R Scott wrote:Completely feasible, not sure if it is practical.
The house will need a full subframe instead of relying on the trailer, pushing your weight to probably more than a pickup can tow. At that point, you might as well build it out of a container and move it with a semi truck. It isn't hard to bump out the sides of the container to get your 10 foot width.
thanks, so if i do it with the trailer i would have the subfloor made of 2x4s and 3/4 plywood, what would the subframe consist of if i build it on those beams?
This is something ideal i would like to do but i know it wouldn't be that simple, just asking for opinions on how realistic or not this is.
i wouldn't move the house more than once or twice, and not too far so it would be perfect to be able to remove the trailer and reuse it for other things.
I thought of making the house wider, 10', and putting beams on each side, they would stand on metal columns and concrete pillars, this way the trailer could slide in and out as you can see on the images.
In that example the house is 10'x22', makes sense for me to make it a little wider also because it won't be moved often, so i would get a permit to move it.
I live in a mountain area so lots of winding roads and some steep slopes, just wondering how realistic it is to move a tiny house in such terrain, would the house structure need more reinforcement? do you know any cases?
I would like to build a small one at first, maybe 8x12' or 10x10´not sure but it wouldn't be a 10x30` for instance.
As Allen says, if you mean the bottom of the burn tunnel i made it like you say, the flue system 10" lower than the burn tunnel because i made an ashpit at floor level so i had to raise everything,and it all works perfect without a fan or anything. I guess the gases just keep falling until finding the horizontal pipe.
just curious ,what material and dimensions are the elbows you have made?
that looks great, i built my first recently and also didn't know the dimensions for the manifold but i did it very similar in size to yours and it's working great, i have it running all day .
here are pics from that
allen lumley wrote: Karl M : I think we are going to have to let Leonard Allen give use a class in making stove pipe. If by now you had been on schedule to burn out your barrel, you
would have learned about how to deal with galvanized pipes tendency to outgas heavy metal zinc, so that we can use it! however at 1/3rd to 1/2 the price. I will
switch to the lightest grade I can find ! Think like fire, flow like gas ! Your PYRO - LOGICAL PYRO - MANIAC For the Future / Good of the the Craft !
As always, your comments and questions are always solicited and always welcome ! BIG AL !
allen lumley: I suggested the experts, like you, give us a class!, sounds like a better idea:) i think any galvanized pipe is expensive in our area, hence the idea of using bricks, like that fantastic ecodorp rocket stove, is it possible to do in smaller scale?, what should the cross section minimum size be for an 8" system if using bricks for the flue system
i don't think so if the cross section is bigger than the combustion unit, but i'll let the experts weigh in, i've seen one example on the web but i don't know the details , look for "ecodorp rocket stove".
and as you can see, i didn't use elbows either as they are expensive too, the elbows are just brick boxes, probably not the best solution but it's working just fine so far.
you could also make the entire thing from bricks
Can somebody please clarify for me then how big the burn tunnel's diameter needs to be?
People recommend Ianto's book which states that it needs to be smaller than both the feed's and the heat riser's diameter, but Ernie mentions that it should be the same.
Which one is it because currently my RMH mock up has a burn tunnel with a smaller diameter and the draw is inconsistent..if i make it the same all the way through will that solve the problem?
Another issue raised by Jeremy is the notion of having a larger diameter for the heat riser. Can the heat riser's diameter be larger than both the feed tube and the burn tunnel?
Would the ideal diametrical setup look like this:
burn tunnel<feed tube<heat riser
or maybe this:
burn tunnel=feed tube<heat riser
burn tunnel=feed tube=heat riser
Thank you for your insight...
i think it only means that nothing should have smaller cross section than the burn tunnel so not to create bottlenecks, so the feed tube and heatriser cross section should be equal or bigger than the burn tunnel
i made it all the same cross section and it works fine, not sure about the other options as i haven't tried them.
I am in Argentina, and steel is also not cheap, i wanted to make the heatriser with refractory bricks but ended up buying a used 8" cast iron pipe 8mm thick, so far so good after 2 months, maybe it lasts 2 winters, but i also tried to make the insulation with a castable mix so when the pipe burns away it all doesn't fall apart.
So the castable insulation is another option when not using bricks for the heatriser.
there are different ways to do it, someone uses clay, cat litter, paper and perlite i think.
as for sawdust, i wish i heard that before, i would have used that too!
