Rocket Stove w cast riser...

Hi Everybody

I've been lurking here for a while, reading many of your responses and tips.

Until now I have preferred a more portable arrangement for my first rocket stove, though I'm still not sure about the safety of such an idea, due to carbon monoxide (CO) concern.

Anywho, I drew up this design yesterday morning and played around with it a little bit today. My plan is to use vermiculate with refractory mortar at a 4:1 ratio on a 4" riser, 1" wall thickness, then possibly insulating the riser with a 1" kaowool (inswool) blanket, then sealing the outside of the blanket with another 1" wall again of 4:1 vermiculite & refractory. I'm curious if the kaowool (inswool) blanket is necessary, however; should I just go with a 3" wall of vermiculite & refractory?

What about the system here? 4" good? Should I go with a 6"? The barrel is 25"H x 17"W.

How about my graphics here? I believe these are pretty close to scale; I did them in Powerpoint. Please let me know your thoughts. Thanks all!

Regards

K.

Kevin Prata wrote:

What about the system here? 4" good? Should I go with a 6"? The barrel is 25"H x 17"W.

While 4inch has been used for a cooking rocket stove, 6inch seems to be the minimum for a rocket mass heater. Even with no mass and just a barrel people have had trouble with 4 inch systems running stable. My barrel was only 18inch diam. but a 6inch riser still fit ok.

Len Ovens wrote:

Kevin Prata wrote:

What about the system here? 4" good? Should I go with a 6"? The barrel is 25"H x 17"W.

While 4inch has been used for a cooking rocket stove, 6inch seems to be the minimum for a rocket mass heater. Even with no mass and just a barrel people have had trouble with 4 inch systems running stable. My barrel was only 18inch diam. but a 6inch riser still fit ok.

Ok thanks Len! I altered the document to reflect a 6" system. Hopefully I've got all the numbers right so far. Later!

More updated drawing. I considered a brick riser, but it doesn't work for my purposes, at least not right now. A cast riser will work.

I'm curious about adding two additional barrels on top of the usual barrel design, to work as stored heat radiators, similar to a masonry stove like a Finnish or Swedish Kakelugn.

The idea here is to have the first inner barrel sitting 2 or 3 inches above the riser, then have another barrel over that one forcing the radiant heat downward, then another barrel two or three inches above that one, with a gap at the bottom, radiating heat up to the top again, and finally a flue exiting out the top rather than the bottom.

Will this improve the overall design, or diminish it? See image here.

Kevin Prata wrote:I'm curious about adding two additional barrels on top of the usual barrel design, to work as stored heat radiators, similar to a masonry stove like a Finnish or Swedish Kakelugn.

The idea here is to have the first inner barrel sitting 2 or 3 inches above the riser, then have another barrel over that one forcing the radiant heat downward, then another barrel two or three inches above that one, with a gap at the bottom, radiating heat up to the top again, and finally a flue exiting out the top rather than the bottom.

Will this improve the overall design, or diminish it? See image here.

it might work., one thing i would be super careful about is to make sure that all of your barrels are big enough.

if any of the areas past your burn tunnel are smaller in overall space than your burn tunnel you wont get draft and the rmh wont work.

as long as you are sure that all of your areas are equal to or larger overall area than your burn tunnel you should get draft no matter what you do as long as you dont go over the total recommended length of an efficient RMH.

i dont have all the answers, im still in the process of building my first, but you should check into what i said and see what you can learn.

Kevin Prata : Adding barrels between the Heat Riser and the Outer barrel is definitely thinking 'outside the box', and that is Always a good thing, I always test
my reaction against my 'But we have always done it this way' alarm. And you have it going a mile a minute, but on reflection I do not see this working and
this is why !

After the hot exhaust gases leave the Insulated Heat Riser and slam into the underside of he Top of the barrel they start giving off heat, cooling, becoming
denser and falling vertically down to the 'manifold' which turns and channels the flow of gases into the horizontal chimney!

To promote the separation of the two streams, so they can both work- push-me, pull-you- we add insulation to support the two different temperature zones !
A second inner barrel would slow the radiation of heat out into the living space, without a wide differential in Temperatures between the two gas streams the
flow might reach equilibrium and stop ! Everywhere in your system the gases need to be hotter at the top and cooler at the bottom, the hot gases rise then
cool and sink!

