• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies living kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • raven ranson
  • paul wheaton
  • Jocelyn Campbell
  • Julia Winter
stewards:
  • Burra Maluca
  • Devaka Cooray
  • Bill Erickson
garden masters:
  • Joylynn Hardesty
  • Bryant RedHawk
  • Mike Jay
gardeners:
  • Joseph Lofthouse
  • Dan Boone
  • Daron Williams

Horizontal Riser  RSS feed

 
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I am wondering if the riser (the insulated section where secondary burning occurs) can in fact be horizontal?

Since "downdraft" seems to apply to anything that doesnt go up, I assume this would be a downdraft design?

I want to have one long tube that consists of an insualted "burn box" followed by a "riser" where secondary air is inserted and finally a 90 deg turn up to "chimney" where the heat exchange occurs.

I have not seen any rocket stoves like this and I am wondering if there is a reason that they all turn 90deg into the "riser" whether it goes up, down or horizontally. Is there a reason other than everyone has vertical space available (I dont) ?
 
gardener
Posts: 2707
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
93
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
That's a discworld riser

I've been thinking about it, and theoreticaly, i think it could be done. But you're loosing the self drafting of the heat riser, and have to rely on the stack effect of the chimney to create the draft. Which we have to do anyway, if pushing long lenghts of tube. Mind you, i wouldn't use a vertical heat exchange in the chimney, but rather use bells. Vertical heat exchange in the chimney seems too unpredictable.
Filename: discworld-riser.skp
File size: 258 Kbytes
 
Posts: 37
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

mike Splendid wrote:I am wondering if the riser (the insulated section where secondary burning occurs) can in fact be horizontal?

NO! Riser is vertical. The reason for the riser is that you need something to power the movement of hot gasses through the system. Place your heat riser as early as possible and as high as possible in the system! This will cause a greater sucking action which will in turn suck the maximum air into the system which in turn will cause a more efficient burn and in turn push the exhaust gasses through the system to heat the mass and exit at the intended exit point.

Lets just imagine for a moment that you can do what you want to do...run the fire, heat, gasses horizontally as far as possible...for a good clean burn you will have incredible heat, heat that will eat up most materials including steel. Or you will need very expensive materials that can take the heat as well as an electric fan/motor pushing those hot gasses along.

The idea you are proposing is not one that would be very practical and would be prone to many engineering difficulties. Perhaps there is a way, but (if that way exists) that way would take a great deal of research and costly materials to achieve.

 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
.skp viewer
http://www.anycad.net/the-free-skp-file-viewer-skpviewer.html

I still cannot vie that file. Can you post a .jpg?

>but rather use bells.
wassat?


@Michael
I understand. I guess I am not clear why the riser is vertical? I assume because hot air rises and we want that to cause draw, but if that were true then what about the downdraft designs?

So if we can go donw whay cant we go horizontally and let the hot ir rising in the chimney section cause the draw in the system?


Added:

So to go a lkittle further into the logic here, I am heating a 5gal propane tank filled with water (that is slowly circulating under slight pressure from a sump pump)
I DO NOT want 5 gals of hot water perched atop a 5 ft riser. That meas building a large superstructure to hold it al and it ends up looking butt ugly and makes me nervous. I want the propane tank CofG LOW. Really I want it sitting at the end of a horizontal tunnel and for it to be the base of a chimney that encloses it.

The next part is that while I could cut and grind for week and whip out the MIG, I want to do this in a few hours with some fire bricks on the ground. Simple. Easy. Love it! So Really I want a long tunnel that is part firebox and part "riser". My idea is to run a number of smalled metal tubes into the "riser through the firebox to provide more air for the secondary burn. This will heat the air on the way through the firebox and its easy to lay some lengths of metal pipe at the base of the tunnel protruding out.

I am just not sure about the functioning of the "riser" portion of the tunnel.
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Well I had to just go and get SketchUp



I assume the deisgn has the fire box and the secondary combustion area next to each other to compact the footprint.

