length of exhaust pipe in mass ?

thanks for all the great video's .I just finished my first attempt . Thanks to you, Erica and Ernie and Paul I am pleased with the results and the clean burn. we are still interested in the dvd set on rocket mass heaters in time but the tilapia in our solar green house aquaponic system were getting cold so we went for it...I will post some photo's if this allows me to. Thanks again for all you do !!
The green house is under 200sq/ft so we only used 16' or so of pipe in the mass ,as to save room in the green house. I was just wondering your thoughts on the length of the exhaust in this application ?
Any feedback is appreciate (be gentle )

George Brabant : I just came back from dealing with someone else's manufactured crises and your lovely build showed up as a New Thread and brightened my day !

I tried to guestimate the size stove pipe you were using calling the bricks 9'', the general rule is to only calculate the horizontal distance, but to count every elbow
as equal to 5' of pipe, with 6 elbows and a 'T' to flow by you have done Very well for a 6'' system and better than good for an 8'' system, all the vertical pipe is working
for you, thou 15' of vertical chimney is only good for 10 ' of horizontal chimney and only then if well over the peak of your structure !

Something tells me that this will not be your last RMH ! More pictures, do you have a worm component to your aqua-ponics set-up ?

Looking at your Barrel, you Could have done a better job of paint removal, here we are falling to get the word out and need to do better. Have you been to our Sister
Site richsoil.com ? there you can click on a link to rocket stove videos, which show the best method we have, properly done you should of had about 3-4 feet
of flame coming out of your chimney, turning your barrel into a 'pocket rocket first' is mostly a piece of showmanship to grasp the workshop participants attention, but
also works well !

I have a reputation to uphold as a mean old grouch, so Ill mention the lack of a Ash Pit in the Transitional Area where your vertically falling hot exhaust gases turn at
right angles to flow through your horizontal chimney ! For the Good to the Crafts As always,comments/questions are solicited and Welcome, PYRO - Logically BIG AL!

Have you been to - wait for it, this does not come easy- You tube and typed in web4deb channel in its search field ? If not you will learn a few new things, if
you have not been there recently you will learn a thing or two ! A.L. (there is a lot of crap in many other places on You-Tube )

Thanks Big Al ! I did use 6" pipe . I had not heard of counting elbows as 5" of pipe but that makes sense (slowing the air flow).The ash pit you speak of , I am not picturing it ? I put a T clean out at the the transition from the barrel to the mass ? In hind sight wish I ha put a T at the far end of the mass where the 2 elbows change the direction back toward the rocket.I designed it to make the burn chamber longer with a little modification if needed .it seems short and I have well more than 3 times it's length in vertical insulated pipe . Any thoughts on this ?
I stopped the pipe with a T out the back of the green house just over head height of 2' or so below the roof . I was concerned about running un insulated pipe outside - fearing the cold pipe would harm the draw ?
I was able to get most of the paint off with sandpaper. I tied the wet news paper on the out side to transfer the heat and remove the paint. It seemed to be working until I had duck vs. chicken fight out side distracting me - only to return to dried , flaming news paper ..... it got exciting for a few moments ! I live on a small 1/8th acre in town so I try to keep the smoke down and not draw too much attention but in hind sight the pocket rocket would have saved me a lot of stress
I do have red wigglers in my aquaponic system . I hope to put a RMH in the house next year . After learning the ins and out this winter
I have been drawn in and now I am late for that 4 letter word .Thanks Again Al!

George : you may be right about he location of the 'T', if I had had the luck that you have had (the extra tall heat riser probably ), I would be very temped to follow your
present design again except using hard ware cloth to shape my passage from the bottom of the barrel to the horizontal chimney freehand, and bigger with a lower pocket
below the level of the horizontal piping to capture fly ash, if it is not collected here in your ash pit, it will travel farther ! and be a bigger problem downstream with just the
one clean out !
I am sure that you will discover several things that you want to change in your next model after you have lived with it a while ! The next trick is to figure out what
modifications you need to make to have at least a little drop off in temps that simulate an overnight low that plants are used to, and still deliver enough heat to protect your
plants in the wee hours of the morning without actually being there. You have to learn the heat regulation, and I am not the guy to go to for plant physiology ! web4deb?

