Brick Rocket Mass heater

Does anyone have any advice, for making a RSMH out of all brick? I was thinking it would look a little nicer and would have more thermal mass for radiant heat.

My thought was to use fire brick for the combustion chamber and use regular brick, to replace the steel drum, for radiator surface.

Any suggestions? Has anyone done this before? any drawings maybe?

Harpman wrote:
Does anyone have any advice, for making a RSMH out of all brick? I was thinking it would look a little nicer and would have more thermal mass for radiant heat.

My thought was to use fire brick for the combustion chamber and use regular brick, to replace the steel drum, for radiator surface.

Any suggestions? Has anyone done this before? any drawings maybe?

Check out this youtube video:

Rocket Mass Heater Stove Wood Refractory Masonry Hermon Heater

He's selling the plans for this if you're interested.  On his channel he has videos showing how easy it is to start it up, etc.

Keep in mind that without the steel drum, you don't get any quick heat -- you have to wait for the brick to heat up.  He mentions in a comment that he did add a drum to the structure last fall.

go for it. 
I do have a question or two however; have you ever built one?
is there something about cob that limits its attractiveness? I am trying to understand why a rigid form like bricks is considered so much more appealing than being able to sculpt something into almost any shape you can imagine?

Ernie wrote:
go for it. 
I do have a question or two however; have you ever built one?
is there something about cob that limits its attractiveness? I am trying to understand why a rigid form like bricks is considered so much more appealing than being able to sculpt something into almost any shape you can imagine?

cause bricks remind me of lego's

oh and cause some people think a 55 steel drum sticking outa the floor/wall/bench is ugly I expect thats whe bit they want to not see

I do not have any problem COB. I just do not know how to make it. But I do not like the 55 gal drum look. So my thought was to replace the steel drum look for brick. If you can use COB instead of the drum I would use COB instead.

Can you use COD instead of the steel drum?

the 13 dollars for the book download here is well worth it,
I finished the book before it had a chance to cool off from the printer

http://www.rocketstoves.com/

Well thanks for the answers to the questions.

yes you Probably could build a rocket stove out of COD it would solve folks barrel problem at any rate; however briefly.

What's COD?

Harpman wrote:
I do not have any problem COB. I just do not know how to make it. But I do not like the 55 gal drum look. So my thought was to replace the steel drum look for brick. If you can use COB instead of the drum I would use COB instead.

Can you use COD instead of the steel drum?

Assuming you mean COB (the clay-based building material) instead of COD (the fish), I think I can answer the question.

The 55-gal steel drum has been used because a) they're cheap, b) they're plentiful, and c) they provide a structure that can handle the heat and airflow of the output from a rocket-based heat source.  There's another thread here that talks about building a 5-brick rocket stove, using concrete blocks.  The structure is effective and would be excellent in an emergency or disaster environment.  It would NOT work in a permanent structure, because the heat generated by the stove would eventually cause the concrete brick to become brittle and crumble.  The stove generated heat in excess of 300 deg. C. (over 560 deg. F) -- that was the highest the thermometer would go.

I think over time, using cob instead of a steel drum would result in cracks forming.  Even the tiniest cracks leaking to the outside would immediately reduce the efficiency of the system, and would eventually result in having to rebuild the whole thing.  In addition, the steel drum enables heat to begin radiating almost as soon as the fire is lit -- an important consideration on a snowy January morning.  Using cob instead would mean the cob would have to heat up first before it would begin to release any heat to the room, i.e., the kids would already be in school before it started being useful.

On another thread, I asked about the possibility of painting the barrel black (which to me would immediately take it out of the area of "old 55-gal oil drum" into "essential heat radiator") as well as building a decorative brick lattice around the outside of the drum, perhaps an inch away from the steel.  To me, this would still allow the steel drum to begin radiating heat as soon as the fire is lit (although most of it would be going up instead of out through the lattice openings) as well as providing some childproofing by making it much more difficult for little hands to be burned on the side of the drum.  (Or grownup hands, for that matter -- I'm not the brightest porch light on the block.)

it is a fish IQF'ed or frozen in blocks some reach great size and could be used temporarily for the barrel.