I dont see a reason this could not be one long horizontal section. It would certainly flow air better that way...
 
Posts: 52
1
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

mike Splendid wrote:.skp viewer
http://www.anycad.net/the-free-skp-file-viewer-skpviewer.html

I still cannot vie that file. Can you post a .jpg?

>but rather use bells.
wassat?


@Michael
I understand. I guess I am not clear why the riser is vertical? I assume because hot air rises and we want that to cause draw, but if that were true then what about the downdraft designs?

So if we can go donw whay cant we go horizontally and let the hot ir rising in the chimney section cause the draw in the system?


Added:

So to go a lkittle further into the logic here, I am heating a 5gal propane tank filled with water (that is slowly circulating under slight pressure from a sump pump)
I DO NOT want 5 gals of hot water perched atop a 5 ft riser. That meas building a large superstructure to hold it al and it ends up looking butt ugly and makes me nervous. I want the propane tank CofG LOW. Really I want it sitting at the end of a horizontal tunnel and for it to be the base of a chimney that encloses it.

The next part is that while I could cut and grind for week and whip out the MIG, I want to do this in a few hours with some fire bricks on the ground. Simple. Easy. Love it! So Really I want a long tunnel that is part firebox and part "riser". My idea is to run a number of smalled metal tubes into the "riser through the firebox to provide more air for the secondary burn. This will heat the air on the way through the firebox and its easy to lay some lengths of metal pipe at the base of the tunnel protruding out.

I am just not sure about the functioning of the "riser" portion of the tunnel.


What downdraft designs are you talking about? Rising heat is what powers a rocket stove, or any wood stove without a fan for combustion. Even long burn tunnels reduce draft, requiring a taller riser. Establishing draft with a long tunnel isn't easy.

Why do you think you need secondary air before you've done any testing? Excess air will just cool things off and require more 'makeup air' to be heated.

Extracting heat at the base of the chimney will also reduce draft. Extracting heat at the top of the heat riser helps the gasses flow downward.
 
Posts: 243
Location: near Houston, TX; zone 8b
1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
We tested a system where the exhaust went up into a steel drum and then it was supposed to go into a chamber under the burn tunnel. It didn't draft properly and we had to tear it down. It was a smoky mess.

If you want to understand about bells, we have an explanation at our blog site. Basically, bells are chambers where the exhaust has space and time to stratify by temperature. The hottest gasses remain at the top of the bell. The cooler ones sink out and flow into the next bell.

One of the things that makes this work really well is that ~80% of the exhaust is Nitrogen which was never involved in the combustion and, consequently, isn't as warm. It goes out faster and leaves the heated gases to conduct their heat to the inside surface of the bell.

Our bell-based designs draft really well and don't need a steel drum.

A bell is not the same design as a contraflow flue.
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
 
Posts: 2413
46
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Michael Skowronski wrote:The idea you are proposing is not one that would be very practical and would be prone to many engineering difficulties. Perhaps there is a way, but (if that way exists) that way would take a great deal of research and costly materials to achieve.



Hi Michael S., et al,

Perhaps I am misunderstanding your out look of Mike's question, yet must share that if you premise was completely accurate...the historical design, application and service of Hypocaust, Kangs, Ondol, etc would not exist and function as they did and do.

Mike, I haven't the time now to complete it, yet hope to post soon a dialogue on the traditional systems mentioned, how they work, and ways they may be incorporated into permaculture architectural designs. If you start some in depth study of these systems...it may give you some insight into what you are thinking about and trying to achieve within you perceived plan.

Regards,

j
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
This is the bell?

 
Satamax Antone
gardener
Posts: 2707
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
93
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

mike Splendid wrote:This is the bell?



To me a bell can be any type of container, where gases stratification can occur, and has low entry and exits.

This one is a double bell. Any type of bell can do.
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
OK. I here is my first (ever) Rogket design






The draw is mediocre as expected. I need a chiney. The heat is all dissapting to the fire bricks. I couldnt find vermiculite today. but the design works.

