rocket mass proven design? is this normal?

hello racketeers
we are a building group from israel and we have built 10 rocket heaters until now.
we keep on feeling that either we are doing something wrong or that this is the way this things work.
http://www.youtube.com/watch?v=RZtbMGDT2Mk&feature=youtu.be
http://www.youtube.com/watch?v=WtsuyPNDznU&feature=youtu.be
sorry about the noise - people worked there.
i guess i'm looking for sharing of experience.
i'm trying to understand was it a good idea to make this rmh thing a business.
for instance - hight of the wood - if a client must cut it to the hight of the feed it reduces the likability for it to work. also occasional smoke back.
this is our in making web site - kamin-masa.co.il
thanks
adiel

Adiel Shnior :
Welcome to Permies, and a big Welcome to the permies '' Rocket Stove'' Forum Threads, You will long remember your First posted Forum Thread !
As you are the first signed-on permies member of your group, you are now the senior member until we fix your build,and the dragon inside your
'rocket' is happy, and they have signed in as members too !

Yes I can see that you have problems, actually quiet a few, and I am sure that I didn't spot all of them. When I list the faults that I have found please
believe that there is a fix for all of them, and if the listing makes for negative reading, again we hate bad rocket stoves and love all of those that are
out there trying ! We will soon change you into them that have already done IT ! For starters you need to make a successful build in the 6'' - 8'' Dia-
meter range before you try deviating from a "Proven Design" !

I do not know that you are using as a 'Proven' design, but I think that you have deviated from that design in a lot of ways ! Because there is so much
Jreck out there on You tube , you should probably skip watching it all together until you have successfully created a working rocket stove !

Please consider my strongest recommendation to go to 'rocketstoves.com' , to pick up your PDF copies $15.ooU.S. for all the copies you want(!)
of Evans' and Jacksons' Great Book - 'Rocket Mass Heaters' - There is STILL no other book in any language* with as much 'Rocket Stove Family'
information! (and I don't make a dime!)

O.K., In no Special order, You should have learned to make a 'pocket rocket' and used that to help you burn the paint off of the outside of your barrel,
you are pumping toxic crap into the air (and what was in the barrel?) hardly a good sales pitch !

Your Feed Tube is too big, this could be dealt with by capping off part of the air flow into the feed tube, channeling air past the wood that you are burning.
You are teaching yourselves bad habits right now at the start ! Always use the straightest wood that you can, and always put the big end in first, that will
cut down on the number of wood pieces that hang up to nearly Zero !

Always burn at least 3-4 small chunks of wood together, the increased surface area for the same amount of wood will allow for a better, hotter burn with
each piece supporting and kindling each other !

You want the wood that you feed in vertically to remain vertical as they are burned up. When your wood falls over horizontally it can smolder and block
part of your 'Burn Tunnel' affecting your draft ! I think your 'Feed Tube' is to deep !

The J-Bend style Rocket Mass Heater, R.M.H. with vertical loading, is a very good model to learn on as it can not be operated incorrectly without smoking
back into the house ! It is the perfect stove to learn on. Having said that, the J- Bend R.M.H. is not a wood stove that you leave, and the owner who tries
to operate it that way, will be unhappy with it from day one!

Finally, and this is a very hard idea to grasp in it's entirety, the Cross Sectional Areas, C.S.A.s of your R.M.H. Must be keep constant at your Feed Tube,
Burn Tunnel, And Heat Riser / Internal Chimney, and also at the top and sides of the barrel, and Especially within the Transitional Area, where your hot
exhaust gases sweep thru a 90 Degree arc funneling out past your first horizontal clean out and into the horizontal pipe of your thermal bench !

I could spend days describing just the Transitional Area, and its need to control how you build and insulate the R.M.H.s Base ! This is another reason why
I am Strongly recommending the "Rocket Mass Heaters " Book ! I am sure that other members will also want to explain to you exactly why the Cross
Sectional Area C.S.A. of a R.M.H. is so important,and they would be right, we just need a little help with your original understanding of this concept within
your whole team which is why the recommendation to get '' THE BOOK'' !*

If this comes across as too Negative or to bossy, consider that I once was where you are and made many of the same mistakes !

For the future of the Craft ! Be safe, keep Warm ! Pyro Big Al ! - As always you questions and comments are solicited and are Welcome ! A.L.

* There are adaptations of 'THE BOOK' , in French Spanish and (?) for those who think better in their 'mother tongue'

allen
thanks for the good intentions
i read the book several times.
i also went to a workshop in montana with ernie and erica.
and i've built 10 rmh by now.
feed is not to big. its 15 cm by 15 cm (its a 7" system). c s a is same all the way exept the tunnel which is a little bit lower then 15 cm.
gaps - barrel to top riser its 3" (more then needed. is it a problrm?)
barrel to riser sides - also mor then the c s a.
the manifold is 10" (also more then needed but lots has been said about making it wider)
so.
about the wood - this is part of the quetion - is it has to be so spesific? is it not possible just to put wood and thats it?
notice that if we rattle the wood every 15 minutes the problem quite goes away.
mmm.