I assume however it was a prod at my occasionally hitting the wrong key on this tiny little keyboard. I shall laugh now....HA HAHA HA.

Ernie wrote:
it is a fish IQF'ed or frozen in blocks some reach great size and could be used temporarily for the barrel.

I assume however it was a prod at my occasionally hitting the wrong key on this tiny little keyboard. I shall laugh now....HA HAHA HA.

You know, that had a vaguely creepy tone to it ...

(backing away slowly now...)

Hi All,

I'm new on the block, recently been hit on the head by a rocket stove, and now drawing, reading (got the book in pdf:-) en this weekend digging in and under the (wooden) floor to produce a reliable massbearing capacity in concrete.

I also don't like the barrel in sight, so I'm glad with the question and answers, but still not satisfied. Is there a reason not to? I would like to produce a COB wall around the barrel but with a gap from about 2-3".  Would this barrel-skin or bricks like mentioned earlier, take away to much heat or speed for that matter to be able to warm up the mass? I'm a little bit concerned about condens. Or should I just put a bucket under the upgoing outlet through the roof and go for it?

I built a brick riser RMH last year, but it leaked & now I have to rebuild it. I would appreciate any advice.

I have no problem with barrels, but I would like to sell my house at some point, & I sense it'll be easier to pass off my RMH as a masonry heater for insurance purposes. With a barrel, its obviously something else.

I have included a couple pictures from when we were first getting started. Initially this was a case of using what we had around the house. In this case, that meant

An old Waterford 104 MKII woodstove, 12"X14X18"

Some stove pipe & an all metal chimney.

A brick pad for the Waterford.

A bunch of cinderblock.

A lot of red bricks.

A limitless supply of adobe dirt.

Wood, lumber, & sawdust.

With those items we set about building our RMH. I made an adobe mold, & with sifted adobe & sawdust made my own firebricks, 25 in all. I did some basic testing, the 4"X7"X12" adobe firebricks worked pretty well, surprisingly.

The Waterford serves as fuel chamber, it has a 4 inch opening out the back to the riser. This gives it a narrow, but extremely short, horizontal burn "tunnel". The interior of the Waterford is where I load fuel, obviously. The fire adobes made a ~7" square riser, ~36 inches high. I used mud as mortar.

The outer chamber, what would normally be a barrel, I built of bricks with sifted mud mortar. These I covered with mud plaster efter they leaked on the initial test. Because I didn't think the bricks would give the temperature differential needed to push the exhaust out, I paid too much to have someone cut me an 1/8" steel top & angle irons to bolt it to the brick. That was actually the last item added, once I was well into the project & everything else was done.

From the outer chamber, the exhaust goes into an adobe bench. We did use some cob to insure against cracking, & topped it off with a mud/plaster of paris mix.

The total length of the bench is ~18'. It makes an "L"around the room, then loops back to the chimney exit, where it goes up through about 12' of 6" stove pipe. It would have been better, yes, to have the mass in the middle of the house, but it wouldn't work with our floorplan. This makes the total horizontal exhaust ~36', with four 90 degree bends, plus 3 more 90's in the metal stovepipe.

Since we initially did not have stovepipe or ducting for the bench, we used carefully arranged cinderblock as you should see pictured. The large gaps were covered with bricks, & the whole thing sealed with quite a lot of adobe/cob/plaster. I put in 3 cleanouts.

When I started the RMH up, it did the roaring rocket thing, but it smoked. I added a fan to the chimney to give it some pull when starting. Then it worked better. The burn chamber & riser clearly worked, as  the steel top was very hot & bowed upward almost an inch as the stove warmed up. We did several burns a week over the course of a couple weeks, slowly building up.