Yes I understand that you are trying to duplicate the way a Masonry heater works, but in that case the stored heat in the bricks recharges the flowing gas
columns releasing heat to warm gases rising in one column, and removing and storing heat- cooling a second columns sinking gas flow, some people will also
recognize that this is the way The kidneys concentrate sodium before excreting it !

This would also add unnecessary work into regular maintenance, turning a simple barrel / Heat Riser inspection from a simple job to a complex one taking
most of the day ! Ether the Cob Thermal Bench, Or one or more "Bells" will provide the heat storage without the (To ME ) seeming unnecessary complication

In your sketch up you have No insulation under your burn tunnel, this will both slow down the speed at which the Burn tunnel comes up to working temperature
and potentially expose your floor to those temperatures, as this intentional on your part, ere you seeking to make the floor be part of your thermal mass, this
has been done, and irks for most people ! this is not often compatible with a concrete floor, the lime in portland type cement can not take the heat, and any
moisture that penetrates the floor will cause the concrete to chip and spall ! With the placement of insulation you ill have to think about the practicality of your
lifting pipes, They may be just fine, it just bares a second Thought For The Good of the Craft ! Big AL

Hi Allen, Troy

Thank you both for the responses. For now I will just keep it simple. Gotta start somewhere!

I am dealing here with a partner suspicious about anything remotely responsible or sustainable. Soooo, I need things to be conservative and as small as possible and still work....

Along those lines, can you suggest what might be a reasonable thickness of the core material surrounding the burn tunnel? I was planning on 4" on all sides of the tunnel, though I'd like to go with 3" if I can get away with it safely.

Thanks again all!

K.

Kevin Prata : Can we get a little more information from you ! A simple sketch-up of your house, and total square feet. Also what is your starting Idea of a general
location and the type of floor, whether on a slab or crawl space, 1/2 or full basement! As well as making sure to protect all your exposures,, the same as you would
do with any wood stove or space heater we have to design for the new load on your floor joists !

With a requirement to make it as small as possible, you may want to consider the Rocket Mass Heater RMH as a Room heater, rather than a whole house heater,
much more like the Traditional image of gathering around the Fire place ! RMHs work best when placed in the very heart of the home, regarded as a fine piece of
built in furniture, a Feast of hand crafted art to be passed down through the family from generation to generation!

Located in the central part of the home, tending it becomes automatic and unthinking, requiring a few seconds without disrupting the flow of daily life and habits as
Your family lounges on and around it ! Tending a Rocket Mass Heater should be like having a well endowed Bank Account, into which you put small timely deposits
of very dry wood chunks, and receive dividends in the form of Heat ! Warm, soft ,relaxing heat !

In childcare when we talk about toilet training we say that- first the parents get trained, then the child gets trained! :p With the RMH close at hand we quickly and
instinctively pick up on the clues that tell us when our Rocket needs attention! I promise smell should not be an issue, and the clean up issues are a lot smaller !

Any attempt to place it in a remote location out of ear shot and line of sight, will result in often failing to catch the right moment to 'tend to' our RMH, and having to
stop what you are doing and walking back and forth to tend that wood hungry monster , the farther away it is the more its needs get magnified and it becomes a
Drudges chore, and you start looking for excuses not to tend it ! Very much like the child needing potty-training a remote location for ether one just does not work.

The End result is Your RMH serves you no better than you serve it !

This is where I recommend that you goto> rocketstoves.com, to Download your PDF Copy $18.oo, of the brand new 3rd addition of Ianto Evans' Great Book
''Rocket Mass Heaters" !With over 100,000 RMHs built world wide, Most of them have been made following 'The Book' and 95% of all the 1st time builds
( that worked ) were made from 'The Book'

I promise you that this will save you time, money, and much frustration, as you quickly learn a new vocabulary to allow you to speak with all those builders and use
a common language and KNOW you are talking about the same part and its proper dimensions and orientations! And I don't make a nickel off of this .

To answer your last question, your Rocket Burner needs additional insulation around the bricks or cast core, so visualize the Burn Tunnel space surrounded by bricks,
insulation and enough layers of Cob, Structural Cob, and finishing coat to make its foot print larger than the 55 gal drum setting on top, and being rather pear shaped
as it narrows slightly towards the Feed tube ! I hope this helps and is timely. For the Good of the Craft !

