Rocket Stoves

thomas rubino wrote:Very Cool Peter!
Besides being functional it is a work of art!  

Congrats on version #5!
Is there a version #6 floating about your head?

Hello Thomas and fellow Permies enthusiasts!  

Greetings from the Canadian PNW. We are currently enduring a 10 day run of cold liquid sunshine that has us trying to avoid early sunsets and soggy outerwear during our winter solstice!  

Yes and Thank you! Yes! There will be a Frankenstove Mark 6!!! Soon to be built and this time it will be documented online in a step by step series from the “ground up” so to speak…… it will take every thing I have learned from the “Frankenstove Franchise featuring what I have done wrong on previous builds and how they got resolved in “Frankenstove Mark 6”
However, Frankenstove 6 will be a unique build for a 8’ x 12’ greenhouse over an aquaponic fish pond for growing lettuce and other greens year around!!! Yes! Another ambitious project that I wish to share!
This will include a sizable increase of thermal mass to help regulate the temperature during late fall to early spring. It will be wood pellet fueled as all other Frankenstoves and be of a 3-4 inch ceramic tube riser. You will have to follow along for other modifications that may be interesting for those that may wish to build their own. I hope to keep tooling down to a drill, a grinder and a flux core welder to keep the build feasible with respect to fabrication cost. I also promise to pull out one of my older builds to “recycle and reincarnate them” keeping the spirit of continuous improvement with Frankenstove modifications like its iconic movie namesake!  
It’s good to be back on forum! Stay tuned!

Hello Peter,
I'm writing for just one reason: I want a small rmh for a small space - about 300 square feet. Whenever I look at rmh designs, they are gigantic. Yours is small. Maybe you or someone here can advise me: can I build a small rmh? Do you know? (I'd rather not be as high-tech as your designs, if possible.)

Shodo,

In theory you could build 100mm/4" BBR system. The ISA for such a heater would be around 2.4 m2, so the heater could be 30x30x55". However the small systems, with riser diameter less than 5" may not always work as desired. They are more demanding in workmanship and material selection.

Thankss, Cristobal. It's  a start. I probably shouldn't do the "more demanding" version, but 30" is very small so I can go a little bigger.  

Cristobal Cristo wrote:Shodo,

In theory you could build 100mm/4" BBR system. The ISA for such a heater would be around 2.4 m2, so the heater could be 30x30x55". However the small systems, with riser diameter less than 5" may not always work as desired. They are more demanding in workmanship and material selection.

Hello Fellow Permies!

A long time ago in the Frankenstove Vertical RMH franchise, I promised the forum that I would perform an "Autopsy of the Frankenstove 2" In true Canadian fashion, I apologize for the extreme wait. With Frankenstove 6 on the drawing board to heat an aquaponics greenhouse, I feel that it is important to visit the "teardown - destructive " take apart of Frankenstove to make F6 (Frankenstove 6)  benchmark build so many of you interested in building your own have some guidance of building my version of these amazing stoves.
I am trying to attach photos so you can see how the intense heat affected "F2" but it seems my tech savvy is not letting that happen. So, I will explain in text.
Here is what I noticed in the teardown,
1) The refractory material recipe worked perfectly and held up to the heat without issue.  It cured to a solid, difficult to dig out of the metal housing. This is encouraging as there is the possibility to make a solid core riser without having to use the factory made ceramic tubes if you choose.  I have some spare 4" diameter ceramic cores so F6 will utilize them in the new build
2) The metal internals were severely damaged due to extreme heat stress and thermal cycling basically destroyed the metal riser causing a crack where the weld was on the pipe. F6 will redesign the horizontal burn tube to host a 4" ceramic tube and avoid as much metal in the burn zone as possible. This will include the redesign of the Wood Pellet Feed System and corresponding pellet ash retrieval system.
3) The bell  was relatively clean and very little fly ash was in it after years of use. F6 will be designed where the bell housing will be removeable for inspection.
4) The cast iron pan used as a deflection wall to direct the flames up the riser had a 3"hole where the combustion flame met it and fortunately the refractory held up with little to no damage. Obviously, once again the thought of using any type of metal in the riser / combustion area is not a great idea and will, in time will fail and need reworking.

Again, my apologies for not being able to post any pics

Thanks!

Hello Fellow Permies!  
Here are the photos of the Frankenstove Mark 2 Autopsy I recently performed as promised... Finally figured out the picture attachment issue!  Yay!

The first photo shows the retired Frankenstove Mark 2. I did some work on the pellet feed and it proved I needed a larger opening for higher output temperatures.
Photo 2 shows all the parts that were in the refractory matrix
Photo 3 shows the split of the Vertical RMH where the horizontal burn chamber meets the vertical metal riser insulated with refractory.
Photo 4 shows an attempt to dig thru the refractory material which had the consistency of concrete!
Photo 5 shows the blast damage from the horizontal flame meets the 90* transition to the vertical riser! The intense heat burned a hole right thru the cast iron pan! Fortunately the refractory poured behind the pan and maintained the integrity of the heat shield to divert the flame vertically!
Now that you can see what I am talking about, you can see that metal has no place in the vertical riser in the world of RMHs! The extremely high temperatures cause severe spalling of the metal to failure and causing a major inconvenience to replace the "innards" of your stove.
I really hope that any newbie comes across this thread will research better riser materials in their build seeing proof that metal risers are a bad idea.
The Frankenstove Mark 2 lasted a few years heating a 2000 square foot home using wood pellets without issues; other than burning out pellet baskets. So, I still struggling to build the ultimate pellet basket that works without burning itself up.  The Frankenstove Mark 5 has improved on this issue and the lessons learned will be relayed to the development of the Frankenstove 6, which will be built to heat an aquaponic greenhouse.
Stay tuned as Frankenstove 6 is under design build and I am optimistic to share the build with all y'all.
peace health and happiness!
Peter Chauffeur

Yes some good informative photos that might well help future builders.

Hello Fellow Permies!  Great News up here in the Canadian PNW!  

“Frankenstove 6” has begun fabrication. I have been given the Grace of my Wonderful Wife Patti to shift some of the items on the Home Job List and I will be posting the progress of the build as I go!  I will try to keep the construction simple by using basic tools such as a drill, grinder, welder and hand tools. This project will use extensive welding to create a Vertical Thermal Mass Rocket Stove that will be used in an 8’x12’ greenhouse that is built over a 8’ diameter aquaponic pond to grow food like lettuce kale and arugula.
The main materials will be one 100 lb propane cylinder, one 30 pound cylinder, some square tubing, ceramic tubing and refractory cement and an aluminum toolbox! Yes! This will have the general look of the F5, but much more compact to fit in the greenhouse. Of course, it will be wood pellet fed and of course, not require any electricity to operate. I know my design strays wildly from the grassroots style of rocket mass heaters on this sight but it’s design may inspire others to push the envelope when the decide to build ther own!  I should also like to continue with the 4” diameter riser that has operated in Frankenstove Models 3, 4, and our current operational Frankenstove 5. So without further ado, here are some pictures of the start of the build. Stay tuned, be safe, be warm, be Kind!

Hello Fellow Permies from the Canadian Pacific North West!

GREAT NEWS! Frankenstove Mark VI development reached another fabrication step and I would like to share it with you!  The main body has taken shape as I have massed the materials necessary to safely build on a shoestring budget but continue to use the best materials necessary.  Once again the riser is made up of 4" ceramic tubes and encased in a refractory mix that will act as my vertical thermal mass. This time it will be housed inside an aluminum truck box  and used inside an aquaponic greenhouse previously mentioned.  As pictures are worth the proverbial thousand words, feast your eyes on the build so far!
As you can see in the attached photo the 4" ID ceramic core rises 40" above the 3.25" x 3.25" ID thick walled firebox.  You will also notice two angled secondary air inlets that intersect the riser and horizontal firebox along with the 3/4" FIP at the bottom of the modified 30 pound inverted propane tank ( the bottom secondary air intake also acts as a fly ash extractor which keeps the 100 pounder repurposed propane tank bell clear of ash) This has proven successful in the Frankenstove Mark 5 and has been made more compact as previous experience in ash collection is very small compared to expectations.  Also it was made smaller to fit inside the available aluminum box.
The refractory is a blend of perlite, fireclay, silica sand, portland cement (and finely granulated refractory that was used to build Frankenstove Mark 2( recycled proven material to keep production costs down).

I know what you are thinking... why the second angled secondary air inlet? I thought you would never ask.  If you've been following this thread from the beginning, I was experimenting with atmospheric steam to reduce NOx and improve moisture in the burn tunnel.  Well I thought I would give that another try once I get this build dialed in. If I don't need it a simple cap will seal its fate.

So, this refractory core will take a while to cure as I do not wish to make the same mistake I did with my original Frankenstove Mark 1 causing the refractory to crack due to heat stress.  I am also working on building a better wood pellet basket and an improved secondary ember burning containment/ primary ash catcher!

I know this build is beyond the skill set of a lot of  the basic designs of rmh builds and many on this site say that a 4" riser system cannot function like larger diameter riser designs but this thread is testament to relentless trial, error and "what - if " thought experiments. This build can be done with a grinder, drill and a basic knowledge of welding along with basic hand tools and I encourage anyone who is handy to give this design a go with safety as the prime directive.

Stay tuned and thank you for 6,000+ views on this thread!

Well Fellow Permies, The refractory cement mixture has been given 24 hours to set and it is time to SLOWLY cure it by introducing a slight warming of the casting. To do this, I found one of my smallest propane torches and set it up to send heat down the centre of the square burn tunnel and then flow up the riser by convection where a slight restriction at the top would keep the riser temperature warm enough to speed up the drying but less than 100*c (UNDER BOILING POINT OF WATER ( 212*F) so it doesn't cause the casting to crack during the curing process.  Although the temp spiked at 160*F in the riser, I managed to get the riser temp to regulate around 130*F  by moving the lit torch back towards the mouth opening of the burn tunnel.(See Photos). I have left the 10" cardboard post setting tube forms in place to insulate the cast while it slowly cures. I also strengthend the vertical riser with reinforced with rebar and wire screening 1/4" (hardware cloth) during the pour  to keep chunks from falling off in the future. I will remove the form later once I can be certain everything is well cured.  I once worked for a chemical company that had to spray a refractory mix on the walls of a large thermal oxidizer and curing the refractory meant slowly adding heat to cure the mix once application was complete. This was called building a heat profile. Although I lack the engineering background, the process was to keep the internal temperature below the boiling point of water for 24 hours.  So, my rather small "thermal oxidizer" aka riser tube will also be kept below said temp until I can feel heat permeating the outside of the form  I will also drill a  borehole in the centre of the outer ring of the refractory mix to confirm that the heat is migrating in a radial direction. currently this temperature is around 101*F so I know it is working. you can also notice the colour of the cast refractory is also lightening up which suggests that there is less water in the mix.  i know that it is very important to do this process and not to rush it, as I experienced a crack in my original Frankenstove creation as I failed to dedicate due time for the mix to cure and no regard to building the heat profile to drive out excess water.  Steam is a powerful destroyer due to extreme expansion.
I will probably go through  6 bottles of propane to achieve this heat profile to be sucessful... that will give me time to fabricate the 100 lb bell from a repurposed propane tank in the next few days.
slowly but surely  Frankenstove 6 will come to life. stay tuned for more developments as the build continues

Very interesting build, did I miss read the bit about using re bar in the riser?

On your last build, have I missed what your actual layout is? or build steps?  It just appears to be there,  as well as a proposed Bell? ( heat extraction chamber ) or is this your tool box, down the road.

You also mention this list,  "The main materials will be one 100 lb propane cylinder, one 30 pound cylinder, some square tubing, ceramic tubing and refractory cement and an aluminum toolbox!"   But it would appear that you have used an sannen tube fairly extensively? Or maybe I am missing something,   And lastly, do you expect the steel tube ( where your torch is shown ) to last for the life of the stove? Just curious?  Maybe this area of metal comes out during your build.  If this metal is allowed to spall out of the system, does that change your dynamics of heat production with this unit?

Sorry for all the questions, about your interesting design.  Lastly do you intend to regulate the temp or amount of wood pellets burning, by adjusting the air inlet? with More Air equaling more pellet burning. Or is this one basic level of pellet burn?   Am curious.

hello Mr. Weinberg,

Thank you for your barrage of questions regarding my "Frankenstove Mark 6 vertical thermal rmh" It is a pleasure to discuss my design and I look forward to you sharing your ideas about my build with me in "Moosages"  rather than involving the general population on permies.

