The first lighting was a total smoke fest
if and only if the wood was less than 6" in length would they burn relatively smoke free.
otherwise the draft wasn't strong enough to pull the fire into the system
I have 18' of rise on the chimney and the smoke/steam barely oozes out
adding burning paper in the base of the chimney did create a nice draft, for only as long as it burned, once it went out, the draft fell back to not much

maybe it is because the mass is damp (as is the inside of the duct pipe in the floor)
maybe the steel can around the feed box is upsetting the draft requirements (as in riser should be 2x feed tube height)
I don't feel like it should matter though, with it's being so much larger than the feed tube opening

maybe the space between the top of the barrel is too far/close to the top of the riser
maybe the firebrick liner in the riser is just too cold/damp (after 6 months)



I'm pretty sure I'll have to dig it out of the ground
the main riser/barrel, not necessarily the feed tube/metal can

not today though

I looked into the TROUBLESHOOTING section of ROCKET MASS HEATERS by Ianto Evans and Leslie Jackson
Here is the direct quote from the end of the bit on " Stove smokes into the house"

"The first time you light your new stove, don't expect immediate success. Don't be downhearted if it smokes like crazy and it's hard to get a draw. With any new masonry stove which is still cold and wet when you first fire it, there will be an adjustment period. Use the primer, light it up with the driest, thinnest wood you have and be patient. It may take several hours for it to start burring really well."

in other words, I need to go eat smoke for a while and see if that does it.

Charles; When I have a wet core & mass I expect trouble. My first core and mass took 4-5 weeks of hard burning before it was truly dry and heated up. Be patient keep burning .. it will get better.  I keep a small electric fan on hand and when it starts to smoke back I blow down the feed tube.... works great as long as you are in the room, the fire will quickly start roaring . Take away the fan and in a few minutes or an hour it may try back smoking again.  Just keep giving it extra air sort of a turbo effect,  make that dragon roar, get it hot  before too long you will start to see an improvement.

I am pleased to announce that THAT DRAGON HAS ROARED!!! or whatever. The rocket stove in the barn seems to function adequately after only a few hours yesterday and most of today. Actually it was working pretty well after about the first hour today. Maybe the first few hours. I did try pointing a fan into the feed tube. Pretty much the exact fan in the picture above. If the fan helped, I would have to say that it helped push the excess smoke out of the metal can and further into the room more quickly than the drafts would have on their own. So no fan. An hour of working in a smoky room was enough.

The thermal battery is still damp, so that will take some time to actually heat up, but the riser is dry. I figure that a dry and pre-warmed mass will automatically improve the draft. That will just take time.


The one alteration I did to the stove was to add a single brick to the feed tube. From the book I think.  This made the opening of the feed box 15 square inches smaller. This choke point popped the draft up enough to keep the stove going. Or so I thought. Before I put the last load of wood in for the evening, I pulled the additional brick out of the feed tube, to see if there was "excess" draft. I went from fully effective, smoke free roaring draft to a meager draw without the strength to pull the smoke down from wood that was only 3-5" long, well below the upper surface of the horizontal thru tunnel.

Tomorrow will see how it starts up after being open to the draft all night. I'm leaving it open so that the moisture can continue to vent. The metal can around the feed tube has a lid that is effectively air tight. I haven't get it figured yet. But I do know that being to at least slow the draft between firings will help hold the heat in the mass. With the amount of moisture still present in the feed tube I figured to just let it breathe.


This thing is just sucking down the wood now. Granted, I'm burning mostly hemlock lathe boards. But so what? It's working. It's not filling the room with smoke. For day 2, I'll take that as a win.