Rocket stoves in Greenhouses , our own forum topic

James 'Derek' Hersher : O.K. then, a slightly delayed Welcome to Permies,and a big Welcome to the Rocket Stoves Forum ! Lets jump right in, only you can tell how much
of your greenhouse you will Need to heat in the early days of your 'growing season' Initially you will only need heat in your grow beds, later the only protection your small
plants will need will be row covers ! This is especially true if they are being protected by heated and raised grow beds!

Raised grow beds will make your life easier and mark the exact location of your horizontal pipe runs, you will not be walking on your grow beds!

Due to the high humidity in your greenhouse, You will not want to store the wood that your Rocket Mass Heater R.M.H. needs inside! A simple wood box with a pass thru
door will save you from trying to carry wood in through an open door while you are trying to keep your greenhouses heat inside !A 8'' R.M.H. can easily 'push' the exhaust
gasses 50' and then pass out through a side wall, to a vertical chimney.

Have you been to - 'rocket stoves.com' - to get your PDF copy $15.oo of Evans' and Jackson's great book 'Rocket Mass Heaters'? There is still no other source of
'Rocket Stove Family' information as complete - in any language ! ( and I don't make a Dime ! )

For the Craft ! Be safe, keep warm ! Pyromagically Big AL ! - As always, questions/comments are solicited and Welcome ! A. L.

Allen thank you for your replay. I would like to heat the greenhouse year round. I am looking for the best way to do so with not much cost. Also want to keep aqueponics water warm without needing a heater in each tank.

James "Derek'' H. : The first thing I am going to do is to send you to a site where you will be asked have you got 'the book'! 'rocketstoves.com' there is STILL
no other book in any language that contains as much 'Rocket Stove Family information' in any language ! This allows you and the rest of the members to
speak a common language when addressing a problem !

Please go to You Tube and put - ' web4deb ' - in the search Tool ! I usually tell other people that I have sent there, to scroll down to his "Rocket Stove' Playlist,
however most Greenhouse people get lost on the way there !

I will still be here for 'Rocket Stove Family' Questions, and will tell you- you must build a basic model before moving on ! Big Al !

For the Good of the Craft ! Be safe, Keep warm ! PYRO - AL ! - As always, your Questions/Comments Are solicited and Welcome ! A. L.

Thanks again Allen for the help. I will be sure to check that out and also the book you had talked about as well. I do go by my middle name to save the extra typing for next time.

Derek

I have just started to build the RMH again. Below are some pictures that show the general location of the fire box and heat riser. It will be 7x7x21 inside the firs box with a 7" heat riser. I am going to make the heat riser at least 63" high. It will then be insulated with a perlite/clay mixture. 55 gallon drum on the outside. The area the exhaust gases are flowing into has changed considerably from my first attempt. Any feedback helps!

W.O.W. thats a big step forward, you can conceivably create such a good draw that a large share of your heat is exiting the vertical final chimney ! Monitoring the final Temps
is the Easiest way to tell ! Good luck Big AL !

Hey all, new to this site and forums in general.. but my reason for posting here is to access the collective mind. As we all know two heads are better than one. Right, so, on to the main reason i'm here.

I am trying to heat a 30x96 greenhouse with a rocket stove! I know it will have to be bigger, but how big? I have drawn up some plans that give the heater a kiln-like firebox. Also does this mean I will need a larger riser? I'm thinking no.. because the main objective of the firebox is to be able to hold lots of wood so you can walk away from the stove, but I'm certainly no expert..
In addition to all this expansion of the heater business, it was also an objective of mine to pull as much heat as possible from this stove. To achieve that I have decided to go with Geoff Lawtons model of a boiler. The only exception being instead of running the water to a faucet or shower I will circulate it Beneath and Around our Aquaculture tanks. The remaining hot air will then be snaked through a thermal mass(such as in traditional RMH's).

