Jesse's Modular RMH Experiment

Hi Jesse, et al

This company makes prepared vermiculite mortar for fire resistance / fire insulation.

http://www.pullrhenen.nl/thermisch/en/vermiculite_mortel.html

Note that the product description suggests that the finished weight is approximately 20% of the weight of mortar alone; that seems to suggest a 4:1 or 5:1 ratio of vermiculite to refractory? mortar. The page shows a table with given ratios from 1:2, 1:3, 1:4, 1:5, up to 1:12. But the table isn't clear as to which material each side of the ratio refers. It seems here to suggest mortar:vermiculite (mortar/vermiculite).

What do you think?

Naturally, that perlite mortar or vermiculite mortar from Pull Rhenen seems ideal, but I don't see it for sale anywhere! Perhaps the next best thing is the vermiculite or perlite with pre-mixed refractory mortar at the 4:1 ratio, maybe 5:1 if we can get away with it.

Thinking a little more along the lines of reusable forms.... That same guy that did the 5-gallon plastic drum rocket stove with vermiculite and refractory did it with plastic plumbing pipe. He used 4" pipe, coating it with used motor oil. First he poured the mortar mix into the bottom of the bucket, then setup the pipes, then poured the rest of the mortar mix over the pipes and up to the top of the bucket. Once the mortar set, he slipped the pipes out lickity split in 5 seconds, real simple.

Soooo.... Perhaps you could easily re-use the outside of the cast box form, done in plywood, and swap 4", 6", 8" or even 10" pipe depending on whatever size system you are building.

While I think I prefer the square burn tunnel and feed designs, I like the idea of reusable forms like this.

This company makes prepared vermiculite mortar for fire resistance / fire insulation.

This sort of material is suitable for the heat riser, but is probably not sturdy enough to put up with jamming wood into it for the burn tunnel portion of the rocket heater. I believe you will find it is very crumbly and easily broken.

Perhaps you could easily re-use the outside of the cast box form, done in plywood, and swap 4", 6", 8" or even 10" pipe depending on whatever size system you are building.

The problem with this idea is that the length of the burn tunnel needs to match the internal "Cross-Sectional Area".

Ok I can understand that. Aside from swapping the different sizes, separate reusable forms for each size might still be a useful approach....

Then again....

Perhaps we can simplify the burn tunnel and the riser with ceramic board?

This stuff looks great!

http://skylinecomponents.com/In-Stock_CeramicFiber.html

Would you need 1" or 2" board, at what temperature rating? 1800, 2100, 2300, 2400?

Seems like we could easily get away with 2" 2300 2x3 sheet, $59. The 1" stuff is $35.

I found the 2" 2300 2x3 on eBay for $119, free shipping.

Have you checked the modulus of rupture on that board after its been heated?

Is it tough enough to put up with pieces of wood being jammed from the feed tube into the board?

Cindy Mathieu wrote:Have you checked the modulus of rupture on that board after its been heated?

Is it tough enough to put up with pieces of wood being jammed from the feed tube into the board?

Tough cookie this stuff is hard to figure!

Here are a couple of 1/2 scale molds (the first to make it this far) almost ready for the maiden slip casting attempt:

Hi Jesse

Pardon the obvious (perhaps), but... how do the pieces fit together? It seems like two left sides and no right side. Perhaps half of the bottom and half of the top?

Confused!

Ha! Yes I can see how this would be confusing. It's not obvious at all really because the form on the left was an idea I've already discarded. I might use it just to practice slip casting, but it may (probably will) go straight into the archives. The form on the right is the first one I've pulled off that's consistent with the 4 piece idea I posted images of a little while back. The idea is to see if I can even pull the technique off before making more forms.

HI
I'm new and just started playing with the rocket stoves. And I apologies if I am butting in. I seen your cardboard forms, nice. You mention they are not sturdy enough. One thing I do know is fiberglass and concrete. Have you thought of using the cardboard forms to make fiberglass forms. It would be a simple process of coating them release agent then with cloth and resin. (Maybe fiberglass resin is not in keeping with the forum but they would be reusable) also when placing the concrete would it go easier if you would take a electric sander and put around on the form to "vibrate" the concrete in place. Just some thoughts.
I'll be watching with interest.

Hi Jesse, et al

This afternoon I assembled the burn tunnel form (interior / Inside form) for my first rocket stove, thanks to tips from Matt - broaudio - on YouTube. I also glued the walls of the outside form. I used a jigsaw to cut the inside forms from hardybacker board from Home Depot (3' x 5', $10) using a glue gun to assemble the forms. I might put up pictures tomorrow ciao

Hi Everybody

Here are my design files. Perhaps you can use them as well for your project. I can email you the PPT file if you send me a message.

K.

The slip casting piece of the experiment has been going for about a week and a half now. Not much progress has been made.

