Forums:

Masonry stove diy build: feasible?

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 9 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Hi there; after much deliberation, research, and indeed soul searching, my husband and I have decided we just can't do a rmh in our house. At least, not this house. Believe me, we really wanted to do one, and even got so far as to make a trial rocket outside on our patio. Part of our issue was the look of the barrel, and part of it was the difficulty in placing the rmh; we have a small, two storey brick semi-detached house (that is, it shares a wall with the house next door) and the only place we could feasibly put a rmh would have had to exhaust up our existing fireplace chimney; and we were not confident that it would be able to draw up the full two stories plus attic.

Anyway, we're now looking at a masonry stove in the existing fireplace, but are wondering if this kind of build is doable for complete and utter amateurs. We've done a little research (and are still in the research phase) and are looking seriously at the design in the following pdf: http://www.dnr.mo.gov/pubs/pub781.pdf called the Missouri Designed Masonry Stove, which is made of firebrick and common brick. The proposed idea is that we build the stove onto the existing concrete hearth (possibly extending the hearth to accomodate), and either build into the fireplace/chimney, or partially demolish and then rebuild into the existing fireplace (I'm a little skeptical about this second possibility). Either way, we would use the existing chimney.

We have no bricklaying experience. We have no real building experience either, other than some basic carpentry--certainly no experience in demolition. We understand the basic principles for the masonry stove, but we've never used one or even seen one in use. I would appreciate any feedback; is this sort of build doable for amateurs? We are not planning on a huge stove; probably no taller than about 4 or 5 feet and 3 feet deep--though I haven't actually measured the existing space just yet. Will we be able to use a stove like this with our existing chimney? Is partially demolishing the existing fireplace even possible, or does that sort of work need a professional (will the chimney come crashing down on us and our neighbors)? Does this sort of stove have a margin for error or do we have to be extremely precise in our build?

I appreciate any thoughts!

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

allen lumley

pollinator

Posts: 4154

Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''

I like...

posted 9 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Galadriel Freden : You have hit the nail square on the head! The Rocket Mass Heater RMH works best when the House is built around it! NOT when the RMH
is shoehorned into an existing location just because a chimney is close!

To answer your last question, With even a small change in design the places that require room for expansion change in scope(size) and location It is difficult
to see how you can make a negative decision where failure may cost you say 200 pounds max, to then favor a decision in favor of a build that will easily
cost several multiples of that figure !

Seriously you need to take a little more time to consider your options !

For the good of the Crafts Big AL

Success has a Thousand Fathers , Failure is an Orphan

LOOK AT THE " SIMILAR THREADS " BELOW !

Joe Braxton

Posts: 320

Location: NC (northern piedmont)

posted 9 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

I'm far from an expert, but I believe if a stove of this design will draft using your existing chimney, then a masonry bell rocket should do as well or better. It's really all down to the inside surface area, how much heat is absorbed by the masonry, and the exhaust temp. Do a lot of research, ask questions of the proper folks and you will do fine.

Mike Cantrell

Posts: 567

Location: Mid-Michigan

I like...

posted 9 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Hi Galadriel,

I think the key to your conundrum is this:

You need to know that the firebox and the mass are independent.

By that, I mean you can mix-and-match them.

What you're calling "RMH" is a firebox and a mass: the firebox is a J-tube rocket, and the mass is a cob bench.

What you're calling a "masonry stove" is also a firebox and a mass. The firebox is just a chamber, and the mass is the set of brick flues.

Could you attach a J-tube rocket to a set of brick flues? Yes. Could you build that same combustion chamber attached to a cob bench? Yes indeed.

And other options to mix in there are batch box rockets, and masonry bells. Any of the three fireboxes is completely compatible with any of the the masses.

So it sounds like you're ruling out a Wisner-style, by-the-book Rocket Mass Heater because of space constraints. No problem; I personally am too. But that doesn't mean you have to rule out a J-tube firebox! They're independent, and you can have one without the other.

For me, the ideal build, and I'm jumping through some hoops this winter so I can build this this summer, is a batch box rocket with a masonry bell.

(The difference between a batch rocket and a J-tube is the speed at which the heat comes out- they're about equally efficient, but the batch box dumps it all out at once, and the J-tube spreads it out over time.)

And the advantage of a bell or bells over some flues is that the bell isn't so picky about closing the damper when you're done burning (to keep the warm chimney from drafting your warm room air out), and that it's an awful lot easier to build, insofar as it's just a hollow box.
There a whole bunch of layer-by-layer drawings of bell-type brick stoves here:
http://www.stove.ru/index.php?lng=1&rs=201

And a set of articles about the principles of how and why bells work. You'd need to adapt them to put in a rocket firebox vs. the plain firebox that 's included.

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 9 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

allen lumley wrote:
Seriously you need to take a little more time to consider your options !

