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Length of Flue pipe  RSS feed

 
Posts: 7
Location: central texas
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Hello!!!
I am very excited to have recently heard of a rocket mass heater from a friend, just in time to install one in our papercrete barn-apartment that we are putting up on the side of the barn!

My first and most definetely not last question is about the length of the flue piping. We have a 20' X 48' space that will be turned into one living room with 3 adjoining bedrooms side by side going down the length of the building. We would like to build the RMH in the living room and have the flue piping and bench go the full 40 some odd feet down the length of the building to eventually go out the roof on the far side.

Is this too long a distance to get efficient heat on the far side?
Will it cause any problems at this length?
Would we have to make any modifications to the design to
 
gardener
Posts: 1279
Location: latitude 47 N.W. montana zone 6A
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Nila; First thing to do is get your copy of ianto evans book, wood stoves you can snuggle up to, after you read it most of your questions will be answered. I am no expert ,having built only one rmh but i believe that with an 8" system and almost no bends you will be able to push your heat 40' + no problem and if you are putting a vertical chimney thru the roof at the end then you should be good for more. What i can tell you is how awesome these stoves are! I live in northern montana and i am easily keeping a greenhouse at 40 degrees + all nite ! with NO FIRE after 10 or so !In an insulated house in texas a fire every other day will proble keep you toasty. Tom
 
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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books fungi hugelkultur solar wofati woodworking
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Nila Madhava : I totally agree with T.R., You can go with a couple of different options to get Ianto Evans' book "rocket mass heaters"(stoves you can snuggle up to) through
Amazon or Alibris used-books, and wait on delivery , or you can support the creators at rocketstoves.com and Download a PDF copy for $15, print up the copies you can use,
and have it in your hand within 1/2 an hour !

Read the whole thing cover to cover a couple of times, The good news is while you will increase your vocabulary a little and uses a little 3rd/4th grade math, here is an enterprise that
requires no new Clothes, Some slight improvements in the original build can be learned here at Permies.com and you will have time to get your materials together

The bad news is there are very few places in the whole build for paper-crete or any cement products ! (or Steel) due to the working temperatures that give us our great efficiencies !
 
Nila Madhava
Posts: 7
Location: central texas
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Thank you Thomas and Allen for your speedy and informative replies) That's good news Thomas! I was crossing my fingers that we could push that 40' mark, thanks for the vote of confidence. I will be purchasing that book Allen, probably online HTML so we can start reading it right a way:::we almost have the floor done and we'll pour the walls next, and then the RMH, so the faster I know what i'm doing(relatively speaking) the better)
One question though Allen:::did you mean that the papercrete walls were not compatible with an RMH or that it didn't incorporate any papercrete in its constuction? I assume the latter but you never know:::thanks Allen!
 
allen lumley
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Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Nila Madhava : Within the Rocket burner we quickly reach temperatures that cause the breakdown of the lime in the cement used to make paper concrete,
and we need a much better insulation to place around or Combustion Core, and as he Papercrete is not very dense as compared to rock, it will nether
absorb, store or transfer few heat as well as straight Cob which is just builders sand and clay and you can think of as mortar !

No one likes damp floors, cob loves it and will soak up lots right through your Concrete floor if it(the Floor ) is not sealed well, the finessed concrete can get
a coat of water glass if it is too porous, other wise we will have to elevate Your Cob Thermal bench up of the floor!

The flip side of this is if this sealing step were completely ignored, AND we didn't put enough insulation under the RMHs combustion chamber we could easily
cause the water retaining concrete floor to spall off large chips under the Rocket !

Again, as long as the soil around and under your house is well drained and or/ Adequate Vapor Barriers are in place, this is a non problem ! BIG AL !
 
