Rocket Stove Heating Element

[FreeParty]

I am wondering if anyone has experimented or is using a rocket stove to heat their brew?

I am thinking of constructing a three tier keggle structure and heating my barrels with independent rocket stoves. I am still in the dreaming stages and looking for help on the dimensions of the stove.

Those of you not familiar with a rocket stove, basically, it is a very efficient wood burning stove. In operation it does not create smoke because nearly complete combustion of the fuel is achieved. Its fuel is finger sized sticks.

Help me brainstorm with positivity on why this will work and possibly save home brewers money by not buying expensive stoves and fuel. I am aware of the hands on approach in this set up but that is why I home brew. If I wanted an automated machine to brew my beer I would buy manufactured beer.

 

[FooFan]

Never used a rocket stove before so I am not up to speed but....
I would wonder how well you can controll the heat. I have a three tier stand that runs on propane, one burner for each tier. When I brew I make many flame adjustments many times...

 

[Chemkrafty]

I'm familiar with the rocket stove design from reading permies.com. I don't see any reason why this wouldn't work. You'd just need to put enough forethought into the design so it is large enough to heat 6-7 gallons (assume 5 gal batch). for the BK. You would need a separate one for the HLT.

For temperature control, You could potentially design the system to raise or lower the stove, roll it in and out from underneath, or maybe a fan to turn on and blow some heat away from the pot?

 

[Varmintman]

Mind you I am not familiar with a rocket stove. I wonder how many BTU's one would put out though. Heating a house verses bringing a big pot of water to boil are 2 different animals

 

[Ppeg34]

I am in love with this idea.

Let's say as a conservative estimate that there are about 6000 btu's per pound of seasoned wood (from my few moments of internet searching). Let's say that you need to bring 12 gallons up from 50 degrees to 212, that's 162 degrees.

There are 100 pounds of water in 12 gallons.

It takes 1 btu to bring 1 pound of water up 1 degree F.

It would take 16200 btu's to bring 12 gallons up to boiling (half of that for 5 gallon batches).

Let's say that we get about 30 percent heat transfer from flame to boil kettle. We are getting 1800 btu's per pound of wood transferred into the kettle.

16200/1800 = Exactly 9 lbs.

So a very rough estimate is that it will take you 9 lbs of wood to bring a 10 gallon batch up to temperature.

I think this is very doable and would absolutely love to see you pull this off! If you do, please document with many photos.

 

[japroto]

I am wondering if anyone has experimented or is using a rocket stove to heat their brew?

I was wondering that myself and have read about rocket stoves on Permies.com, here is a link to get more info if you are not familiar with rocket stoves...
http://www.youtube.com/watch?feature=player_embedded&v=t4kX6i4qGRw

I think it would be really awesome to have a rocket stove setup but I don't know what level of control you would have over the heat being put out. It's crucial to be able to control the heat output of a burner otherwise you can't dial in the right temps. For example, I use a banjo burner on my keggle setup and I can't leave the burner open full bore or things get crazy hot, I have to dial it down to the lowest setting once I have a boil going. Definitely an interesting thought though and Im sure it could be made to work with a little ingenuity.

 

[Monster Mash]

You will definitely get a lot of soot on your pots but I don't see why it wouldn't work.

 

[feinbera]

Presuming he's got a big enough stove to bring his pots to a boil when it's going full blast, a combination of adjusting the height between burner and kettle and simply choosing strategically when to add more wood should give OP the ability to maintain temperature -- if he's willing to invest in good thermometers and watch his system like a hawk.

I did wonder whether nine pounds of sticks or thinly-split logs would be hard to come by, but, some quick googling puts a cubic foot of wood at anywhere between 25 and 50 pounds; cut that in half to account for the air space between small, irregularly-shaped pieces, and his nine pounds of feed stock would be a pile a foot on a side and somewhere between five an ten inches high -- seems imminently doable.

I do wonder if you couldn't "throttle" a rocket stove, restrict the incoming air-flow to slow down combustion and cool things off, much like closing the lid on your grill when you want to cool down the coals? This would be easier to build than an adjustable-height system, but it seems like it might result in smokey, incomplete combustion.

 

[reynolds5520]

You should be able to improve efficiency by jacketing the kettles. If you find it hard to keep a clean hot fire while throttling back the fuel supply, some additional control could be gained by using dampers to divert the exhaust flow away from the kettle.

I did some experiments years ago with a rocket stove to replace a low efficiency cast iron wood stove in my house. It was a high thermal mass design cast from refractory concrete. The concept was good but there was one major flaw. I should have used a ducted outside source for the combustion air. The stove was very good at sucking all of the warm air out of the house.

 

[purplehaze]

Excellent idea, I am about to embark on a heater version of this. What's the amount of wort you want to boil with this?