For the good of the Crafts Big AL

Al, you are right, we are still just researching at this point. We don't want to commit ourselves to a project we can't afford/can't make work.

Mike Cantrell wrote:

And the advantage of a bell or bells over some flues is that the bell isn't so picky about closing the damper when you're done burning (to keep the warm chimney from drafting your warm room air out), and that it's an awful lot easier to build, insofar as it's just a hollow box.
There a whole bunch of layer-by-layer drawings of bell-type brick stoves here:
http://www.stove.ru/index.php?lng=1&rs=201

Mike, thanks for your input. If what you say about the mass and the firebox is correct, that certainly gives us a few more options for our space! I have read very little about masonry bells, and don't think I quite understand the concept. Is it something like the barrel in the rmh, but made of masonry/brick?

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

Mike Cantrell

Posts: 567

Location: Mid-Michigan

I like...

posted 9 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Not exactly.

Here's the specific article with the explanation. The metaphor of the lake in the mountain was what made it clear for me; YMMV.

(Click through for the illustrations. )

http://stove.ru/index.php?lng=1&rs=16

In order to better understand the essence and the advantages of the System of “free gas movement” Kuznetsov presentation let’s view the following. Let’s imagine a river flowing into a mountain lake and running out of it forming a waterfall (fig. C1). The water fills the whole lake’s cavity (up to the lip of the waterfall) irrespective of the cavity form. Everybody knows that water on the surface of the lake is warmer than the water in the depth of the lake and therefore the upper layer of warm water is running out into the waterfall. Cold water remains in the lake. The whole process of water movement described in this case does not require any external energy and runs due to natural power. Therefore this process is natural, optimal and expedient. If we create a vertical partition, which doesn’t reach the bottom, as it is shown in Fig. C5, the system will work due to natural power (according to the law of connective vessels), but a certain amount of cold water will start running into the waterfall from the cavity bottom too.

As is known, air is heavier than the hot gases, the latter fill in any cavity turned upside down completely. If we turn the fig. C1 by 180 degrees and fill in the lake cavity with hot gases instead of water, we will get a solution shown on fig. C2. Let’s call it a “bell”. The movement of the gas flow in this case (similar to movement of the water in the previous example) takes place due to natural power without any external energy applied. Moving gas flow carries heat energy and products of combustion in stoves of any convective system (“convective” means “based on principle of convection”). Let’s take a closer look at these two components of gas flow. Let’s look, due to what the gas movement takes place and what are the features of the system? Let the electric heating element 1 be a heating source. With an electric heating element there is no need to remove products of combustion, and channel 2 on top can be closed. In this case, the hot gases’ movement in the bell takes place due to the gravity force without external energy of the chimney’s draft. The hottest gases come to the very top of the bell, the coldest ones, being the heaviest, accumulate at the bottom of the bell and run into channel 2.

allen lumley

pollinator

Posts: 4154

Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''

I like...

posted 9 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Mike Cantrell wrote:Hi Galadriel,

What you're calling "RMH" is a firebox and a mass: the firebox is a J-tube rocket, and the mass is a cob bench.

So it sounds like you're ruling out a Wisner-style, by-the-book Rocket Mass Heater because of space constraints. No problem; I personally am too.
But that doesn't mean you have to rule out a J-tube firebox! They're independent, and you can have one without the other.

For me, the ideal build, and I'm jumping through some hoops this winter so I can build this this summer, is a batch box rocket with a masonry bell.
[quote/]

Mike Cantrell : I agree with wait you are saying, or at least its spirit, its the physics of the two builds that make the 'letter of the law'' so Important.

A Masonry stove has three components , a fire box, and a carefully arranged series of passages designed to extract the maximum amount of
heat energy.

Because of its build there are many different points within the mass that are at different temperatures from each other, for that reason the CORE
of the Masonry Stove is not one monolithic construction! This Core is actually into separate zones that ARE Not mortared, glued, cemented or attached
to each other the separate masses expand at different rates and in some builds these Expansion gaps are finger width !

The craftsmanship that go into this part of the build is such that many of the Masonry stoves put in homes today contain cores NOT Built locally, but
are imported items and cost tens of thousands of Dollars / Pounds /Euros

The Masonry stove has an exterior Shell that contains these gases and as that Shell is of a more uniform temperature with changes occurring much
more gradually this Shell CAN be of a Monolithic single unit construction !

The Ianto Evans' RMH copied by his disciples and others now exceed 100,000 Units !

It is unimportant to this discussion if the Heat Riser is called part of the fire box, or as a single unit of a separate 'masonry stove type core '.

The point is If properly made it is of monolithic construction with NO Breaks or gaps to allow different parts to expand at different rates, This simplifies
construction, The Metal barrel then finishes making up all of those other Smoke passages in one single piece with no need for any breaks or gaps
due to uneven expansion and contraction - you could easily say it serves as the outer shell while replacing most of the Masonry Core!

