What is the perlite in the concrete for? Just discovered these stoves today

I only discovered these stoves this morning. I've watched some videos on you tube and seen several where they are mixing perlite with concrete. Being thrifty I don't want to buy this and have concrete already I don't need. If its to keep weight down I don't care about that. I want something to boil water for canning. We have 4 large enamel containers we use for canning and now Its taking too long using propane outside not to mention trouble using camping stoves. I want to build something outside to boil my 4 large (5gal I guess) containers.
Right now I'm only wondering about the perlite and looking at the cheapest designs. I have got large spot to build something, wood and can make just about anything I need.

The perlite is for insulation, not weight. Concrete does not perform well in the kinds of heat that develop in a properly tuned Rocket Mass Heater.

For the purpose you describe, I recommend looking into "Rocket Stoves", which are not the same as Rocket Mass Heaters. The Heaters are optimized for holding warmth and dispersing it over time to warm an enclosed space, while the stoves are really intended for cooking.

Both use the same principles to provide very efficient combustion, it's how they use the heat energy produced that is the driver for all the differences among the designs.

Rosco Heber : Welcome to Permies.Com, our sister site richsoil.com, and a Big welcome to the Rocket and Wood stoves Forums! With over 22,000 Fellow
Members world wide, you can come here 24 / 7 , and expect to find someone who wants to talk about what you want to talk about ! Their widely, even wildly
different points of view will stretch your mind, as you will stretch theirs!

The first thing we want to establish is that you want A Rocket Stove, and in your case a large one, A home built Rocket Stove should allow you to produce a clean
burning fire comparable in every way to The best Commercial Wood Cook Stove you can buy, and you will be able to use close to 80% -85% of the heat energy for
large batch canning operations !

What you DO NOT WANT is A Conventional/Traditional Rocket Mass Heater, The RMH is designed to give off 40% of its total heat energy as Prompt heat, radiating
the heat energy off of the Barrels top AND sides, While the Arrangement of the Internal Chimney called the Heat Riser and the barrel top can be configured to
promote most of the heat energy radiating off of the top, any insulation on the sides of the barrel will merely transfer the un-radiated heat to the Thermal Mass
to be radiated off at much lower temps, this is the other 60%, and is a direct result of having been created to work that way !

Unfortunately the freaky high temperatures of a Rocket Stove built with your needs in mind both requires the use of insulation,and precludes the use of any Form
of Portland Cement ! The lime component in the Cement, or concrete made from Portland cements will Fail !

I have been doing a little research for you trying to find units of a decent size to allow you to make such a unit at home, hopefully One of the other members will
have better luck, mostly what is out there will have to be scaled up for you !
Please GoTo===> www.youtube.com/user/aproresearch?feature=watch [i][/i

This is an institutional model and can be costume sized by you to the size of your 5 gal~ish pots ! For the good of the Craft ! Big AL !

I've been watching videos and reading all day and have some idea about this whole topic now. I'm wondering how to get the max amount of heat from one of these for heating the pots we're going to use for canning. Last year I tried doing it with a fire and pots on a grill I made but it took way too long and we didn't get anything done efficiently. I've got various materials on hand and am thinking of making a few prototypes. I'm wanting max heat and if possible self feeding fuel.

Try looking into pot skirts. They are a flange thing that directs the heat right up against the pot. They greatly increase the efficiency of cooking. It allows you to squeeze efficiencies from a smaller fire.

Use this

With a J tube instead of the old L tube, and may be insulate the barrel for more heat.

Rosco Heber : Erica Wisner ( Erica and Ernie Wisner are our forum leaders for Rocket and Wood Stove Forums !) has an experimental Build similar to the Aprovecho
model with a vertical feed , and she and Ernie have got internal components up to Forging Temperatures, And there is a considerable discussion on its use as part of
the [ 4th DVD of 4] that is for sale here at Permies.

Again everyone here is very much into Rocket Mass Heaters, but Know that you have to have something more like the earlier Rocket Cook Stove, I am actually
amazed we have not been able to help as much as we would like !

