Rocket Stove Heating Element

[Monster Mash]

The only drawback is flame control. If you see a boil over coming on there is little you can do about it.

 

[Ppeg34]

As a general rule of thumb it seems like a horizontal chamber diameter of half of the burn chamber diameter is the sweet spot, with a heat riser diameter as large or larger than the burn chamber.

I am now thinking I am wrong on this one. Although this seemed completely right in my experience, I am seeing a lot of places say that all chambers should be the same diameter all the way through the system. I think the big risk with making the horizontal chamber smaller than the rest of the system means that the restricted horizontal chamber can cause your feed chamber to burn too quickly. This would mean too much fire and not enough air flow which causes smoke back. In an outdoor application this wouldn't be the end of the world, however.

 

[Varmintman]

I have to say I was a doubting Thomas at first when I started to read this thread but now I am thinking this will be a cool project. Kind of has me thinking about something for the house and a hot water tank

 

[Monster Mash]

I made a rocket stove out of an old turkey cooker pot and sawdust. I put a hole on the side at the bottom and put a pipe in it, also stood a pipe up in the center and packed it with sawdust. I removed the two pipes and lit the sawdust from the bottom hole and it drew air in as it burned. The only problem it I could not put it out without soaking it with water which ruined the rest of the sawdust....


Here is a video

 

[Ppeg34]

Here is my newest design. With the addition of an adjustable air inlet, you should have a pretty high degree of control over temperature. The wood would be loaded vertically into the feed chamber and a cover placed over the top to prevent uncontrolled airflow.

The sketchup doesn't show any jacket for the keggle or anything like that. Also the dimensions should be a tad smaller to accommodate the keggle.

Let me know what you guys think.

 

[reynolds5520]

Restricting the airflow can make for an inefficient and sooty burn. A wye pipe with dampers below the kettle could be used to adjust the heat level at the kettle without restricting airflow, bypassing the excess heat away from the kettle. Maybe a thermostatically controlled damper could be used to keep the heat even while you dial in the fuel feed rate.

 

[Ppeg34]

While browsing the internet on how to bring this dream to fruition I stumbled upon this:



It is a series of 8 videos on exactly how to make a rocket stove out of a barrel. The one they build uses a 60L (15 gallon) cooking vessel. It looks to be just the ticket.

I guess the one improvement that everybody says is necessary is temperature control.

 

[philber]

I guess the one improvement that everybody says is necessary is temperature control.

Good find. The answer to your question may be in part 2 of this video. He stated that the hot air gap must be the correct size otherwise too much heat will go up the chimney and not be transferred to the cooking pot.

If you raise the pot and/or divert hot air up the chimney then you could, theoretically, control the heat to the kettle. I think heat changes would be slow so under/overshooting will be a problem.

But it is good to know that if the world goes to sh!t we can still brew beer, just camp out near a grain silo

 

[FreeParty]

With a rocket stove and all wood burning stoves the temperature of the fire is a function of amount of fuel and type of fuel. Hardwood burns hotter than softwood, fir bark burns hotter than hot, etc. Also with a boil over, just pull out the fuel.

Most of the heat is transferred to the cooking vessel and not to the drum in this case. When there is no fuel in the burn tube there is no heat going to the vessel (hot enough to continue a boil).

 

[Ppeg34]

Yeah I am with both of you on that. I am thinking this would be no problem to be the boil kettle. My worry would be that for an HLT it would be too difficult to hit target temperature without an under/overshoot for your mash. Although, I am confident that once you build it you will have enough of the moving parts in front of you to figure all of that out. That's typically my philosophy at least. Sometimes it works and sometimes it doesn't. Of course if you really want an extreme degree of control you might as well go electric.

I was pretty amazed at the ingenuity of the process to build that thing, though. Absolutely no power tools necessary and the thing is practically free except for the pot, fasteners, and combustion tube. The way they build it, power tools are almost more trouble than they're worth (that almost seems like an oxymoron).

But it is good to know that if the world goes to sh!t we can still brew beer, just camp out near a grain silo

If beer was the one thing keeping anybody on these forums from exiling themselves from humanity I am happy to announce that this should no longer be a hindrance.

 

[mattd2]

Yeah I am with both of you on that. I am thinking this would be no problem to be the boil kettle. My worry would be that for an HLT it would be too difficult to hit target temperature without an under/overshoot for your mash...

You could just boil the water in the HLT = 100°C then mix with cold water coming out of your tap to get your target temp?

 

[Ppeg34]

Well that's about the most no-nonsense thing I have ever heard! :cross: