Peter Chauffeur

Hello Phil,

First, thank you for your poignant definition of “horses for courses”, I now have a new phrase I can use when it comes to a basic design using the bare minimum of materials. The problem with your saying horses for courses” is that horses don’t play with fire!

Second, I misread your “cast riser” as cast iron!  Oops. My first two stoves had metal riser ( high temp 3” muffler pipe) that had a surrounding poured refractory casting surrounding it. The metal pipe suffered thermal destruction and I documented that several times on this thread.

Third, we can agree that an oil drums are the bare minimum for enduring the heat blast exiting the riser and concentrating a lot of heat which caused further distortion and stress on the thin gauge bell that are ubiquitous in conventional rocket mass heaters. These are copies in “by the book” the builders you have suggested and it does have an overlooked safety issue.  As you have described from your experience, the oil can you used needed to be replaced with a 5mm flat steel plate.
Oil drums were made and designed to transport oils and other liquid ingredients at normal earthly temperatures using the oil drums as a “one-off” means of getting to the customers locality in a relatively safe manner. Oil drums were not designed to take heat stress cycling and combustion gasses. So, from a design perspective they are actually a poor choice for Rocket Mass Heaters heat output is far beyond what the oil drums were designed for.
Yes, oil drums work and sometimes right at the envelop of thermal failure like your stove did where you needed 5mm of flat plate steel to modify your “eight year build”.  Just because “ by the book “ builds or “that’s what the authorities did! “ on the subject are using, doesn’t mean there are better alternatives. That is what I’ve done in developing 6 different rmh’s over my years looking at the deficiencies in the designs of others. Every design isn’t perfect but if you don’t look at the designs of others and ask yourself, “ What can I do differently to build mine better?”, then you are not taking the dialogue of building a better more useful RMH for others to ponder on their development for better builds of their own.

Fourth, I understand that rebuilding/ modifying a RMH can be a huge undertaking and usually involves an on-site rebuild /repair and the cost to do it may be prohibiting to the builder that used the cheapest available, but let me ask you to consider this question. If I was given the knowledge that “burn - thru” of oil drums are a possibility and some other builder said, “ Hey! All you amazing people building these rmh’s that you can replace sketchy oil drums with a safer bell made from a 100 lb propane tank that you can get from a junk yard for $20?”  Would you not consider a safer alternative?  I would.

Fifth, I know that my builds aren’t something you build on a weekend with some good old boys and a case of beer!  It took time. It took problem solving. It took documentation to put it on this site so other, open minded researchers and enthusiasts could see that there are other designs out there that have different attributes that may be out there and the road of development is documented along the way! This thread is the culmination of many years of building and operation of my adventures of designing and building gravity wood pellet feed, space conscious, Rocket Mass Heaters that, can be used in house and one to heat an aquaponic greenhouse. I have taken this build thru 6 evolutionary builds; on one single thread so there is continuity that others can see. I refuse to sit on my laurels and admit what I’m doing is, good enough!”  Of course not! RMHs make sense for relatively cheap environmentally sustainable heat for anyone willing to consider them.  However, if you look to push the “mud and straw builds and consider more “appropriate technology” which by my definition means using the best available materials “ you will come to the conclusion that RMHs have to develop from what is to what is MORE possible.

Finally, your design works for you! You do you. I am proud of all my designs; for all that went well. and more importantly for all that didn’t go well.  What I’ve learned and painstakingly tried to guide others in the possibility of their being to undertake a build on my design. My innovative spirit and tenacity to keep building and posting on this thread that has been viewed over 7,000 times is testament that other Permies see the need for innovation on the basic designs on this site. Is my quest for a better RMH over? No. There are many avenues that my designs you have seen on this thread and some I have  kept back pending further review and development. It is because I have built a RMH that can push past the status quo challenging what a person can build with ingenuity and basic tools (drill, grinder,welder( time and patience!))
Stay tuned, I’m still pushing the envelope on what my RMHs can achieve. Enjoy where you are in this journey, my designs have places to go! And I’m certain that there are those that are interested in following!
Thank you for your interest.

Be Safe, Be warm

Phil Stevens wrote:

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.

Hi Phil, I have to admit I enjoyed your posts but I have no idea what your reference to horses have to do with rocket mass heaters. As for “building it by the book” I would appreciate you provide information where it suggests a metal riser and the heat specification for your oil drum and where it says to cut off the top and adding 5mm plate. I’m certain that the seam of your oil can will be the next thing to heat fail due to thermal cycling. I think your book needs a re- edit!
I do agree with you that the thickness of oil drum barrels are way too thin to take the massive amounts of heat exiting the riser and there is a need to add a thicker flat plate of steel to prevent your ceiling or home burning down due to a melt thru during operation.
I also agree that a metal riser is a poor decision to use which is why I chose to dole out $100 for the proper ceramic 4” I.D.  Tubes to withstand the heat.
Choosing a 100 lb. Propane cylinder for the bell was the engineering product of choice as their thickness and quality of metal are designed to take massive amounts of heat while containing propane and preventing a rupture leading to a BLEVE (if the pressure valve fails)
I will include a picture of the inside of my ceramic riser shortly after shutdown looking down the 3/4” threaded “scully fitting” that used to hold the brass valve. The glowing red area is where the horizontal burn tunnel hits the vertical ceramic riser.
My design is solid, takes a bit of craftsmanship and safety engineering so I can leave it to heat my home and hot tub while I’m out enjoying riding my horse in the Great Canadian pacific northwest!
Build it right the first time. I strongly suggest you get an empty , devolved 100 lb propane cylinder for and replace you re-engineered oil can for safety’s sake.
Be safe and be warm.

Patience Permies;  all will be revealed.

The ALOHA RMH was specifically built for my greenhouse/ aquaponic garden. The design compact, low footprint and totally manufactured from repurposed, easy to find materials that anyone can get in their hands on. The exception to this statement is the ceramic 4” ID refractory tubes.

Anyone who can operate a drill, grinder and basic welding skills can build this!
Stay tuned patrons of Permies!
Stay safe, be warm, be kind

Hello Permies!  

Frankenstove 6 is ALIVE!!!  But with a new name. May I have the honour of introducing The ALOHA RMH.

It is with extreme gratitude and excitement that I wish to announce the successful launch and operation of the much awaited Frankenstove 6  (ALOHA RMH) to make the journey from the “Manufactorium” to the aquaponic greenhouse!

I now have the opportunity to grow food year round due to this RMH novel design.

Thanks for all your encouragement and the 6800 views on all my previous builds from the original F1 through to the F5.

For those of you wondering why the name change is because I wanted the name to reflect the warmth given off by this design.

ALOHA RMH has taken all the lessons learned from every single one of the Frankenstove series and refined them to make this new brand possible and I owe a special thanks to Permies for giving me the opportunity to pursue this experimental build to fruition!  

I plan to do a build video on ALOHA to explain how you can build one completely from repurposed materials ( except for the ceramic riser)

Be warm, Be safe, be kind…

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!

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.

Metal Risers! DON'T DO IT!!!  UNLESS YOU HAVE A THING FOR FAILURE!!!

Yes, I made the mistake twice! The first time was out of ignorance and the second time was foolish!

What I learned that I was lucky and used a refractory mix surround the riser which basically sacrificed the metal riser as the form.

Learn from the mistakes of others; you won't live long enough to make them all yourselves.  

I suggest you look up my posts of my designs on this site to help you perfect you rmh.

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!

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

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.