Dialing in measurements and materials (I may have, after finally abandoning all hope, landed a local source of gray river clay ) and interesting in some barrel perspective...
I am casting an insulated core and heat riser. The latter being 14" at it's widest (filled with all sorts of insulation due to creating a 6" system) and rethinking the 50 gallon barrel. It's just HUGE, and the 32 gallon barrel really fits my space so much more naturally.
So the details and questions that arise are thus:
The 50 gallon barrel will yield a 4 1/2 in gap all the way around the heat riser.
The 32 (it might be 30, to me what matters are the measurements...) gallon barrel will yield a 2" gap around the heat riser.
I am running less than 20 feet of pipe in my bench, with three elbows going into a sound/solid/reliable chimney inside the living space, the first four straight feet of pipe is a highly insulated water heating element right after the plenum and first clean out then elbow. I am more interested in the heat getting to the water heater (in an open system, no BOOM+SQUISH here) and bench than the barrel, and know that insulating the barrel is a no-no...
What are the advantages, disadvantages, pros and cons of the barrel sizes for this system?
With my (rather busy winter) work schedule I am looking at only a couple of hours of burning about 14 hours apart.
I am willing to take the pains to make the smaller barrel fit uniformly over the heat riser if it will be enoughcooling, pumping and pulling.
Thanks for having a look and weighing in! I'll be casting the core in a couple weeks and will soon be creating a thread to document the process. The latter only being fair, as I have learned so much from others doing so, and hoping to hear from the like!
Prescott H. Paine : Sometimes I can tell and sometimes I can't, Have you been to rocketstoves.com to get your PDF Copy $15.oo of Evans' Great Book "Rocket Mass Heaters",
there is STILL No other book in any language with as much 'Rocket family' information for the homeowner D.I.Y. builder! With over 100,000 R.M.H.s built world wide, most
were built by people using "The Book" - and 95%+ of the 1st time builds (That Worked) were created using 'THE Book'! ( And I don't make a nickel ! )
Size does matter, the way a Rocket Mass Heater, R.M.H. creates the Thermal (Heat Energy) Differential Engine, is by the amount of heat that is radiated off of the barrel from
its top down to the bottom on the sides, Counter-intuitively, the Smaller Barrel, which must give off the same amount of heat energy as the larger Barrel must due so at a
higher temperature, this is mentioned on page 36 (d) in 'The Book'.
This is the reason that when your 3 year old wants to be 'picked up' they are such a good cuddle, with a lower skin area to weight (surface area to mass) they have to radiate
off that heat at a higher temperature ! I would definitely go with the bigger barrel because it will give you more options when it becomes time to shape your transitional area!
Some of the grey and some of the blue clays super expand/contract with heat cycling and will need more sand to get between the micro clay particles, this works to reduce the
amount of expansion and contraction that will cause cracks in your Cob ! You will need to make some test bricks !
Your fellow members here at Permies and to a lesser extent myself are so busy signing the praises of the R.M.H. that we sometimes fail to mention some of the important
things like how to 'run' a J-Tube style Rocket, and very importantly its proper location within the home ! Your R.M.H. should be given Pride of Place at the very heart of your
home! When it is so placed within arms reach as you Go through your daily house chores, and where you relax in what is generally your evening your Rockets throaty roar and
gentle heat will be ample reward for the minor distraction of fire tending, and can be a great Conversation starter and Show Piece !
A typical days operation would be something like this, You start your fire with the smallest, straightest and driest wood you have, and for the next 1 hour you carefully build
up the internal temperature of the Rocket stoves combustion chamber, when the burn tunnel has had a chance to start glowing red hot you will know it because the wood
that you feed it will nearly spontaneously burst into flame! This is the point that you can fill the feed tube with 3-5 wood pieces and expect to get some where close to an hours
burn, 3 - 4 hours will easily get you 10 to 12 hours of stored heat, 6 - 8 hours of tending faithfully to the needs of your R.M.H. will get you 20-25 hours of stored heat !
If the R.M.H. is not given 'pride of place' in the heart of the home, but is placed out-of-sight, out-of-mind, or where it has to go to reach the start of the vertical chimney, and
out of earshot, your Rocket will be "out" more often than on. Tending to it will grow to be a chore, rather than like each piece of wood that you feed it being like putting money
in the bank with Automatic Withdrawals paid in warmth and comfort !