Nila Madhava
Posts: 7
Location: central texas
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Big Al, thank you for your reply about the papercrete:::so the floor is wood. We are laying down the treated rafters now, and then we're gonna put some osb particle board on top of that, followed by bamboo panels nailed to the plywood:::is that ok for the rocket stove to sit on or do we have to raise it off the wood floor? You mentioned vents too. Im sure the book has all this info, I'll get that tomorrow. Sorry for the confusion, just the walls will be papercrete.

My heartfelt thanks, Nila
 
allen lumley
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Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Nila MadHava : This is a bit of a workaround, I generally do not send people to U-Tube Land unless I can send them to a specific users channel as there is so much
stinking shit our there !

I don't know if you remember when people looked askance at you if you said you got information from Wikipedia, at one time it could get spoofed too damned easy.
wikipedia tightened up their act and the peer review process just about guarantees good info from Wikipedia !

Right now on You Tube there are thousands of videos of people doing Dumb stuff, rocket mass heaters Are one example. Someone builds a flaming franken-clone
and calls it a rocket stove, or A rocket mass heater, and we know it will hurt people, not only can't we stop this- we know '' as sure as the night follows the day'' that 4
months from now there will be a hundred more franken-clones -O.K. Rant over

Goto> You Tube, in the search field type in> Rocket Mass Heaters with that final 's' it will prompt you do you want >rockets mass heaters with ernie and erica

Clickon>rocket mass heaters with Ernie and Erica or continue to type in ''- - - with Ernie and Erica'' and click on the search field icon to take you to the next page !

At the new page you will see several short video clips by Village Videoclick on the by village video this will take you to a next page where there will be a
series of 19 short videos making up ~3/8ths~ of a 2hr video on exactly the type of Installation of a RMH on a wooden floor !

The Very first collection of videos is rocket mass heater scenes, find the pointer arrow on the right hand side and cause the videos to slide sideways until the
last thing says view all 19 items. Enjoy !

Still more information available at ernieanderica.info ( they are both moderators of the Rocket and Wood Stoves Forum/Threads here at Permies and personal friends !)

For 'The Book' Go for the PDF download, it will let you make all the copies you can use and you can have it in your hand in 1/2 an hour !! BIG AL !
 
Nila Madhava
Posts: 7
Location: central texas
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Big Al, oh man, thanks for all the good info!
Looks like I got some video watching to do, and some reading)
Stoked(pun intended) )
 
Posts: 1442
Location: Fennville MI
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Nila Madhava wrote:Big Al, thank you for your reply about the papercrete:::so the floor is wood. We are laying down the treated rafters now, and then we're gonna put some osb particle board on top of that, followed by bamboo panels nailed to the plywood:::is that ok for the rocket stove to sit on or do we have to raise it off the wood floor? You mentioned vents too. Im sure the book has all this info, I'll get that tomorrow. Sorry for the confusion, just the walls will be papercrete.

My heartfelt thanks, Nila



Nila, short answer - you will need to insulate the wood/bamboo floor under the rocket mass heater core. Temperatures in the burn tunnel can approach 3,000 F and if only a quarter of that gets to your floor, you're looking at possibly igniting the floor. Depending on how you build your core, it is possible to actually incorporate the insulation into the core build.

For example, if you made your core from a perlite clay mix, and the section beneath the burn tunnel floor was 6 inches thick, you would probably be ok. But if your core is just stacked firebrick and that firebrick were laying directly on your bamboo floor - that would probably be Bad.

As to a 40 foot run - from my understanding (and I have built only one very experimental RMH myself, so, take appropriate grain of salt) at a straight 40 feet you are right at the limit of the system.
 
Nila Madhava
Posts: 7
Location: central texas
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Peter:::thanks for the info on the insulation. Good stuff! Ya we don't wanna burn the house down so I think I'll be taking your advice for sure. Don't know yet what the core will be made of so we have time to figure that out. As to the length of the Flue Pipe, my only question is: How far down will it actually give of significant heat? Enough to heat the room on the far end of the 40'? By my understanding, the temps coming out of the exhaust end only run about 90 deg. so that makes me assume that the RMH will give off less heat down on the far side:::
 
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