How is aluminum as a rocket mass heater internal ducting material?

Hello everybody,

I recentley purchased the 'Rocket Mass Heaters' book by Ianto Evans.
I am gathering information from the book to succesfully construct my rocket stove mass heater ( 8 inch/ 55 gallon in my case).

The material to uses for stove pipe (for tunneling/internal duct) mentioned by Ianto : steel or aluminimum ( 9 meter/30 feet in my case).

My question : has anyone experiance with aluminimum stove pipe for tunneling/internal duct ? Or should I take steel pipe instead ?
Is there any restriction to the thickness of the aluminimum ? What temperature should I excpect in de tunnel ?

Warm Regards (Rossi style)
Johannes.

Johannes W.: Welcome to PERMIES ! And congratulations and a big Welcome to the premies Rocket forums ! You will long remember your first Post here !

The only factor in choosing what type of stove pipe to get is price ! Get the cheapest pipe you can get, that should be the lighter weight cold air return round
ductwork, all pieces within the Thermal bench should be considered sacrificial forms only ! However do not economize on needed clean outs, or the stove pipe
leaving the thermal mass and exiting the house !

Here you need to check on your local building codes, if they want insulated or Triple wall, I would give them what they want, while you may not need an Vertical
chimney going all the way to the peak of your roof, plan on it, and its costs and add sections as you discover you need them ! Plan on a last clean out as you
transition from the horizontal to the vertical after your thermal mass !

Please give yourself plenty of extra room for the Transitional Area from the bottom of the barrel to allow for a sweeping turn, out through the Rocket Stoves
Base horizontally and straight out through your first clean out - that 'T' should be positioned horizontally both ways to make using the clean out the easiest !

Plan on making your first trial burn, Outdoors after you have burned off your barrel, hint look at creating a pocket rocket stove to help you burn off your barrel ,
pages 76, and 77! Hint hold out for a barrel with one end removable and held in place with a clamping band ! This will make inspection and clean out
(and clean up) easier !

For the good of the Craft ! Be safe, keep warm ! PYRO Logically Big AL ! - As always, your comments and questions are encouraged and welcome A. L.

Johannes W. : I see that I did not address Aluminum pipe/ducting, That was do to my thought that you would be able to get a lightweight cold air return grade
(blue'd) steel for less than the price of Aluminum pipe in any grade or thickness! I would not use the aluminum to make up the Heat Riser or the first 6 ft of the
Thermal Mass ! Outside of that, again price should be everything!

You can call, or go to your local building supply, or hardware dealer. What you want to do is end up talking to the Guy/Gal that has been there the longest, and
knows what is in stock in the back room. Tell them you only want the lightest and cheapest grade as you are going to use it to make a form around which you
are going to pack Cob tightly - True! tell them its an Art project and you don't care what in inside looks like, it should never see the light of day - True ! Tell
them you plan on finishing your Art project with a dress coat of white on white Lime or gypsum plaster - True ! If they question whether your Cob can stand up to
the weight of your sculpture, tell the that you are trying to recreate an age old technique that uses chopped straw for reinforcement - True! You can tell him you
have plans to Test the use of chopped fiberglass matting and hardware cloth and know a Guy that knows a Guy if needed - True

The idea here is to find the store clerk that knows about that slightly rusty pile of the light weight stove pipe they thought they would never get rid of ! Failing in
that, you want to know if the suppliers they use might have some of that light weight pipe gathering rust and dust in a back corner of the warehouse !

Nine meters is just short of 30 ft, we usually figure that every Elbow that we use is ~5'~ worth of additional frictional resistance to flow. Every 'T' used for a clean
out slightly more, and Two Elbows needed for a reversal of direction equal slightly more than 10 ft. of frictional resistance to flow, Depending on the care that
you build with, you should be able to have a total run of 50 ft, this is probably safe for you on a first build !

For the Good of the Craft ! Be safe,keep warm ! PYRO Logical Big AL - As always, your Questions / Comments are Solicited and are Welcome ! A. L.

