Rocket stoves in Greenhouses , our own forum topic

Hi folks. I am new to the permise forums and this is my first post. I have been considering building a greenhouse (perhaps pit type) and putting a rocket mass heater inside for heating the green house. My question is, how do you control the temperature with a rocket mass heater? Is there a way or not? How warm does the mass such as cob usually get. Most plants like a warm place to germinate but then a little cooler temp for growth. Is there any way other than venting the greenhouse to control the heat level? Thanks.

Whatever your greenhouse shape, design and material used, the cheapest way that I can see to add raw thermal mass, is to insulate the perimeter to two times the depth of your frostline. If your frost line is 18 inches, then insulate to 36 inches. This turns the ground under your greenhouse into thermal mass.

Now, the idea is to HEAT that thermal mass, and I believe a rocket Mass stove can do that. (You may add additional thermal mass as you wish. Water as part of an enclosed system requires a very small wattage pump to circulate it. And it can be used to transfer heat from your heat source to your ground.) The problem is where to put the RMH?

The two main designs are 1) Full wall glazing. All the walls allow sunlight in. These work great if you get mostly skydome light. 2) South facing glazing. The northern wall is insulated (and maybe some or all of the east and/or western walls. These work the best for areas that have direct sun light, presumably from a low in the sky sun to the south. In the latter design, the heating system would go against the north facing wall.

The issue that I see with using a RMH in a greenhouse is that people don't live in greenhouses. There isn't going to be someone there to feed the standard RMH little sticks of wood all day long. So either you need to design some continuous fuel feeding system or come up with a way to have your fuel burn by itself for several hours at a time. MY idea is to do the latter, and to do it with a batch charcoal making stove.

The retort design for making batches of charcoal seems like the answer to me. You fill it with wood that you want to turn into charcoal, you surround that with some kindling to get the process started, and you stand back and let the thing go. The gasses that are released by the wood heated without oxygen exit the inner chamber and burn at a very high temperature when they hit air. They continue to off-gas for several hours. And when there is nothing left but carbon, the process stops. There are several videos of these stoves on youtube. I will not bother posting any in this thread. But check them out on your own time.

Now the trick is incorporating a charcoal making retort into a RMH design. This may not be straightforward. The batch method presents some logistical issues. you need to open the thing up and remove your inner drum, barrel or whatever, and allow it to cool before opening. One other issue, a charge of wood turning into charcoal puts off a LOT of heat. Seriously. You would need a fast heat exchanging system to cool all that exhaust fast enough for the gravity draw system of a RMH to work properly. AND you don't want to cook your plants in the process. Charcoal retort stoves tend to have a minimum size or else they will not off-gas long enough to be self sustaining. I think a 25-30 gallon inner drum is about as small as you should go. Smaller than that, and they will not put out enough off-gasses.

I basically agree with Hilary except for the charcoal part. You're still going to have to keep feeding the RMH heater on a regular basis, plus spend the time making the charcoal.

I heat my GH with a RMH and use it to heat about 2000 gallons of water and also the ground as a thermal mass. There is so much mass, that running it for 8-12 hours hardly makes a difference in the general temperature (Except for the air which warms up from the heat that comes off the barrel). But at night which it drops down into the 20's, the greenhouse will stay in the 50's

If you have some time to kill, here are the video playlists for the history of my RMH and building of the greenhouse:
http://www.youtube.com/playlist?list=PLtIuZ9K-UzcNnCmoKicRLzYQndplSkUuR
http://www.youtube.com/playlist?list=PL919FC3C22FE4116C

I would love to see more of this project that Bradley has going on. Thank you for the photos. Please keep us abreast of your progress.

Hilary thesane wrote:Whatever your greenhouse shape, design and material used, the cheapest way that I can see to add raw thermal mass, is to insulate the perimeter to two times the depth of your frostline. If your frost line is 18 inches, then insulate to 36 inches. This turns the ground under your greenhouse into thermal mass.