Dim. of the Firebox are 2'Wx3'Lx18"H (it'll have a parabolic shape to it)


How much heat will this stove put off?
Will it heat this space? If not how big will it need to be??

p.s. this is Lawtons video for those who have not seen...http://www.youtube.com/watch?v=1oDpmmsqHwQ

Joseph Fetherolf wrote:Hey all, new to this site and forums in general.. but my reason for posting here is to access the collective mind. As we all know two heads are better than one. Right, so, on to the main reason i'm here.

I am trying to heat a 30x96 greenhouse with a rocket stove! I know it will have to be bigger, but how big? I have drawn up some plans that give the heater a kiln-like firebox. Also does this mean I will need a larger riser? I'm thinking no.. because the main objective of the firebox is to be able to hold lots of wood so you can walk away from the stove, but I'm certainly no expert..
In addition to all this expansion of the heater business, it was also an objective of mine to pull as much heat as possible from this stove. To achieve that I have decided to go with Geoff Lawtons model of a boiler. The only exception being instead of running the water to a faucet or shower I will circulate it Beneath and Around our Aquaculture tanks. The remaining hot air will then be snaked through a thermal mass(such as in traditional RMH's).

Dim. of the Firebox are 2'Wx3'Lx18"H (it'll have a parabolic shape to it)


How much heat will this stove put off?
Will it heat this space? If not how big will it need to be??

p.s. this is Lawtons video for those who have not seen...http://www.youtube.com/watch?v=1oDpmmsqHwQ

Hello. Not sure if you already saw this video but the concept is really cool and looks like something that will heat a large space.

Kudos Amos for the Japanese? youtube link.. fascinating..

I am elated that Joesph is another person looking to heat a larger green house.

I need to get and absorb the RMH book before I unload questions...

That being said.. I have seen only a few people or videos ever of the feed tube on the exterior - as I would think one would want for a green house.
and that makes me wonder how long the feed hole can be from the burn riser on the inside and to what proportions of extra height it will have to be to accommodate the extra length.

I could easily envision a distance of 3' to 4' between the two in and out of the wall of a green house.

I think the stove being built in the previous video is a Korean Kang. The language doesn't sound Japanese to me.

Here is an update video showing the progress on my RMH. Still some work to finish up on the greenhouse before it starts getting cold.

Amos Valenti : Knowing that it will be difficult to keep fire wood dry in a greenhouse - what have you worked out for wood storage ? Big AL !?

allen lumley wrote: Amos Valenti : Knowing that it will be difficult to keep fire wood dry in a greenhouse - what have you worked out for wood storage ? Big AL !?

Thanks for the feedback! The area where the RMH is is separate from the greenhouse but sure to be humid as well . The plastic wall is not in place at the moment. I also have a covered area set aside for bulk storage. I'll post another progress video soon!

Bump Big Al !

here's the status of my rocket stove in the greenhouse,,, first fire (indoor test burn)

Hi Everyone,

I have been reading the forum for a while. I have also looked at all the web4deb videos. There is one thing I couldn't find.
Has anyone insulated the ground where the exhaust is running through?
I was thinking of excavating a foot of dirt, putting in blue board or another type of waterproof insulation, so that no energy is
waisted on heating the ground beyond a foot or so deep. And of course also vertical insulation at the perimeter of the greenhouse,
so no heat escapes laterally away from the greenhouse. (oh, that seems to have been answered... twice the depth of the frost line)

Second question. Has anyone calculated how much wood they burn to heat their greenhouse with a RMH?

Third question. Sand is not an ideal medium for storing heat. (I think). what are people using for thermal mass around their exhaust?
Gravel?

I am planning an aquaponic system in a geodesic dome, made of wood, covered with polydress keder film (bubble film but better).
The dome is 22 feet in diameter. I want to heat it to be able to keep fish through the winter. Also, apparently the necessary bacteria
to keep the aquaponic system going don't do very well below 55F or 15C. I live in Belgium. Mild winters (average but not too much sun.
Average max temp 6c and average min temp 0C, november through mid march)

Jef

Brooks Miller wrote:hi frank - thats awesome - looks like you've spent some time with sketchup!

i have a few questions/critiques.