Hello Allen,

thanks for your input. It makes sense not to take aluminium the first section of the tubing/tunneling.
Also the barrel lid /clamping mentioned in your first response is usefull information, like : http://www.youtube.com/watch?v=4usXIAoy9us

I wonder : is the barrel clamped on a smal section of a second barrel ?
I also wonder how the barrel is cleaned, taking the lid of, or unclambing the barrel ?

Warm Regards,

Johannes.

Johannes W. : Yes, exactly like that, while I don't trust most You-tube sites this is a good series of Rocket Stove videos, THIS whole series can be trusted !
Paul W. the background voice, is also the'Boss' here at Permies. Ernie and Erica Wisner Attempted to teach me how to build rocket stoves So That I could
pass on the information, any failings are mine !

After you burn out your barrel - see video - you will cut out the other end, which then becomes the barrel bottom that mates to the Cob at the base of your
Rocket Mass Heater, We throw away the old gasket from the removable end, replace that with a fireproof rope gasket, and use the barrel as you see it in the
video, or clamp two Barrels together end to end too allow for an extra tall 'Heat Riser' - 'internal chimney' !

Yes Generally, you unclamp the band from around the top of the drum allowing you to do a quick inspection, cleaning, however you need to have a clean out
at the base of the Heater, whether you have that type of barrel or not !

Keep up your research, and come back here often with any concerns. If you can think of it, Ten more new members want to Know too!

For the Good of the Craft ! Be safe, keep warm ! PYRO Logical Big AL ! - As always, your comments / questions are solicited and are Welcome ! - A. L.

I have Promised Paul W. to describe the Rocket Stove Family this way -

1) The Rocket stove is for 'Outdoor' Cooking, and Feeding ! - Momma stove

2) the Rocket Mass Heater is for Heating, your home and Feeding its Dragon ! - Papa stove

3) The 'Pocket Rocket' is for Outdoor Heating, and - 'Picket lines' and 'Preppers' and 'Ice fishermen' - Red headed Bastard child !

Johannes W. : Sorry, I wanted to send you to - ' rich soil.com ' - when you get there, scroll down to and click on 'rocket stoves' the set of 12 videos can be
completely trusted ! Again I am sorry for my forgetting to send you to the address i was trying to send you to ! Big Al

I am curious if anyone has any information regarding the use of galvanized duct pipe as an alternative. I realize exposing galvanized pipe to heat is generally a no no, but I'm not sure that the lower temps of the exhaust would be of concern or not. Any help would be so greatly appreciated?

Graciella Ellis : Welcome to Permies, and a Big Welcome to the Permies 'Rocket Stoves / Rocket Mass Heaters' Forum Threads ! You will long remember your first few
posts Here at Permies !

The only Exterior parts of your Rocket Mass Heater possibly exposed to the air in your dwelling are the ones immediately between the R.M.H., and your
Thermal Mass Bench ! We take care of the galvanizing on the first 6' or so of our stove pipe when we build our 'pocket rocket', to burn out the interior of our drum,
and burn off the paint on the outside of the drum ! Everything else is safely buried in your Cob !

I have not run into any Aluminum stove pipe here in the Northeast, it may be a regional thing. I have heard of Aluminum stove pipe used with a trailer furnace
installation but again, have never seen it recycled ! Four or five feet down stream within the Thermal Mass should be more than safe !

There is nearly a complete discussion of how to deal with stove pipe and barrels in the previous discussions here in this thread !

Because you have not said that you have your PDF Copy of Evans' and Jackson's Great Book, Rocket Mass Heaters I am suggesting you go to cobcottage.com to
download your Copy $15.oo U.S. for an unlimited number of personal copies, there is STILL no better book in any language for 'Rocket stove family information' !
This is an essential first step for any Future Rocketeer,saving hundreds of hours in research and understanding our vernacular ! G'luck, come back here often !

For the Good or the Craft ! As always, questions and comments are solicited and are Welcome ! PYRO - MAGICAL Big AL !

Thanks allen,

I still think I'll try to find ungalvanized pipe first and foremost, as I have received very mixed answers to that question and would rather just not risk it. Anyhow I do own Jackson and Evans book, although they don't touch specifically on the galvanized question. We will more or less be following their design as it is our first RMH and they seem to be some of the better sources on the subject. Thanks for the help though. Always good answers and conversation here at permies.