Now, the idea is to HEAT that thermal mass, and I believe a rocket Mass stove can do that. (You may add additional thermal mass as you wish. Water as part of an enclosed system requires a very small wattage pump to circulate it. And it can be used to transfer heat from your heat source to your ground.) The problem is where to put the RMH?

The two main designs are 1) Full wall glazing. All the walls allow sunlight in. These work great if you get mostly skydome light. 2) South facing glazing. The northern wall is insulated (and maybe some or all of the east and/or western walls. These work the best for areas that have direct sun light, presumably from a low in the sky sun to the south. In the latter design, the heating system would go against the north facing wall.

The issue that I see with using a RMH in a greenhouse is that people don't live in greenhouses. There isn't going to be someone there to feed the standard RMH little sticks of wood all day long. So either you need to design some continuous fuel feeding system or come up with a way to have your fuel burn by itself for several hours at a time. MY idea is to do the latter, and to do it with a batch charcoal making stove.

The retort design for making batches of charcoal seems like the answer to me. You fill it with wood that you want to turn into charcoal, you surround that with some kindling to get the process started, and you stand back and let the thing go. The gasses that are released by the wood heated without oxygen exit the inner chamber and burn at a very high temperature when they hit air. They continue to off-gas for several hours. And when there is nothing left but carbon, the process stops. There are several videos of these stoves on youtube. I will not bother posting any in this thread. But check them out on your own time.

Now the trick is incorporating a charcoal making retort into a RMH design. This may not be straightforward. The batch method presents some logistical issues. you need to open the thing up and remove your inner drum, barrel or whatever, and allow it to cool before opening. One other issue, a charge of wood turning into charcoal puts off a LOT of heat. Seriously. You would need a fast heat exchanging system to cool all that exhaust fast enough for the gravity draw system of a RMH to work properly. AND you don't want to cook your plants in the process. Charcoal retort stoves tend to have a minimum size or else they will not off-gas long enough to be self sustaining. I think a 25-30 gallon inner drum is about as small as you should go. Smaller than that, and they will not put out enough off-gasses.

Hillary, are you using a system like what you describe at this time? My only experience with the retort furnace is in using one to make bio char and over all it was a big disappointment for me. I used the system where you put the retort inside a concrete block structure and build a fire under the retort furnace in order to get the wood in the retort up to temp to burn off the gasses. I felt it took so way much more wood to make the char and the char we got out of the system just didn't make the whole procedure worth it to us. Perhaps in a much more inclosed area like a RMH the gases would help keep the fire going much better then they did in the bio char setup we had. The gases did help once the whole system got hot enough but they did not keep the fire going by themselves to finish the process and more wood was needed under the retort to keep the process going to the end. That is my only experience using a retort and , as I said, it left a bad taste in my mouth . Do you have any photos of your system? Thanks.

As I understand if I make a reply it will automatically inform of any new information. We are going to build a greenhouse next to the house we are currently finishing up, and we want to heat with a rocket stove, so this thread is perfect for us. It would seem that with all the question about moisture that you should just pour a concrete slab. The upfront costs are going to be maybe 200 dollars for the slab on an 8 by 20 ft gh, but you could put pex tubing in there for radiant floor heat, and use cob. We already have a 4,000 square foot greenhouse with a concrete floor, and there are never any moisture problems in fact it is usually the opposite. Attached is our blog, and you can see the current gh at greenhouse becomes. With the slab and twin wall we grow through the winter in zone 5 with no heat. We want a place for our torpicals. http://luckydogfarm.wordpress.com/

Thank you very much for starting this thread.

OK Folks, I have been reading here for years and have gotten a wealth of great info. Now i need help! Propane is expensive and i went through 2-100# tanks last fall heating at night only from the end of September till mid November in order to get my harvest of Tomatoes and Peppers. I would like to start heating March 1 and would only need to heat at night as the daytime temps will be fine. I want to build a rocket stove but don't want to take up too much room. Is it possible to build a small stove using 4" pipe? I figured i could run a straight run from one end to the other with no elbows. The other issue is we have no clay i know of in NW Montana. Is there another way to make cobb? Here are some photos of what i have to work with. FWIW it was 38 outside today and 75 when i opened up the hoop house. After the door was open for an hour it was still 61 inside! This hoop house is 16' x 20'

Mathew, you want to keep reading this site and searching. I can't recall where but, I believe someone said 4 inch pipe didn't allow enough draw. The whole idea with the RMH is to heat enough "mass" to release heat over time. Your question is good though and something I am curious about. Just how big is big enough? Perhaps with determining the number of BTU s needed for the space and the number of BTU s a RMH gives off, the answer will be achievable? Then you can determine if it will do what you need. Does your high tunnel have two layers of plastic over it or just one? Some folks out our way are using two layers and a small fan to help create a layer of air space to help insulate.

Denny Nebgen wrote:Mathew, you want to keep reading this site and searching. I can't recall where but, I believe someone said 4 inch pipe didn't allow enough draw. The whole idea with the RMH is to heat enough "mass" to release heat over time. Your question is good though and something I am curious about. Just how big is big enough? Perhaps with determining the number of BTU s needed for the space and the number of BTU s a RMH gives off, the answer will be achievable? Then you can determine if it will do what you need. Does your high tunnel have two layers of plastic over it or just one? Some folks out our way are using two layers and a small fan to help create a layer of air space to help insulate.

Thanks Denny. I do remember seeing something about that. I only have 1 layer. Would like to do a second but $$$$ are tight. I got my woven poly from these guys. http://www.northerngreenhouse.com/products/polys/wovenpolys.htm

Hey Matt,

I have a similar hoop house..pics on this site. I used Bentonite clay for my stove; built it in Decmember, still going strong. There is a cheap, cheap cat litter, I think it's called Special Kitty, sold at WalMart, that is only clay.
The only drawback I've found is that you have to be in the hoop house maintaining the fire. It's not like a regular wood stove, where you load it and don't mess with it for 3 hours. RMHs need attention every 45 minutes or so; at least mine does.

I've taken to pulling a solar pool cover over my hoop house on the real, real cold nights (teens and below). That helps to contain the heat.

Duh, my pictures are on the page before this. What kind of propane heater did you use???

Mike

Feeding the stove every 45 minutes is going to be a problem for us as well. Maybe there is a better way of doing this, and the problems is the cob. If the cob takes one hour/inch to heat up then you have to keep that fire going all day long to get 8 hours of heat at night. What if you used phase change materials instead of the cob? I did a lot of research on this when we first built our 4,000 square foot gh. It wasn't going to work because we were only thinking about using sun to heat the materials, and we don't get enough sun here to heat the materials, but maybe it would work with a rocket stove. These materials were patented and when the patents expired some of the materials were pretty simple if my memory serves me. What do you think?

I've posted it elsewhere on this forum, but I have a pellet feeder design on my RMH that burns without having to do anything- just clean out the ash when the pan gets full. The hopper holds 6-7 hours (80 pounds) of pellets. I just fire it up and walk away.

Latest Pellet feeder design video

Rob, how much does that work out to? I'm getting just under $10/day, but not sure if I'm doing the math correctly.

That's about right. I'm paying $4.18 for a 40 pound bag at Home Cheapo. I keep the temps in there between 55-60. When it goes down into the teens at night, the worst I've ever done was 4 bags, but I it was the weekend and I was trying to work in there so I made it warmer. Most days, I burn just 1-2 bags. Total building size is about 1100 sq ft.

If you compare that with burning fuel oil, we're around $3.50/gallon. A furnace that can heat about the same will burn 1 gallon an hour ($3.50/hour) whereas this burns 12 pounds/hour (about $1.25/hour). Plus it's a renewable fuel!