It does this in a manner that greatly reduces the Time and skill sets necessary for this part of the construction, reducing its cost to hundreds of $s
And virtually eliminates future maintenance issues and Costs of Masonry Core or Shell !

You mentioned the use of a damper while discussing bells, this is something i have never heard of as Dampers are unnecessary with a J-Bend style RMH,
Have you heard of others recommending this practice - I may easily have missed something as I am only at the research stage of adapting Bells !

Late Note : I really liked you analogy of the river/lake ! A.L.

Success has a Thousand Fathers , Failure is an Orphan

LOOK AT THE " SIMILAR THREADS " BELOW !

Mike Cantrell

Posts: 567

Location: Mid-Michigan

I like...

posted 9 years ago

6
Number of slices to send:

Optional 'thank-you' note:

Send

Al,
I'm not positive that I follow what you're saying below.
(I'll answer the easy question about dampers last.)

If I've got you right, you're saying a Wisner-type RMH is easier and cheaper to build than a masonry stove. I'm going to disagree.

It's certainly true that people spend $10k and up on masonry stoves. I'll concede that, no problem. But that's all for the looks. It's not related to the function of the masonry stove, only the appearance and the construction style.
It takes a skilled mason to lay brick and firebrick level and accurately, and to design the complex flues. And skilled masons cost big bucks (ok, large quantities of brick and firebrick, purchased new, they cost big bucks too!). But just because it's often done that way, that doesn't mean that's part of what a masonry heater is.
A masonry heater is a firebox and a set of flues. The firebox doesn't have to be spendy. It's exactly equivalent in skill and material to a J-tube rocket, and exactly equivalent in material to a batch-box rocket (easier in skill). If you want them built of firebrick by an experienced mason, the firebox of a masonry heater is going to be no more or less expensive than a J-tube rocket. And if you build them0 yourself out of two sacks of castable refractory, then the firebox of a masonry heater, again, will be no more or less expensive than a J-tube rocket. People typically pay through the nose for one and not the other, but that's coincidence, and not inherent in the design.

And it's precisely the same with the mass. A masonry stove has a set of flues, usually in the shape of a ceiling-high box. A Wisner-type RMH has a set of flues, usually in the shape of a bench. What's the difference? Nothing but the shape. You could have volunteers lay used ductwork in a ceiling-high rectangle of cob, and it would be very inexpensive. Or do it yourself with homemade adobes. Or you could hire a professional mason to build flues in brick in the shape of a bench. Very spendy. As above, people's habits are to spend five figures on masonry heaters, and to scrounge for Wisner-type RMHs, but that's not inherent. [u]That's just habit. They would cost the same if you built them the same way.

So where I was going in my last post was, you know what's much easier for a DIYer (or a professional) than a ceiling-high rectangle with flues going through it? A ceiling-high rectangle that's hollow! It's easier, and it's arguably better-performing. So that's my personal plan. A bell-style masonry heater, rather than a flue-style.

Here's what I meant by the three fireboxes and the three masses being interchangeable. I can't say that all nine combinations of these have been built:

Ok, dampers: It may have sounded like I was saying you need a damper on a J-tube rocket with a cob bench. Not what I meant. Rather, traditional masonry stoves (with a firebox and flues) include a damper. The warm stove wants to draft even after the fire is out, and at the point, having warm air go up your chimney is counterproductive. The only reason for warm air to go out is to carry combustion exhaust. No combustion, no air movement needed. So they include a damper that you shut to make the air stay put.
By contrast, a bell design, since only the coolest air in the bell is leaving out of the exhaust at any given moment, it's not so critical. It's still better to block it off and keep your room air inside, but even if room air is entering the bell, then whatever is coolest is exiting. Your warmest air is still hovering at the top of the bell, not escaping until it sheds its heat to the mass, whether dampers are open or not. So that's a small advantage of bell-style masses over flue-style masses.

allen lumley wrote:

Mike Cantrell wrote:Hi Galadriel,
What you're calling "RMH" is a firebox and a mass: the firebox is a J-tube rocket, and the mass is a cob bench.
So it sounds like you're ruling out a Wisner-style, by-the-book Rocket Mass Heater because of space constraints. No problem; I personally am too.
But that doesn't mean you have to rule out a J-tube firebox! They're independent, and you can have one without the other.
For me, the ideal build, and I'm jumping through some hoops this winter so I can build this this summer, is a batch box rocket with a masonry bell.

Mike Cantrell : I agree with wait you are saying, or at least its spirit, its the physics of the two builds that make the 'letter of the law'' so Important.

A Masonry stove has three components , a fire box, and a carefully arranged series of passages designed to extract the maximum amount of
heat energy.

Because of its build there are many different points within the mass that are at different temperatures from each other, for that reason the CORE
of the Masonry Stove is not one monolithic construction! This Core is actually into separate zones that ARE Not mortared, glued, cemented or attached
to each other the separate masses expand at different rates and in some builds these Expansion gaps are finger width !