Think like Fire, Flow like a Gas, Don't Be a Marshmallow ! As always your comments and Questions are solicited and are Welcome PYRO - Logically BIG AL !

Hi Allen

Thank you again for quick response!

I will attach a few pictures here of the house and the floorplan (approx. scale).

My neighbor had a copy of the book, but hasn't done anything with it!

I thought I might put the rocket stove (rocket mass stove, preferably) on the hearth next to the fireplace, if I can vent it out the fireplace like I saw Charles doing with his "Mini Rocket Mass Heater" on Proboards.com.

The house is two-story with a full basement, walk-out.

I have fire clay, refractory, perlite, vermiculite, and 1/4" fiberglass strand that I planned to use for the core and the riser, then set a barrel (either 15 gallon, 20 gallon, or 30 gallon) over the riser. Ideally it would be great if I could have the barrel low enough that it might tuck into the fireplace, though of course I prefer that it be outside the fireplace for the radiant heat.

My house is in a microclimate zone here on the side of a mountain in New York, about 35 minutes north of 42nd Street. We typically get a bit more snow than the surrounding area.

Best

K.

Here's the floorplan (approximate scale), the fireplace, and the rocket stove design....

A totally unrelated observation. If every house had great overhangs like this one, most issues relating to water getting into walls, window frames and basements would be eliminated.

When I read about the double barrel idea, my immediate thought was --- " That would turn off the pump". I think Allen covered it pretty well.

Kevin Prata : You have a very beautiful home ! there is one almost identical about three blocks from my house, on the banks of the Oswegatchie River, across
from the school I walked to everyday !

Someone had a passion for stone, they loved working with it, and sculpted the house and grounds with love and pride, we should try to do as well as they !

How thick are your basements exterior walls, You may be even more blessed than you are aware of ! We are also going to need the size of your joists, the
distance from joist center to joist center, and the longest length they span, I am expecting no surprises there but lets do due-dilligence! Pictures would help!

I looked very carefully, and I do not see a chimney in the two exterior pictures you included, It is possible that you may have multiple flues in you chimney,
have you used it, has it ever been inspected, the fastest way to get a handle on the structure would ordinarily clime up on the roof and count the number of
flues and flue sizes ! As long as every thing is in good condition I would hope for multiple flues rather than one large ox-cooker central flue !

I am going to ask if you have been to Ernie and Erica Wisners website, www.ernieanderica.info where they have a great deal of information on preparing
for your build, lining up materials and tools and parts, making sure that you don't have paid help standing around because you are 1/2 a yard of builders sand
short, and you haveto run somewhere to get it from Home Depot by the Bag,load it in a car and drive back to the work site !

They also have generic plans that you should look at while making plans of your own !

I need to do a little research and get back to you ! For the Good of the craft ! Big AL

Kevin Prata : I use my presence here at Permies.com, to Rail against the Crap in U-Tube land, be very cautious of Anything you see out there. Most
of it is Bad, Riddled with flaws or even down right Deadly, I call them Frankin-clones, Paul W. our host here calls them 'Flaming units of Death' !

I want to direct you to a series of short Videos, that covers the First 3/8ths of the building of a Rocket Mass Heater as a retro fit in a manner compatible
with the ideal build and highly desirable in a house like yours !

Please goto> www.villagevideo.org, from that page which has the village video logo with a hardwood tree at the top off the page I want you to clickon> the
You-Tube button, which will take you directly to the correct page to watch all 19 short video clips in one setting!

Near the top left of a stack of Village Video's videos there is a title that reads Rocket Mass Heater Scenes to its right there should be a flashing play button
for you to press, this should load all of the videos to play through in the correct order ! If you stop watchi ng,or get called away you may have to start at the
beginning ! (www.villagevideo.org )

You will see why I have sent you here, and you can decide for yourself if you want to purchase the whole video, to my knowledge it is in every way superior
in every way to anything else out there ! One of the sets of plans offered by E & E is for this build!

In the interest of full disclosure My wife and I assisted at a work shop hosted locally and taught by Ernie and Erica Wisner, and we consider them to be personal
friends ! Enjoy the video For the Crafts ! Big AL !

