Portable RMH what to use for the burn chamber and up pipe?

I want to heat a large tent 20x32.

I understand using any metal short of tungsten for the burn chamber/up pipe will not work long term.

Needs.
Be able to relocate so heavy bricks are not a solution.
Not looking for super light. (the tent is 700lb)
The tent has lots of ground level access ports so I will want to take the exhaust out of the tent at that level not through the roof.
The tent is double wall and can seal very well will want to feed the heater from an outside pipe.

I have looked at lightweight fire brick and pumice concrete.
Any ideas on what material I can use to for my burn chamber and up pipe?

I am skilled at building all sorts of things I want to build it not buy it.
I have seen dragon heaters' cores I don't see where they would allow for drawing air from an outside source. and I would rather make it myself.  

Once again my big question is what to make the burn chamber and up pipe out of.

Thank you.


 

I'm building out of Perlite and Rapid Set Cement All.
I wet the Perlite,let it drain,then I mix the two ingredients at 1 part Rapid Set to 6 parts Perlite.
I stack square wooden forms around a round metal duct,mixing and packing as I go.
I have not fired these cores yet, but they do set up hard.
The Rapid Set Cement All is available at Home Depot at about $20.00 american for 50lbs.
I chose it because it is a Calcium Sulfoaluminate cement , with at least one msds document listing the decomposition  tempature at 2460°,which is a little low for use in a rocket core,but time will tell,and you can't beat the price.

EDIT: 2190° is the expected highest tempature in the core.

The Perlite costs me $4.00 for 2 cubic feet at my locally owned feed n seed nursery type place.
Perlite sinsters at 1598°,melts at 2300°.
I was going to substitute one or more part of the Perlite with fireclay,to assure strength at high temperatures,but around here it's hard to source and about as expensive as the Rapid Set.

Being mostly made of Perlite, the core are pretty light.

Of course, insulative refractory bricks would work as well, but they are neither cheap or easy to come by.

Ceramic fiber board insulation.
https://permies.com/t/65256/portable-collapsible-rocket-stove-deck

Carrie, it's early days yet. I tried to post a video of my first burn with no success.

Do not use metal in the burn tunnel and riser.    In fact, it can even be a bit dodgy in the wood feed.    Metals will spall or melt at temperatures much lower than we are shooting for (2000 to 3000 degrees F).

Next up:  portland cement spalls at 600 degrees.  So that doesn't work either.

Perlite starts melting at around 1400.  We have lots of perlite glass blobs from risers that had perlite.

We have a few portable cores here made with refractory cement.  Pretty heavy.  

The best core we have is made from ceramic fiber.  Pretty spendy.  

I think that it would be wise to make something from duraboard for the burn tunnel and riser, and then firebrick surrounded with duraboard for the wood feed.  And then foam cement around all that, complete with a perlite/portland cement or foam cement for the manifold.

paul wheaton wrote:Perlite starts melting at around 1400.  We have lots of perlite glass blobs from risers that had perlite.

I am now a sad puppy. But how sad?
Have the perlite risers melted entirely or are they just replete with blobs of perlite glass?

On another note, if perlite isn't going to sinster into a glassy tube, a granular material that will burn out without leaving much residue could be substituted,leaving insulative voids in the riser after firing.

You guys do know that this is what DVD 3 is all about in "Better Wood Heat" - right?

I sure didn't. Looks like HD streaming costs about what I've spent on the two cores I'm working on.
A single "disk"might prove worthwhile to me.
For me, if the cost of auto repair lessons approach the cost of a car,tools and access to Youtube, I'm gonna pick the latter.
Same with baking bread,for instance.
I found out where to source the ingredients cheaply enough that every loaf could be a learning expirience,rather than a risk of precious resources.
I have at least a hundred dollars in high quality bread baking books, but it's the notes I've gathered from my own experience,and forum threads that have served me best.

Anyway,I think I'll go ask Matt Walker about his experience with perlite in cores.

For the OP, I just noticed Matt has a video up about using ceramic fiber board in rocket stoves:
http://donkey32.proboards.com/thread/2315/ceramic-fiber-build-discussion

Matt is super helpful,as is everyone at Donkey' s rocket stove forum,so check it out,they might able to help you with your quest

The 4-DVD set has Matt Walker in it.   And Donkey is going to be here for the rocket mass heater workshop jamboree in a couple of weeks.

Hi, I did a portable rocket stove/mass heater for my house. Because I rent and I'm not able to have a wood burner or rocket stove in the house. So what I did was I had 3 x 25 litre metal drums  welded together with a basic 90° pipe inside it. Then packed it with perlite and slag rock that I found on a beach not far from a steel making plant. It had a metal lid on top of it. I then adapted/cut up a shopping trolley/cart, put a strong metal Base plate that can take the weight as it was pretty heavy. What I did then was I did a burn outside for 2-3 hrs till the mass in the drums was pretty hot(too hot to touch, then let it burn out and when the fire had gone out, pushed it in my back door and into my kitchen in the early evening and it stayed there till the next morning, and was still hot then. I regulated how much heat came from it by putting foil over the top of the flue pipe, as hot air rises from the inside of the upright as it was heated/warmed by the mass. I did use thin pipe which burnt through after two years but it kept my 3 bed house toasty warm through the night even on cold nights here in the UK. It was even hot enough to keep the house warm through to the aftenon the next day so was near enough piping hot for 20hrs. I've got thick steel pipe this year and will be changing it to a 2 drum rocket stove as the 1st one was VERY  HEAVY. Hope this is helpful.