As an interim solution the propane Turkey roasters that quick fry whole (THAWED) Turkeys in oil, arevery much in a class of their own for BTU production ! Big AL !

Hi,

as you need an oven to heat big containers, you perhaps beststart with a big variation of a rocket stove plus a matching pot skirt, tailored to your geometry. Have a look at this Rocket Stove
Lesson Book from Rechorocket.com Rocket Stove Lesson Book

good luck
Ludger

Like this idea for the skirts. That "institutional rocket stove" with the pot inside really seems like what I need. Most of time I would only be using these big canning pots. I watched the video and now I'm going to get the materials and make one. If it works like I think it will I'll make three more. Sure wish I was still working at the weld shop with all that free metal, plate rolls, and a cnc plasma table.
I might want one of these mass storage for my greenhouse or heating my outdoor workshop. Thinking on how to make some sort of self feeding system. I'll keep looking and reading. I found the book everyone is talking about(Ianto Evans) at scribd.com where I can read it for free. Y'all are being a big help Thanks

Rosco, i don't know how moveable you need it to be, but it could be intresting to use refractory innards, for the longevity. I don't know how long an institstove lasts, but with refractory flue liners, it could last more. And if you want self feeding, use a J tube.

I've watch their vid on building this Institutional Stove a few times. It says they are using "special heat resistant metal" for the combustion chamber. On another of their vids showing them building the stove with all the fancy sheet metal equipment I believe he said its 310 Stainless. Anyone know what gauge this is? Stainless sheet is kind of hard to come by out here away from the big city.

For good stainless, look for used restaurant equipement. Usualy there's a seller not far from you, who will have a skipfull of old stuff, with fridges, air extractions, diswashers etc.

Rosco Heber wrote: I've watch their vid on building this Institutional Stove a few times. It says they are using "special heat resistant metal" for the combustion chamber. On another of their vids showing them building the stove with all the fancy sheet metal equipment I believe he said its 310 Stainless. Anyone know what gauge this is? Stainless sheet is kind of hard to come by out here away from the big city.

310 references the particular stainless alloy. Could be pretty much any gauge, specifying alloy type doesn't help with gauge estimation. Typical ductwork runs around 20 to 24 ga, I believe.

If I were going to use steel to make a J-tube for a rocket, I would be starting at 12 ga. and would be happier if I could get 1/8th inch. I would be afraid that the lighter gauge material could burn out if a hotspot developed, or just soften and melt through. We are talking some pretty crazy heats in the burn tube.

This link has a chart regarding the High temperature resistance of various alloys of Stainless steel. Stainless Steel is obtainable via web order from something like on-line Metals, but really expensive.

Stainless Steel - High Temperature Resistance

Rosco Heber : I am sure that the Good people at Aprovecho have fielded this question before, I would try Googling Aprovecho Newsletter,
Find their "ABOUT'' link in their blue banner at the top of the page, and Follow the 'Contact Us' information !

And then come back here and tell us us a blow by blow of how it went ! For the Craft ! BIG AL !

Cindy Mathieu wrote:This link has a chart regarding the High temperature resistance of various alloys of Stainless steel. Stainless Steel is obtainable via web order from something like on-line Metals, but really expensive.

Stainless Steel - High Temperature Resistance

Chart was real helpful. I possibly can get me some 304 free. Place i used to work had pallets of 6in ss pipe remnants I put off to the side to buy for scrap and then sell. Then company decided to see themselves. I'm going to see if any of the guys there will get me a couple of pieces. I wokred
I've bought from these metal dealers many times, when I worked at machines shops. In big cities they have places you can go in and get cut right then. They sometimes have remnants cheaper. In Kansas City their was a scrap yard that had a whole stainless section. Now I'm in Ozarks and the pickings are pretty slim. Good dumpster diving factory (Skil) went to China.
Looking at vid I think they are using 10 or 12 gauge.