Kevin Prata wrote:I'm curious about adding two additional barrels on top of the usual barrel design, to work as stored heat radiators, similar to a masonry stove like a Finnish or Swedish Kakelugn.

The idea here is to have the first inner barrel sitting 2 or 3 inches above the riser, then have another barrel over that one forcing the radiant heat downward, then another barrel two or three inches above that one, with a gap at the bottom, radiating heat up to the top again, and finally a flue exiting out the top rather than the bottom.

Will this improve the overall design, or diminish it? See image here.

I am pretty sure that would "work" as you put it, in the sense that the flue would flow ok. However, I do not think it would gain anything. The reason the masonry heaters gain from the extra flow paths like that is because the walls are made of thick (compared to a barrel wall) high mass brick and all of that brick is collecting mass. In the case of barrels the barrel wall mass heats up quite quickly and is fully saturated in only a few minutes, after that it can only radiate to the room. Adding a second barrel only adds the mass of the barrel... 50 lbs? not much anyway. A masonry heater's bricks are measured in tons. A RMH cob bench is measured in tons for that matter. This is how I added mass directly to the barrel (the barrel is 18inch diameter from a water heater). The bricks are held against the barrel with wire threaded through the holes in the bricks. It uses metal riser and feed and so I expect the these parts will need to be replaced with much use, but it was mostly in the experiment range in any case so far. I think I spent around $25 for parts everything else was free from garbage. I think the metal parts will be replaced with ceramic flue parts next. But I will probably continue to use rock wool for insulation. The bricks around the outside of the barrel do not seem to detract from the rockets operation (this has always been the biggest question I get from RMH folk). I do use a sealed fuel feed and a horizontal air intake though I can't do anything the way everyone else does...

allen lumley wrote:
I looked very carefully, and I do not see a chimney in the two exterior pictures you included,

Looking very carefully at the front (summer) view of the house I do see a hint of "brick red" about where the floor plans indicate it should be. But you are right, not enough to tell anything. It looks like electric heat has been added in the form of baseboard heaters (from the floor plan) so it is unlikely there is more than one flue. However, the flue may be quite small for just the FP in a small house (small by todays standards). The normal (read contractor) solution is to run a SS liner up through. I think I might go metal plate with a hole... but I am no pro and have not tinkered with that type of a setup so a better opinion than should be queried.

Hi Allen, Len

The house was built in 1910 by a local businessman, Stephen Underhill, whose family owned the Croton Brick Works (something like that) and Croton winery before the brick works was torn down to make way for the New Croton Dam. The family went bankrupt by 1925 and moved to California.

I believe the house was built from Croton brick and stone from the dam building project.

Stephen Underhill's nephew visited a few years ago and gave us some pictures of the house shortly after it's construction, showing a large kitchen garden - almost 1/4 acre - and a large chicken coop behind the shed in the backyard. The shed is now converted into an insulated cabin; it has chestnut beams under the floor.

In the basement of the house is a barrel-vaulted root cellar / wine cellar, under the front porch, extending the width of the house, made of the red Croton? Brick.

In the basement, the ceiling joists are 14 inches apart, from the inside edge of one to the inside edge of the next. The joists are just under 2 inches wide. I believe they are made of chestnut (hard to say). Against the outer wall, in the basement ceiling under the fireplace, I see a brick barrel vault; however, I cannot tell if it is supporting the fireplace hearth as well, or just the firebox.

I can think of an ideal position for a good size thermal mass (see pictures) - but I'd get in trouble if I did that. Instead, the fireplace hearth, which you will see in a picture this afternoon, might be a better candidate, for now. I would estimate it at 6 feet long by 2 feet wide, in front of the fireplace; the fireplace opening is approximately 24 inches deep, 34 inches high, 30 inches wide. I will try to get more exact measurements today and hopefully get a few more pictures....

Chat later!

Hi Allen, Len, et al

The outside wall is made of solid stone, 14 inches depth under the fireplace, and 18 inches depth under the front wall the width of the house.

I got a fairly decent picture of the barrel vault under the fireplace/hearth?

See pictures.

Soooo... Whatever I said about the stone for the walls being from the New Croton Dam construction? Wrong!

It was locally sourced, from the backyard!

This is palisade stone.... Heavy!

That's a tulip tree next to the boulder. Twelve of the tulip trees here are over 125 feet tall. The neighbors had two of them in their front yard; those trees fell over during hurricane Sandy.