You will also notice that when you are trying to burn less than full loads, that restricting the flow of air at the Feed Tubes Surface with a flat slab of stone/brick/Paver,
will channel the air better around the wood fuel and Stimulate your Dragons Appetite !
Everyones R.M.H.s Dragon has its own temperament that you will quickly learn, simply from listening to the loudness of its Roar ! The fact that this is a cliché, does not
change the fact that this is true !
For the Future/Good of the Craft ! Be safe keep warm ! As always your comments and questions are solicited and Welcome ! PYRO-MAGICALLY Big AL !
that is true, it works much better when covering part of the feed tube's surface, about half of it or even more too
i have a similar system and adding the mass didn't affect performance, could it be that ash is accumulating somewhere? in my case ash accumulated on the heatriser top, i have a closed barrel but i'll have to cut it and make a lid so i can clean that area at least once a month.
We built a rocket mass heater and now after we finish covering it with cob we have to add the plaster finish to the bench and around the heater. I asked and read about it but i found there are many ways to do it, for instance, someone told me the mix is 1 part clay+water, 1 part glue, 3 parts fine sand, and someone else told me 4 buckets of clay , 4 buckets of sand, and 1 pound of glue. i will do small tests but what do you think is the best proportion for this application?
Peter Berg wrote:Highlander,
The item you're missing here is the chimney stack. The stove is working as it should because it's outside. When the greenhouse is built around it, the game will change in the way that the roof of the greenhouse should be airtight, otherwise the stove wouldn't draw. Moreover, it will draw much better using a vertical stack.
Of course you should use insulation instead of sand, but it's your stove, you're entitled to make your own choices.
The vacuum cleaner is blowing a bit too powerful, I would say. Why not blowing from the top at a lower rate, you could refill without problems then. In case you would like to make a waist oil drip it's best to have something like a bunch of criss-cross large nails welded together as a bird's nest at the bottom. This way, the oil will have a large hot surface to evaporate on.
In my case the vertical chimney really made a difference ,it would smoke in bursts before , but when adding the chimney the draft stabilized and works very well, also i tried the p-channel mentioned in other threads and it also helps alot, seems like a turbocharged draft, the flame is more steady and strong.
allen lumley wrote:Leonard A : congratulations,a good job carried through to a great result ! AND a fantastic clean out ! Keep coming back here, mostly we need to have a
'few more of them that has done, to those that are doing !! " Stick around and collect some apples ! For the good of the Craft ! b.s.,k.w., PYRO-AL
Thanks Allen, this was a newbie, rookie first time build, and it would have failed miserably without this forum ,thanks specially for your help and Peter Berg.
i hope it still works after covering all up with the bench!
well, it works! like a true rocket!
we added the outside chimney , seems that did it, no smoke when starting a fire, no backdraft, no smoke when the fire goes out, no smoke at all!.Also we were impatient as we should have waited for it to dry a little.
before adding the chimney we pulled the barrel and the insulation had swollen like an inch above the tower as you can see in the pictures.
you can also see the brick box "elbows" which could be a problem because the condensation is getting in the clay mortar, so we'll have to do something about that.
other than that all good so far, we should start covering the bench!
allen lumley wrote: To All : I know I'm overstating the obvious here but, We have a design that is capable of great efficiency in turning wood, ESPECIALLY small wood,
into heat energy, it has a name and that is - Rocket Stove ! After we have created this minor(!) miracle, we still need to deal with this gift properly
If we make a serious effort to use this great gift and not squander it the way that conventional Wood Stoves do, we are given a second miracle. When
we use this boon from mother nature as we must believe we were intended to use it, (and store it for later use ) frugally, it's name is Thermal Mass .
Its use reveals this second gift, the latent heat of vaporization, which we 'get back' and use or store as the flue gas temperatures drop back below 212F!
And what cost do we pay, what burden must we bear to be given this benison. Its simple, we properly design our thermal battery/mass to use all of the
heat energy to a point near 150 F or lower at the outdoor chimney, and allow for the drainage of condensed water vapor in the last 1/4 of the Thermal
Mass! For the good of the Craft, be safe, keep warm, PYRO magically -Big AL
Is it worth to insulate the outdoor chimney?,i'm making the exhaust go out horizontally then the vertical part outside rises almost from the floor to about 3 meters, someone told me it would be good to insulate that maybe with some glass wool around all the outdoor part of the exhaust.
Can't the downhill slope in the last 1/4 hinder the flow ?. could it all be uphill instead and drain the water back to the ashpit in the manifold ?
