ash cleanouts and pipe -galvanised? chromenikkel? untreated steel? for mass rocket heater

Hello all,

We are currently gathering materials to build a rocket stove. We are based in Bulgaria, and unfortunately stove pipes standards are different here, 5 inch (13 cm) being the maximum available. We would like to build a standard, recommended 8 inch (20 cm) system so we need to have the pipes and bends especially made for us or order them through a specialized heating/ stove shop. Both options are costly as you can imagine.

The guy at the metal workshop gave us three options that he can use to make the stove pipes and any corners:

Chrome nikkel metal sheets - most expensive
Galvanised steel sheets - in between
Something they called Red metal - which we think is untreated (rusty?) metal - cheapest


Have been reading on galvanised pipes, and pre burning them, for the pipes in the cob bench which would make it slightly cheaper. http://donkey32.proboards.com/thread/373/afraid-galvanized-pipe-anyways

Would anyone be able to give us some help our thoughts on what we can best use from the above?

Another big question we have is about the clean outs. We have been reading Ianto Evans book, and he stresses there that the piping in the bench needs to be absolutely sealed so there is no danger of dangerous gases or monooxide escaping. With what would you seal them? But then... I just don't understand how this can go together with the clean outs that you need to be able to open regularly and will most likely not be 100% sealed at all. I also read about the solunit stove that seems to have the last clean out outside the house, where the exhaust pipe goes up I assume and the clean out is straight ahead (T shape). He mentions there that he also often has to prime the system there by burning newspaper in the cleanout so that the air starts flowing. http://ilovecob.com/archive/living-with-the-rocket-stove.

thank you enormously for any help!

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 !

Hello Allen,

Thank you so much for your very helpful, timely and elaborate answer This is helping us to make decisions and to move on with the project. Will go for cheapest material for pipe runs then, and get better materials for the T's and the bits that go outside through the wall. Have looked at the video on burning the barrel and pipes too. We are thinking about using 8 inch t junctions, and then using standard size (5 inch) plug holes and caps (that you can buy here cheaply) by fitting them in a short length of 5 inch pipe (the standard here), and cobbing that short piece of 5 inch into the 8 inch T junction pipe, to plug the hole. I assume that won't be a problem for the air flow since that is just a small section to the cleanout and the "main run"of the pipes is uninterrupted 8 inch pipe? We think this is a good idea because it will be difficult to get good airtight plug caps made for us especially in the right diameter of the whole system.

One more thing I have noted in a few places that you might be willing to comment on: making a sort of wider space or chamber that the hot smoke/fumes/gases move into when coming out of the barrel and are then channeled into the 8 inch pipes; here are two links that describe it and show it. http://donkey32.proboards.com/thread/337/helpful-hint
https://picasaweb.google.com/seedballs/HJRocketStove_Details


This sounds/looks like a sensible thing to do. It will also help us because our barrel to bench stove pipes connection will be under a bit of an angle in the horizontal plane because the barrel needs to be well away from some more combustible materials near the wall (beams), and this gives us the possibilty to sculpt that bit making it exactly right, instead of having a piece of metal made under a certain angle that will probably not be right

Again thank you very much for your time and help!

Helena Davies : I have a lot of fun every time I try to help on a overseas build, fortunately you have done all of the hard work already!

Yes, due to Turbulence and Laminar Flow losses you really do need a much larger opening than the Cross Sectional Area rule says, easily double and be very generous with your
ash pit, The HJRocketStove build does several things well, and we need to go over them ! He? created both a large hole in the transitional area, and then used some kind of mesh
Hardware cloth, or chicken wire like you find under stucco, to create a large ash pit and horizontal transitional zone out of structural cob,left it rough finished, and then after the
cob in this area dried, he went in through his clean out to smear a finish plaster made with fine sand over the inside of the transition area, the fact that he was using an 8 '' cap
made applying the finish layer much easier than trying to do it through a 5'' clean out cap ! Before I leave this build I most comment on his being trapped by a blind mind set,
after trying so hard to have a perfectly level horizontal pipe coming out of the transitional area the next thing he did was use two elbows to raise the height of his horizontal run
to a new higher plain .