Little more detail -

The hearth is 71 inches wide by 23 inches deep.

The fireplace opening is 36 inches wide by 30 inches high, 34 inches high at the bottom of the capstone.

Either of these might be a good position as well, as far as the thermal mass, anyway. But still, I might be restricted to the hearth, as a practical matter.

The small room with the sofa and two desks is my office, in the corner between the kitchen and the living room.

The dining room is opposite / adjacent the living room, looking out westward from the living room sofa into the dining room and windows to the backyard.

Len - the design of the house is Classic American craftsman style. Crummy auto-correction keeps capitalizing my words!

This particular design is called "a story-and-half" (1-1/2), opposed to a 2-story, because the long roof lines and large roof area conceal much of the second floor.

Here are another couple of pictures showing the fireplace flue(s) and the chimney. What do you think of the top? Would that single wind cap suggest it is a single flue?

Kevin Prata : Again you have a very beautiful home, I am trying to flip back and forth between pictures to orient myself to the build ! *

I am afraid that Barrel vaulting is pretty much a lost art, I am completely over my head here ! I will post a note to have Jay C. White Cloud look in on your build,
I am sure he will find it fascinating ! You really need to have this area carefully checked by a Master Mason. I had hopes that we might be able to redo part of
the original fire place and hearth to give you a sneaky Rocket Mass heater and re-sculpt the other part to give you a Rumford style fire place!

Down in your basement a second barrel arch made of a massive Concrete pour may be the safest way to provide for protection of your hearth! I would hope it
will not come to that AND, I Will Not propose any changes that will materially change your houses character!

I do note the presence of gas lines, water, and drain lines and ? the appearance of a? Natural Gas furnace's? Horizontally discharging chimney next to the
Fieldstone chimney in the Northside Exterior picture ?

I need to find another Forum thread to go to so that you get an idea of what else is out there for quality work, it will also give out a chance to see someone who has
lived with her Rocket Mass Heater for 5 months at the time the video was made, and is happy ! Don't be a Marshmallow ! BIG AL !

Hi Allen

Yes we have a gas water heater and gas furnace in close proximity beneath the fireplace. Not the brightest arrangement, but that's where the water and gas lines come into the basement. Probably these days in new construction that would not pass code. I will get a picture of it in a few minutes and post here.

In the meantime, I have completed a simple drawing of the hearth and firebox with measurements. See picture below.

Also here is a picture of the oven in the kitchen. This is an Aga, a cast-iron heat-storage oven, nat. gas. The house had a similar oven in its original construction, fueled by coal. I'm curious if this stove could be converted to a rocket stove from nat. gas. Of course I won't be doing any messing around with it for now! But someday the conversion or replacement will become a necessity, given what I believe will be the exponentially rising cost of fuels.

In my former professional life, I studied securities and energy markets, for about fifteen years. By now I am pretty darn confident that between Q3 2014 and Q3 2015 we will begin to see lots of volatility in the energy markets especially, and overall energy prices will rise, probably at a geometric rate in the first few years, then turning toward exponential increases three to five years out. Hence my interest in rocket stoves and all things alternative energy!

Thanks again!

K.

Hi Allen, Len

Here is a picture of the water heater and furnace (pardon the junk!). The furnace feeds water (steam?) radiators upstairs. These are the original cast iron radiators; they weigh several hundred pounds each. Until about 1930 or so the house was fueled by coal, and the coal dump was in the back corner of the house beneath the dining room. The coal chute has been filled-in with concrete. Now we use use nat. gas.

Another option might be, rather than having the RMH in the house, to have it outside on the cabin terrace or on the deck. See pictures. Maybe I could build a short cob wall into and around the bench to concentrate the heat inward.

Regards

K.

Kevin Prata : This is Your Build, obviously your fellow members want this to be a success, and ten members will have 10 ideas of how best to do your build.

Pretty much I think that we follow the 'Do no harm rule'. Occasionally, one of our more skilled members will suggest something that they have the necessary
skill set to pull off, and without meaning to, they can sound very insistent that it is the best or only way, in this case we will have to deal with more than a few
trade offs !

Several thoughts right off the Top of my Head, where is the discharge for the Gas Hot Water Heater, the interior basement picture seems to show it venting out
through the lower part of the chimney base !?!