I think I need to shorten the secondar burn tube a lot and I need a MUCH bigger burn box.
I may wrap the bricks in fibreglass roof insulation tomorow. I hate that stuff but I dont know what else to use.

I need about 10x the energy out of this thing. Perhaps a 55gal drum as the burn box?
 
Cindy Mathieu
Posts: 243
Location: near Houston, TX; zone 8b
1
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

I may wrap the bricks in fibreglass roof insulation tomorow.


If your fire is the proper temperature, your fiberglass will melt.

Your design seems very far afield from the specifications in the rocket mass heaters, 3rd edition. Do you have the book?
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
IM trying to build this with a HORIZONTAL RISER out of bricks

 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hello Cindy. No I dont have the book yet. Does it dicuss horizontal risers and a design like mine?

Can you could tell me how it is "far a field"?
Are you talking about dimensions or insulation?

Insulation, perhaps I could use one of these
http://www.zircarceramics.com/pages/fullproducts.htm
or vemiculite
http://www.engineeringtoolbox.com/insulation-temperatures-d_922.html
or Rockwool
http://www.rockwool.co.uk/why+rockwool-c7-/fire+resistance#
or Pyrogel
http://www.thermaxxjackets.com/products/insulation-materials/pyrogel-xt/
Microtherm
http://www.microthermgroup.com/low/EXEN/site/hightemperature-insulation.aspx

The weight of the bricks needs to rest on the insulation in a horizonatal riser design - another problem to solve



Are these the dimensions you are referring to?



What material do you make these out of? I assume it reflects heat and insulates?
THese are nice cores. If I layed it on the ground so the riser was horizontal and added a chimney, would it still work as well?

What I do not want is a design dictated by the 3ft riser like this:



 
Cindy Mathieu
Posts: 243
Location: near Houston, TX; zone 8b
1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Mike,

The book does not cover horizontal risers. To me, the whole concept doesn't make sense; by definition, a riser should go up. I don't understand how the heater in the video you presented works. I don't know how well it tests out as far as efficiency. I don't see how the wood is loaded. Consequently, I can't help you imitate it.

Are you trying to heat living quarters or water?
 
Cindy Mathieu
Posts: 243
Location: near Houston, TX; zone 8b
1
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

If I layed it on the ground so the riser was horizontal and added a chimney, would it still work as well?


No, it wouldn't. The hot gases want to go up. Even the hypocaust designs mentioned earlier in this thread rely on the fire being below the floor.

The burn tunnel is cast refractory, the feed tube is steel and the heat riser is vermiculite board.

I think you are fighting physics with this horizontal riser idea.
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
>Are you trying to heat living quarters or water?

A Small pool.

Yes I take your point about fighting physics. Perhaps the way to do this is to go up and then come down in another vermiculite board tunnel before entering the heat exchanger i Have built. ie no 55gal drum. contain the neat on the way back down... so wait, does that mean I could use a riser that is half as high?
 
Satamax Antone
gardener
Posts: 2707
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
93
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Well mike, heating a pool necessitate a continuous heating. I would be dubious about heating one with a rocket type heater.

Most of the J tubes are chocking on embers after a while. More than 4 hours continuous burn, at the desired rate to heat your pool would be hard to attain.

Batch rockets are a bit better in that regard. But are temperamental. If you overload them, they belch smoke. And are a bit less efficient than J tubes.

I think your best bet would be on insulated mass heating the water.


 
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
59
books fungi hugelkultur solar wofati woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
mike Splendid : There have been a series of assumptions made and lots of divergent thoughts, but let me take a crack at this !

After it was discovered that really tall smokestacks sucked a lot of Air and Combustion gases and Particulates through themselves the benefits were totaled-up and
it was found that the temps at which the fuel burned went up, the air around the power plant /boiler became much clearer and cleaner! and in many cases by channeling
the required combustion air through the factory the workers air quality was improved too !