For the good of the Craft, think like Fire, flow like a Gas, Don't be the Marshmallow! As always, comments/questions are solicited and Welcome, PYRO- Logically BIG AL !

Al: I see what you mean about the ash catch lower than the horizontal pipe , making a wind eddy of sort . I also thought a ash catch built into the bottom of the feed tube would help. After reading your post this morning I was feeding it to fast I think an some of the more solid coals were pushed into the burn chamber choking it a bit an causing some burn back. I think I will try to increase the burnchabber length and incorporate a ash catch or low spot for the coals to collect while they complete there burn . Any thoughts on this ? I

George : I like to have as much insulation wrapped around my fire bricks as I can, and if an ash pit were evacuated directly under the Feed tube it would limit the amount
of insulation I can have !, that being said, an ash pit with a few days ashes in it will act quite a lot like insulation, and the crunchy bits will cushion any wood chunks that fall
in the last several inches.

Always have several chunks burning together rather than fewer bigger chunks, the more the merrier, and they feed.off of each other, better and better, getting your Rocket
super hot faster, Always put the bigger end of your wood chunks in first , they will be less likely to 'hang -up' that way! I actually think that you can kinda sweep the hot
embers and coals back towards you a little, if you are getting complete combustion of the charcoal at the end of your burn due to the still freakishly high Temperatures of
your combustion chamber/burn tunnel, I think you should be happy!

Two thoughts, living with a working RMH beats any other option, I would rather talk with the man who has fed his house dragon for a year than talk to the guy who built 10 of
them in a year, but was never there to listen to the Throaty Roaring Chortle of a Happy House Dragon ! The 2nd guy, I could get all of the information I wanted in 20 minutes.
The first guy I would set down next to and listen to his stories and watch and listen to his fire most of the Night ! That being said, your cob will only get harder day by day for
years, it will never be easier digging than it is while you are reading this !

It is hard (not impossible, but hard ) to jump on a guy when he has already done what you want him to do! In fact the best rule I know of is to catch a man doing something
right ,and give him/that some recognition ! Usually, most builders are a little more tentative and I get a chance to tell them to go to - ' rocketstoves.com ' - and get
your PDF copy $15 of Ianto Evans' great book - ' Rocket Mass Heaters ' - Still the best blah blah blah- You should do it for your personal library, and to run off a copy
to give to jealous friends ! If your Feed Tube is 16'' deep your Heat Riser should be at least 3 Xs as long and the length of the Burn Tunnel should be 'very close' to 1/2 the
height of the Heat Riser(or shorter) ! You can guestimate this or get the book and learn to figure it out, its only old 4th or 5th grade math- so no worries, right !

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

Al : thanks for spending your time with a novice like myself . I am passionate about things I do and tend to jump in head first. I believe one of the permaculture concepts 90% observation and 10% effort. I am 50/50 at best and tend to go backward often as a result(learning the hard way).
It appears I have been some what lucky on this build . I seem to be getting a good burn and my dimensions are close - My feed tube is 13" deep,my heat riser is 38," my burn tunnel is 18"-4" of heat riser and -4" of feed tube (if I understand it correctly ) so 3 x 13" =39" /heat riser 38". my burn tunnel ,if I am understanding where one starts and the other stops,is only 10"so could be lengthened the 3" by turning the one vertical fire brick in the back of my feed tube horizon tal(or stop being cheap and purchase one more box of fire brick) and moving the feed tube back 3" before finalizing the mass?
I am going this moment to purchase Ianto's Rocket mass heater book and thank you again for the help Al (do you go by Al ,Allen hope" big Al "didn't offend
I will post some pictures of it in action this morning . I am getting a good clean burn as far as I can tell from the exhaust being mostly heat waves and I have sanded almost all of the paint off and the barrel is blueing nicely .when you put your ear to the fee tube there is a definite rocket soun

George : I will answer to everything but 'late for supper', so now a childhood name is a self-imposed reminder to cut back on snacking, And get more exercise !