You presently have what I call an ''OX Roasting'' Fireplace! At the very least you should be able to Dry Stack firebrick to reshape It into a 'Rumford' style fireplace
( You probably never heard of him, he fought on the losing side in the Revolutionary War, and invented the Percolator/ Coffee Pot too!

I totally agree with your view of the likelihood of all Fossil Fuels jumping in price, at the present time all fuel prices are being artificially held in check by the glut
of new fuel supplies now available through Fracking, when the industry gets export terminals to allow them to ship LNG to Japan and Europe, our prices will go up!

I know that when obstacles block our path we try to fine easy ways around them, in this case you have considered moving Your Rocket Mass Heater RMH to a
remote location, see my earlier comments, this is a path that will probably only lead to frustration. If on the other hand you wanted to make a practice RMH for
your littleCabin, this would be a fantastic way to practice for Your whole house build down the road aways in time !

By now you may be starting to think I am a one trick pony, talk a good story and refer you to Ernie and Erica Wisner, in this case I wanted you to see a compact
8'' Rocket system made as a day bed and capable of heating a house similar in size to yours, up here in Extreme Northern New York by the Canadian Border. The
layout is unique to the location, and the wishes of the building owner - who basically got a RMH for hoisting the Rocket Workshop and the cost of materials ! Note
the stone work on the sides !

( Ernie and Erica Wisner live on the West Coast and I do not think that they will be East of the Mississippi this year)

At the left hand top of this page you will see the following >

permies>>forums>>rocket stoves ………….clicking on> rocket stoves will take you to the listing for all rocket stove Forum Threads,newest 1st,
Please find and click on video :great rocket mass heaters in upstate New York and Quebec it is the first video that I want you to see > Chelles - - -
while the stone used for this was mostly angular , your build certainly can weather in to look much like what you already have !

You have posted more material and pictures and I must sign off to see them and this is a good place to stop ! Big AL !

Hi Al

Correct, again! Both the water heater and the furnace are directly below the fireplace, and both of them vent out the wall beneath the fireplace, and of course directly beneath the fireplace ash dump. Like I said, not the best circumstances here!

Anywho, I am also considering the RMH in the cabin as a practice for a larger RMH in the house. Perhaps a 4" or 6" system would be easily sufficient in such a small space as the cabin. I believe the cabin is approximately 8 feet by 12 feet. I have attached a picture here.

On another note, regarding energy markets, I've been kicking around the approximate dates a little bit, waffling back and forth and in between the years 2014 and 2017, though my best guestimate remains early 2015 when we begin to see some pretty heavy dislocations in the markets.

These are some pictures from the house as it was in 1915.

The workbench is still there; the old guy was blind and used to build row boats in the basement.

That's the chicken coop behind the shed.

Correction --- Ernie and Erica live in the Okanagan Highlands a few miles from Canada, a long way from the coast . They get some real winter up there. Their former city of Portland Oregon has much milder weather and was not an ideal spot for testing heating technology.

Kevin Prata : TOTALLY of topic, but W.o.w. what a period piece place you have, There are site designers who would pay to walk through your house
and take pictures, It would also be a great on-location shoot for something like a remake of 'The Sting', Back in the days when doctors waiting rooms
always had copies of the 'New Yorker', i used to see ads for set designers looking for period pieces, it has probably been 15 years since I have
seen That Mag ! Big AL

Kevin, this thing begs to be retrofited with a batch rocket!



If only your hearth had enough ISA to be done properly. I'll try to have a looksee at the whole dimensions you've given.

That needs to be turned into a bell. Forget about ugly barrels!

Hi Satamax

I've been trying to figure out the batch box thing, following your "Adventures" thread with Peter and Donkey over at donkey32.proboards.com.

I wonder if the fireplace would have to be deconstructed to build the batch box design though.

Kevin Prata wrote:Hi Satamax

I've been trying to figure out the batch box thing, following your "Adventures" thread with Peter and Donkey over at donkey32.proboards.com.

I wonder if the fireplace would have to be deconstructed to build the batch box design though.

I also think you would get more out of brick work than a RMH because of the limited space. However, I would suggest against using the existing fireplace as a bell. The FP mass is coupled to the outside air. Cost is probably more important though. What are your resources though? What materials do you have? does the land have? Am I right that there are more rocks than clay?