Adiel Shnior: First a little history, The "Rocket Stove'' Family evolved like this !

1) The Rocket Stove was created first ,and we say of it ; 'It is for cooking and feeding the whole house' mostly used outdoors

2)The 'Pocket Rocket' was next, and we say of it ; 'It is for heating all outdoors', Picket lines, Prepper / Doomsday-ers, and Ice Fishermen !

3) The 'Rocket Mass Heater' was next ,we say ; It's for heating your house, and for feeding your Dragon !

Originally, the Rocket Mass Heater, R.M.H. was thought to need very strong durable materials to survive the high internal temperatures that created its great
efficiency! Also the original people who worked on the R.M.H. expected it to be adopted /adapted in 3rd world countries out of local materials !

A second generation of Rocket Mass Heaters, R.M.H.s were constructed with clay ceramic and fire bricks - trying to use materials that transferred the heat
through themselves without failing. The heat energy not lost to the mass of older bricks and heavy steel pipes produced hotter fires quicker, improving
efficiencies !

A third generation is being built today out of refractory materials like perlite and vermiculite , mixed with clay slip or Water Glass as a binder, again we are seeing
more heat not lost to the mass creating hotter fires faster ! Many more improvements have been noted and are being researched, this is where you will find
tomorrows R.M.H.s

The J-Tube, Vertical Feed R.M.H. is 20+ years old and was originally designed to be a poor mans Masonry-type stove, burning wood very efficiently and storing the
heat within built-in furniture at the core of smaller houses, We are seeing houses being designed today Around R.M.H.s as large as 3000sq feet heated successfully
in climates similar to the Mediterranean Basin Climates!

The generally accepted way to feed the Dragon that lives in every R.M.H., is to feed it several small straight pieces of very dry wood as often as once every 1/2
hr while the whole thing comes up to its working internal temperatures,then every hour for 5-8 hours to produce and store enough heat energy within your
thermal battery for the home owner regulated heating needs of the next 20 - 25 hrs !

As such, the most successful and happiest owner of a R.M.H., is one who gives the R.M.H. the 'pride of place' within the owners home where the R.M.H. is rarely
more than a few arm lengths away and can easily deal with feeding the R.M.H.s Dragon as a routine duty quickly tended to. The owner who places their R.M.H.
out of hearing range will never truly be able to tend to their Dragon and will be dissatisfied with it and the Dragons needs for attention !

For the future of the Craft ! Be safe, keep warm ! PYROLOGICaL Big Al ! - As always, your Questions and comments are solicited and Welcome ! A.L.

Adiel Shnior : If a fan is needed to make it work, then I believe there is a restriction somewhere. Try my original suggestion to use at least 3-4 pieces of wood
every time after you have a nice glow when looking down in your Burn tunnel. If the wood continues to try and burn out the Feed tube, with smoke back then I
would Tear it apart and re-build even closer to your original specifications. There are several films Showing How Ernie And Erica Wisner Prepare barrels for
burning, both here and at the sister site richsoil.com. Usually Ernie makes a Friday night ritual of lighting off at least one 'Pocket Rocket' with clay mache`

For the Future of the Craft ! Be safe, keep warm ! PYRO-logic Big Al ! - As always, your Comments and/or Questions are solicited and are Welcome ! A. L.

Adiel, from your videos, there isn't enough wood in your feed. Basicaly, a rocket given dimension for the feed tube is usualy the size of the burn tunel, but, it's filled with wood, making a kind of venturi, which accelerates the flow of air, helps burning, mixes the gasses etc. Having the feed tube slightly larger than the burn tunel first of all, isn't too good in the case of having just a few sticks in it. Because the air doesn't go fast enough around the wood. I'd say resize your feed tube a smidge to be the same as teh burn tunel. Or restrict the air entry on top. I fit a firebrick on top of half the feed tube of my six incher when i'm in this case. What kind of insulation do you have around the burn tunel? Around the heat riser? What is your burn tunel material? And what about heat riser material? Just a daft question , don't you go from square burn tunel to round heat riser?

satamx - there was enough wood. this is the end of the load.
the materials are fire bricks for the feed and half the tunnel and kiln bricks for half the tunnel.
riser is a square stainless with ceramic fiber around it.

just for understanding -
do you operate your rmh without rattling the wood at all?

thanks for your time

Well, if you think there was enough wood, good on you!

Some rockets are easier than others on the wood going down side of things. Higher feed tube can help using longer pieces without binding. Another thing, have you heard of a Peter chanel?

do you mean donkey's channel?
can you please tell me if you are operating without touching the wood at all?
you are saying some rmh more then others.
do you know about a list of "this is how rmh should behave (in terms of ash, tending, smoke, smoke backs.....)"? things that are not different in every stove? do you understand what i'm asking? i'm looking for understanding just how much a product is it? lets say compering to the average wood stove?
thanks.