my only immediate concerns with putting the pipe directly into the water would be water tight welds/unions, loss of volume (space for fish to live in considering size of an aquaponics greenhouse), and how you would control the heat.

my idea with heating a tank of water and then moving it was because you'd be able to put the circulation loop in the pond on a thermostat so you don't go overboard on heat....but maybe you kinda can't go overboard?? i think the cool part to me about heating the water is that then whe you use water to irrigte, you're irrigating and spreading that heat out into the whole greenhouse more evenly.

questions:
1. how hard is it to cut rock wool plates, where do you get them, and how good are they at insulating?
2. whats up with leaving the top of the first piece of the heat exchanger uninsulated?
3. how would you make the stainless below the surface watertight? do you have access to a TIG welder onsite? what size pipe wall?
4. are the pipes in the bottom of the water representing your irrigation pipes?


looks great, and thanks for sharing.

an update to my design is that we've done some rough figuring and think that just heating a mass beneath the fodder trays may actually be enough to heat the whole thing....that way our cob mass running through the brooder sections radiates up and warms trays, and the plant water pulls the heat into the pond.

cutting and setting posts today - ill "post" some pics tonight!

Hi,

I think you do need the barrel in your system anyway. Sure, you need the heat riser foremost, but if i understand, you need the barrel to radiate some of that heat off, to keep the
flow of the gasses going. What you could do is have tubing with water go around the barrel? I'd keep the system open as well, so there is no pressure buildup.

Jef

Amos Valenti wrote:

Joseph Fields wrote:I know this is a little off topic. Does anyone have any kind of removable insulated hip walls in your greenhouse. I was thinking of filling some sandbags and building hip walls around the inside to keep the cold from creeping in at ground level. Then I recalled how much filling sandbags sucks and thought I would ask for advise. I was thinking wood chip filled bags would be a lot lighter to take down in summer time.

We have used bails of hay/straw in the past and it seems to be effective.

Hi Joseph,

To add to that, sandbags won't do the trick I am afraid.
In my opinion, sandbags get as cold as a brick non-insulated wall. Bails of hay like Amos mentions or wood chips
in a bag (because it traps air) would do it.

Jef

Hello everyone.This is a small virtual tour of my greenhouse with a RMH. Construction is nearly wrapped up with just some cleaning and organization to get things in order. We used mostly free and found materials throughout the whole construction process. Things are really working out great so far. Burning mostly hard woods but use some pine to get things moving in the heater. There are a few things that need some improvements so a more detailed video to follow up on just the RMH is in the works.

I have noticed on occasion, accompanied by just the right wind direction, my system back drafts. This involves smoke back, fire back, loss of flame and then lights back up like flipping a switch. I have read up on the subject and have decided on using some kind of wind baffler at the top of my outside stack. I see the round, spinning balls on the top of houses and wondering if there are better options. Any suggestions?

Amos Valenti :W.O.W., A lot of work it appears to have turned out well good layout, i will wait for the longer Tour ! Big AL !

Nice setup Amos!

Jef

Wow Amos,

That is an amazing greenhouse you have there! How has the gravel been so far as a thermal mass? We live just near Cleveland so our climate is pretty much the same. As soon as we get our property we're planning on the same type of greenhouse with the in ground RMH. So damn cool!! Keep us updated!!

Jennifer

Jennifer Charlton-Dennis wrote:Wow Amos,

That is an amazing greenhouse you have there! How has the gravel been so far as a thermal mass? We live just near Cleveland so our climate is pretty much the same. As soon as we get our property we're planning on the same type of greenhouse with the in ground RMH. So damn cool!! Keep us updated!!

Jennifer

Thanks for the kind words! The thermal mass is actually the clay soil, covered in pea gravel, then covered with a layer of blue stone. The pea gravel does seem to warm up really nice thou. Here is a more in depth video of the RMH in action.

Nice setup Amos. How does it heat the greenhouse? what route does the smoke take? i.e. is there cob under the grrnhouse floor and around the fish tanks?

Still working on my rocket stove, added some cob yesterday, here's a pic of where I'm at now.