There were two things he could have done differently, the 1st one was to raise the whole R.M.H. up to an equal height to start his horizontal run, this would have saved him from
having to deal with the increased friction losses of the 2 Elbows. Because they were used in a vertical (climbing) plain and not a horizontal plain he cost himself some where around
6' - 8' of additional distance the thermal Bench could have gone. Raising the R.M.H. would have raised the top of the barrel to a height that you would not be happy with ! Or since
he proved that he was capable of manufacturing such a nice transitional area I would have re-done the exit with a slight vertical tilt and by using just 1 Elbow adjusted out to 135
degrees, I would have achieved the same end result !

On page 24 in my copy of Ianto Evans Book I learned about off-setting the barrel to protect exposures, check it out, There is no rule that you need to have your horizontal plain
come out on the same side as the side that the Barrel is off-set towards, but thats what works for me ! For the good of the craft, Keep warm be safe ! PYRO-Logically Big AL

Dear Allen

Could you please explain/illustrate what you ment by the redesign of Iantos RMH with a drawing/sketch or photos ?

Warm Regards
Johannes

Dear Allen,

Thank you very much again for your comments! We have been back to the metal workshop again today and we will go for galvanised, because the other even cheaper material will probably not hold shape. The pipes are going to be way cheaper now, maybe only a third than we initially thought. They can also make the T pieces with airtight caps for us in the right 8 inch size so that will help with cleaning and plastering with smooth plaster of the chamber as you suggested. The price of firebricks has gone up though They are almost double the price if they order the amount we need now so to reduce costs we are going to make the heat riser from steel shape and perlite / clayslip mixture instead of firebricks as initially was the plan. The guys in the shop are trying to persuade us to add a bit of fire cement to the mix of perlite, so that if the steel burns away the perlite will hold shape better? would that be a good idea? I am hoping to post photos of our progress so that it will be useful for others to see how we get on....

Helena Davies : Bubbling up inside me is the punchline for an old joke that I had totally forgotten - And when their ships come in, they'll make ' Davies Navies !'

Your experience with the Tin Smiths is typical. I start a project, look thru my junk, make a couple of phone calls to scrap yards, the RE-Stores (Habitat for Humanity)
and then allow as to how I will have to go to Lowes, or Home Depot ! I forget how easy it is for us over here !

In the Rocket Stoves Forums I have "bumped up" the forum thread ''A castable burn chamber'' Scroll down to the bottom to read Matt Walkers answer
about the use of Furnace/Refractory cement ! ( then read the whole thread, lots of good hints ! )

My attitude is that I expect my Perlite/Clay Slip Heat riser to last about 4-5 yrs, by that time I am actually expecting a more affordable cast Heat Riser that will be
more efficient, at that time I will probably want to rebuild everything !

Yes please show us pictures starting from when you 'burn off' your barrel and hear Your Families Dragon's voice for the 1st time, I'm going to wish I was there !

Be safe, Keep warm! all comments are Welcome ! BIG AL !

J. W. : I don't think that the Rocket stove I commented on is a Peter Burg Build ! If so I would have given him credit, I made a remark about using 2 elbows where a single much
straighter one would be the way that I would have gone from the transition zone/clean out/Ash pit , to channel my hot exhaust gases up to the higher level that the builder
decided he? wanted to start his horizontal run at, The reason 'I think' that I would want to do this is to reduce Turbulence and Friction losses ! Hope this answers your
question.

again while I know that I have seen these pictures before, I was basing my comments mostly on what I was seeing ! Outside of my strong desire to always decrease Elbows,
which is a personal opinion, I think my comments were fair and well conceived, perhaps my failure was in not clearly communicating MY ideas!

I should never try and type long messages when I am too tired, If I have miss-comunicated again I willingly accept the fault ! MEA CULPA !! I'm sorry ! Hope this clears things up!

For the Craft, Be safe, Keep warm! As always, all questions and comments are solicited and Welcome ! PYRO - Magically BIG AL !

Dear Allan,

don't feel the urgue to answer me as soon as possible. I can wait.
Like I once mentioned before, I really appreciate your comments !