Hi guys! I've been lurking for a while, and well it's time to jump in. Question. Does anybody know of anybody in the Spokane Wa. or Coeur d'alene ID area that would be willing to help me build my first stove? I'm building a Large greenhouse for our CSA business Hopevalleyfarm.com and want to avoid any major "beginner" blunders with my Rocket Stove. Thanks for any help you can give me.

Rob Torcellini wrote:I've posted it elsewhere on this forum, but I have a pellet feeder design on my RMH that burns without having to do anything- just clean out the ash when the pan gets full. The hopper holds 6-7 hours (80 pounds) of pellets. I just fire it up and walk away.

Latest Pellet feeder design video

I don't suppose you would be willing to share any dimensions with the rest of us? The hopper sounds like the way to go. I hate the thought of buying wood pellets but, the firing a fire every 45 minutes will probably nullify the rocket stove for me. I could see walking up and down the hill to the green house every hour through the day but, having to do that through the night would just be something I'm not willing to do. Maybe propane isn't such a bad idea after all. Is there anyway to increase the size of the firebox to the point much more wood could be used to allow a much longer burn time? Thanks

Can anyone understand this. Water is the most abundant phase change material.

http://www.helpfulgardener.com/phpBB2/viewtopic.php?t=40228

Rob, I love what you are doing, and I spent some time at your website looking at how you do things, but I have 20 acres of hardwood that is virtually free.

Yeah, I have more trees than I know what to do with here too....but it consumes too much of my time to harvest them. I"ll spend around $800 to heat the greenhouse for the season. Sadly, it's money well spent if it frees up my time to work on other things.

Is $800 for the geodesic dome only? How much income can you get for that $800 expense?

I'm not questioning anything you are doing because I don't have answers and I have been messing around with this for years. I don't heat our 4000 sq ft green house and right now I get around 5 pounds/week of greens out of there, which is only $50 dollars in income. Everything picks up from here on as the days get longer but it has been pathetic for the last 2 months. We make some money growing micros in our living room.

One thing I see you is had a lot of romain in your video. Romain is probably our worst performer in the winter. Kale, chard, bok choy and miners lettuce produce the most mass this time of year.

Thanks, this is a good discussion.

yeah, there is no money coming out of the greenhouse right now. I'm picking about 5 pounds of tomatoes a week and 15 head of lettuce. (That's actually butter crunch that's in the videos). I don't have the entire greenhouse running yet...too many other projects going on at the same time. At some point, I'll start doing official counts of the produce, but for now, during the winter, it's a loss.

It is hard to compare because greenhouse can mean so many things. Yours is a geodesic dome. Ours is an old cow barn with a concrete floor, insulated north wall and twin wall on the south side. Without heating we never get below 25 under the plastic which we use as a secondary cover. Without heating, we still "grow" through the winter here NY State, and like your stuff is finally starting to really grow again. For the RMH greenhouse we will berm the back side of a block wall insulate the ceiling and have curtains to cover the windows at night. Our bermed house never gets below 32 degrees and we hope we can duplicate that in the heated greenhouse. What we are noticing is that even in this time of low light the figs and meyer lemons that we have are growing like crazy and have a lot of fruit on them. Lots of leaves probably because of the low light, but the lemon leaves have more C than the fruit, so we have been using them in a lot of teas and meals. The fig leaves are amazingly healthy for you as well. Excited to hear at this latitude you are getting tomatoes. We figure we will put figs, lemons, papayas, green tea bushes, tomatoes and perhaps some beans in the heated greenhouse. The unheated greenhouse is really perking up now so it would be a waste of space for greens in the heated greenhouse.

Working on some kind of bladder filled with water to be used instead of cob. The barrels would appear to take up too much space. Anyone have any thoughts on this.