The metal chimney leaked smoke indoors, & I sealed it like crazy with high-temp silicone. However, it stayed cool to the touch. The metal top of the heat riser, & the bricks themselves, leaked too. I sealed the top with silicone, & the bricks with mud plaster. With each burn I sealed up more leaks, until I thought I had it. Then on the last burn, I think the mud mortar & mud plaster dried & cracked, & it leaked catastrophically from the outer layer of brick.

So, at that point I threw my hands up & went back to the drawing board. Now coming back after studying more, finally reading Ianto's book, & reading a lot about the european masonry stoves, I think I can pick out my numerous mistakes. Feel free to point them out for other reader's edification.

The one's that come to mind are:

The RMH creates a pressurized outer chamber. Brick is not meant to be pressurized.

Mud morter, & mud plaster are not very tolerant of repeated heat cycles. I did not know about refractory mortar. I am considering trying to rebuild the outer chamber (barrel) with refractory mortar, & possibly tile. I am trying to keep it as thin as possible, & am considering various combinations af brick & tile. Any help in this arena would be very appreciated. I am also open to any other alternative. Again, I have no problem with barrels, but I feel my insurance might.

The bench is too long, & has too many bends. Hearing Paul's podcast with Ernie & Erica, where they said "Each 90 adds 5 feet" was very helpful - belatedly. I am going to  cut that length in half, & have the exhaust exit at one end of the L rather than looping back to the original chimney location.

Using cinderblock was a bad idea. I should've forked over for round, smooth stovepipe that doesn't create drag & turbulence that impedes flow. I don't think I can change this problem, but hopefully halving the horizontal run will make up for it. On the plus side, haivng a row of cinder block between the horizontal flow & the outer wall will make more heat radiate into the room.

Using the existing chimney is simply not an option. The stove simply cannot push exhaust up 12', & having a fan on that side will never pass any sort of code. I should've taken it down & used the pipe in my bench, but there it is. I am planning to cut a hole in the side of my house at the end of the bench, & vent out there. The question is, how high? Should it just be a horizontal vent straight out through the back of the bench, or should it rise up a little like a pellet stove vent? With a straight horizontal I am concerned about wind blowing exhaust back in. With any sort of rise I am afraid I will be back to smoking out the front.

The fuel chamber of the Waterford is too big, & doesn't create enough pull near the front door of the stove. It does OK once the door is closed, but you have to tweak the from vent a lot to keep it either going out, or smoking. I may put an adobe fire brick in the bottom to make it less tall inside, but that'll give less room for fuel/ I tried vertical feeding - the stove has a top hole with a cover plate. That didn't work very well, given the lack of pull. Again, partially covering the opening helped.


SO, that's it for our experiment. Please, offer your advice as I begin rebuilding in preparation for next winter.

Hi, also new here, and want to make a rocket mass heater.  I have no objection against the barrel look, just not sure how easy it is to get one here (I live in an east block country).  I'm sure I can scrounge one from somewhere.

I wondered how they managed to get the barrel on the book cover looking so shiny?

I also wondered, I think I read somewhere that Ernie Wisner was thinking of using pea gravel as mass instead of cob.  Has anyone tried this?  I wondered if I made the bench with a straight frame, tiled, and then filled it with gravel surrounding the pipes, surely that would retain and give off heat in a similar if maybe better fashion then the cob?  And it also might be easier to change things or move it later, just scoop out the gravel?

I also have a question on the "outlet"  In many cases I see this as a pipe next to the barrel, going vertically and out near the ceiling.  However in one diagram I saw that the outlet pipe just went straight out horizontally (like close to the floor).  Which one is better?

I'm not terribly technical and I'm getting into these things at an older age, but feel very excited about the prospects of this.  Will get the book as soon as next pay comes in.

I'm incredibly pleased that you all have taken the trouble to make a forum and come up with the all the permie ideas and looking forward to implementing them.

I have been reading this over and was thinking the following;
brick is basically sand and sand does not conduct heat that good. Why not use Stone, most stone conducts heat much better than brick does.
Just a thought

I agree, i will try to make my RMH out of local stone, or maybe some upcountry granite that stores heat really well.  I think (real) thermal mass is important for any heating/cooling needs.