The craftsmanship that go into this part of the build is such that many of the Masonry stoves put in homes today contain cores NOT Built locally, but
are imported items and cost tens of thousands of Dollars / Pounds /Euros

The Masonry stove has an exterior Shell that contains these gases and as that Shell is of a more uniform temperature with changes occurring much
more gradually this Shell CAN be of a Monolithic single unit construction !

The Ianto Evans' RMH copied by his disciples and others now exceed 100,000 Units !

It is unimportant to this discussion if the Heat Riser is called part of the fire box, or as a single unit of a separate 'masonry stove type core '.

The point is If properly made it is of monolithic construction with NO Breaks or gaps to allow different parts to expand at different rates, This simplifies
construction, The Metal barrel then finishes making up all of those other Smoke passages in one single piece with no need for any breaks or gaps
due to uneven expansion and contraction - you could easily say it serves as the outer shell while replacing most of the Masonry Core!

It does this in a manner that greatly reduces the Time and skill sets necessary for this part of the construction, reducing its cost to hundreds of $s
And virtually eliminates future maintenance issues and Costs of Masonry Core or Shell !

You mentioned the use of a damper while discussing bells, this is something i have never heard of as Dampers are unnecessary with a J-Bend style RMH,
Have you heard of others recommending this practice - I may easily have missed something as I am only at the research stage of adapting Bells !

Late Note : I really liked you analogy of the river/lake ! A.L.

Also, thank you for the compliment on the lake analogy, but that's Kusnetsov's writing, not mine.

Glenn Herbert

Rocket Scientist

Posts: 4526

Location: Upstate NY, zone 5

574

posted 9 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Very well put, Mike! I think that's the first time I've seen the whole comparison argument in one place.

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 9 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Thank you Mike, for this well-articulated explanation. I understand your point much better and shall do some more research.

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

allen lumley

pollinator

Posts: 4154

Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''

I like...

posted 9 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Mike Cantrell : My whole point is that The outside shell of a Masonry Heater IS NOT There just for show ! Without that outside shell you do not have
an air tight Unit !

The masonry core is made up of different sections with different expansion rates, for this reason they must include Breaks and Gaps in the build to accommodate
the different expansion and contraction rates !

In no way or manner am I running down a master mason when I say that most of them will use an imported core and just build a shell around it ! With the use
of one of these cores and just on time shipping he can keep a full crew working and complete many Masonry units a year

Other Masons will have 2 or 3 designs to replicate for building their own core - and due to the need for precise placement of the breaks and gaps stick closely
to the design as there is potentially NO room for deviation !

Master Masons who build Masonry Heaters take yearly workshops to learn of new designs, mostly replacing old with new and sticking to their core of 2-3 working
designs for their cores ! Again very little deviation is allowed for differences in individual builds

Simple Masonry cores are multiples of 10s of thousands of dollars, then Your Mason finishes the build !

It is my opinion that the skills required for building a Rocket Mass Heater and a Masonry Heater are worlds apart, one needs little experience and can be picked
up with the build and the other requires an actual amount of time as a journeyman.

Materials, the use of the Barrel and ductwork creates building forms and jigs that allow quick and accurate lay-up, and the materials used allow for much easier
modification to the build as we go along !

Clay and Sand can literally come from the ground under your feet, Little modification of these materials are necessary. It took me a long time to develop a basic
technique for splitting brick and my rate of wastage is much to high to call my rudimentary efforts a marketable skill.

I aspire to someday make a Working Batch box modification, and I expect that to be as far as I will need to evolve my skill sets, I consider the batch box a step
up in skill level !

Good luck with your future build, please do share your build with us as it progresses ! For the Good of the Craft !
Big AL

Success has a Thousand Fathers , Failure is an Orphan

LOOK AT THE " SIMILAR THREADS " BELOW !

Mike Cantrell

Posts: 567

Location: Mid-Michigan

I like...

posted 9 years ago

3
Number of slices to send:

Optional 'thank-you' note:

Send

allen lumley wrote:Mike Cantrell : My whole point is that The outside shell of a Masonry Heater IS NOT There just for show ! Without that outside shell you do not have an air tight Unit !

Ah, I see!
Ok, still.... yes, but no.
To have the outer shell built by a pro mason, out of new brick, expensive.
To have the outer shell built by a homeowner, out of homemade adobes, free.
Choosing the former route, is a choice people make only for looks, not for function. Anybody who's handy enough to build a Wisner RMH is handy enough to build the outside shell of a masonry heater! It's just a box!

Building code requires masonry heaters to be double-skinned so that even if the inside skin cracks, the outside one won't, and it will remain airtight, and no exhaust gasses escape. A careful DIYer can absolutely achieve that. It's just a box!

allen lumley wrote:Simple Masonry cores are multiples of 10s of thousands of dollars, then Your Mason finishes the build !