Marty Spehar wrote:Nice setup Amos. How does it heat the greenhouse? what route does the smoke take? i.e. is there cob under the grrnhouse floor and around the fish tanks?

Still working on my rocket stove, added some cob yesterday, here's a pic of where I'm at now.

Thank you. The exhaust gasses flow through an 8" pipe into the greenhouse, bends around the grow bed, and exits through the back of the structure. The pipe is roughly 24 inches below the ground and was back filled with clay, then a 3 to 4 inch layer of pea gravel and then topped with PA blue stone to walk on. The direction of the gasses is as follows: 45 degree turn from the 55 gal. drum stack to a 90 deg T (clean out access) to a 90 deg elbow to another 90 deg T at the start of the vertical climb to the outside, and finally through 2 more 90 deg before exit. In total the gasses travel through approx 50 feet of 8 inch duct with 5 90 degree bends. In the future we can eliminate 1 of the 90 deg bends but for now it is fine. The ground is all clay with a high sand content from being next to the river. It is basically unmixed cob without the straw which is very convenient. Since the fish tanks are in the ground, below the frost line, they stay relatively warm. Without running the heater the coldest the water gets is 50F. We do plan to use one of the tanks as an additional thermal mass by heating that water with the rocket mass heater. We did not want to back fill to the tanks with cob yet for experimentation purposes. All in all the heater is doing a fine job of heating the greenhouse. The temperature of the greenhouse can be up to 30 degrees warmer than the outside while burning and the ground is still warm well into the next day after a burn. We are still losing a fair amount of heat though gaps and cracks in the structure so once everything is buttoned up we will take better records of the temp and report back.

Success!!! I guess at least my GH stayed above freezing last night. I burned about 20 lbs of sawdust/WWVO yes WWVO, the WVO I have, I burn in my vehicles, the crud that I wouldn't dare put into my tank is waste, it's got shortening/bits of french fries and other impurities. I mix the WWVO with sawdust and roll the mixture into logs wrapped in newspaper.

I've been experimenting (read playing around) with a small fan blowing air into the combustion chamber. I'm thinking the CFM of the fan needs to match my 4 inch stack, too much air and smoke is pushed out the log feed tube. Thinking of adding a fan outside on top of the stack, drawing exhaust out. Since the exhaust isn't that hot, a fan there might be my best choice. I don't want to use a "whirly bird" as it would need to be covered or draw air through the system 24/7, with a fan I can turn it on and off when I start my RMH

Still need to add a lot more cob. currently there's probably 500-600 lbs.

Last night was the first test, outside temps low 20's with the stove burning it was a constant 52F inside. Temps on the heater cylinder (propane tank) approached 500F at times! Exhaust temps (after the cob but still inside GH) ran about 170 so I was wasting quite a bit of heat. Also there was about 100 pounds or so of wet cob, which brought the humidity in the GH up 96% (a couple more % and it would have started raining inside. I'm wondering if the evaporation of the wet cob effects the overall temp in the GH. I know it takes 1 BTU to raise the temp of 1 lb of water 1F. so a lot of BTU was used in drying out the cob. Next burn the cob should get hotter but is it a wash? between steam heat and cob heat, I'm thinking cob heat will last longer (What I want).

This AM outside temp inside GH 34.2 (after sunrise) lowest temp 33.6

Well here's a video I put together yesterday showing the construction of the GH

Marty Spehar : You should be producing a high proportion of glycerin, that and some soaps, and traces of a fuel oil, Some commercial enterprises use and sell this 'waste stream'
as a cleaning material ! Other than that little tid bit , the chinese have a pressed sawdust and coal dust flammable brick that they sell on street corners for little brasiers to set at
peoples feet. maybe 5'' round and 4-6'' tall and perforated like the way some bricks are made today, just thought that if it works for them (not really great, but it works ) the
addition of more air spaces !might help your design ! For the Craft ! Big Al!
'

Copy that success Marty, Congratulations!

We stopped burning at around 10:30 pm. Approx burn time 5 hours. Coldest point in night was 17F. Internal temp of greenhouse at 6:30AM was 52F degrees before the sun.