Question, what if anything did you put down onto the floor, to protect the wooden decking I see that you built on ? This could be a future issue depending on the
amount of insulation (and type of) that you put around the Feed Tube, Burn Tunnel, and base of your Heat Riser! Also others following behind you and seeing your
build might discount the need for extra floor bracing, you are probably approaching 1 1/2 tons, and in attempting a larger system with fewer bends get into real
weight, and support problems !

Damn George, You have got 7 elbows and 2 "Ts" in your system, I suppose telling you your system will not work is stupid at this point ! Even though Ianto Evans
the Father of the Rocket Mass Heater, RMH was successful in horizontally exiting his horizontal chimney(s) sideways out of his buildings, he was/is building in a
sheltered hanging valley, with a great micro-climate and steady prevailing winds during a short heating season ! I tell every one that when they plan their build,
plan on the cost of a vertical chimney going about 5' above the highest peak, you may Never have any problems with getting a good draft as long as where you
have exited your building is Always on the lee side of the house/prevailing winds ! IF you have to add on you can save yourself some money by using the galvan
-ized stove pipe everywhere after the Cob Thermal Bench !

Actually, I was/am a little concerned that you reported such a quite rocket sound in your RMH, but now I see why, I can not tell you with any degree of certainty
that you can make any changes safely to your system without turning a slightly sluggish system into a flop, So Now, I guess the best thing to do is wait for and
read 'The Book' and then you decide what to do next ! Could you have gone straight up through the roof at the point you introduced the 2nd to last bend ?

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

Al: I put down a slurry layer of cob and then 2" of perlite and then another 1" or so of cob .then the fire brick burn chamber. Underneath thfloor joist ,that run perpenicular, I built a double 2x 6 to carry the load on two new footings . I have swung a hammer my whole life .I f there is any movement I will reinforce .
The 7 elbows an 2 T's did concern me. I have the last horizontal pipe just below the bench surface and with minimal effort (Ihope) I could exit next to the barrel straight through the roof , removing2 elbows and a T.I am exiting the building between the green house and my home, on the leeward side of the green house . In your opinion would I be wiser to go ahead and o this for fear of slow performance ? It is working well but is probably sluggish as you suggest . How do you feel it woul flop ?
I have the PDF for RMH's By Ianto an will dive in in the next few days.
Thanks for helping me stop being a marshmallow !

George : As I see it you are doing a bit of a high wire act, but have yet to put a foot wrong. If YOU are a Marshmallow, you are buried some where in the middle of the bag,
completely un-toasted!

Thanks for taking the time to explain how you dealt with the floor issues, It is important for the visitors that follow, here to Your Forum Thread that they don't see something
in a picture, and misinterpret it! I know that you will keep an eye/ear on things in your own build ! In fact I am sending some Builders in Progress to your thread who have
questions now ! For the Good of the Crafts, BIG AL !

AL: (and any one building over a wood floor: I suggest a minimum of 6" insulation between the floor and the burn Chamber !

lessons learned : SAFETY FIRST !!! ,if you read on line 4" of insulation use more (not less ) putting a piece of $10 masonite/hardibacker or the like is money well spent. when II covered the periltie my cob was very wet and most likely mixed in that spot and I think the clat transmitted the heat ... Any thoughts ?.
It gave me a huge scare so I will read the book and increase the insulation, I will go to 6" with durarock under and two layers of perilite sandwiched ,between thin layers of firm clay/cob above being sure not to get any mixing where the burn chamber is.
Something else I noticed is that by test firing it before ading the final mass and drying it out the two layers did not bond well .I put divits in it and wetted it before starting .
Feeling a little over whelmed right now but what doesn't kill us (almost) makes us stronger .I will add a picture of the poor bonding

George"Golden honey toasted''Brabant :My hat is off to you, it takes more than an honest man sure of his convictions, it takes a brave man to face his mistakes,many would
never step forward as quickly as you to identify a simple mistake to his fellow members and peers !