No, no, the WHOLE project is often over $10,000, but the CORE isn't.

Here's the AlbieCore, at $1,900, which includes tons of extras- your steel doors, screws, seven sacks of cement, rope gaskets, even the saw blades. The works.
https://mainewoodheat.com/masonry-heaters/the-albiecore/

TempCast only sells through dealers, but their website says:
The cost of a complete Temp-Cast core kit, not including chimney and facing, will generally fall in the range of $4000 to $5000 - contact us for current prices and shipping costs for Temp-Cast core kits.
http://www.tempcast.com/pricing.html

MasonryHeater.com offers seven different cores, from $3,900 to $6,900. They include mortar and gaskets, but not doors or tools.
http://masonryheater.com/MasonryHeaters.html

And the important thing about these cores is that they're both the firebox and the flues. They're both the combustion chamber and the mass. What's missing is the finished surface (stone, brick, etc) and the accessories (doors, handles, etc, although the AlbieCore does include the doors). So I hope it's not confusing for readers. Above, I was talking about how the different types of fireboxes are interchangeable into your different types of mass, but now we're lumping them together. These masonry stove cores are both the firebox and the mass. You buy them together, assemble them together, and then put a custom skin on them on-site.

Allen Lumley wrote:It is my opinion that the skills required for building a Rocket Mass Heater and a Masonry Heater are worlds apart, one needs little experience and can be picked
up with the build and the other requires an actual amount of time as a journeyman.

Kind of, but only kind of.

The skill to build one of these (By Gimme Shelter:

Versus one of these (By Jon Alejandro, who's an awesome inspiration):

Yes, that's worlds apart.

But I'm saying that if you pay a pro mason to build a Wisner RMH out of brand new brick and stone instead of used ducts and cob, it ain't gonna be cheaper.
And if you want a masonry heater that looks humble, and you're not afraid to get dirty, it ain't gonna cost ten grand.

The difference isn't in the nature of the device, it's in how you choose to build it.

I mean humble like this one, built with cob and some firebrick:

Source: http://www.handprintpress.com/home-heat/cob-firebrick-masonry-heater-experiment/
Quote from this article: "All in it cost about $1200 in materials. (Firebrick, gas for my pickup, saw rental, discount door, flue tile, firebrick mortar and castable refractory cement…little things add up in a hurry). Labor is a factor here, with the time needed to do the cob facing. I had visions of a $500 heater in materials, but that is for another time."

How's that stack up to Erica's recent assessment of the cost to build a RMH? Dead on. https://permies.com/t/41377/rocket-stoves/Cost-Estimating-Rocket-Mass-Heaters
Erica: "I think you could easily spend $4000 to 5000 if you purchased all-new everything, including all-new masonry materials without shopping around much, instead of using site-sourced or local fill dirt.
Double that if you wanted to get fancy with premium facades and finishes. (My emphasis.)

Al, I like and respect you, and hope this doesn't sound like bickering! I'm having a good time here, because I think this is valuable information to bring to Permies. Permies tends, in my humble opinion, to be THE place for Wisner Rocket Mass Heater information, but we're pretty light on other wood-heat techniques. So I'm doing my part to flesh it out. The more information, the better.

Dale Hodgins

Posts: 9002

Location: Victoria British Columbia-Canada

707

posted 9 years ago

2
Number of slices to send:

Optional 'thank-you' note:

Send

I intend to build a Wisner style rocket in a larger space, at some point, but for now I am more concerned with water heating, cooking and mass heating with one low clearance device. I have no space for a barrel and no desire for a bench.

My masonry stove is incomplete, but I hope to return to the farm and finish the job in February or March. My only cost has been $55 for a 55 lb bag of fireclay.

So far I have 3 days into it. By the time it's done, I expect to have 7 days into it.

https://permies.com/t/43542/rocket-stoves/Dale-Rocket-Powered-Mass-Heater

20150121_094904.jpg

20150121_152713.jpg

20150121_143721.jpg

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 9 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Thanks Dale; great thread, and I look forward to seeing and reading about your finished stove.

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

Amy Saunders

Posts: 25

posted 9 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

I am so grateful for these articulate explanations, Mike, and for the back and forth discussion, all of you. It has given me an idea for my own situation.

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 7 years ago

6
Number of slices to send:

Optional 'thank-you' note:

Send

Mike, Al, if you're still here: I did it.

I made it like Mike suggested, with a 4 inch batch box, and a double chamber brick bell. The heater is just over a meter tall, and the opening shown in the picture is for a black oven; the firebox is on the right side. I made the firebox about six inches longer than specified in Peter van den Berg's charts, though the other measurements were as accurate as I could make them. There is also a cast iron griddle top set over the second bell, using some fiberglass stove rope as an expansion joint between it and the clay mortar.