I know that this is not the angelic chorus you are used to hearing, but not knowing your location and seasonal heat load, I gave you an Northern New York/ Canadian Winter
answer, as a matter of fact, I am going to give you a shot at seeing a Video of a build my wife and I helped Ernie and Erica Wisner Build during a workshop a year ago !
go to the Rocket Stove Threads page and find the thread ' Two more great working mass heaters in upstate New york and Quebec (rocket stoves Forum at permies)'
The first one is the one I am referring to, and yes, The woman is really that well organized, and she did save all the Fly Ash her R.M.H. Created! For the Good of the Craft !
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 !
Success has a Thousand Fathers , Failure is an Orphan
I won't reply to everything in your multi-tiered reply (THANK YOU!) but will shoot off some instant-gut responses
I am in DownEast Maine, it can be dark and cold and bitter, and while I can't smell the ocean at my house, it's only 20 miles away. It's brutal here, but not as bad some of our northern interior brethren...
My RMWH is front and fucking center, as it were, not master piece like, but "this is the heartbeat of the house" (the 'plant) and all about ease of wood delivery, splitting and feeding, sitting on bench/nearby rocking chair dragon feeding care, or so I am visualizing!
Ianto speaks of a 1.5 to 2" gap 'tween the HR and Barrel and that just seems so tight to me, thus my posit, query...
p. 23 (hard copy thanks...) specifically mentions 1.5 inches and I am looking at that with wonder. I can plug those numbers into my equation, do the math, but I am looking for direct feedback from those that might have tried one barrel and had smokeback, or another and had entirely too much draw, or the top of the barrel melted but the lower sides never blued, or the stove only putted along until....
So thanks for your comments, I appreciate them, but I am looking for more specific details. Bigger isn't necessarily better in my book. Barbie is a mutant, Zucchini with a wilted flower on it and no seeds is just right for me, and well, anymore than a mouthful is wasteful.
I'm into efficiency and delicacy, not blunt and burly. I'm fine with moderation, but don't use a 10# hammer when a gentle whap'll do me...
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
Prescott H. Paine : I don't really care how to get the message acrost, This is ADULT Education, while it's been proven over and over again that with kids, if you catch them young
enough their minds are like sponges, With Adults you have to get them to see WHY they need to know this piece of information, and then they probably will take it in ! Kinda ! So
if it takes the lead from 'Ten inch Nails' and vibrato- 'skool !
The other day I realized that I had misspoken myself and basically told a fellow member here at permits to experiment with bentonite clay, the crap they make kitty litter out of,
and I Knew I'd made a mistake but I had not finished making the connection between slimy/soapy Blue clay and Bentonite, fortunately a fellow member caught this, and I will
always have that fact gleaned from my mistake at my fingertips.
However, the guy with a dump truck load in his side yard can point to the pile and say,' and don't use this stuff', he has a near constant reminder that you don't use bentonite /
Blue Clay! Thus is Adult Education- 'Why do I need to Know this' ?
Ianto Evans book is a great primary tool, better than everything else, because there is No everything else ! 1.5 inches is a good minimum distance for a 6'' system and 2'' is
good for a minimum for a 8'' system. We want the gases at the top of the drum to churn aggressively in a 'Toroid or doughnut shape' at this point, mixing the gases for final
combustion, and also creating still more heat (and Sound) from the turbulence! This is the last place that we build in turbulence, and are willing to take some losses from laminar flow
if we gain a smooth transitional area where the Hot exhaust gases go from Falling Vertically to flowing horizontally through the transitional zone, over a large Ash pit, and Clean Out
"T", before entering the Cob Thermal Mass Bench ! Here you should go as high as 3Xs the Cross Sectional area with a big cone shape, or funnel, as that is its function !
You can of-set the Barrel to protect exposures, and throw heat in a specific direction, but I would always have the Transitional area Directly below the off-set ! Hope this helps, and
is timely, 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 welcome and Solicited ! PYRO - Magically BIG AL !
Success has a Thousand Fathers , Failure is an Orphan
I live in Wesley but work in Calias in the mornings and then split my afternoons up between Lubec and Pembroke. I drive more than I like, but it's working for now, a busy winter with school calendar breaks here and there.
Are you from the area, live around Wash Co somewhere? If you have a functioning rocket stove I would love to see it!