That sounds good, local stone, etc.

I am wondering, isn't gravel stone, but just smaller particles?  Would it make a difference that it's not massive big hunks of stone but many small particles of stone?

I would imagine gravel would work but u'd have to contain it somehow.  Although the air pockets between gravel don't have much heat storage capacity like solid stone.  i would imagine the larger diameter the gravel the better.

I had the idea of making a metal frame and resting mesh on the sides, then leaning large tiles against the mesh, then filling with gravel to the top of the first row of tiles, putting another row of tiles and filing up to the top of that tile etc.  And then on the top - horizontally, rest more tiles.  When I get that far and if it works, I'll let you know.  I'm on a tight budget so it will prolly be in september.  Let me know if you think this is a flawed idea, ok?

Just what was said about the air, air does not store heat you so will loose there. other ideas sound good and good luck.

ok, thanks!

Daisy wrote:
then filling with gravel to the top of the first row of tiles, putting another row of tiles and filing up to the top of that tile etc.  And then on the top - horizontally, rest more tiles. 

sounds good...You must have a supply of tiles and gravel?  Use whatever's available... the denser, the heavier... probably will have the most thermal mass.  You can always use stones, river rocks, etc.  You may also want to consider mixing the gravel up with some available clay soil to get rid of the air pockets. 

I'm planing to use some river rocks and then pea gravel (very small) so there should not be much in a way of airpockets.  I will buy the gravel but it is very cheap here.

Because I will have to do this on my own, and I'm a bit older, I thought I would try to make it as doable as possible for myself. I think faffing around with clay or cob is going to be more then I can manage and will create big mess (knowing me).

I have some tiles, but am also considering possibly getting a sheet of copper cut to size, I understand copper conducts heat quite well?  I will look at the cost and decide.

First thing I will check to see in the cellar to determine if the weight is going to be ok, or if support is needed.  Then will proceed accordingly.  I think it's going to be ok.  Will keep you posted, and thanks for getting back!

Make sure the mass touches the metal tubes that supply the heat, if only air or mostly air, I think you might be wasting your time and money..

Absolutely!  I will pour the small pea gravel all round the pipes and fill the "form" with it.  I don't think there will be any air in there at all to be honest.

I'm actually very excited about the project, I've never done anything like this, but will post up here as I go along, and put up pictures.

Take care and have fun!
I love it when Women get into working on projects like this.

In your statement above you said isn't pea gravel the same as river stone, or just stone. The answer is mostly yes, but due to the size, it will never hold the same thermal mass of heat, and will dissipate the heat quicker than large sized stones. If you surround with pea gravel, then add in larger pieces as well, it should serve you right though. Take care and have a great build and a great week!

Ah, tha't what I was wondering, whether the fact that the gravel stones are small makes a difference in the matter of giving off heat.  I will rethink this a bit more then.

         Daisy, for the densest mix use granite along with whatever smaller gravel you can find and mix this with sand of mixed sizes. A mix like this will weigh approximately 160 pounds per cubic foot and the tightness between particles will ensure good conduction and minimal convective currents. The specific heat of this mix will be very close to   .2    Firebrick has a specific heat of  .25 but it is not as dense. This mixture of granite and smaller aggregate will give you the maximum heat capacity for a given volume of RMH. A pure rock material may not have as quick conduction through the thermal mass as a mix containing clay. If there is a machine shop near you it might be possible to get metal filings to add to your mix. This would speed up conduction through your material. You mentioned that copper conducts heat well which is true but aluminum is a better conductor of heat and it is cheaper.

Dale, I only saw your response just now.  thank you.

I've had some delays but will go to the shop next week to get the supplies to make my stove.

I have a few questions. 

I now have one 210 liter  barrel (I will get the top cut off, it contained oil, and I will clean it) and a smaller barrel for putting the wood in.  I've found rocks, and I'll be getting the gravel.  I've measured and will get the framework pieces cut to size with holes drilled so I can screw it all together.   I will use aluminum or metal sheeting as the "wall" to hold the pepples inside and will also have this cut to size.