Rocket mass heaters do tend to show fire creep, especially when burning soft wood. This can be (partly) alleviated by a feature which people do call a p-channel or Peter-channel. This is best described in the "Small scale development" thread over at Donkey's rmh forum.

Your videos doesn't show anything of the innards of the stove, what the length of the bare horizontal pipe is etcetera. Also, what the length of the vertical stove pipe is and what the end temperatures of the gases are. The bench, when completed, will loose the heat not as quickly as the bare horizontal pipe. A stove featuring a completed bench will behave differently, almost quaranteed. Please provide more information, as much as you know, it's impossible to diagnosticate the problem otherwise.

You say the transition area is made of a 10" pipe. This doesn't say anything about whether or not a restriction could be there. Please measure this area, the distance from the exhaust pipe to the side of the burn tunnel is very important. Information about this probable bottleneck spot is in the "Helpful hint" thread.

When there's no restriction anywhere in the stove, especially in the transition area, the other thing you could do is to provide a short piece of small barrel around the feed tube as shown in the book. This will prevent the air coming from the sides, instead it will come from above almost exclusively. Moreover, this metal ring will shed it's heat easyly to the surrounding air, keeping itself below self-combustion temperature.

adiel shnior wrote: do you understand what i'm asking?

Nope, sory, i'm wayyy too stoopid!

Adiel Shnior : We seem to be guilty of answering Questions that you have not asked ! I seem to be more guilty than Satamax and Peter Berg ! I am re-stating
the questions as I understand them to make sure that we all have a chance to address your concerns !

Making this a Business - Yes, BUT ! You have to find the right Client ! Your real work will start after you complete your Rocket Mass Heater Build !

Wood height - You can burn everything from twigs to wood pieces approximately 6 cm longer than the top of the Feed Tube, blocking as much air flow as is
needed to channel a rocket-y airflow past your wood fuel ! A metal collar can be a supplementary tool to extend the height of pieces to be burned but for safeties
sake, I personally would not add more than 14-15 cm to the metal collar, and would check carefully that Radiant heat from the Feed Tube / Burn Tunnel was not
making the metal collar hot - increasing burn and smoke back !

How would you stop a smoke back or flame back condition if the wood is longer than the Feed Tube is tall !?

About the wood - Soft wood finely split is o. k. for kindling, dense soft wood can be mixed with hard wood only if it does not throw off resin fueled sparks. Again
the J-Bend vertical feed R.M.H. was designed for continuous attention, feeding its Dragon small dry wood in batches, a good minimum load after your R.M.H.'s
up to Temperature would be 3-4 pieces ! This is not a Fuel and Forget wood stove !

Rattling the wood - If you knock off glowing coals from the wood, you increase your surface area to wood mass/volume, it should work better ! Always load the
wood into your Feed Tube with the large end down !

Have I answered your issues with the R.M.H., or have I misstated your areas of concern ? Please post us a reply to let us know HOW we can help ! Misdirected
help is worse than no help at all !

For the Future of the Craft ! Be safe, keep warm ! PYROLOGICAL Big AL ! - As always questions and comments are solicited and are welcome ! A. L.

Satamax Antone - sorry i probably wasent clear. i appreciate your help very much!
what i meant was is rmh is a stupid proof stove. just put the wood and forget for an hour and a half. or is it has to be maintained every 15 minutes.
allen lumley and Peter Berg - thanks. i'm trying this things and your comments are assuring me that i'm not far from the result people get all over.
Peter - i tried the p channel. i couldn't tell the differens.
about the manifold - by your equations we are ok. meaning i believe the gap around the riser is big enough for the smoke profile to pass.
mmm.
so manny variables.
tomorrow we are going to build another one. people here like these dragons. hope i wont create fals expectations for them.
thanks again to all of you

adiel shnior wrote:Peter - i tried the p channel. i couldn't tell the differens.
about the manifold - by your equations we are ok. meaning i believe the gap around the riser is big enough for the smoke profile to pass.

Adiel,
Yes, it's true, there's no discernable difference to the naked eye. The Testo gas analizer won't agree with you though, that apparatus will detect a lot more than we do. When using a properly implemented p-channel there are no CO peaks anymore, the exhaust gases are very frugal in hydrocarbons. Much more so as compared to a RMH built "by the book". Admittendly, this feature will add some complexity to the very simple design.

When you are searching for a rocket stove which won't show smoke-back, look at the batch box rocket. That one could be loaded and left alone for about an hour and a half but has got the disadvantage of needing a proper door. Besides that, it is a very tight design, a relative small deviation of the layout and it won't do what it says on the tin.