I am using this thread as a "soft Launch" of my "Frankenstove Franchise" of Vertical thermal rmh prior to a series of " from the Ground Up manufacture on a youtube site and monitize my efforts on the plans.  This is not your typical build of the "mud and straw builds" that are ubiquitous on permies and I have a profound dislike of using thin gauge oil barrels as bells for the builds I see on this site.

1. my layout is similar to the F5 build earlier up the thread. my steps will be divulged in a future video series. Everything in the build sequence has been photographed and will be released, rest assured.
2. the bell will be the venerable thick gauge 100 lb. propane cylinder that will be welded to the section of the 30 lb. base.
3. the 4" heavy wall burn tube remains.  previous use of this material has survived relentless use in the F5 for years up to temps of 960*F and temp cycling to room temp daily. I have experienced some spalling on my smaller square tube burn chambers of previous builds of smaller dimensions.
4. there is some temperature adjustment via a proprietary sliding pellet basket; which has taxed my creativity to the limit that I will get into the video.
Thank you for your engagement in my design
Peter Chauffeur

Fox James wrote:Very interesting build, did I miss read the bit about using re bar in the riser?

Hi James, Short answer, yes, three 1/2" spaced at 120* apart to take the stresses of off vertical rotation to move it like an acetylene cylinder 50 metres  from the Frankenstove Laboratory / Manufactorium " to greenhouse.
these rods are located at the extreme outside of the 10" sonotube and are fastened to 1/4 inch hardware (wire) cloth. which will prevent parts of the refractory from falling off due to continous thermal cycling daily. (preventative measures ) You will have to wait to see how the resultant casting of my refractory turns out when I remove the sonotube form. Expansion / contraction should not cause a problem due to its maximum distance from the ceramic core.

More progress in the Frankenstove Mark 6 today!  The long awaited BELL was cut to fit over the riser and rough spots ground down ( the welds that held the base and valve protector ( which was repurposed to be the base of the 30 pounder)) I am also working on a manual winching system that will lift the bell above the riser and then lower it into position for welding to the base of the RMH. Here are some pictures of today’s progress

Hello Fellow Permies,

Today, progress was made by securing a method to set the bulky (and heavy) Bell over the riser using an old crank winch from a boat trailer and the trusses of my Manufactory (tool shed). This allows for a safe and secure lift so one person can do the job alone.
Using a plumb line, the burner / riser assembly was centered and the bell was raised using a Tee fitting on the top of the bell. See the pics below as pictures are better illustrations than words. This method of placing the bell has been used in the Frankenstove Mark 5 build and there is a slight swing of the bell as the riser assembly IS directly under plumb line. The bell will be lifted off as this was done to insure the whole RMH would fit inside the aluminum box.
Measure Twice, fit, Remeasure again and celebrate the process before the welding begins!

Hello Fellow Permies and “Frankenstove vertical RMH” enthusiasts!!!