The biggest benefit was in escaping any punitive legislation or strict enforcement of anti-polution laws because these tall smokestacks carried their ''toxic gick'' off to
the next County, or State, or Country !

Our short little Heat Riser with internal gas temperatures around 1500+dF is the equivalent of that much cooler super tall Smokestack.

As the hot exhaust gases slam into the inside top of the barrel they churn and mix and finish burning off the last of the hydrocarbons and often the top of the barrel
will be hot enough to glow red-hot. As the heat energy is radiated off of the top and sides of the barrel the exhaust gases cool, become heavier and sink ! It is the
combination of the Rapidly rising hot exhaust gases and the cooler /denser gases failing down in the space between the outside of the heat riser and the inside of the
barrel that creates the push me-pull you magic that allows for the super efficient gasification and consumption of the wood AND the Ability of the rocket mass heater
RMH, to flow the cooling exhaust gases 30 - 50 ft' horizontally through the thermal mass to the final Vertical chimney !

You can now see that in your pictures you are cooling the exhaust gases prior to them getting to the the Heat Riser, and without the barrel over the top you actually
just have a stubby little chimney, In your last sketch with the water tank above the flame path you still only had a short, inadequate chimney, not a true Heat Riser !

Now is a good time to mention that as soon as you place a barrel over the heat riser you must put up a final vertical chimney, when the Barrel goes on, the Vertical
Chimney must go up !

This is where I recommend that you goto rocketstoves.com, to Download a PDF Copy(s) of the brand new 3rd Edition of Ianto Evans' " Rocket Mass Heaters "

With 100,000+ Rocket Mass Heaters RMHs made world wide, most were made following 'The Book' and 95% of all of the 1st time builds ( THAT WORKED!) were made
from 'The Book'.

After you have read the book, you can Be Sure that when you come back here you will be using the same simple terms to describe the size, shape, and orientation of
each part and their relationship to each other and the Whole Rocket ! For the Good of the Crafts !

Think like fire, Flow like a Gas, Don't be the marshmallow! As always your thoughts, comments and questions are solicited and welcome ! Big AL !
 
Bob Jackson
Posts: 52
1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

mike Splendid wrote:>Are you trying to heat living quarters or water?

A Small pool.

Yes I take your point about fighting physics. Perhaps the way to do this is to go up and then come down in another vermiculite board tunnel before entering the heat exchanger i Have built. ie no 55gal drum. contain the neat on the way back down... so wait, does that mean I could use a riser that is half as high?

What physics allows pushing the heat back down without penalty to (canceling out) the draw?

I'd build a rocket/barrel stove and heat the water on top of the barrel in an open container that could overflow into the pool. You don't have to use a big heavy container.
 
Jay C. White Cloud
Posts: 2413
46
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi mike Splendid, et al,

I got back to this today and "scanned" most of the feedback you have been getting with your questions...Satamax, Allan (another apple to you Brother...great break down of RMH-etc) and others are hitting on some key features now...THE FIGHTING OF PHYSICS...

Whenever a student or colleague brings one of the "new combustion" concepts for feedback...my first question is how much study of "similar" traditional systems has there been done...and...how much modeling of those (for comparison) has also taken place against the "new wheel."

I LOVE "creative thinking" and the folks behind them...as a teacher/facilitator...I get very frustrated with those that try to "reinvent wheels" with thoroughly examining, understanding, and building simple wheels first. This saves a great deal of time, and facilitates the..."possible improvement"...of an old concept. Seldom (ever?) does it come from just stumbling onto a thought and fussing with a..."I think it shall work...it should work to my understanding of it...I will make it work"...this just gets to be druggery.

I believe, at this point, there has been some wonderful info shared, some paths revealed to travel down. Perhaps on our part...(definitely me)...not a complete understanding of your goals. So, perhaps take what has been offered and build a working model to your specification next to "known working models" and compare...

Good Luck,

j
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Perhaps on our part...(definitely me)...not a complete understanding of your goals.


