Sophie Gell

I have built a RMH and multiple outdoor rocket cooking devices in Delaware County NY, somewhat near Eastern PA. I'd love to build one for someone or help out. Email: gell.sophie@gmail.com

https://permies.com/t/146580/worked-codes-RMH-Delaware-County

https://permies.com/t/163599/rocket-ovens/Barrel-oven-encased-cob

hello I am nearby in delaware county bordering otsego! I am a 25 yr old floundering around up here. I have built a rocket mass heater, am in the process of building an outoor kitchen with a rocket oven and cookstoves/earthen countertop. And more builds planned for the spring and summer. Always looking for more...

pics!

Wanted to post an update on this project!

We got very far, then a set back. Looking forward to finishing in the spring.

It's a 6.5" J tube powered rocket oven, but as stated in the title, we used cob as the shell. For the metal fabrication of the inner barrel, I followed the permies plans exactly. The J tube dimensions are somewhat unique, as they have to be so that the oven is not too high.

Fabricating the metal frame to hold the barrel 2" above the riser was rather tricky. Constructing the armature to support the cob out of Luan, was easier than expected and seems to have worked well.

Once it was cob time, it was pretty much smooth sailing. Until the rainstorm. I was planning to do a 'smoothing coat' of just sand and clay to set the tiles into. Then come back in the spring to plaster when it warmed up again. Well I did that, and then a very windy thunderstorm blew the tarp off and set me back quite a bit. Lost a good amount of material, it just slid right off under the weight of the water and gravity. I threw what I could back on, expedited the roof. And now we are on hold until spring. Will update.

I did get to fire the oven a couple times, got it to 350 without trying too hard, and it was still wet. I am hoping for much higher temps. The exhaust was very hot, so I installed a damper but haven't tried it out since. Felt like walking a fine line between wanting to fire to dry up the cob shell, but not wanting to burn out the armature before cob could support itself. In the end not sure it mattered much.

Quick update!

Finally got a finish coat on after a year and I am very pleased!
The finish is extremely hard, even the areas that remained somewhat rough do not break or dust off.
And I'm having pretty much zero dusting.

After the plaster went on I did 3 coats of linseed oil. You can see that the oil was not absorbed evenly resulting in some discoloration. I suppose I could apply another coat to the areas that remained light but I don't want to smell it right now.

Recipe I used:

3- Fine mason sand
1 - Equal parts clay slip- horse manure
1/4 c boiled linseed
1/4 c powdered milk
handful cattail fluff
I added some ochre pigment too

In one of the before pics you can see serious water damage done to the pure cob my previously leaking chimney. Well now the chimney is fixed and I even spilled a cup of tea on the surface of the heater- it stayed as puddles and was not absorbed by the plaster. My mind is blown. Yippee

Oh! I did make the mistake of leaving the linseed oil to cure on the tiles in between coats. I did not know it would gunk up like that. Scrubbing each and every tile with mineral oil was a pain- now I know!

Hi Nancy and Trevor!
Sorry for the delay but cool to hear there are interested neighbors. I did finish and ran it all this past winter. Still need to get to the finishing coat though.

Thanks all! I will have to make a temporary frame for the cob or brick out of willow, or plywood. It seems that, understandably, the expansion of the metal frame causes the masonry to crack/shift over time. Do you tend to use high refractory materials for the j-tube as you would on an RMH? It seems most people are just going with regular brick. What did you use Thomas?

Additionally, I've been binging a lot of youtube videos of wood cookstoves like this:  
I am surprised that the fire would come out of multiple places and still remain strong enough to heat the pans. Do you buy it?

Hey yall.
So i'm developing a plan for an outdoor kitchen: (barrel oven, rocket stove, and a griddle bbq setup of some sort. At first I was wondering if all could be powered by one J-tube. hot air going up riser, into one end of oven chamber around and out into a tunnel with an opening for a stove, a griddle, and finally a looong chimney at the end. Now I don't feel too confident that exhaust would be hot enough to be of much use after going through the oven system.

So now I think I will give each feature a separate core, but I'd like to keep them aesthetically part of the same cob "form". I know that most rocket ovens have a metal outer layer, which makes sense bc of contraction and expansion. I've been looking at this oven https://www.firespeaking.com/videos/wood-fired-barrel-oven-video/ , it's not powered by a rocket core but other wise seems like a similar idea. If I built a brick cavity or was able to make the outer cavity of just cob somehow, is it likely that this thermal mass would affect the technology in some other way?

Thanks,
Sophie

Hi Gary!
Thanks. When you say your final coat of plaster, do you mean your final coat of cob? So same mix as the rest, but with the addition of wheat paste? and may I ask what ratio you would use with that. Thinking maybe this plus linseed is the simplest option.

Hello!
It has been a couple months but just wanted to pop in with some updates.
My RMH has been doing a great job keeping me warm through this cold winter, though I am excited for the temps to go up and to give it a nice long vacation.
Overall its been great, I'd say that it does use a bit more wood than I'd expected to need prior to completion, still significantly less than the wood stove, although definitely more processing labor required. On the days that I work i generally start burning it around 6pm to 10 pm (with the door closed) when I go to bed. In the morning I am cold, but my room is still significantly warmer than the other rooms in the building. All that being said, it has been below freezing for around 2 months now, and it operates in a traditionally built semi large, one floor building with lots of windows, but no passive solar, and no other forms of heat. For the most part, I am warm, so I'm happy.

Now that spring is growing near, I am starting to think about a final coat for the heater. My top coat now is just a pretty smooth careful layer of cob. There is plenty of dust and sand to sweep up one the regular, and any water drip or spill is a bit traumatizing. Some tiles are lifting out, and some of the sharper corners have little chunks missing.

I guess the 3 options are clay plaster, lime plaster, and or linseed oil?

Looking into lime but I am concerned about the freshness of Type S Lime (what appears to be available), and concerned that I won't have much luck getting a fresh batch due to covid and all.
Clay plaster seems more simple but I will need to collect some very specific materials. (Manure, cattail fluff, very fine sand). And will the clay plaster protect the cob from occasional water damage?

I guess the third option would be another thin (corrective) coat of cob and then linseed oil.

Curious on your thoughts! Hope everyone has been safe and well.

Curious if anyone has any reccomendations,