We 're lighting it up as we build it,i'll post photos later ,the insulation is still wet, .so far it worked well but at times it smokes, in bursts, or when you just start a fire and it goes out then it smokes alot, because the system is cold i guess, but it shouldn't do that i'm sure.
, we'll test making the chimney outside higher before anything else. but maybe we got the flue system wrong. or could be the whole thing is still wet?
The system has a 1 1/2" gap between barrel and insulation, a little offset. i hope this is not the problem as taking the insulation apart to make it smaller would be alot of work!
the top gap is 5" just not to have to cut the barrel.
one problem was that i couldn't find 8" pipes and elbows in stock so we made the pipes from metal sheets, and the elbows are made with bricks,so because of the square cross section they are larger than the pipes, i guess this should be ok since all is kept at 8" or larger but never below that.
allen lumley wrote: Leonard Allen : Part of the magic of a good working Rocket Stove is the heat gain in the system as the 'flue gases' cool down below 212 F.
At that point we gain the rather surprisingly large heat of condensation. Due to all of the variables, it would be nearly impossible to tell when
and where in the Thermal Benches Stovepipe that this condensation begins. This should be one or more threads all to thereselves ! The point
here is thatapproximately the last 1/4 of the pipe should slope slightly downhill to allow water to drain out of the pipe to the out doors! Any slope that is enough to be visible is enough slope !
There are out there high efficient, Home heating, Forced air oil and gas fired furnaces that for a variety of reasons have a 'booster fan' inline in the
exhaust pipe, The failure rate for the 'booster fan' in oil fired furnaces runs ~5 years~, thats three replacements in the 20 year warentee'd life of
the Furnace, the failure rate for gas furnaces seems longer, none of these fans are like what S.G. B. suggests and would be a D.I.Y. build 1
For the good of the craft, be warm, be safe, PYROmagicly - Big Al
I'm just building the flue system so the pipes are still in the open, it will be only 15' horizontal run, but i'll do some testing before covering it all up for good.
i'm making it about 4" from the bench top, which might be made from wood boards instead of just adobe.
Leonard Allen wrote:Yea, maybe grinding the bricks inside to a curved shape can lessen this problem, or filling the corner walls in curved shape too, not sure.
That's the idea. The shaped bricks would eliminate most of the problem, filling in corners could only been done reliably in the two corners opposite the tunnel.
I wonder though , how much does it affect the flow? enough to create backdraft?, Could i compensate for the bottleneck by making the riser a bit higher to create more draft?
Here is the bell with the position for the flue pipe and the ash cleanout door, i read it has to be bigger than system size, not sure we made it too big, small, or if it's too low compared to the barrel.
That bell box measures about 15' x 15' and 20' down from barrel to ashpit
i'll try to do a test by sealing the bell with a temporary roof.
allen lumley wrote:leonard A. : how long the metal Heat Riser lasts depends on your location, climate, and comfort issues and how much area you feel you have to have warm ,
saying that, expect it will actually go through a couple of heating seasons, when it fails it will fail from the bottom up, as the upper reaches of the Heat Riser
seem to be a slightly oxygen deficient environment retarding rusting. This is proved by the fact that there are barrels out there that have been the sole barrel
used through 20+ years of Rocket Stove use w/out failure/replacement !
if it lasts two seasons then is more than enough, the area to heat is about 400 sq feet, and i'm in 42deg latitude in Patagonia, so it's cold but not extreme.
allen lumley wrote:
On my next build I hope to use a sacrificial light gauge piece of 8" stovepipe, or sonotube, on the inside of the heat Riser I make with packed Clay Slip and
Perlite, I'm hoping to get 2-3 yrs. before I need a rebuild, by that time I am hoping to get or make D.I.Y. replacement ceramic castable parts.
You need to start looking for the barrel with one end removable that is held in place with a clamp band as an upgrade to the type of barrel you have now.
After you remove the only end left in that barrel you can install it with the ' cut ' end down and the clamp banded removable end up so that you have a way
to check the Heat Riser and all other internal parts by detaching the removable end and clamp band even performing checks between individual heating cycles.
Being able to check it will give you a great feeling of comfort and it will make rebuilds a little easier !
i couldn't find that barrel yet but it would be ideal specially if i use the iron heatriser i showed above.
Ceramic parts would be great, if i use the iron heatriser i'd like to make the heatriser insulation castable, i've read someone uses paper, cat litter and clay, not sure how that is prepared though.
allen lumley wrote:
I don't have any handle on how long your floor tiles directly under the Rocket Stove will last, I believe you have insulated the base of your Rocket Stove well.
