use of metal

Been lurking for months - time to engage.
Three questions:
If the idea is heat radiated from a "mass", and if a steel drum is - as I perceive it - a fairly short lived element of the RMH, why not have the barrel replaced with stone (besides, my wife thinks they're too ugly!)?
If the metal pipes that are used for the exhaust gas are oxidized out in several years, why not use just a stone path for the exhaust gas.
And, if these metal parts need to be replaced after a few years, does that mean that these beautiful "benches" have to be torn up to put in new metal?

Thank you all for the dedication to this idea and forum.

David Crawford

David Crawford : Welcome to Permies, and a Big Welcome to the Permies Rocket Stoves Forum Threads ! We will try to separate the Jreck from the Facts ! Even Though
the Rocket Mass Heater R.M.H. is 20 years old, There are no reports of barrel failures in these seasonally operated heating Units. This is really not that surprising, as the
vast number of barrels out there are of a heavier gage of mild steel than found in the Heat Exchangers of most Fossil fuel fired furnaces ! Quality control for 55 gal Drums
with their simpler construction and Time tested Durability is also visually easier, because of their track record only a percentage are actually pressure tested in spite of
their primary purpose, In fact a higher percentage of 2nd hand barrels are pressure tested than new barrels ! When we use barrels to make Heat Exchangers for R.M.H.s,
we are taking a superior product and up-cycle-ing it !

Speaking of Fossil fuel fired Furnaces, try and find one that guarantees its heat exchanger longer than 20 years ! Will your wife have the same husband in 20 years ?

There is a type of Wood Stove with all stone masonry Construction, they Cost Tens of Thousands of Dollars, parts and labor ! The skills of which would take 5 years to
learn ! This is a Heating unit designed for D.I.Y. Construction by poor people in third world Countries, and can be made for a few hundred dollars or less, depending on ones
ability to scrounge !

The pieces of stove pipe used in the construction of the Rockets Heat Riser / Internal chimney are sacrificial forms, we could just as easily do our construction phase
with cardboard tubes ! The Heat exchanger is what is left after our sacrificial stove pipe fails, the fact that the stove pipe lasts in place for 1 or more heating seasons before
failing is a non issue !

Despite frequent comments to the contrary, Round pipes carry the hot exhaust gases more smoothly and hence more efficiently !

Again, the stove pipe should be considered as a sacrificial form ! A rank amateur can learn the basics of making Cob in an afternoon, making bread dough will take more
teaching talent, practice, and skill. Packing Cob around stove pipe is much easier and faster than stacking irregularly shaped flat stones and requires no mortar !
Remember we are dealing with a round pipe, a circle is sometimes called a Perfect Arch !

There is no Need to tear apart a properly constructed Thermal Mass Bench !

For the Future / Good of the Crafts ! Be safe, keep warm ! As always, your comments and Questions are solicited and are Welcome ! PYRO - LOGICALLY Big AL !

Yes I think they will last a fairly long time when done correctly, if not past one's life time you can also cover the barrel with decorative metal skins I do like the copper wrapped around the barrel, I can see it transition heat quite effectively. If the drum radiated glowing hot than cooling that is quite stressing on a thin gauge metal, you can look at it like smoking a pipe, where the carbon forms in the bowel, making a carbon bowel which allows the pipe to last forever with periodic maintenance so if the barrel and piping has a nice thin layer of carbon performs the same function.

I was looking at a chart not too long ago and I noticed that marble has a high thermal conductivity. I would imagine that making the box for the mass heater out of marble then installing the round pipe then covering everything inside with cob would make a fine mass heater. It would be much better than making the box out of wood which would act as an insulator as well as rot from the micro organisms in the cob. As for the barrel look around and find a Stainless steel barrel and I bet you could make a really sweet looking mass heater.

allen lumley wrote:
There is a type of Wood Stove with all stone masonry Construction, they Cost Tens of Thousands of Dollars, parts and labor ! The skills of which would take 5 years to
learn !

The price amount has dropped drastically in the recent years as the popularity has grown. I'm not sure about the rest of the country but masonry stoves are popular in the East. I have actually considered taking a workshop on building one.

Here is a link to a website for Lars Helbro
http://www.stenovne.dk/englishpage1.html

Rion Mather : Did you mean for the pictures you posted to this thread to represent Masonry Heaters actually constructed at a Masonry Stove Workshop ?

There are two main components in a So-Called-Masonry-Stove ! The Interior 'lungs' of a Masonry stove, the Heat Exchanger Core part, and the Exterior skin. If you
want to use a masonry stove as the main source of heat for your home you have Two ways to get it ! Hiring a Masonry contractor to install one, or Building it yourself !

Using Most Contractors, you will be tied to a commercially constructed Heat Exchanger Core , Most likely imported, cost delivered to your building site 4-5,000 U.S.D. !
Then the Master Mason takes over, his job is to create the stone skin and whole house heating stone channels with A series of Expansion-joints specifically tied to the
Individual build for this location !One misplaced expansion-joint and you have a Crack in one of these two components that must be fixed by partial or complete de-
construction of the Masonry Stove and a re-build! This is why you will need a Master Mason and will pay for the privilege of doing So !

If I were aware of a Masonry Stove Workshop in my area I would ask about where the Masonry Heat Exchanger Core was coming from ( I personally don't know of an -
North American manufacturer of Masonry Heat Exchanger Cores ) the skills required to build a true Safe Masonry Stove can not be taught during a two week School,
I Believe you would end up paying for the privilege of being unpaid labor ! I think that the best outcome of one of these Workshops is an on site built Masonry Stove,
participants who now know this is beyond their skill set and the Mason/contractor with a list of potential clients !

Rodney Johnson : Did you mean to describe any Wood Stove with a layer of carbon coating its interior walls as a desirable characteristic, or mode of operation !?! I hope
that you have never seen a Wood Stove of any Kind or Manufacture that had / has an interior Like the one you describe!

I mention this Only because someone following your post might believe that you had personally seen a Rocket Mass Heater Operated this way - In fact the R.M.H.
Can not be operated in this manner !

The Carbon soot build up you describe would be highly insulative, keeping almost all of the heat energy trapped within the stove pipe and exhausting it to outdoors ! While
I have seen Fossil Fuel fired Space Heaters that plugged, it was due to operator error and using the wrong grade of fuel !

It would be hard to believe that even a wood fired Water boiler could be operated in a manner to create the conditions you describe, the next hot fire should create a
Creosote / Chimney Fire.

I only promote this viewpoint as being my own observations, offered only for clarity and with-in the spirit of " Play Nice "! My goal is only that which is- - -
For the Future Good of the Craft ! Be safe, keep warm ! As always your comments and questions are solicited and are always WELCOME ! Big AL !

I meant that link to be a resource for Masonry Heater info in general. Lars is very well known.

I can't imagine a huge difference between the quality of workshops that would provide RMH DIYers training and one that would provide training in stone masonry.

There are American companies that offer masonry core kits. There are also many American companies, mainly in the Southwest, that offer kiva kits.