Some water barrior





screened clay


may first cob batch




Then I added straw because I forgot I was going to do an insulative layer first, so it was a thin layer of cob w out straw
then w straw
Next is getting the riser insulated



THe insulation will be 8in by its completion

We would like to build a rocket mass heater for our greenhouse here in Jay, Ok. We would like to find someone that is near to us that has a rocket mass heater up and running that we can see first hand. Anyone out there that is within a 4 hour drive, that wouldn't mind our coming to see their heater working. We also are into aquaponics in our greenhouse. We also raise Tilapia for aquaponic gardeners. Appreciate any information you can give us. Our email address docproc@brightok.net God bless Randy

allen lumley wrote: Rocket Stoves need DRY Wood, most greenhouses are Artificially high humidity areas, wood stored out of the greenhouse will result in high traffic at the start of the greenhouse heating season when we would like to keep the heat in the Greenhouse !!!

Admittedly, I haven't read this whole thread yet, but it would seem to me that if you could design a RMH that allowed for the feed tube to be placed on the outside of the house, this problem would be resolved.

Now, my million dollar question is this...I am using a design found in Bill Mollison's Introduction to Permaculture to build a chicken coop with a attached hothouse. My big concern is that the hothouse/greenhouse part of the building will not be warm enough for Michigan's crazy random 2 degree days in winter and so I'm interested in adding a RMH to mine as a backup plan. My problem is the size of the building. This greenhouse is going to be small, like 20 sq ft at most. The coop will be about 16 sq ft and since the coop has to be raised, there will be a gap of about 2 feet beneath the coop which will servers storage space, possibly a place to put my mass and ductwork. Does anyone have any ideas on how to miniaturize the designs for the RMH so that I could use it in this small of a space?

the new version of insulation

kinda draggin my feet on the insulated riser
going to line the floor w insul sheets before "massing"

Bradley,

I've been looking at the pictures of your rocket and I'm interested to know what kind of brick you are using. Is that refractory brick? Also, I have not ever seen anything but a metal chimney type of heat riser assembly. Do you think the square design of yours will have an effect on the reburn within the barrel once you get it finished? I love the idea, it seems like it will last forever, but with the way the smoke circles between the top of the chimney and the barrel, I would assume that a round design would work better.

I'm looking to build one of these in the spring, so please let me know how well your design works! Thanks.

Great thread you guys!
I just wanted to let you know I'm working on a set of plans for greenhouse rocket mass heaters. It's based on about 5 greenhouse heaters that Ernie and I have worked on over the years, modified with insights from those experiences. (e.g. the importance of the exit chimney design to avoid exhaust stagnation under cold, damp planting beds).
We need some more test cases before we can call this set of plans 'as-built and successfully operated for over a year.' We don't publish anything that hasn't been proven out, but we do release them privately if you're interested. If you'd like a sneak peek, or to be a test site, email me and I will happily sell you the draft version for $20. It's 20 pages and about 4 MB, with a couple of concept sketches.

As an incentive, if we sign you up as one of the first 3 or 4 test sites, we will happily give you an hour or more of dedicated Q&A time, and draw up your accurate as-built scale drawings for our eventual publication. (I will do the drawing, based on your description; this can happen before you build it so you have custom scale drawings to work from, but I need you to let me know if you change anything).
We have one guy in the Reno area so far who's doing a long bench for a or 6x24 mini-greenhouse setup, and a local guy (East Cascades highlands) who's got a geodesic dome. For breadth, I'd love to get a larger-scale commercial greenhouse example, and some test sites in Midwest or maritime regions.
I'm going to be a little choosy about test situations, so we get a set of heaters that work well and are all variations on a good basic example.
A non-pressurized aquaponics heater would be very popular, but I think that might be too advanced for this set of plans. We have a couple of clients who may be doing this with our advice/help in the near future.
If you plan on doing a horizontal chimney, I will be less interested in doing custom design work because we've had so many problems with that feature - though if yours works great I would love to hear about it.
There's also Rob's awesome work on his gravity-fed pellet hopper, in a greenhouse and already working, but I think that's too advanced to include in the basic plans. He's given us permission to cite it as a case study when we get the technical manual out instead.