Anyway, all that aside, back to the RMH deal. The first thing is that to keep it on the hearth would mean having it "sideways". That is the feed would have to be to one side.... Hmmm, What if you had two barrels one on either side with the feed in the centre. The feed in the centre feeds into the barrel on the right (because that side is closer to the centre of the house and so should be the hotter of the two). The exhaust of the right barrel (set up in standard RMH style) goes behind in front of the feed hole and into the left barrel. The riser for the left barrel only needs to be a 45degree bend to direct the gas flow somewhat upwards. The second barrel would act as a bell and the hot gas entering the left side would rise to the top and sit letting the barrel remove heat from the gas. The cooled gas would get pushed down by newly arriving warmer gas. an exhaust at the right rear of the left barrel would enter the FP through a heat shield and insulation before going up the flue. This would give a balanced look and for the space remove the most heat from the flue gas.

I would suggest 18inch barrels to leave room for mass on the outside. I, personally, would put mass on the outside of both barrels but not cob or anything monolithic that would likely crack. My favorite method is to use common brick with the holes and put wire through the holes to hold the brick against the barrel. Because they are not mortared there is nothing to crack. Your floor is beautiful, I wouldn't want to wreck it. (I have kids to wreck floors for me :/ ) Circle concrete slabs can be added till the top one feels not too warm.

A batch firebox in the centre could work too.... I can't really design one of those though. There are lots of plans around that would get the flue gas back to ground level where it could split and routed to both barrels at once.

You seem to have lots of rocks around I don't know if it is possible to wire them to the barrels or not. (by drilling holes through them)

I know my thoughts have sort of floated around from topic to topic and back. I have been writing and thinking at the same time. I have tried these or very similar ideas and had them work except where I start using words like "might" I would suggest building and testing outside (even just without the mass) to make sure everything flows.

Kevin Prata : Len Ovens raises a very good point about the fact that your vertical chimney is coupled to the outside and will always be a major source of heat loss.

I expect that insulating and boxing in your chimney to uncouple it from the out doors would easily pay for itself in just a few years with the expected efficiency of
your present boiler system !

I do think a batch box system is a much more difficult build for a first ever build, but longer burn times and the potential for a window that would allow you to look
at the fire is a big plus, however splitting your hot exhaust stream in two, and running it to two separate barrels is so tricky I know of no one who can testify to
seeing a split system working! I have raised this challenge here in these Threads at Permies before! Combining them would make diagnosing any future problems
very difficult indeed ! For the Good of the Craft ! Big AL !

allen lumley wrote:
I do think a batch box system is a much more difficult build for a first ever build, but longer burn times and the potential for a window that would allow you to look
at the fire is a big plus, however splitting your hot exhaust stream in to and running it to two separate barrels is so tricky I know of no one who can testify to seeing
a split system working! I have raised this challenge here in these Threads at Permies before! Combining them would make diagnosing any future problems very
difficult indeed ! For the Good of the Craft ! Big AL !

Running into two barrels from a firebox would work... would they get the same amount of flue gas? ... probably not, it would be best the favour the right side though as it can see more of the room and so loose more heat to it. In that case they would both be acting as bells and not part of the burn process. I would agree about the difficulty of a firebox build. But there is always a back yard to try things in Looking at the MHA Wildacres photo reports and seeing things built in a week and torn down again is very inspiring. The main thing though is if there is room for the firebox and a skin outside of it. Even in the single skin builds I have seen the firebox seems to sit inside another skin. So with 23inch width there is 14inch of wall? and only 9inch left for firebox. (assuming we want the firebox door to face the same direction as the FP does now... and I would, I think, looks are important)

Using the J-tube rocket however would mean using the two barrels in series, one after the other, the first as part of the rocket and the second as a tradition bell.

The main reason I suggest two... is for looks The closer the two can look one to the other the better. Having it look reasonable style wise would be even better. Keeping the whole foot print on the hearth makes removal so the house can be used for a movie a possibility. It also skirts around the whole building on top of wood thing.

Just my 2 cents on the batch box. I have built and test several variations of the box and heat capture bells, barrels etc. We wanted to offer the casting for sale at Dragon Heaters. But alas after LOTS of time and money down this rabbit hole here are my thoughts.