Today was an absolutely exceptional day as I literally rolled “Frankenstove Mark 6” out of the Manufactorium and did an initial burn /test fire using hardwood pellets.  Using the wood pellets as the fuel source to continue the curing process will give me an idea as to how fast temperatures increase instead of propane which would mean using a “Tiger Torch” and may add way too many BTUs to of  refractory core too fast and do damage which is what I’m trying to avoid. Experiencing the increasing volume of the “roar” of this progressive and latest design was so rewarding and I cannot do it justice with words! A new design of a more robust pellet basket / carburetor has developed a consistent pulsating and reverberating echo that could be heard from a distance of 15 feet!, has made me feel that a giant leap for a rocket stove with a 4” ceramic riser a reality and welcome advance in the Frankenstove Family of low footprint vertical thermal rocket mass heaters!  
For those who haven’t been following this post from the beginning, it is important to “cure” the poured material by slowly cooking it with slow increments of heat and increasing time durations with cooling times between the cycles.
I am trying to avoid a “catastrophic failure event “ which occurred during my first “Frankenstove “ Mark 1 where a full blown fracture caused by uneven heat expansion.  This event caused a major crack in the refractory which I had to seal with high heat silicone which made me appreciate the “slow and steady” approach when dealing with proper building techniques and respect for research with respect to safely with refractory break-ins…. Without catastrophic breakages!!! Pun intended.
Also a new approach and design for a pellet basket / “carburetor “ has been designed to get around the “burnouts” I have experienced in my many previous basket designs and is interchangeable with the Frankenstove Mark 5 design. I took the interchangeable approach so I could evaluate its improvement even before the test firing of the Mark 6.
Upon rollout from the Manufactorium,  a propane torch preheated the combustion chamber and wood pellets were added down the feed tube and heated into nicely glowing bright orange embers with the classic horizontal flame accelerating progressively to the 90* where it hit the firebrick and proceeded up the ceramic riser. A short burst of smoke and then nothing but turbulent flames started up the riser. A short feed tube was filled with pellets and the roaring rocket sound amplified!  It was ant this moment I felt the elation,   And success that years of design through trial, error, thought experiments had cemented  my joy that this design has already exceeded my expectations!!!
So, please celebrate with me and view the photos below. The runtime of the first burn was jet to less than an hour with external burn tube reaching 700*F+ and top internal ceramic riser temp reaching 350*F.
An expected very small amount of steam was exiting the thin piece of sonotube ring at the base of the riser.

Hello Fellow Frankenstove Enthusiasts!

Epic Day here at the Frankenstove Manufactorium!!!

Today the bell was finally lifted above the riser and lowered into position over the riser, centered and welded together. To make a sealed unit. Yay!  

Then the unit was rolled into the aluminum housing to confirm fit and to determine where the 4” exhaust pipe was going to be located.

It was determined that the exhaust pipe will be located just to the left of the feed hopper which will keep it away from the double skinned polycarbonate of the greenhouse walls. Stainless steel flex pipe will then run the exhaust straight up and do a 90* bend and run out the gable end of the greenhouse using a B-vent.
Unfortunately, I have to go do a work contract and will be back in a month to finish up the build so please be patient and stay tuned!

Well done, looking forward to the first ignition…..

Peter Chauffeur wrote:This is not your typical build of the "mud and straw builds" that are ubiquitous on permies and I have a profound dislike of using thin gauge oil barrels as bells for the builds I see on this site.

I'm a big fan of horses for courses...deploying technology that is appropriate to the situation. In my case, I have a glasshouse I need to heat over the winter, but not every night. We only have freezing overnight temps about 20-25 times on average. So I built a 4" J-tube, "by the book" with cast burn tunnel, fireclay+perlite riser, a 30-gallon drum as the radiator (NOT a bell because there is no mass), and a cob bench with the flue piped through it. Materials costs were about $100 for castable refractory mix, fireclay and perlite. The drum was free from the local scrap metal dealer. The cob was free for the digging. I spent about a week or two building it, total labour around 12 hours.

It's been in service for 8 years now and I cut out the warped thin steel from the top of the drum and replaced it with a round piece of 5mm plate. Best griddle ever. I've rebuilt the burn tunnel with firebrick (the cast one disintegrated after three years) and replaced the heavy clay riser with a 5-minute one. So there was an additional material cost, maybe another hundred bucks, and about 3-4 hours to dismantle and rebuild the core. The drum is fine and gets a coating of linseed oil at the end of each season. It does exactly what it needs to do, which is to shed some of the extreme heat after the exhaust leaves the combustion zone, and enhance the system draft via the densification of the cooling and sinking gases. Temps on the cooking surface (did I mention what an awesome griddle this is?) approach 300 C. Readings on the side of the drum usually go from 180 down to 120 from top to bottom. This is not a bell. The thin metal is performing a function quite different from a mass of stone or brick.

The heat storage happens in the cob bench, which warms up to around 35-40 C during a burn and is a really nice place to sit on a cold, rainy night. Someday I might tear it down and replace it with a stratification chamber using barrels cut in half lengthwise, because cleaning out the pipe is not fun and there is a bit of ash in there that is hard to reach from the cleanout ports. But the basic design is performing brilliantly, and the humble RMH should give many more years of service with minor maintenance.