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rocket stoves

Looking for a workshop Heater - something like the cottage rocket

Posts: 270

Location: S.E. Michigan - Zone 6a

posted 1 year ago

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I have a metal 20' x 20' building that I use as a workshop (Versatube carport) in S.E. MI. I need to provide some quick heat for a couple of hours during sessions in the spring and fall. I'm following Uncle Mud's cottage rocket and it looks like it is the solution for me, but I have a couple of questions. I do like the vertical footprint as it takes up less floor space.

Is there a reason the feed tube is inside the circle of the drum? It looks like that would really limit the length of the wood you can put in. Is there any reason why the feed tube couldn't be moved outside the barrel?

Also, do I need anything besides the heat riser in the barrel? I don't think I need mass as I'll be in the workshop for an hour or two and then I'll be done.

I will not be using this during the coldest months of the year so what size system should I work towards? 6"?

I'm open to any suggestions that would provide a solution for me.

Thanks,
Jerry

Starting on developing a 10 acre permaculture homestead in a sub-urban area. see http://www.my10acres.info

Gerry Parent

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posted 1 year ago

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Hi Jerry,
A typical J tube build has the feed tube outside the diameter of the barrel.
It appears that Mud probably just condensed it further in to make the unit more compact for those tight cottage builds.
In your scenario, mass isn't necessary as much as radiant surface area.
Have you considered placing a second barrel on top of the first?

I used a 6" double barrel system for many years in my 20'x20' workshop with 10' ceilings with no problems.
Larger 7 & 8" systems will hold more (larger diameter) wood and burn a bit longer. Personal preferences...

Silence is Golden
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Douglas Alpenstock

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posted 1 year ago

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Hey, did you look at this thread? 9 years and working fine.

https://permies.com/t/29007/Repurposed-lb-pig-rocket-heater

John Weiland

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Location: RRV of da Nort

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posted 1 year ago

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In addition to those already posted, please see if any of the design in this link is of use: https://permies.com/t/42529/FWIW-Rocket-stove-heater-concept#333627

Please also note the excellent comments/criticisms of the design in the subsequent responses within that thread. Wow!....I can't believe I submitted that entry around 7 years ago! These stove is still operating just fine.....with the taller exhaust stack as recommended. Still hoping to add mass to it sometime......but admittedly it's a prototype and I fire it up only about 15 - 20 times a winter. Good luck!

“The most important decision we make is whether we believe we live in a friendly or hostile universe.”― Albert Einstein

Jeff Bosch

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posted 1 year ago

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Gerry is correct.

The feed tube is inside the barrel for compact design and less likely to stub your toe in a limited space area like a cottage.

No, there isn't anything special in the workshop models of the cottage rocket.

I would second Gerry's suggestion for a double stack of barrels for maximizing the radiant surfaces.

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Jerry Ward

Posts: 270

Location: S.E. Michigan - Zone 6a

posted 1 year ago

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For a double stack of barrels, how high does the heat riser go? I bought Paul & Mud's e-book on heat risers and assume the 5-minute riser is the way to go for this application. But the book doesn't address if it is important to have the heat riser within X% of the top of what ever barrel you have.

Starting on developing a 10 acre permaculture homestead in a sub-urban area. see http://www.my10acres.info

thomas rubino

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posted 1 year ago

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Hi Jerry;
I use double barrels on my shop stove.
The 48" riser is just below the top of my first barrel and the second barrel is empty.
In the early days of RMH experimentation, placing the riser within a few inches of the lid was common.
This was thought to create a "secondary burn" assisting with complete combustion.
Later testing and the development of the Batch box design proved that having the riser shed its heat fast is better than slowing it down with a sharp corner.

20220709_110851.jpg

20220916_175857.jpg

Snatch block to ease second barrel install /remove

For all your Rocket Mass heater parts.
Visit me at
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Gerry Parent

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posted 1 year ago

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Jerry Ward wrote:For a double stack of barrels, how high does the heat riser go? I bought Paul & Mud's e-book on heat risers and assume the 5-minute riser is the way to go for this application. But the book doesn't address if it is important to have the heat riser within X% of the top of what ever barrel you have.

There is a minimum distance but no maximum (within reason).
Just create your heat riser the length it needs to be proportional to the system size and your good.
With all the space above the riser, the hot gasses have much more room to move around, shift directions and of course give up as much radiant heat as possible with minimal friction.

Silence is Golden
For all your RMH needs:
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thomas rubino

rocket scientist

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posted 1 year ago

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Hi again Jerry;
I like an 8" J-tube over a 6" simply because you can use larger wood and it will burn 45-60 minutes before reloading.
A 6" has a very small feed tube and requires feeding every 30 minutes or so.

For all your Rocket Mass heater parts.
Visit me at
dragontechrmh.com

Jerry Ward

Posts: 270

Location: S.E. Michigan - Zone 6a

posted 1 year ago

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8" tube sounds good.

Has anyone tried building the burn tunnel out of clay chimney flue? You would need some specialized tools to cut it to form the turns for the wood feed and the start of the riser, but I have access to those. From what I've read the heat riser gets really hot (goal is 2,000-degree range) but I don't know how far down into the burn tunnel that heat gets.