I finished the brickwork today, after about 30 hours of work spread over three weeks. It took longer than I had anticipated--I hoped to finish within one week, but I was working on my own while also caring for my child and a husband recovering from surgery

I also made some mistakes during the build that had to be redone.

The firebox is hand formed from clay/perlite. The secondary air channel is made from a hollow steel tube belonging to an old bed frame--entering from the side of the firebox, rather than the front.

I was very nervous about lighting it today, but I first lit a small candle in the firebox next to the port, and when I saw the flame drawn in, I was confident enough to light a small kindling fire. Once lit, it drew immediately and made the rocket noise, even though it was just a little fire. It continued to draw very strongly with no smokeback for the entire burn. I only burned about a dozen small sticks and bit of paper for my first fire.

There was some small escape of smoke through the oven door; I used a piece of calcium silicate board as a temporary door so I could test the system and luckily there wasn't enough smoke to set off the fire alarm. I also used three bricks stacked up as a temporary door to the firebox, which helped the fire rocket even more. I will seal the oven door properly and continue making small test fires until the stove is dried out (and also until I lay my hands on a bit more firewood). I will probably add a layer of clay mortar on the very top to ensure a good seal up there, and may do a clay plaster later on over the whole structure to pretty it up--I'm fully aware it's in the Functional, rather than Attractive category right now.

If I have any problems as I continue to test, I will report back. I'm so happy it's done and I did it entirely myself.

DSCF0005.JPG

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 7 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Here's a photo of the inside of the firebox. I formed it by hand using fireclay and perlite.

DSCF0004.JPG

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 6 years ago

2
Number of slices to send:

Optional 'thank-you' note:

Send

Update, a year on.

We burned regularly last winter from November to March, then the stove really started to smoke. It was so bad it became unusable, but as it was spring, I kept putting off opening it up to find out the problem...until this month: oops.

Well, the riser had a big crack in it, and I guess it started to smoke once the outer form for the riser finally failed after so many burns; there was no way it could draw in that condition, and as I'd made it with clay-perlite mix, I really couldn't see a way to patch it up--I had to make a new riser. I also made a small repair to the top of the firebox which had cracked slightly--this I could repair from the top with more clay-perlite mix. As I had a little spare, I put a piece of calcium silicate board on top of the firebox to add extra insulation.

When I originally made the double chamber I made the entry to the second chamber quite low down, and that chamber never seemed to warm up much; I decided to block that entry up and put it right near the top instead. Though we've only been burning it gently this week, already there's a noticeable difference and we can tell the second chamber's capturing more heat. Even the first chamber seems to be warming up more quickly compared to before.

With the new riser it's been pulling very strongly and purring nicely. We haven't had any smokeback (yet). We're still only burning small diameter wood (twigs and sticks basically) and it's amazing how little wood can warm it up. I'm sitting next to it now and it's radiating nicely against the back of my head :)

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

Jan White

pollinator

Posts: 1455

Location: BC Interior, Zone 6-7

511

I like...

posted 6 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

Do you know why the crack formed?

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 6 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

I think I probably didn't pack the clay-perlite down hard enough, or maybe evenly enough when I first made it. I did spend at least a good hour tamping it down, bit by bit, but it was such a tedious job...! That's my guess.

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

Panagiotis Panagiotou

Posts: 97

posted 6 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

How much space in your house does your 4inch batch heats up?
What do you mean by double chamber bell?Do you make one bell that is being divided on the inside by a wall?

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 6 years ago

2
Number of slices to send:

Optional 'thank-you' note:

Send

The room that gets the most benefit is the living room where the stove is. It also helps warm up the kitchen adjacent, but less so. The upstairs isn't much affected by the stove.

The bell is divided into two chambers, yes. The second chamber exits out my existing chimney.

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

Ralph Kettell

pollinator

Posts: 290

Location: The Arkansas Ozarks

I like...

posted 6 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Galadriel Freden wrote:I think I probably didn't pack the clay-perlite down hard enough, or maybe evenly enough when I first made it. I did spend at least a good hour tamping it down, bit by bit, but it was such a tedious job...! That's my guess.

I am going to experiment here soon with coating some keys areas of the burn path in a variety of designs with a clay slip made with a 50-50 water / sodium silicate mix. If the area of the stove in question, gets hot enough, the clay/sodium silicate coating should turn to glass and be quite hard. As a result it should shield fragile areas from some of the damage that heat extremes, heat cycling and physical abrasion cause over time. I wonder if it might have prevented your hand crafted packed perlite design from cracking. Just a thought.

Sincerely,
Ralph

Panagiotis Panagiotou

Posts: 97

posted 6 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Can you show us how you design this stove?I love that i looks small and cosy.
Did you follow Peter Van de Berg's design with the batch box and the bell or you improvise it on your own?

thomas rubino

rocket scientist

Posts: 6316

Location: latitude 47 N.W. montana zone 6A

3188

I like...

posted 6 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Hi Ralph;
I had a perlite cast core for a while. I experimented with sodium silicate (water glass) myself.