To reciprocate for this customization / private consultation, I'd request that you commit to reporting back:
- performance in different seasons, including some detail about your climate
- numbers (like square feet and details of your greenhouse membrane) to calculate approximate heating loads;
- amount of wood or other fuels you're using, and
- any troubleshooting you had to do, or notes on your learning curve and things that surprised you
- verification that any as-built drawings I generate for you are substantially correct. (It would suck if the performance depends on some little tweak you've made, that we forgot to mention in the plans.)
Most of this we can discuss right here so everyone can share, and we can exchange some of the more private details by email. I will always request permission and citation details before publishing any quotes or project info from other contributors.

I'm not offering compensation for using 'your modifications' in the design publication, just FYI. If you make a dramatic enough modification, it probably won't be included anyway.
Most of this info is public domain. (You can find a lot of it on these forums, in bits and pieces that we've put out over the years). The service I'm providing in order to sell the plans is clear, well-summarized info and good drawings, verified by performance in the field. Of course, once we publish the plans you're welcome to sign up as our affiliate on Scubbly, link to the plans from your blog or website, and make a percentage on everything you sell.

If you're interested, feel free to PM or email me. questions@ernieanderica.info
We're getting marvelously busy, and I don't get as much time to enjoy following these threads as I used to. Most of the discussion and reporting can go right here where everyone can share, but it may take a PM to get my attention. I respect if any test sites want to keep specific details private, like exact locations or family names. If you want me to respond to a specific post, it helps to include a link.

Thanks, and best of luck with all your projects. It's exciting to see so much going on!
Yours,
Erica W
http://www.ErnieAndErica.info

p.s. Off topic, but - you should check out Paul's videos on Kickstarter, especially if you are interested in that aquaponics hot water thing. It's a set of 4 based on our recent workshop in Montana, with the technical innovations on cast cores, 'boom squish' (hot water), and also a really solid and fun presentation of our basic Fire Science.
Wood burning stoves 2.0

Lucas Harrison-Zdenek wrote:Bradley,

I've been looking at the pictures of your rocket and I'm interested to know what kind of brick you are using. Is that refractory brick? Also, I have not ever seen anything but a metal chimney type of heat riser assembly. Do you think the square design of yours will have an effect on the reburn within the barrel once you get it finished? I love the idea, it seems like it will last forever, but with the way the smoke circles between the top of the chimney and the barrel, I would assume that a round design would work better.

I'm looking to build one of these in the spring, so please let me know how well your design works! Thanks.

the next step is to insulate the chimney to 1.5 in of the inside diameter of the burn barrel
barrel = 22in
insulated riser will be 18"

kind of putting this aside. its 80 now
but havent totally set it down
i will definitely finish the chimney

Hello to all I am new to all of you. I have been trying to build a rocket stove for this very reason.I live in Canada where it gets real cold. I have built 4 stoves with very little success the last one sort of worked. Can anyone tell me if a ceramic flew tile wood work for the riser. If so would it have to be insulated? Or how much mass one would have to have to keep the temp high enough over nite so the plants don't drop flowers. I understand that it will depend on the size of the green house.

I've seen a few articles on climate batteries, http://rfhs-greenhouse.blogspot.com/2010/03/ready-steady-go.html , like that one. It help disperse the heat. I've also seen a few on using compost, because the break down generates something like 104 degrees constant heat. http://youtu.be/NxHm9AYOAG4 . Iwas thinking of a combo of the 2, that would only require a small fan to push the air. That would be more constant than a rocket stove and use the leftovers from your spring and summer harvest for fuel.

Great thread! Really got my creative juices flowing. Been planning a 12-month aquaponics greenhouse for a while and I may finally have a place to start it later this year. After seeing someone's RMH U-shaped bench, I thought something like that might be perfect! Surround the fish tank with mass benches, on top of which will rest the grow beds. I guess now I need to think about an appropriate mass for such a wet environment... Suggestions?