My questions are:

1.  I can't get any stainless steel stove pipe here.  They have "regular stove pipe" that everyone uses for their 'Pechka's" (stoves)  I can get enameled or un-enameled.  I'm not sure if the pipes are galvanized or not.  Can I use the enameled pipe inside the mass of the heater?  I read that galvanized was bad.

2.  The widest stove pipe I can get is 5 1/4" diameter , my barrel is 22 1/2" diameter, will this be ok?  (I will have two courses of the pipe next to each other in the mass part)

3.  The barrel is painted, what will happen if I leave the paint on?  it looks like it is baked on and difficult to get off.  It's quite hideous red with bulgarian writing on it, not exactly my "item" but I have a feeling that trying to get the paint off will take me a month of daily sanding.

4.  I am trying to get perlite, but not sure if I can get it here.  Would I be able to use wood ash as insulation material for the riser?

5.  My floor has laminate, underneath is wood.  I will have it supported underneath from the cellar. My plan is the put aluminum sheet on top of the laminate, then a layer of 1" sand as insulation, then the rocks and pipes, surrounded by pea gravel.  Does that sound ok as far as insulation goes?  Or should a put more sand or some other insulative material?

I'm trying to source some firebrick, wish me luck!  When I have it finished, I will take picture and post.  I can't wait

Be very careful with the barrel with the paint!

Why not go and get a stainless steel garbage can? Turn it upside down, no cutting no paint removal, no harmful chemicals?
just my .02c worth

I would love to get one of those, but we do not have them here.  I was fortunate to get the oil barrel.

Stainless Steel Garbage Cans in Canada;

Princess Auto
Home Hardware
Canadian Tire
Rona
US chains here that carry them; Home Depot, Lowes

good luck

sorry just saw where you live, Bulgaria !

How about, any used hot water tanks? remove the wrapper, inside you find a tank;
Any big used propane tanks? get someone to cut the top off, then use that. The propane tank can be cut easily by someone who works on gas tanks, or hwe systems, they have the knowledge to do it safely.
How about a used oil tank? cut one in half, stand it on the cut side, now you have a place for the heat to rise into.
Just some suggestions, I think the paint on the tank you have is too dangerous. If you go to a shipping yard, they might have some that only have lettering on them and mostly blank metal.

take care

   When old chimneys are removed the firebrick are often discarded. They are perfectly reusable as long as they don't break up. They can be sourced by contacting anyone who does renovation work to old homes, through demolition contractors and by running ads stating that you're looking for old brick. Use the best ones or purchase new ones for the feed tube.

  There are types of mortar made from clay which are suitable as mortar for recycled bricks. When you purchase this be sure to mention to the salesperson that this mortar will become extremely hot. Don't reuse any bricks which contain a  coating of white fibrous materials as that may be asbestos paste.  

    Another product which packs very tightly and will give good thermal conduction is crushed rock Road base. This material usually goes from three quarters of an inch chunks 1.5 cm and progresses to smaller and smaller sizes with plenty of stone dust. If this is available it will save you mixing time since it is a ready to use product.

   Good luck: Dale

ok, well on the barrel front, I just paid to have the barrel, so I guess I gonna have to figure out a way to get the paint off.  I'll start a fire in the back field and put the barrel on it after I have the top cut off.  The people that will cutt the frame for me will also cut my barrel.

Regarding the firebricks, ok, I gonna check on used chimneys and such like.

Dale, when you speak about the rock dust and the road base material, are you meaning I should use this instead of the gravel as mass?  Or should I use this as material in the riser?  Forgimme if I sound a bit stooopid.  This building stuff is all new to me

Thanks for all your input, this really helps me.

  Dale here.

    The rock dust should be part of your gravel mix so that you have particles ranging in size from microscopic to up to several centimeters in diameter. This will allow for tighter packing of the material, better conduction of heat and it will maximize the amount of total heat stored in a given volume of material.

  It has nothing at all to do with the heat riser which should be made of metal and insulated.