While I could tell you that you came close to getting away with it, the face that you were building over weathered boards meant that you already had 1 strike against you, those
boards were already partially pyrolized do to weather and UVa and UVb rays !

That and the compaction of the perlite beads, mostly due to the rapid rate you were moving to complete your build worked against you, please note that in no way am I telling
you that you must replace those older boards ! Just that we most make more changes than you and I were both expecting !

For starters,you have lost nothing at all but a little time, we cant get that back, but we can move you in the right direction !

For a safer build over a wooden floor which is an unusual combination for a Green house goto - ' villiagevideo.org/products/rmh/scenes/ ' - this is actually ~3/8ths~ of
a video that I only now about 3 hrs ago got to see in its entirety! however I had already seen the part that you had seen including all these parts dealing with safely building on
a wooden floor !

After watching this I think you should ere on the side of caution get the whole DVD from Villiage video and follow a similar course as shown here ! Big Al !

Al: LOL - George golden honey toasted Brabant may have to be my sign in name . Thanks ! it was a large slice of humble pie that I am thankful for and will eat with a smile (eventually )! I am glad I caught it when I did. I am looking at the village vieo FB page and have requested to join the group. I will certainly buy the video and do more home work. I see some pictures and a reference to Ianto's book about leaving an air space . I am excited to start the rebuild but will settle in and read for today!
I have a few ideas but want to read now and view the video's then consult with you again . your help is and has been much appreciated Al !
Peace -George golden honey toasted Brabant

Geo.G.H.T.B. :I just now FB'd them and left a few words of apology for badgering them them during production delays (overdue on my part )They announced a
$10 off by entering the word ,burn' in the correct box ! Big AL !

Al: I have began the rebuild .I covered the floor with tin foil,left a 2" gap built off of condrete board at that point. I then made a 2 1/2 " base for my j tube from solid used brick and sived cob.
I also changed the transition from the barrel to the T clean out .more pic.s soon .
I thought I woul post this in hope you would see it before I was to deep to address any concerns you might have ?
Thanks Again
G.H.T.B.

George G.H.T. & Permies Cloud : I would love to see a 4'' Air Gap between the plywood wall and your RMH, possibly split into two gaps with foil shiny side out over some
backer board, this would also create circulation from under the bench and up that wall, Watch your Tan line ! Big AL !

I like the improvement in the Transitional area ! for your next couple of builds consider using some wallboard gypsum compound or even grinding up some sheet rock sans
paper to make the walls smoother, any compound left over will help keep the Cob from cracking around the Cob Barrel interface ! Lets see if it Drafts better, with a deeper
Rocketeer roar ! A.L.

George,

Very cool to see someone else building a RMH for the 1st time!! My husband and I build a small practice one outside last night to get some experience with the combustion chamber and the spacing between the feed inlet.
I'm curious did you use clay from the ground for your cob mix or did you buy some? Oh, what kind of sand did you use? I'd like to post some pictures of our little RHM but I'm not sure how to do it. Thank you so much for sharing your experiences (good and not so good ) with us!! Good luck and I look forward to hearing about the rebuild.

Jennifer

Jennifer: How did the test go ?
I used clay from our property , we have a high clay content down about a foot or so.
I added some masons sand (crushed rock not rounded beach sand ) you can get at any gravel/rock or mason supply . I did a soil test (shake a jar full of soil and water ) and I have a fair amount of sand in the soil already also.
I add pictures with the attachments tab next to the options tab when posting.
We finished the rocket stove /barrel and exhaust this weekend.
I am very pleased at this point with the operation of it all(BIG THANKS TO BIG AL! )
I will post some more pictures of the changes to the system .

George,

The pictures look really Great!!! Great job on the texture it looks very smooth!

The 1st test burn didn't turn out so well. So after more reading on this site I found that our riser was too narrow and not tall enough. We just put a simple 6" stove pipe on top of the burn chamber exhaust and it worked perfectly!! Our kids loved the rocket sound it made!