Amos Valenti wrote:Copy that success Marty, Congratulations!

We stopped burning at around 10:30 pm. Approx burn time 5 hours. Coldest point in night was 17F. Internal temp of greenhouse at 6:30AM was 52F degrees before the sun.

Guess adding more insulation on the North wall of my GH might help some,,, 52 before sun I'm jealous,,, tonight will be another cold one,,, gotta go make some logs,,, really want to automate the feeding of fuel,,, thinking an auger type device,,,

On a side note, is there some reason that the RM stoves people build have a removable top?

Marty Spehar : The trend here is to call drums - barrels, and barrels - Drums, actually the ones with the removable top are Food grade drums, i.e., never supposed to store
liquid petrochemicals ! Based on two facts- most of your Fellow Members who are building Rocket Mass Heaters RMHs, have gone to these barrels for convenience, and for
ease of cleaning out Fly ash deposits, I see that your last Rocket build comes directly off of the sides of the 100 Pound L.P.G. tank you are using without using a manifold for
channeling your hot exhaust gases, or clean outs, especially as you start firing up a newly installed Cob Thermal Bench you will generate a lot of fly ash that will need to be
dealt with *!

Our answer generally is to create an ash pit ether directly below the drum or below and outside of the drum for ease of getting in there through a 'T' Stove Pipe Fitting and
a Cap used as a clean out, However with a Drum that has one end open and held on by a clamping band, You can ether pop the top off, and get in there with a shop vac -
and reach the ash pit from there, or topsy-turvy use the removable top to mark out your layout so you can see how things will fit together and then when you need to do a
cleaning, Lift the whole barrel off of the Heat Riser chimney ! Ernie and Erica Wisner our Co-moderators in the Wood and Rocket Stove Forum/Threads, like the removable
top, and also sometimes use a drum and a half to contain a really tall Heat Riser.

*With ~100,000~ RMHs made World Wide in the last 20+ years we have had several Barrels changed due to an excess of caution, but Zero reports of Drum Failures. Also
even though the drums of today are lighter than the barrels of Twenty years ago, they are still heavier than the Ductile steel gage used in the Heat Exchangers of commercial
Fossil Fuel Fired Forced-air Furnaces, (which is what the drums serve as in the RMH ) and the commercial heat exchanger get a pro rated 20 year guarantee !

Though only the very top of the barrel ever sees 500*F, this is well below the 2400*F found in the well insulated burn tunnel and heat riser, you may be interested in going to
wikipedia to understand what causes the failure of steel when you try to use it in those last two locations, Look for High Temperature Hydrogen AttackFor the Good of the
Craft ! Big AL !

Not a very good night, would have lost all my vegetables(if I had any in there) with a temp of 31.2. Put the last log on at 11:30 checked GH temp at 7:00 outside temp 21. Looks like I need more mass and more insulation.

At this point in time, I'm not concerned about cleaning out any fly ash. I got to cut down on the smoke inside the GH, if the door is opened to quickly, I get a puff of back draft, thus I was experimenting with a fan.
But my concerns about a fan is it drawing more outside air into the GH? Been thinking of putting an air intake outside, but I'd have to deal with the drain tile I put in,,, grrr

I have another 100 lb LPG Tank available, too old to trust it for LPG so I can use that for modifications. I can length the heat riser stack, and lower the exhaust outlet.

I really would like to heat the water in my 750 gallon fish tank (no fish yet but it is filled with water) would it be better to pull the heat from the burn box, or the LPG tank?

I could have a sleeve welded over a 6 inch pipe to create a heat exchanger and heat water from the burn box and remove quite a few BTUs early in the system, letting the RMH soak up the rest.

Marty Spehar : you need air locks for your door, also because of future high humidity , you need to plan on having a well protected Wood box outside your Greenhouse,
with a pass through door to keep your wood as dry as possible!

Do I understand that you are using a vertical Feed Tube to supply wood to the stove, and have an existing outside air supply which you have to disassemble to add wood?
I think that you should be able to turn on an inline fan only before/while you are adding wood and then switch it off for your normal operation, If you are getting a good
clean high, Temperature Burn -you should hear just as loud a rocket sound from your stove not just when you are boosting it with a fan !

