Mass Heater Design Question

I'm interested in designing and building a mass heater, something like you might find in Eastern Europe.
Lots of bricks, build a small fire, hopefully it will radiate heat for 12-24 hours.
Here's my question: lots of designs seem to force the hot smoke to flow down, usually with a bypass valve for starting.
I want to know if you design one that flows left/right but just up does that have any disadvantages?
Will it draft better? Will it be as efficient for heat?  

Hi Paul, welcome to
Permies!
European masonry heaters have been in use for hundreds of years.
Then, there are Montana Masonry Heaters, also known as rocket mass heaters.

European heaters use a super hot fire that travels through serpentine channels and heats the bricks.
They are complex to build, and a licensed stove builder must construct them in some states to get insurance.

Montana masonry heaters utilize a rocket core, most commonly of a  Batchbox design.
This core is mounted inside a stratification chamber" bell, " which is really an empty brick box.
The hottest air rises and displaces the cooler air, which sinks (stratifies) to the bell's lowest portion,  locating the exit chimney and leaving the bell.

Here are some interesting threads you might enjoy reading.
https://permies.com/t/270559/Stratification-chambers-Bells-explained
https://permies.com/t/272271/distinctions-RMH-type
https://permies.com/t/267527/Shorty-Core-bell
https://permies.com/t/238503/Batch-Rocket-Build
https://permies.com/t/248275/Batch-Rocket-Double-Skin-Bell
https://permies.com/t/272921/Shorty-Core-party-dress-clay

Paul,

Designs with complicated channels were already criticized 90 years ago. Frequently it was empirical approach being passed from the master to the disciple without (or against) the physical justification of such a design. Professor Grum-Grzymajlo theory of free gas movements suggested using stratification chambers that are both more efficient (multiple channels affect the speed of gases) and also easier to build.
These heaters are efficient and probably clean enough, but rocket fireboxes are more efficient and cleaner and last but not least - scalable. Being not esoteric like some obscure designs, it's also easier to find solid information and advice help when building them.

Hello Paul and welcome to the wonderful world of radiant wood heating with masonry mass. Your first statement is that you are "interested in designing and building a mass heater". Can you also state your ultimate goal? Is it to tinker and find new and innovative ways to heat with masonry based on previous design concepts or are you looking to build based on proven design development? Either goal is valid with the former taking a long term commitment to experimentation while the later will leverage the experience of long term experimentation by others.

The reason for my post and question to you is that the decision to go down the road of building a heater can initially seem like a daunting task. As you do your research you will find that a batch box with masonry mass will meet your operational goal then the major work has been done and well documented. If you haven't studied Peter van den Berg's website, https://batchrocket.eu/en/, I would encourage you to take time to read it in it's entirety. Peter has perhaps done the most scientific research into refining the design and has been kind enough to share his hard work for all to benefit.

As Peter says; "Follow a proven design and get proven results". I can attest to this being fact as I fire my batch rocket in the morning and evening and it performs perfectly each and every time. The earlier post by Thomas Rubino will also provide links to help visualize the build process and end result. Best wishes for your successful batch rocket journey.

Hi, thank you for the responses.  
My question is  is to find a reliable design and build a masonry heater.
I am not seeking information about rocket stoves.

I'm asking about the design of a masonry heater. Like the masonry heaters you find in Eastern Europe or Russia.
Lots of bricks, a door, some cleanouts. Something to heat a small home more efficiently than a steel wood stove.

My question was about the design of the smoke flow channel.  Some flow just up, through channels, some flow up and then down.
Is one of these more reliable, efficient or some other advantage to either model?

Forgive my ignorance but it would seem to me that making hot air flow down is sort of counter intuitive. Perhaps it releases more heat this way?

Paul,

Probably you do not realize that rocket type firebox is used iby numerous builders in normal masonry heaters, weighing 1.5 to 3 tons, having single or double skin, sometimes with kachel second skin. This is what I meant as a good and scalable solution and we can help.
Rocket stoves made from metal or utlizing ugly oil barrels is another story.

Yes, I am interested in avoiding the steel oil drum design or the steel rocket tube. All brick. Thanks

Maybe something like this?