Things to think about:
-Ceramic, fire brick or light weight cement for the combustion chamber will last longer than metal. Having said that you still may want to build your test stove out of metal for ease of construction. (A metal bucket or barrel, metal pipe and perlite)
-Experiment with the diameter of the "L" tube to get the heat output you need to boil large volumes.
-The use of a "J" tube or a "tee" would make it somewhat self feeding.
-To use a rocket stove for your MLT may be a bit of a challenge.

In addition using an insulated pot skirt will make the stove much more efficient. I use this with my propane burners with excellent results.
See this thread- https://www.homebrewtalk.com/f51/saving-propane-time-while-winter-brewing-393425/

 

[japroto]

You will definitely get a lot of soot on your pots but I don't see why it wouldn't work.

According to the permies.com articles on rocket stoves you would get a really clean burn, "exhaust is nearly pure steam and CO2 (a little smoke at the beginning)"...
http://www.richsoil.com/rocket-stove-mass-heater.jsp


Cool image of how it works...

 

[purplehaze]

Here is at least one person using a rocket stove to brew with. It does not have dimensions but you may get a few ideas.

http://www.greenhomebrewing.com/?p=54

 

[FreeParty]

Great help everyone, thanks. I am making my keggles next week and then onto the rocket stove, which I cant wait to share.

One thought/question on the topic of mash tun:what if I made a conical false bottom for faster and better draining of the mash. Has anyone tried this? Is it worth the effort??

 

[tony4308]

I bookmarked a bunch of sites on youtube about rocket stoves last summer and was thinking along the same line of op, with a twist i was thinking steam see this ---> https://www.youtube.com/watch?feature=player_embedded&v=EY6QOB8pql8

Then I saw a way to fuel the steam and keep the kids busy --->
http://home.fuse.net/engineering/videos.htm

And the free plans to build the presses for the fuel---> http://home.fuse.net/engineering/

From Paper and Leaves---> https://www.youtube.com/watch?v=6cvE4jp8-78

any way you get the idea a herms system only backwards pumping steam through the wort to get it to boil. think it would work or am i Mad as a Hatter? Remember 40 psi of live steam..... And then ...don't get me started on the Mash Tun

 

[Ppeg34]

Thats not a bad idea. It is a lot easier to control steam than it is to control combustion temperature and air flow etc.

 

[Monster Mash]

I built a rocket burner that burns wood pellets and has full heat control. I wouldn't use it for brewing because it would make a sooty mess on the pots.

Here is a video of it working. Click on the pick....

 

[FreeParty]

I have thought about using the RS to create steam but I do not know it would be easier to control than controlling the amount of fuel placed in the combustion chamber. Would a steam jacketed kettle be the ideal way to heat the kettle? Is the steam used in some kind of heat exchanger? How does one control the temperature output of steam heat in brewing????

Also, I do not see the problem in a sooty mess on the pot. I have come across a guy who says he rubs dish soap on the bottom of the kettle before putting it on the burner. The soap is a barrier between the smoke and the kettle. The soap also is there to be used for its intended purpose once the kettle is ready to be cleaned.

I dont know what a rocket burner is as pictured above. I dont believe it is related to a rocket stove other than in its name.

 

[Monster Mash]

I dont know what a rocket burner is as pictured above. I dont believe it is related to a rocket stove other than in its name.

Actually the one I built is a wood gas stove, as the wood burns air goes over the top to burn the smoke which makes a very hot burning fire.

 

[Ppeg34]

Here is a photo of one I built out of old bricks and cinder blocks from the woods. I used clay dirt and water as mortar.

I mocked it up without any mortar and think it worked better before. I am thinking that this may have something to do with there still being a lot of water in the clay mortar and this is preventing the burn chamber temperature from getting as high as it could be. I am hoping that once everything dries we will see a boost in performance.

I think if you wanted to use keggles its going to take a bigger stove. I also cooked up some stir-fry in a wok last night over top of it and it worked like a charm. Got the pan super hot and everything came out great.

I am also wondering about using a pot skirt/wind screen. I think that would make this thing exponentially more efficient. I have also seen most other rocket stoves use insulation in their burn chamber and I am thinking this would result in a huge boost in combustion efficiency. I still get quite a bit of smoke and I only sometimes get that rocket sound wave that people talk about with their rocket stoves.

I will probably dismantle this thing at some point and try and make it bigger.

Total cost: $0.00

If I had enough money in my account to play around with i would look into building one with vent pipe in a bucket with insulation and a pot skirt. Yes, I know fiberglass insulation is dirt cheap and so is vent pipe and a metal bucket.

Actually, I might rather buy a cheap welder and some scrap metal and go that route.

Hope you'll put some tires to the pavement soon and try something like this out.

