Helena Davis : Welcome to Permies.com And a big Welcome to the Rocket stove and
Wood heater Forum Threads, You will long remember your 1st few posts here at Permies.
You need to regard ALL of your 8 '' pipe to be sacrificial forms, Expect that they will all lose their integrity and fall apart ! There for Cheapest is best, hands down. With the
lightest grades of stove pipe, you need to be very careful that they do not get crushed during installation before your cob and infilled rock becomes a monolithic structure.
Take a look at our sister site, richsoil.com, and click on 'Rocket Stoves', there you will find a set of videos of a series of
Rocket Mass Heater R.M.H. Builds done by Professionals,
or under the direction of Pros . The 8th?
video shows you how to burn out your barrel and also cause a change in the way zinc galvanizing is bound to the stove pipe, note the
change in appearance in the stove pipe from shinny to dull, This is a very important step and
should not be passed over !
With due care, which would require a full build of your new R.M.H. outdoors (minus cob) to prove that you have a working rocket before moving it indoors, and then carefully
bedding in your stove pipe, and taking care with a 2'' layer of structural cob followed by a finish plaster coat for waterproofing and beauty, you will have a sealed unit that will
quickly convince you of its utility and safety.
As a Fireman/EMT I in no way wish to down play the dangers of exposure to
Carbon Monoxide, at the time Ianto Evans wrote 'The Book on Rocket Mass Heaters' we had been
through two major Oil Embargoes, and A lot of people were creating flaming units of death, sometimes calling them Rocket stoves or Mass heaters ! You will note that these
units are always operated with open feed tubes, sometimes being partially blocked off to more directly cause the inward flowing air to channel past the burning wood ends !
Clean outs are 'goes into' plugs that should seat into a 'T' or a tight fitting metal ring that has had several flat headed roofing nails pre-driven through the ring to help that ring
lock into the cob, this is checked after every cleaning, or sign of trouble with a candle, or a little incense, or a twist of a sweet smelling herb like sage, to check to make sure
that a leak is not pulling air into the R.M.H., If air is not being pulled into the thermal bench during normal operation, you will not have a problem with C.O. after your nightly
shutdown !
Again all the metal used to make up an insulated heat riser will burn up, and the stove pipe that you are using to make a form should be only considered as a sacrificial form!
save your money for good quality 'T's and clean out caps, and any locking rings to help seal the clean outs, some times people will place decorative tiles over to clean outs,
to hide them from little fingers that just want to SEE inside and they can be covered in clever ways that increase safety, but that is a personal decision .
Many years ago when i was in the service I found myself on a " if it moves, salute it, if it doesn't move paint it " detail. This is a great rule for building your R.M.H., at every
step along the way you should have a bucket of Clay Slip *, and paint everything that will get covered in cob, this is everything from the place where you plan to seal the barrel
to your Rocket,all the way down to the floor, every gap is your enemy slowing the transport of heat
energy through your Thermal Mass and every bond made linking cob to its
neighbor makes the whole system tighter stronger and helps transport the heat through your thermal mass that much faster !
* this is more easily demonstrated that talked about, ask a potter to show you ! If you tell them what you are doing they may have a common barrel where different types of
clay find them selfs at the end of the day, you may end up with a
gift of more additional clay that you can use, a tour of the pottery shop, and or a willing helper ! Hope this helps
and is timely ! For the good of the Craft !
A late note, 'I love cob' has a beautiful house and he fairly reports what it is like to use HIS R.M.H., in HIS location! Y.M.M.V. !! Never, Ever, consider a damper in your R.M.H.
Think like Fire!, Flow like a Gas!, Don't be the Marshmallow!, As always, your comments and questions are solicited and Welcome ! PYRO - Logically BIG AL !