TO HEAT A SMALL POOL
I am heating a 5gal propane tank filled with water (that is slowly circulating under slight pressure from a sump pump)

So, perhaps take what has been offered and build a working model to your specification next to "known working models" and compare..


Thanks. As soon as I see design that would fit my situation Ill be all over it

yet hope to post soon a dialogue on the traditional systems mentioned


Very much look forward to it
 
mike Splendid
Posts: 11
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks for this:
http://donkey32.proboards.com/thread/1023/accidental-discovery



This implies a slight upward slope with draw. That is now my experience.
A few degrees off horizontal is required. My latest test worked quite well. Ill post pics soon.
 
allen lumley
pollinator
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
59
books fungi hugelkultur solar wofati woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
mike Splendid : I will never be surprised by any thing that Matt Walker brings to the table. Below is a vast over-simplification of Neolithic times, the Late Ice Age
period in Northern Europe, and early adaptation of the use of chimneys, any one wants to build on this probably ought to start a new Thread !

Let me try a little history of early North European houses and even the long houses of native Americans, notably the Iroquois Confederation, you can do a 'Google'
search for Iroquois Confederation long houses images. Both groups had a history of living in extended family groups in these structures with open hearths
only slightly better than 3-rock fires. There was no Chimney merely a hole in the roof

'Draw', or any attempt to channel the smoke remained a problem for centuries ! The invention of chimneys helped all North Europeans, and suddenly their Chiefs
and nobles didn't have to sleep in a common huddle with the Lackeys and Retainers !

Early attempts at both making and smelting Iron from crude ores soon improved with the first chimneys dedicated to improving the draft, or forced conduction of
air (oxygen) through repeating layers of crushed ore and wood charcoal, and eventually 'sea coal '!

As smelting operations grew in an effort to produce for the massive need for good iron products, and to get a few 'economies of scale' The size of these early
smelters and the size of their chimneys grew and draft was improved.

Common practice after loading in the repeating layers of crushed ore and charcoal was to light off a big bonfire in front of the chimney as an aid to getting the
temperatures they were looking for, This lower pre burn would have been contained in a large hearth and was an adaptation of domestic fireplace/chimney layouts
BUT- were often built with the same bent, or broken or angled riser !

It has been reported several times in the past that when a conventionally built rocket mass heater had the Barrel off-set from the Heat Riser, there was a cool side
and a hot side to the barrel, this allowed a level of increased protection for the buildings exposures and allowed for more of the heat radiated off of the barrel to be
directed towards the areas where the heat was most wanted !

Still with me ? O.K., Several people have reported builds where when the gap between the inside top of the barrel and the Heat Riser was Greater than three inches
( >3'' ) -there was a reversal of the cold and hot sides. To my knowledge this was a 'huh' type moment and not much else was done to evaluate or use this
discovery

So what we have here is a well insulated Heat Riser, abet at a sloping angle like the earliest ancestors of Iron/Steel Blast furnaces, and a barrel that has been
reconfigured to be a bell, and gives us a more useful cook top at a very useful height. Followed by ?other Bells? at the builders whim convenience !

This does open up several areas to explore for a safe location for your water heating tank, please do plan on an open system and proceed slowly. Once built, the
fire in your rocket mass heater RMH will not respond well to being dowsed with water, and caping off the top of the Feed Tube will not effectively lower the freakily
high temperatures that your combustion zone burns at ! Only by being able to force MORE water through your Coils/Tank will you be able to reduce the water
temperatures, and only this can ensure that you will never have a Boom-Squish Event when part of your system flashes to steam ! for the Good of the Craft !

Think like fire ! flow like a Gas ! Don't be the Marshmallow ! As always, Your questions and comments are welcome and solicited PYRO- Magically Big AL !
 
What are your superhero powers? Go ahead and try them on this tiny ad:
five days of natural building (wofati and cob) and rocket cooktop oct 8-12, 2018
https://permies.com/t/92034/permaculture-projects/days-natural-building-wofati-cob
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!