1) They are not only more tricky to build and cast they are particularly more tricky for heat capture. Just ask Matt Walker. We both had lots of hair pulling with units that would run fine under one circumstance and then just crash and turn into a dog when the configuration was changed in a seemingly harmless way . The technology has promise and appeal and it will be there in the future, but in my experience, the design is not the stable work horse a rocket heater is. So we have tabled it for the moment. There are designs that work with this firebox, but many that also do not work well. The heat capture design is critical.

2) The fire is designed to burn from the "back" towards the glass door. The result is your looking at your pile of wood, seeing little flickers of light from the back for quite some time. You look and wonder, has my fire gone out... no there it is. Then at long last the fire comes forward enough you see a fire for a short period of time and then coals, and lots more ash than from the same wood burned in a rocket J-Tube.

3) Both the horizontal feed and the J-Tube have to be reloaded at the same interval. So the main advantage lies in its larger capacity and the ability to accept larger wood. It will burn about 30% more fuel per load.

I do agree, with satamax, nix the barrels.

Kevin Prata wrote:
Also here is a picture of the oven in the kitchen. This is an Aga, a cast-iron heat-storage oven, nat. gas. The house had a similar oven in its original construction, fueled by coal. I'm curious if this stove could be converted to a rocket stove from nat. gas. Of course I won't be doing any messing around with it for now!

I have looked at the drawings of an Aga before with the thought of making work with a rocket. But I think it was a bigger model and may have been the coal model. I think the whole left side was a burner of some sort. The flue gas went up and across the bottom of the top plate and then down past the oven and warmer and then back to the flue. A rocket burner would have worked as a replacement in that model but I don't know about the one you have. You need about 14inch of space for the rocket burner... and the patience to keep it fed

Check this out. And some of the other "how tos" on that site.

Kevin Prata wrote:Hi Satamax

I've been trying to figure out the batch box thing, following your "Adventures" thread with Peter and Donkey over at donkey32.proboards.com.

I wonder if the fireplace would have to be deconstructed to build the batch box design though.

I wouldn't deconstruct, you have a lovely mass already there, also, Len and Allen have good points.

What i would do, (i have been thinking a lot about batch boxes and fireplaces)

Make a new front for the fireplace. I would pipe the inside of the chimney with a plunger tube going nearly to the ground, leaving a suficient gap. Which would make the chimney and actual firebox act as a bell. Most certainly, i would use insulated tube or insulate it at least in the straight portion on top of the chimney. I would make the tube go to one side, so the heat riser can be fited in the middle of your actual firebox. Then make a wall of firebricks on the hearth at the front of the batch box. So they're flush. Make two walls of firebrick on the sides, reaching the stoneson each side of the fireplace. And either fit a thick metal plate on top, or firebrick pavers. May be you would need a ledge on the front of the actual fireplace to hold them. You could also do this covered with stones, to retain the original look. But, if you don't want to go with a batch rocket, all of this could be done with a J tube.

Satamax Antone : I for one am having problems following what you want to do here, can you show us some simple plans here in this Forum Thread ?!!

I am afraid that I missed the whole plunger tube thing and will need to play catch-up ! Thanks Big AL !

Hi Everybody

First, thank you everybody for being engaged in the discussion, call-outs to Sandy, Al, Len, Satamax, and Matt Walker as well, since I've been following his discussions and videos for a while.

The bell idea I had not considered. Until now I had thought only about a more traditional rocket stove design, with or without the mass. The bell might address the lack of space for a thermal mass.

I don't know about the local availability of clay. I presume there is a lot of it around here even within the property (5 acres), in addition to millions of tons of stone and probably also several hundred cords of wood (see pictures). Nearby is the Hudson River; would the river beaches be a good source of clay? I wonder if they might be too much laced with PCBs.... Most of the PCB cleanup on the river is done, though I still see the barges out on the river occasionally.

The idea of a still visible flame in or around the fireplace has me captivated, maybe like something Matt did on his outside RMH. I'm trying to get my head around it. However, given the CURRENT layout of the living room, it looks like the taller barrel would have to be on the left side. Of course I'm not saying we couldn't change the layout, but the whole thing will encounter much suspicion from one here who is loath to accept new ideas, has little vision for the future that the rest of us see, I believe, with eyes wide open.

I will play around with a drawing this morning and post it here.