 

[noblebrew]

I had the same thoughts and found this site that has a design tool and some math to help you out.

 

[Ppeg34]

That is a pretty awesome tool that looks like it would result in an awesome finished product. I wish this was an option for me, but I am currently renting...

Add this to the list of never-ending diy projects that will commence once we buy a home.

Maybe this is an option for the OP? In some of the photos on the website they are using some massive pots. I am now feeling like this is extremely doable.

What I could do, though, is convert some of those dimensions to a less involved/more portable option.

 

[japroto]

After doing some random surfing looking up counterflow chillers I stumbled upon the video below which shows how to use a Stovetec Rocket stove to heat up a 40gallon water heater without a pump in about 30 minutes using just scrap wood. I think that the same method could be used to heat/circulate for brewing in a similar fashion to a HERMS setup but without a pump...

 

[FreeParty]

I have still only put the pen to paper on this but this is what i got so far. HLT heated by the stovetec hot water heater by convection using a rocket stove feeding the mash tun by gravity. Mash tun (ale pale insulated with old towels or clothes and maybe duct tape) unheated and feeding boil keggle by gravity. And BK heated by what is called an institutional rocket mass heater. This is named so because it is appropriate technology for large scale cafeterias (institutions). It is constructed using two 55 gallon barrels and one 10 gallon barrel with precise measurements to effectively use fuel and decrease smoke, pollution. I found it on the www.aprovecho.org.

I need to relax on my spring cleaning binge and get this going already and BREW.

 

[japroto]

I have still only put the pen to paper on this but this is what i got so far. HLT heated by the stovetec hot water heater by convection using a rocket stove feeding the mash tun by gravity. Mash tun (ale pale insulated with old towels or clothes and maybe duct tape) unheated and feeding boil keggle by gravity. And BK heated by what is called an institutional rocket mass heater. This is named so because it is appropriate technology for large scale cafeterias (institutions). It is constructed using two 55 gallon barrels and one 10 gallon barrel with precise measurements to effectively use fuel and decrease smoke, pollution. I found it on the www.aprovecho.org.

I need to relax on my spring cleaning binge and get this going already and BREW.

Cool! I would swap the ale pail for an insulated cooler if you could as it will hold the temp much better. When I first started all grain I used a home depot 10 gallon cooler and that thing held its temp really well and was like $40...

 

[FreeParty]

I wish I could find a 10 gallon water cooler where I live. Nothing like that is available, and the camping coolers are small (5 gallon) and expensive ($80). Only in the USA are coolers cheap. So I want to make my own. Does anyone know the chemical reaction for making polystyrene foam? I know I made it in third grade science class but can't remember how. And it is impossible to find any information on the internet, it is top secret I guess.

 

[philber]

I knew I saw one of these setups where a guy had a 5 gal boil going.



Looks easy enough to put together.

 

[japroto]

Awesome videos, great find!

 

[Ppeg34]

After fiddling a bit with the design of the my rocket stove I think I have found a general rule to optimize the burn...

Like I said before, I was feeling like my stove wasn't all that it could be and I believe the reason why is in the horizontal chamber

The horizontal chamber is the area between the burn chamber, where you put your wood in, and the heat riser, aka chimney area. Here is a diagram of what my stove looked like before:

The right, cross-sectional diagram of the stove shows the horizontal chamber as having the same diameter as the rest of the stove, 4.5 inches.

Here is what it looks like now:

The horizontal chamber is now half the diameter of the rest of the stove. This causes faster air flow through the wood, giving it the rockety sound wave you hear so often and a faster, more even burn. From what I have come to understand, the heat riser can be relatively large, but the horizontal chamber's diameter can not be larger than your burn chamber. Also, if it is too small it will cause too much of a bottle neck and you will get smoke back.

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.

The underlying assumption here is that this is completely scalable to any dimensions, which I am pretty sure it is, but we need someone more competent in thermodynamics than I am to comment on this.

Comments or corrections are greatly appreciated.

 

[philber]

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 had recently read or watched a video where they went into the actual numbers on this. Next week I will have some time to play with this and a few designs I have floating in my head. I need something to do during the mash

I do recall the website I found a lot of info on rocket stoves: http://permies.com and hit up youtube for "rocket stove bricks" your design above is easily done with less than 50 bricks, they even have some more simple 16 brick designs, but to get the heat required for 5-10 gal boils a larger more efficient design is needed. I have spent hours fascinated with the variety of designs and applications on youtube.

 

[noblebrew]

on the vary last page are some numbers and math. One day when we settle down I would like to make an institutional rocket stove on which to boil my wort. http://www.rocketstove.org/images/stories/institutional%20stove%20manual%20november%202008.pdf

 

[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 **** 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 **** 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.