Of the things I've tried thus far, I think the slip casting thing has some real merit. There are still lots of kinks to work out. At this rate if I wait to figure it out, It'll be next winter at the earliest, before there's heat coming from my basement. I think the thing to do is to get A core completed and gain some experience sooner rather than later. The slip cast idea will probably become a thread unto itself.

Funny how this is shaping up. The idea I appear to be landing on for a good and inexpensive core "right now" is cobbish in a wooden box (touché Paul)...

At any rate, it's time to start making wooden boxes and filling them with the stuff of a RMH. The "modular" part of the project is something I know I can pull off. Here's a little different view of the overall layout as it stands.

Jesse Biggs :I really like your whole project, and the direction it is headed in ! you totally get the idea that the mass serves us best as a sculpted piece of
built-in-furnature! Just a reminder that the extra elbow in the 180 degree turn at the end will reduce the total amount of Bench you can have by 5' and you
should have a clean out at That Location ! For the Craft ! Big Al

That's a beautiful design! I Like it!

It'll probably undergo several more iterations, but thank you. Here are some views from the other side. Allen, the overall run is about 25' right now, and it's an 8" system so I'm thinking it's still well within range. I appreciate your pointing out possible sticking points so I don't screw things up too bad, so please flag away.

Let the box making begin!

Your craftsmanship is gorgeous!

His photography isn't to shabby ether, you go ! Jesse !! Big AL

Jesse.

http://donkey32.proboards.com/thread/560/half-barrel-system

http://donkey32.proboards.com/thread/609/heated-seating-nyc-restaurant

http://s65.photobucket.com/user/mremine/library/NYC%20Rocket%20Stove%20Build/#/user/mremine/library/NYC%20Rocket%20Stove%20Build?sort=3&page=1&_suid=1390550695375037029796303863593

http://donkey32.proboards.com/attachment/download/345

http://donkey32.proboards.com/attachment/download/346

Thanks for sharing that stuff Max. Got the wheels turning.

By way of an update...

This Saturday a few folks are coming to help me fill the benches with gravel so we're now in full fledged "get it done" mode.

Some pics:

more:

and more:

and one more

Care to give up what mix you decide on for your pours?. Looks like your setting a goal for other to reach to

I ended up using 3 parts perlite to 2 parts fire clay, simple as that. We'll see how it shakes out.

Some thoughts... I live in suburbia (in an HOA even). I've posted this publicly here and in a couple facebook groups. Some people I don't know yet are coming to help me work on it in a few days. I figure it's a matter of time before "bad guys" get wind of what I've done. If I can just get enough time to compare heating bills before and after + prove that it's completely clean and safe + make it "pinterestable", I might have a fighting chance. Other people might even want to do something similar. Probably not, but maybe. A guy can dream right?

There were folks here 2 days ago helping me get things buttoned up. The system is still quite cold and wet and I think some optimization needs to happen, but we did burn a fire in it for about 1/2 an hour. Here are some pics of what happened over the weekend.

You'll notice there's a "fancy" corrugated metal roof wall behind the bench. while looking for the cheapest metal roofing I could find for shelter in my chicken paddocks, I decided 50 cents a square foot was a great price for a finish material and might help me achieve the man cave ambience I'm going for. Also, I figured if I didn't get that bit of the wall finished in some way, there was a real good chance it would NEVER get finished.

more pics:

more:

a couple more details:

You are using pebbles and not sand, right?

It sounds like you went with cobbish. Be prepared for cracks and to seal up those cracks with more cobbish.

It's gravel, but it's pretty small stuff. I found a killer deal on 15 tons. Over time I plan on getting lots of bigger stones buried in there.

I've already had a pretty massive failure in the cobbish riser, which I'm currently fixing. Photos to come. Got a cold snap coming so there's incentive to get this thing cooking.

Awesome project Jesse ! Love it

Jesse-
I've been following your project since the first postings you made. I was intrigued by your use of a mold to cast a core.
I am thrilled to see your work coming to completion. It is a beautiful unique and simple design. I especially like the modular nature of your system.
Will there be some kind of finish coating on top of the pebbles?

A thought about the riser. I'm not sure but the thought occurs to me that using fiberglass mat (or perhaps fiberglass cloth) which is used in fiberglass auto body work (one of my lines of work) would work to reinforce/wrap the cob on the riser. The mat type is kinda like a denser version of those cheap furnace filters i.e. random strands. The cloth type is an actual woven strand material and much stronger. I'm not sure of the heat tolerance of those materials for use on the inside layer of the riser, but I think it's pretty high. It might be cheaper than other alternatives.

I was just reading the shipable core thread when the fiberglass thought popped into my head, and after seeing your post there I think you might be a top contender for a cheap lightweight design. Looking forward to more progress on that front.