We too have clay containing soil here in Ohio so we're going to use that in the cob mix. I think the mason sand is what we're going to have to purchase as well. We can't wait!! Just have to get the fire bricks and we're good to go!!

I'm using google chrome so I wonder if that's why I don't see the option for attachment?

Anyways It looks really great!! Have you finished the rest of the Cob? We look forward to seeing your progress!!! Keep up the great work it's an inspiration!!

Jennifer

Oh DUH!!! I see the attachments!! It was staring me in the face the whole time!! hahah! Now I feel like an idiot!!

Here are a couple photos of the Mini practice Rocket stove. We're going to use the proper materials for construction in the house. Just wanted to get some hands on experience.

Nice ! That is a tall heat riser....I bet it was very strong jet. Thanks for sharing ! you mentioned the materials, I assume the cinder block won't be part of the house rocket ?. I see the small pocket rockets you have also .Love to see more people experimenting !

Jennifer C.-D. & the 'Permies Cloud' : I do not know what disturbed me more in the second picture, The cinder block, The damper being used in a RMH System, or the skull
of little fido to the left of the single brick in the 2nd picture

Most of Your fellow members know that what we saw was part of the outdoor experimenting process, but if we don't point out the obvious things that are wrong someone will
think if they saw it in a picture at Permies it must be right ! Hope you have cremated little fido's remains by the time you get this ! For the Craft ! Big AL!

Hey Guys,

No those were just materials that were left by the previous owners that we put together to get some experience. I know that concrete can't be used for something like this. It just worked for our little practice run. Actually the 2nd burn we did my husband took it off because the diameter of the hole through the center was too small. Oh, the reason we used those stove pipes was those were the only two sections that would fit together. Using only one didn't create enough of a pull. Al, which skull are you talking about???

J.C.-D./Permies Cloud :The little sun bleached one, about six inches to the left of the single brick in the second picture BIG AL

Oh haha!! I was looking for an actual skull of some sort!! That's a piece of knotty wood that we couldn't quite get cut up all the way! We tried to cut the wood into small strips for the RMH but some of the pieces were a pain!! Especially when we only have a cheap walmart hatchet and half of an old ax to cut wood haha

Jennifer

J.C.-D. Thats what You Say ! B.A.L. ! P.S. teach yourself to always put the big end of the wood chunk in first ! That way you should not have chunks hanging up and the fire dying
and you think its just fine ! (though your ear should catch it ) A. L.

George : I am bumping this post to make it easier to find for some new members, don't forget to come back and tell us how its going ! BIG AL

Hey George,

Just wondering if you're still working on your project. Hope all is well!!

Jennifer

Al and Jennifer : I have almost completed the rebuild .I have been running it hard for a week now and have come to know how my dragon operates before posting again. It runs smooth and steady on calm days , but when the high winds came through the other night I would get puff back. I think adding a H made of three T's at the end of the exhaust will stop this. Any thoughts Al? .My exhaust comes out under a raised deck rather than above now and this forms a wind tunnel.I could go straight through the roof if necessary . My other concern is the fire can climb as much as 3" up my feed tube . when the logs are loaded loose or no brick used to channel the flow.I am slightly concerned that my heat riser could be taller ?
This being said I am extremely happy with the results. 18 degrees outside and 76 in the greenhouse when I went to bed and in the high 50's when I woke up. This was with the mass not entirely dry yet .
The air gap between the wall and the mass combined with the 4' gap below the rocket mass keeps the floor cool but a strong heat convection up the wall and out into the room.
Getting this cold snap ,I had to run it hard causing some cracking ,but have added following thin coats to make sure it seals any co2 or other harmful gasses .

George : Fantastic, It's a learning curve more wood split fine, rather the fewer large chunks will always be the way to go !


I was reminded the other day just how small the wood boxes on cook-stoves used to was ! Back in the days when two men set out with axes and a Two-man cross-cut saw to
take a tree down and limb it up we were a lot more Canny (read stingy) with our wood than we became after the introduction and common use of chain saws, so in truth, in
many ways we are returning to the efficient practices of our Grandparents ! For the Good Of The Craft ! BIG AL