Totally agree, this is a great thread. We have been greenhouse growing for 7 years now, and two things we have learned are the benefits of a concrete floor, and an insulated wall on the north side. The first one minimizes the moisture, and the second deals with the worst of the winter winds. Coleman said that it's not the cold air so much as the wind that steals the warmth from your gh. I think there are cheaper ways of doing the floor. I saw something recently where they use what they call concrete dirt or something like that. A whole lot cheaper than pouring a real slab, and I think it would still keep the moisture level down. Zack if you haven't already check out Jean Pain's work with compost heat, and onestrawrob actually was doing it on a small scale site. I had sent Rob a video of Pain''s compost heating methods. You may be able to find it still on his site.

I finished the Rocket Mass Heaters book over the weekend, and recommend it if you haven't already heard of it.

The greenhouse that we want to put the RMH in will be built over this summer. Our current greenhouse is a converted dairy barn, that has a manure trough in it, and we think we might be able to do something with that. The trough is 100 feet long which might be too long for one stove, but if someone has a suggestion, I would love to hear it.

The gh we are going to build will go to the right of the house on the hill, shown on our blog. We will be able to berm the back of it.

http://luckydogfarm.wordpress.com/

Hi Folks - I'm on my second functional rocket stove, and about to design my third. this one will be much bigger and serve MANY purposes. It is going into a 20'x70' bermed greenhouse that will be used mainly for fodder production for my herd of pastured pigs (currently around 150). We're building our chicken brooder into it (6,000 broilers or so annually), and a pond that will be the main heat for the greenhouse, heated by the water heater. The pond will have tilapia and ducks.

Main question is - has anyone built a rocket stove that can heat a 400 gallon tank to boiling? I'm basing my design on one found in David Blume's Alcohol Book, attached.



I will be using the tank as a water heater, but plan on using it in the long term for a still (for drinkable and fuelable alcohol), a mushroom substrate sterilizer, and maybe a beer fermenter, on a day when it isn't being fired!

I plan on building a cob structure around it, leaving one opening over which I can put a Mineral wool - filled metal door for insulation. But I need it for cleanout and access (I think).

I have the area excavated and will be sinking posts a la Mike Oehler PSP for the rear wall, and the rest of the greenhouse is steel hoops from a local guy. The barley fodder trays will be roofing tin. The brooder will be located UNDER the fodder trays, and I may even install a reeeaaaaaly long worm bin under the trays to supplement the broilers in the brooder.

So mainly looking for comments on this whole hootenanny and some comments on larger stoves. I also need to figure out some heat exchanger stuff to know how much PEX I need in my pond for winter heating. A Little mindmap of the whole build:

Brooks, that is pretty incredible. I can't answer your questions, but I would like to know which zone you are in? Please keep us informed.

I'm going to show your stuff to a farmer down the road is an incredible tickerer. He may have a few ideas.

i live in central PA - north of Harrisburg

our farms website: www.NorthMountainPastures.com

thanks everyone!

I know this is for rocket stoves, but I had mentioned up above Jean Pain. When I first found out about him there was nothing on the internet, and you couldn't even buy his book anymore. Looks like that has changed:

Here is an example from siberia:

Mollisin talks about using a partial vaccum on the still to decrease evap temp of alcohol, requiring less heat for distillation. To obain the vaccum it was suggested to hook a venturi valve to a pipe with water flow ing (from a stream) through it. He said it was even possible to just heat with the sun. It's on an audio recording of a pdc from 1983 that's well circulated. It may also be on the recorded pdc from 2007ish. I think it could be tough to boil 400 gallons period I don't know if an 8" rocket stove would do it, but like I said I don't know. Anyhow even without a vaccum you would not have to reach 100c to distill.

Does ANYONE have a design or thoughts on a rocket stove sap boiler for maple sugar production? I'm tapping about 50 now and am basiclly going to suspend a 10 gallon pot over a pocket rocket and boil that outside. I fairly confident it will work for this relatively small opperation. However any thoughts/ideas welcome and I'm scaling up and need a bigger evaporator, one with a 2'x4' pan that the heat will pass under. I have a few ideas but always welcome more especially from anyone with evaporaor experience or rocket stove experience.