I came to the conclusion that it wasn't worth it.

A perlite core, feed tube must be constantly patched if it gets anything but the most gentle of loading.

My water glass improvements helped in the short term but the softness of the core mix would break off anyway.

I never had any issues with the burn tunnel or my cast riser. After moving it three times the metal barrel I built that riser in failed ... not the riser.

My newest stove, a brick bell J tube is built with split firebrick for the feed tube and ceramic board / ceramic blanket for the rest.

Although it works and is cost friendly there will be no more cast perlite/fireclay for me.

For all your Montana Masonry Heater parts (also known as) Rocket Mass heater parts.
Visit me at
dragontechrmh.com

Ralph Kettell

pollinator

Posts: 290

Location: The Arkansas Ozarks

I like...

posted 6 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

thomas rubino wrote:Hi Ralph;
I had a perlite cast core for a while. I experimented with sodium silicate (water glass) myself.

I came to the conclusion that it wasn't worth it.

A perlite core, feed tube must be constantly patched if it gets anything but the most gentle of loading.

My water glass improvements helped in the short term but the softness of the core mix would break off anyway.

Hi Thomas,

Did you perchance try the clay slurry our did you just paint on the sodium silicate. I was going to try to toughen up the surface a bit of the imaginative fire bricks in the feed tube area as I do not have dense bricks and am unwilling to drive 3 1/2 hours each way to buy them.

Thanks,

Sincerely,
Ralph

thomas rubino

rocket scientist

Posts: 6316

Location: latitude 47 N.W. montana zone 6A

3188

I like...

posted 6 years ago

3
Number of slices to send:

Optional 'thank-you' note:

Send

Hey Ralph;
I did just paint it on, and it definitely creates a glass like surface. It would have worked if that rmh was next to my comfy chair and not out in the greenhouse. With careful loading and a bucket of repair perlite cob nearby ... you could use one for years.

Matt Walker coached me when I built my first cast core. He admitted that he had a repair bucket on hand for when his needed patching. Its really not a big deal as long as the stove is cool.

Any sawmills out in your neck of the Ozarks ? Most use a dry kiln for their lumber. They may have pallets of used firebrick getting buried under sawdust... The mill owners go to auctions and buy whole loads of stuff to get the one thing they really needed. The rest gets put aside till they need it... I got several hundred free fire bricks that way... I talked to the mill owner I didn't tell him I would have paid a dollar each for the good ones. Instead I told him about rocket mass heaters ... he looked them up while I was sitting there! Next thing I know he says "take all you need" As long as I can come see your stove when its done!
What A deal !
Is there a deal waiting... under a sawdust pile near you ? ? ?

For all your Montana Masonry Heater parts (also known as) Rocket Mass heater parts.
Visit me at
dragontechrmh.com

Glenn Herbert

Rocket Scientist

Posts: 4526

Location: Upstate NY, zone 5

574

posted 6 years ago

2
Number of slices to send:

Optional 'thank-you' note:

Send

Appropriate materials for the location... I would always use firebrick for the feed (or an air-cooled metal sleeve like mine that feeds the P-channel). The cast refractory (no added perlite) of my core has some cracks and minor abrasion/roughness below sleeve level, but farther in it is still perfectly smooth. My perlite-clay riser in stovepipe is still good though I haven't opened it for close inspection after the second winter; there are no perlite crumbs in ash sweepings. If it does deteriorate after a few more years I may try a 5 minute riser.

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 6 years ago

5
Number of slices to send:

Optional 'thank-you' note:

Send

Panagiotis Panagiotou wrote:Can you show us how you design this stove?I love that i looks small and cosy.
Did you follow Peter Van de Berg's design with the batch box and the bell or you improvise it on your own?

I followed his batch box design, yes. Here's a photo I took during the original build, showing the two chambers. The firebox is on the right side, which is kind of awkward for loading, I'll admit. I decided to use the existing concrete hearth as the base for the stove, and made my bell according to that size; that's why I chose the 4 inch system rather than a larger one, as I knew it could only be a small bell. This small footprint also meant the firebox had to go on the side rather than the front, as it was too long to fit on the original hearth otherwise.

I modified the length of the firebox by about six more inches, as had been suggested in another build (I don't remember whose, it was possibly one at Wheaton Labs). I also put the secondary air tube perpendicular to the port, coming from the side instead of the front of the firebox; it's a hollow steel tube, originally from a bed frame. I was working within a tight budget and am not a welder, and this was the only thing I could come up with. I encased it in the clay-perlite mix as I was forming the firebox. It seems to work.

