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Rocket Stoves

 
Posts: 610
Location: ontario, canada
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i gave you a slice of PIE , first time i've ever given any!  but i don't really know what to do with it. :P  Here's the first rocket i ever made, my first one, i also used a 100Lb LP tank as well.  https://permies.com/t/240/52476/compact-RMH-hybrid-cook-top , it has a couple hundred lbs of homemade refractory mass internally :D  its a 6" CSA system.  i really like the 100 lb LP tank size as well, i called it "compact hybrid"

 
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Hello John,
Firstly, thank you for the pie! It is an honor when someone goes the extra distance to appreciate your work!
I watched your YouTube video of your first Rocket Stove and was very impressed with the design and overall operation. I too get better performance with hardwood pellets but I use softwood pellets for early fall and late spring. Your pellet basket burner is remarkable in its simplicity; I cannot tell you how many hours I agonized on developing a pellet basket that slides in and out of the burner tube so I could facilitate an easy preheat/ lighting process that my family could do in my absence.
I wish I saw your video much earlier in my design of the Frankenstove as I would have held out for a 100 pounder and used that as the form for the refractory. I can see how your stove rocks out as a 6” feed and riser. I’m certain the heat generated is amazing!  The reason for the 3” riser on my design was because it was originally meant to heat a 14’ aluminum stepvan, my original workshop. The only reason why it ended up in the house was, as I was testing it outside , my wife walked by it, felt the heat and said,” This.....whatever it is called, is being painted pink and being installed in the living room before our family Christmas dinner!”  All I could say was yes dear!
I incorporated an ash catcher to my stove because it lacks the draft of a 6 incher but the pellets that fall thru my pellet basket continue to generate heat in the stainless steel pot. Each morning there is about a cup of ash, much like yours.
As for refractory, I have about 24” from base of the cylinder that acts as the thermal mass and preventing it from cracking due to the thermal cycling.
I am trying desperately to source a ceramic spray from Eastwood to coat my riser, but alas, they are located in the eastern states and the cost of shipping to Canada is twice the cost of product. The ceramic coating would prevent deterioration if my metal riser and then qualify it as a rocket stove bu definition (ceramic riser).
I encourage you to throw a high heat paint on your stove and install it in your home and reap the rewards of inexpensive heat and comfort!
FFBD5AD4-6101-47E3-9DB0-ADB68A3DA886.jpeg
[Thumbnail for FFBD5AD4-6101-47E3-9DB0-ADB68A3DA886.jpeg]
Ceramic spray for riser
 
John McDoodle
Posts: 610
Location: ontario, canada
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i was thinking "header coating" before i saw your photo lol.   headers now are commonly made from stainless steel , which i think is also corrosion resistant, never rusts, and can take more heat than regular steel headers.  i used a stainless steel sleeve liner in the original one.  i thought yours was 100 lbs also?   i made 2 different pellet baskets.  one simple which fits the vertical feed tube, and another is a jet type burner, its more complex and fits inside the burn tube rather than the feed tube.  im in canada also!  
 
pollinator
Posts: 195
Location: Nomadic
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Thanks, please keep us posted on updates. Im in the Seattle region and glad to hear a 3” riser will do the job.
 
Peter Chauffeur
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Hello Jeremy,

The 3” riser works well for the design you see. It was meant to couple with the typical wood pellet stove venting kit that you can purchase at any “blue” or “orange” renovation store. I think it is important to maintain a consistent cross sectional  area through the rocket stove.

Going smaller in design ( ie 6” to 3”) does preset challenges. The draft demonstrated by John’s video is very impressive and although my design does make the characteristic noise of a rocket stove the draft by comparison is not. It is for that reason that I incorporated an ash capture system directly below the pellet basket and directly below the riser.  I encourage you to build one for yourself and find out what “ twists” in design you can come up with.
Be safe
 
Peter Chauffeur
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Hello Jeremy,

Another side note to my stove set up. My chimney needed an extension of 36” to increase the draft as the prevailing winds are 90* to the house wall. The extension was about $100 Cdn and helped to prevent back drafts. As I mentioned earlier, scaling down a Rocket Stove does have its challenges.
The other challenge that I can think of now is avoiding brands of wood pellets that have extra long pellets. These have the potential of getting lodged in the feed tube. From the research I have done online, the max length published is 40 mm. Of course wood pellets have a larger market demand in Europe ( 80% of  Canadian production is exported to the EU ) but that equates to 1.75”. The inside dimensions of my pellet  feed tube is 2”x2” so that is something to consider. I would recommend using a larger pellet feed tube and have it vertically mounted as opposed to the current design.
When I built the Mark 2 I poured the refractory around a piece of thick wall square tuning that the 2”x2” burner tube could slide into. I automatically bottlenecked the design by doing this. Fortunately, the stove does work well with the original burner assembly from Frankenstove and I am hoping to do another pellet feed / burner tube /  vertical feed / Steam addition / increased hopper capacity retrofit before the New Year. I have all the resources and parts ( except for the ceramic manifold spray) to do all of this ; just need to avoid the holiday “ Honey-Do” list.

Stay tuned, Be Safe


 
John McDoodle
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Location: ontario, canada
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yes the final stack does make quite a difference in overall performance!  what does the steam do?

take care!
 
Peter Chauffeur
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Steam addition is a way of reducing nitrogen into the combustion stream. Under extreme temperatures Nitrogen reacts with Oxygen to form nitrous oxides, (NOx). Under extreme temperatures the steam dissociates to Oxygen and Hydrogen free radicals and combines with CO and free Carbon in the combustion stream. Refer to Steam Reformation for a better explanation.  The Steam Addition, also adds a few percent of moisture to the combustion mix as wood pellets are generally drier than the ideal moisture content in wood burning.
 
Well behaved women rarely make history - Eleanor Roosevelt. tiny ad:
A rocket mass heater heats your home with one tenth the wood of a conventional wood stove
http://woodheat.net
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