You might like this thread if so - shorty core gets a bell

Paul, you are right, a column of air that is hotter than the air around it will naturally flow up. Being a commercial hot air ballon pilot I can attest to the beauty of leveraging the physics of this means of propulsion. In the case of the rocket mass heater you want that propulsion to occur in a similar manner to push the heat out your chimney but you are managing the direction of the flow in an effort to use the heat to ultimately heat a mass and thus your room.

Understand that what you are working to achieve in heating a thermal mass is the transfer of the heat in the air to heat the mass. The hot air flows up from the combustion core and as it comes in contact with the mass of the stratification chamber it begins to cool so that it changes direction and flows down, continuing to give up the heat in the air in an attempt to reach thermal equilibrium with the mass. Once it reaches the lowest point of the stratification chamber which is typically the point of exit to the chimney it reverses direction again and exits. The less friction created with those changes in direction the better the system will breath and perform. As is experienced leveraging Peter's designs, the combustion core temperatures can reach in the 1,600F range +/- and the chimney exit temperature at the base of the stratification chamber is 200F +/-. This proves the concept of heat exchange, thorough combustion of the fuel, and maximum thermal capture of the system.

I hope this helps.

Burra Maluca wrote:Maybe something like this?

You might like this thread if so - shorty core gets a bell

Hi Burra,
The link you provided doesn't lead to the thread but to the picture only.
Just to let you know.

Peter van den Berg wrote:
Hi Burra,
The link you provided doesn't lead to the thread but to the picture only.
Just to let you know.

Oooops, I think I fixed it. Sorry, not fully functional today...

Here's the link again, just in case - shorty core gets a bell

Paul LeMay wrote:Yes, I am interested in avoiding the steel oil drum design or the steel rocket tube. All brick. Thanks

Hi Paul, I have read your desire to gain info on masonry heaters only but, I think that once you grasp how a modern rocket stove and brick bell is constructed and how it works, it might broaden your prospective and change your mind.
From the outside there need not be any difference in appearance  at all, in other words a rocket mass heater is fundamentally the same apart from the rocket engine is more efficient and the whole system easier to build.
I can understand the confusion in relationship with the somewhat dated oil drum designs but that need not be the case at all.
In very basic terms….  a modern rocket mass heater comprises of a very efficient fire box with a door and viewing window that is situated inside a brick enclosure.
The brick enclosure only contains the rocket stove engine and no complex additional brick work, the actual size of the enclosure is defined and documented and is based on volume so it can be made into many shapes to fit your requirements.
So in summery, a modern rocket mass heated, is a very direct alternative design, that can look from the outside,  virtually identical to a more traditional masonry stove.

Paul, your getting lots of great advice here from the forum group, and I would like to perhaps explain a bit more of "proven design size" subject  and why it is important to understand.

As it has been pointed out, There are system sizes called out, and they are generally 4" up to 10"  meaning a 4" flue can/should handle the 4" size and then if your looking at a 10" this requires a massive 10" flue of which very few were ever installed in a house when built.   But anyway, I wanted to point out the often determining factor of your system size if you already have a flue in place. It will dictate your maximum size.

I will let others toss in, on the BTU's that any particular size will cast off in 24 hours, but it is my belief that if I only need a minimum amount of heat, I light a minimum amount of fires.  I don't feel you will experience huge swings in temp in your rooms.  You will often read or hear directly that in the fall and late springs of just 1 or 2 fires lit in the stoves/heaters. per day.  (that is not much wood)

Now for a bit more technical,   Peter (commented earlier)  has done a tremendous amount of work, that I feel is most important, and that is simply the size of the Internal Surface Area, ( ISA) that is called out for each system size based on the forementioned flue size.    What this means is simply you want enough internal surface area of your BELL to extract as much heat as possible out of the hot air from you very hot fire----Without going to far, say clear down to 85 degrees instead of 150-175 degrees.  The latter temps keep the system going nicely, without worry of a stall ( smoke back into your living areas )

Again, all of the above mentioned items are called out for every size. And all 1/2 sizes can be interpolated.    Then all of the exterior components can be done to what ever degree  of architectural design you want

Hope this helps you along the wonderful path of simplified Masonry stoves.