What is your 'Burn box' and what is it made of, Actually counter-intuitively you do not want to try to take heat off of the Combustion zone, in order to get the Freaky High
Working Temperatures that guarantee the super efficiencies of a Rocket type stove we do not want the cooling effect of water that can never get hotter than Boiling !

When we try to use the combustion zone to heat water, we are also creating the scenario we call Boom- Squish,as Water flashes to Steam. Think Boston Marathon Bombing
with lots more full thickness Full Body burns !

While farther away from the combustion zone is safer, be aware that this system will need a pump, and pump failure can send you right back to Boom-Squish ! For the good
of the Crafts !

Think like Fire, Flow like a Gas! Don't be the Marshmallow! As always, your comments and questions are solicited and are welcome ! PYRO - Logically - BIG AL !

I am burning logs made of saw dust and waste vegetable oil. I've played around with a fan, but don't have one hooked up now. the air supply is not outside, I was contemplating that.

Here's a drawing of what I have.

All interior metals are standard HVAC ductwork. I do not expect the innards to last a long time, but I wanted to know what kind of burn box/stack I need to fabricate.

allen lumley wrote:
What is your 'Burn box' and what is it made of, Actually counter-intuitively you do not want to try to take heat off of the Combustion zone, in order to get the Freaky High
Working Temperatures that guarantee the super efficiencies of a Rocket type stove we do not want the cooling effect of water that can never get hotter than Boiling !

Thanks that's what I was wondering, so I want to keep the burn area as hot as possible.

Just joined the group. Looking forward to learning more about rocket stoves. Anyone heating a full size 20 X 100 greenhouse with a rocket stove?

Tim Griffin : Welcome to Permies.com and our sister site richsoil.com, be sure to checkout our videos posted there and our videos at U-Tube ( there is a lot of-
- Crap out there! ) With over 20,000 fellow members world wide, you should be able to come here 24 / 7 and rap with someone who wants to talk about what you want to
talk about. With different opinions on near everything, they will stretch your mind as you stretch yours !

For the rest of the year we are asking that our fellow members show their (general) location and Climate zone if you Know it, look at your name and L@@K at mine, please
find the Permies toolbox near the top of the page and click on the 'My Profile' Button from there you will be on the right page to add this information! From the toolbox, you
can also reach our own pCloud by pressing search and using the Google Search Engine to do a search for any pCloud information by selecting Permies (only)

You can see where the location of your greenhouse will affect the heat load and also how much detail we put into handling water vapor !

2,000 square feet is a lot of area to heat, even with an 8'' system, it depends on how much you need to raise the internal temperatures, Insulation and type of glazing !
Come back here often, if there is a Rocket Mass Heater RMH, in your future we will help you find it ! For the Good of the Craft ! Big AL !

After several burns during the day a reoccurring trend was becoming obvious. Our greenhouse is located next to a river and in the right wind conditions we would get a backdraft from the RMH casing the room to fill with smoke. The original diffuser we had installed was not cutting it and after reading and searching we decided to experiment with a wind turbine.

Just yesterday I put a 12 volt PC type fan on the exhaust stack, no smoke inside what so ever. Even with the door being opened rather quickly.

I think that you will find out that you MUST cover the whirly bird when not in use, else risking a continual transfer of air into your GH.

Rocketeers and 'pCloud' : I have always hoped that with Rocket Mass Heaters RMHs that there was a working solution to all problems, Right Now my Crabby self wants to use
the dark side of the force to deal with a rockets 'as built' flaws, and I find myself proposing and re-proposing the use of a booster fan! Preferably in the 12-14 volt range with
sensors and multiple speeds like on some of those Foreign 'Metric-ated' cars that could be run off of a car battery backed with a Trickle Charger !

I just wanted to chance to say tat I still regard them as a sometimes necessary Crutch, and would always be looking for 'some other way' That's my two cents !

Don't get me started on doing away with the penny ! Big AL !