The bell itself is around 4.5 feet tall. The second chamber has a cast iron flat top griddle, which doesn't get quite warm enough to cook on, but does throw out immediate heat and can act as a warming plate. It sits on top of a bed of clay-perlite mix with fiberglass rope for an expansion joint between the two. The first chamber is topped with old red bricks, with about a 10 inch gap between them and the top of the riser. Because the bell itself is small, I just lay the top two courses of bricks slightly closer together, rather than straight up and down (I'm sure there's a term for this), so the very top could be bridged by single bricks laid across.

DSCF0048.JPG

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

Ralph Kettell

pollinator

Posts: 290

Location: The Arkansas Ozarks

I like...

posted 6 years ago

Number of slices to send:

Optional 'thank-you' note:

Send

thomas rubino wrote:Hey Ralph;
- - - - - - - - - -
Any sawmills out in your neck of the Ozarks ? Most use a dry kiln for their lumber. They may have pallets of used firebrick getting buried under sawdust... The mill owners go to auctions and buy whole loads of stuff to get the one thing they really needed. The rest gets put aside till they need it... I got several hundred free fire bricks that way... I talked to the mill owner I didn't tell him I would have paid a dollar each for the good ones. Instead I told him about rocket mass heaters ... he looked them up while I was sitting there! Next thing I know he says "take all you need" As long as I can come see your stove when its done!
What A deal !
Is there a deal waiting... under a sawdust pile near you ? ? ?

Thanks for the tip Thomas. I will be visiting sawmills after the holidays in search of fire bricks. Yee haa

Glenn Herbert wrote:Appropriate materials for the location... I would always use firebrick for the feed (or an air-cooled metal sleeve like mine that feeds the P-channel). The cast refractory (no added perlite) of my core has some cracks and minor abrasion/roughness below sleeve level, but farther in it is still perfectly smooth. My perlite-clay riser in stovepipe is still good though I haven't opened it for close inspection after the second winter; there are no perlite crumbs in ash sweepings. If it does deteriorate after a few more years I may try a 5 minute riser.

Further to your comment Glenn and Thomas's as well I will be putting a heavy duty steel rim around the feed opening. That will take the most abrasion. Besides at the moment I am only talking about the engine for my Bugatti rocket stove.

It is not going to be fed fast and furious like a RMH to heat the house.

Sincerely,
Ralph

Erica Wisner

gardener

Posts: 1292

Location: Okanogan Highlands, Washington

397

I like...

posted 5 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Nice project!
One of the major issues with many of the batch box rockets we've seen and helped with is getting the door right - the right air flows, the right secondary air, and the right attachment so that it stays airtight without causing the surrounding masonry to crack or crumble. Custom doors can be $300-700, esp. with frames.
How did you end up solving the door?

I agree with several folks posting above that a person's choice of materials, and who/how much help to hire, is a bigger factor to project cost than the specific stove design. The house itself is also a big factor - if there's an existing slab, and an existing through-roof chimney, you save several thousand right there.
However, for most masonry heater designs, and especially for the standard methods using double skins of cementitious exterior materials, you need a lot more masonry units, and more expensive tools to cut them accurately. These methods do drive up both the material and skills costs, though both can be worked around with scrounging and training. Using earthen plaster as the second "skin" over brick or adobe does cut costs considerably.

We have built bell- and J-style masonry heaters with adobe; and perlite-clay or perlite-straw-clay materials in lieue of brick fireboxes. They definitely wear faster, but for a mild climate where you don't mind annual repairs rather than just annual inspections, they can work. I would tend to look for some harder-wearing split firebrick for the base of the firebox, or some kind of heat-tolerant ceramic tile; repeated repairs get old.

-Erica

Projects, plans, resources - now on the Permies.com digital marketplace.
Try the Everything Combo as a reference guide.

G Freden

pollinator

Posts: 710

Location: West Yorkshire, UK

282

posted 5 years ago

1
Number of slices to send:

Optional 'thank-you' note:

Send

Erica Wisner wrote:
How did you end up solving the door?

Yes, the door. We would love to have a custom door. Well, we actually do: three bricks stacked on top of each other, pretty much flush with the firebox. There is a small gap at the top where they don't quite meet the firebox, and small imperfections at the side which are not air tight. The top two bricks come down when lighting/loading, but are quickly replaced and there's a noticeable difference in the amount of roar once they're back on.

When we load up for lighting the first time, we can't fill it all the way to these bricks, or there will be an initial puff of smoke out the top gap from lighting the paper. I don't count it as smokeback, but it's not ideal; it would be better if my primary air came from down low to eliminate this issue.

Trying to achieve self-reliance on a tiny suburban plot: http://gardenofgaladriel.blogspot.com

If you open the box, you will find Heisenberg strangling Shrodenger's cat. And waving this tiny ad:

GAMCOD 2025: 200 square feet; Zero degrees F or colder; calories cheap and easy

https://permies.com/wiki/270034/GAMCOD-square-feet-degrees-colder