This means that you are not trying to use the floor under your Rocket as a thermal sink, as a positive your rocket stove should come up to temp faster this way!
Be Safe, keep Warm, PYRO Magically - Big Al
excellent! , that's the idea
Peter Berg wrote:
The steel riser will burn through at the hottest spot, in effect, the end which is closest to the tunnel.
Apart from that, I've spotted a bottleneck, it's the transition from firebrick to steel duct. The round riser, projected over the square brick foundation is smaller than the round duct itself. This restriction shouldn't be there, it will hamper the gas velocity downstream of the tunnel.
Yea, maybe grinding the bricks inside to a curved shape can lessen this problem, or filling the corner walls in curved shape too, not sure.
i was advised not to use metal and round shaped heatriser, i take the advice seriously, and ideally i would make it from refractory bricks, but i'm going over budget already so i might use a cast iron pipe, if it lasts through one winter
I got this cast iron pipe from a neighbour who works with metal, it is 8" in diameter and 1/3 " thick, 8mm.
My question is , how long do you think this would last as a heatriser? months , weeks? if it lasts 5 or 6 months it would be fine as i can build another heatriser for the next winter, just not sure how fast it will burn and collapse.
I see in most designs the flue system height from the floor is roughly at the same level as the burn tunnel height, can the flue system be lower? for instance 5" 10" or could this create backdraft from the longer vertical distance from the barrel?.
Another question, can the flue system have a slight slope upwards as it starts from the bell? would it help against potential backdraft? or would it maybe just accelerate the exhaust and not heat the thermal mass as much?
allen lumley wrote:Leonard A. : Basically, I agree with everything Peter B. has told you. A couple of assumptions to start, you have Ianto Evans' great book - 'Rocket Mass Heaters', You have been to 'ernieanderica.info', and looked at their designs, [ these are proven designs, and E&E W. are both moderators on this site as they have Paul W.s' trust ! ]
I also want your confirmation that you are building on a nonflammable surface .
Thanks alot, much appreciated feedback .I bought the book but wasn't sure about the burn tunnel length as they use 7 bricks on edge there,
but on text it says the burn tunnel is half of the heatriser, the difference was that it's measured differently, in the book it's measured from inner edge to inner edge i think , but measuring from the axis gives a shorter burn tunnel as Peter explained above.
I'm building it on a ceramic floor , with the ashpit as the first layer , so the whole structure up to the feed tube will be about 2' high, and the barrel will be about 2' away from a wood board wall.
Picture 1 : The voids created by the 1st layer of bricks can be filled with just perlite, or the local volcanic ash you showed us on an other thread .
Unless you want to make a trade-off allowing much of the heat produced in the Feed Tube, Burn Tunnel, and the Base of the Heat Riser, penetrating into, and being absorbed by the thermal mass of the floor I would apply a layer of heavy duty aluminum foil shiny side up under the 1st layer of bricks, and directly onto the floor, a little clay slip should be the only glue/sealer needed !.
In the area surrounding the outside of the bricks your perlite should be mixed with enough clay to make a golf ball / tennis ball sized mass that while still moist will pop apart if squeezed. [ there will be areas with-in the footprint of your base where the Clay/Sand mix used here should be reinforced with straw as needed to accept weight-bearing from cob used to seal around the base of the metal drum you are going to use! ]
The surface of this layer of Perlite/Cob should be roughly textured to allow for the next layer of P/C to lock together! This pattern should be repeated with all following layers.
If you want to maximize the transfer of the heat at the Feed Tube, Burn Tunnel, and base of the Heat Riser, to the metal barrel, or the Bench/Thermal Mass - for maximum efficiency - then a layer of Aluminum Foil, shiny side up under the 2nd layer of bricks could be used here !
2nd Layer of bricks : The "Cross" formed at the Burn Tunnel end of the 1st layer of bricks is there to help support the metal barrel, and is to be continued up through the next several layers. Much has been written about whether a ash pit is needed, I haven't made up my mind how I will proceed on my next build, which will be The 1st one I build for myself !
This height gives me room to add more perlite, so in the pictures there are about 2 brick layers worth of perlite/clay, and there is volcanic ash below that for 2 more layers.
I think i still have time to add some aluminum under part of the first layer as you suggest.
The ashpit is 7" high, but i can always reduce it or cover it completely if needed,by adding perlite/clay with thin firebricks
I didn't do the cross layout , i'm using a brick ring instead, we're just improvising as we go along here as you can see.
here are some images of the progress, or lack there of!
perlite under the ashpit
this is the barrel which i already burned, i'll have to use that one unless i can find one with a removable end.