Starting on developing a 10 acre permaculture homestead in a sub-urban area. see http://www.my10acres.info

thomas rubino

rocket scientist

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Location: latitude 47 N.W. montana zone 6A

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posted 1 year ago

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Hi Jerry;
They sure have been tried... they crack every time.
They can not handle the fast temperature variances in the burn tunnel.
I believe some limited success was had by splitting the clay flue in half, effectively cracking it intentionally.
Firebrick is your best long-term choice.

For all your Rocket Mass heater parts.
Visit me at
dragontechrmh.com

Jerry Ward

Posts: 270

Location: S.E. Michigan - Zone 6a

posted 1 year ago

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Is dry-stacking considered the best option for firebrick? Leave a little room for movement.

Starting on developing a 10 acre permaculture homestead in a sub-urban area. see http://www.my10acres.info

thomas rubino

rocket scientist

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Location: latitude 47 N.W. montana zone 6A

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posted 1 year ago

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I have only dry-stacked batch boxes.
My J-Tubes were all clay mortared.
No reason not to dry stack as long as your bricks are in near-new condition.
A stiff backing outside of the bricks is needed to encourage them to stay in place.
A J-tube works best with a "Peter channel" providing fresh air and protecting the first brick of your burn tunnel roof.

For all your Rocket Mass heater parts.
Visit me at
dragontechrmh.com

Jerry Ward

Posts: 270

Location: S.E. Michigan - Zone 6a

posted 1 year ago

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Should I be considering a batch box over a J tube? I haven't read much on batch boxes over they years that I've been lurking on Permies.

Starting on developing a 10 acre permaculture homestead in a sub-urban area. see http://www.my10acres.info

thomas rubino

rocket scientist

Posts: 5619

Location: latitude 47 N.W. montana zone 6A

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posted 1 year ago

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Well, Jerry, I consider them a more helpful stove for a busy life.
They burn much hotter.
They use larger / longer firewood.
They have a door to keep things (Kids, toys, dogs, cat tails ) out of the fire.
They burn/ hold coals for 2-3 hours.

The only cons against them. You lose the throaty dragon's roar that an open-throat J-Tube gives you.
And the large view of the fire that is possible with a J-Tube.

I had nothing but J-Tubes for years.
They are an awesome stove.
The large brick bell and double barrel stove in my shop started out as an 8" J-Tube with a single barrel into that same brick bell.
The 6" batch in my studio started out as an 8" J-Tube.

You can build a J-tube first and then convert it over later.
Here is the thread where I convert the studio stove over to a batch.
https://permies.com/t/148226/Dragon-Transformation-tube-Batch-Box
and another
https://permies.com/t/150380/Happily

For all your Rocket Mass heater parts.
Visit me at
dragontechrmh.com

Jerry Ward

Posts: 270

Location: S.E. Michigan - Zone 6a

posted 1 year ago

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I have a 25-year-old air compressor that finally gave up. I think the air tank will be useful in this project.

Starting on developing a 10 acre permaculture homestead in a sub-urban area. see http://www.my10acres.info

Chris McClellan

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Posts: 528

Location: Burton, Ohio

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posted 2 months ago

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Jerry, how is your project going? Why did I not see this thread earlier? Here are some examples of the CottageRocket built as a low mass high radiation workshop heater.

CottageRocket-Manual-double-c.jpg

Workshop Rocket Heater with Double Bells

45368841_10215506304964762_2173400541520986112_n.jpg

Cottage-Rocket-(6-inch-Workshop-Configuration).jpg

A 6 inch Cottage Rocket with an extra barrel for fast radiant heat

IMG_20181113_191058551.jpg

You can follow my latest adventures at
https://www.unclemud.com
https://www.youtube.com/unclemud
https://permies.com/u/164246/Chris-McClellan
Buy my stuff at https://unclemud.com/store/

Chris McClellan

pollinator

Posts: 528

Location: Burton, Ohio

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posted 2 months ago

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If you have more room you can build a workshop batch rocket like this one we built last year at Wheaton Labs. Sorry this is the only footage I have of it but we hope to have plans available for it soon. It takes longer to warm the room than a workshop cottagerocket but it puts out more heat. https://youtube.com/shorts/USxEs6RJdC0

Also the fantastic door and secondary air channel were built by Thomas Rubino. I highly recommend his stuff.

You can follow my latest adventures at
https://www.unclemud.com
https://www.youtube.com/unclemud
https://permies.com/u/164246/Chris-McClellan
Buy my stuff at https://unclemud.com/store/

Jerry Ward

Posts: 270

Location: S.E. Michigan - Zone 6a

posted 1 month ago

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Uncle Mudd,

My project stalled, I ended up building a house. It will probably be spring before I get back to it.

Will you be running a workshop again at your place in OH?

Starting on developing a 10 acre permaculture homestead in a sub-urban area. see http://www.my10acres.info

Chris McClellan

pollinator

Posts: 528

Location: Burton, Ohio

221

posted 4 weeks ago

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I will certainly be running more Build Your Own CottageRocket workshops at my place in Ohio. Please drop me an email at info@unclemud.com Right now I'm in Montana finishing that last workshop build. Here's the pretty video

You can follow my latest adventures at
https://www.unclemud.com
https://www.youtube.com/unclemud
https://permies.com/u/164246/Chris-McClellan
Buy my stuff at https://unclemud.com/store/

Live a little! The night is young! And we have umbrellas in our drinks! This umbrella has a tiny ad:

rocket mass heater risers: materials and design eBook

https://permies.com/wiki/188812/rocket-mass-heater-risers-materials