Ianto is in his book mentions about how to construct the first cleanout/ashpit :
use scraps of 1/4 " or 1/8 " hardware cloth or expanded metal lath or scrap sheet metal. Curve the lath into place to fit the shape using several small pieces, and then plaster
your sand-clay very carefully over its surface. Add extra volume of space at this location, as it is a prime candidate for ash build-up and blockage. If possible leave an ash pit
here up to one-gallon cappacity. An alternative ---if less aerodynamic --- approach is to rough out the box in brick, then plaster it inside and out with cob, really smooth.

Not easy to construct in my firt opinion, so if there is an another alternative to it, then I would welcome it.

I was curious about your remark : 'about using 2 elbows where a single much
straighter one would be the way that I would have gone from the transition zone/clean out/Ash pit'
But I did not understand your explanation.

The easiest alternative I see, is as seen in : http://www.youtube.com/watch?v=4usXIAoy9us , which is a removable upper barrel. Therefore the first cleanout/ashpit can be left out.

Allan, 'for the good craft', take good care of your self, take your time and answer whenever fits you. I can wait.

Warm Regards,
Johannes.

Dear Allan,

don't feel the urgue to answer me as soon as possible. I can wait.
Like I once mentioned before, I really appreciate your comments !

Ianto is in his book mentions about how to construct the first cleanout/ashpit :
use scraps of 1/4 " or 1/8 " hardware cloth or expanded metal lath or scrap sheet metal. Curve the lath into place to fit the shape using several small pieces, and then plaster
your sand-clay very carefully over its surface. Add extra volume of space at this location, as it is a prime candidate for ash build-up and blockage. If possible leave an ash pit
here up to one-gallon cappacity. An alternative ---if less aerodynamic --- approach is to rough out the box in brick, then plaster it inside and out with cob, really smooth.

Not easy to construct in my firt opinion, so if there is an another alternative to it, then I would welcome it.

I was curious about your remark : 'about using 2 elbows where a single much
straighter one would be the way that I would have gone from the transition zone/clean out/Ash pit'
But I did not understand your explanation.

The easiest alternative I see, is as seen in : http://www.youtube.com/watch?v=4usXIAoy9us , which is a removable upper barrel. Therefore the first cleanout/ashpit can be left out.

Allan, 'for the good craft', take good care of your self, take your time and answer whenever fits you. I can wait.

Warm Regards,
Johannes.

J.W. : In the H+J R.M.H. Build there is a picture that is captioned ""this shows the transition area completely encased in cob""

You can see in that picture to the right of the Black Steel Clean Out that the 1st and 2nd fittings leaving theTransitional area
are both 90 degree Black Steel Adjustable Elbows, Had I been there and the choice was mine to make I THINK that I
would have adjusted one of the elbows so that the angle was opened up from a 90 degree Elbow to approximately 135
Degrees, this would have allowed me to enter the top of the transitional area at an angle that should have reduced the
amount of turbulence.

Channeling the hot exhaust gases from a descending vertical,then flowing them across the transitional area horizontally, to
enter the 1st elbow, then rotating 90 degrees, then again rising vertically to the 2nd elbow and the second 90 degree turn
to horizontal has to produce more turbulence then using a double set of obtuse angles to flow the hot exhaust gases into
the horizontal pipe of the thermal bench !

Yes, I am making a major collection of the type of 55 gal drums with one end removable and a clamping ring !

Helena, I am afraid that it is a little late to introduce you to the type of 55 gal drum Johannes showed in his video also I
expect they are scarce in your part of the word, but he is right, it is a superior barrel and you can take the removable top
off to check to see if your R.M.H. needs cleaning, without disturbing the rest of your system, I still will have a ash pit and
clean out at that location - ''Belt and Suspenders '' I hope I have helped every one! For the Craft, Big Al !

Hello Allen,

Just a quick update - we ordered the metal work, but it won't be ready til the end of next week.. so not much happening hope you are well!

Hello, we've continued our story under a new topic. See here: https://permies.com/t/28339/rocket-stoves/test-set-results-pictures-expect#221882

Hi. Im homesteading in oslen krivodol, mezdra and have found supply of 6" / 15cm diameter stove pipe.
Its excellent quality with wonderful swept elbows too more minimal drag. If you want more details or want any let me know.
Ciao ciao.
Cen