Yea, i want to make the riser with bricks and use the pipe i have as part of the flue system instead,but don't have enough bricks yet, only for the combustion unit, which i started building,
the other option as you say is to let the clay cure , in this case though how should the mix be?, same as the perlite/clay for insulation ? or should it have more clay?
I could use that bit of pipe as part of the flue system , but If the pipe lasts one season as a riser i don't mind, i can change it in the spring, but if you say it lasts less and i'll be freezing in july, then i'd do it with bricks.
As for the measurements, to make sure i understand, is this what you mean?, measuring from the axis of each tube:
If i have 4 bricks on edge as bridge between feed and riser (10.5") plus 3.5" on each side,it's a 17.5" long burn tunnel.
Then the feed tube could be about 8.5"?, and the riser at least 35" but could be more as mentioned before?
I was told this is good for insulation, is this true? do you know how it compares to perlite, is there a simple way to test this?
Also did anyone make cob from this ?, i tried but find it difficult to mix as it is very light and the mix remains porous.
In deed! With every answer more questions come up ,thanks again for your help.
I'll try with the burn tunnel length you suggested, with enough insulation .
I can lengthen the riser later on if needed, by using a sliced barrel. Also to try a bigger top gap
Leonard Allen wrote:I understand the idea of a short burn tunnel but I'm confused about the optimal length, as i read it has to be about half of the heatriser ,which would be 16" as the heat riser is 32.5 high. Can it then be about a third of the heatriser height and less too? 9" shorter would be 10.5" long for the burn tunnel, about a third of the 32.5" heatriser.
Try to see it a slightly different way. The tunnel half of the riser lenght is a minimum value, the longer the riser, the stronger the draw. Lengthening the riser would enlarge the mass as well when built out of dense firebrick. That would call for an insulating material, if at all possible and a maximum riser length, not found out yet. So, you ought to define the length of the burn tunnel first, according to that the minimum length of the riser. The feed should not be any longer than half the tunnel and/or a third of the riser. The riser is creating the draw, the tunnel and feed are working against it. Do not stick to the minimum values, I would think. The same goes for the top and side gaps, the top gap (the distance between the riser and the top of the barrel) should not be any less than 2 inch. However it will work fine with 4 inch and even better with one foot!
There is something funny to that top gap, some people followed meticously the recommended values and ended up with a stove that refused to run properly. It turned out to be the top of the barrel became hollow during heating up, thereby restricting the top gap to less than the minimum value.
Thanks for your feedback ,
Since it's my first build i want to make the most proven setup, also winter is looming here as i am in the southern hemisphere , i have only 2 or 3 weeks to build it and i must get it right or i'll freeze! . I will have time to experiment on the spring, i'd like to make one with a small oven for the next build
So i could either reduce the burn tunnel from 19.5" to about 10" as you suggest or make the heatriser taller?, or both?
Would 10.5" long burn tunnel with a 32.5" heatriser(1 barrel) be ok?
would these options work well too?
- 10.5" long burn tunnel with a 48" heatriser(1 barrel and a half)
- 17" long burn tunnel with a 48" heatriser(1 barrel and a half)
As for the top gap, not sure i understand, if the gap between the top of the heatriser and the top of the barrel is too big doesn't this create a bottleneck when the gases try to go down the barrel walls into the exhaust? or on that place there is enough draft to push ?
Considering an 8" system with a metal pipe heatriser , is there a major the difference in performance when using common red bricks instead of refractory bricks for the combustion unit? where in the system is it noticed?, radiating barrel temperature?, the amount of time the thermal mass remains warm?what is affected most?
Leonard Allen wrote:-Is the burn tunnel distance ok like that?
The burn tunnel should be as short as possible, so this could be 9" shorter at least.
- i can't find perlite or vermiculite here, except for the gardening type, i was told that volcanic sand works well as insulant, is it a good alternative?
The gardening type is perfect, in essence it's the same mineral. When mixed with clay slip I would prefer perlite, because the aborption of water is not as massive as compared to vermiculite.
I understand the idea of a short burn tunnel but I'm confused about the optimal length, as i read it has to be about half of the heatriser ,which would be 16" as the heat riser is 32.5 high.
Can it then be about a third of the heatriser height and less too? 9" shorter would be 10.5" long for the burn tunnel, about a third of the 32.5" heatriser.