Decided to build my first stove

Been trying to wrap my head around this rocket stove thing and decided to jump into the mix. I have a 24x36 shop that I would like to add some heat to.

So I'm a total rookie with the steel working stuff, go easy on me.

Here is the video of the google sketchup plans:


And this afternoon I found the parts I need:


Big thanks to tryin2lhard and peapod and a myriad of other guys who have given me lots of inspiration. So much good content out there, will post more videos of the process.

Any comments or help along the way would be greatly appreciated.

Ah so you had to one up on us eh?:>) Pun intended, I like the idea man, pretty cool.

With that thick stainless steel I am betting you will not need to insulate them with the header wrap.

Stainless is an amazing reflector of heat, let alone the thickness your using, I bet that cost you a pretty penny, how much was the stainless tubing?

Looking forward to seeing your finished build man.

Haha, I'll not count my chickens before they hatch :) but yea, have been seeing that stainless makes a nice riser. Thanks for the kind words and advice.

The risers I found from a local shop are a 3 inch (schedule 10?), they got me for just shy of $12/ft, so each riser is 2 feet, 2 of them came in just under $50.

I'm a software engineer by trade, havent welded anything since Jr. High, so this should be an adventure :)

Nice concept. It will be a first I will actually see someone making a double riser rocket stove. The contra-vortex idea is nice. I just noticed that you forgot to mention the secondary air. You need to make a door for the combustion chamber and a door for the wood feeder. I suggest you put an air valve on both doors. You can as well place a dumper at the chimney collar it will allow to save even more fuel. What diameter chimney will you use? Do not forget to make a clean out for the heat exchanger.

After checking that your stove works well, you can even install a glass window on the fuel feed tube.,,

@catropheus I found some 2"x1/2" channel that I was going to put on the bottom (outside) of the burn tube and feed back to the heat risers and pop up somewhere in the bottom. The thought is that it would be hot and preheat the fresh air somewhat.

Can you elaborate a little on what a "dumper" is? I had originally planned on the cap for the feed tube being solid and the air coming in the void on the bottom that is left where the cylinder feed tube overlaps the 4x4.

Definitely want to do the glass door front like I saw in the tryin2hard design.

The chimney will be 5 inch out the back. This seems like it would work as it is slightly larger in area than my dual 3" risers are.

Thanks for the feedback!

For a chimney dumper, take a look at my latest video on Youtube or at trying2hard videos of his stoves.

The secondary air has to enter into the risers as hot as possible to cause spontaneous ignition of smoke and gases, so, air has to be channelled on the top of the flames.

The 5 inch chimney will work fine.

Now, concerning primary air supply, You need to have a possibility to control your primary air. Otherwise you may have difficulties to light the fire or have smoke back draft or other issues. If you build the stove like in the design, it will work fine but you need to cover both bottoms of the feeder tube and heat exchanger.

LOOKING INTERESTING MAN! TWO HEAT RISERS - FIRST TIME IM SEEING THIS. CANT WAIT TO SEE THE FIRE SWIRLING EACH SIDES..

This thing is going to kick out some serious heat! Can't wait to see it in action.

With opposing vortex's you will have some crazy air movement at the top of the heat exchanger.

That guage stainless tubing will not need an insulate, both of my stoves use a similar guage and they perform great without it, even without the secondary air intakes.

If this ends up looking half as decent as the CADs then this will be one nice stove! Very interested to see the final version.

As for welding skills - I wouldn't worry about them....that is what a file or dare I say it a grinder is for right......well it is in my case anyway  :oops: 

Look forward to seeing the next installment.

Thanks to everyone for the feedback. Wanted to post up a couple changes I made based on the feedback I got. I am still lukewarm about pulling the "fresh" air from where I am pulling it. But we'll give it a try anyway.

Waiting on a grinder to arrive so I can get to work. Truck is out for delivery just in time for an xmas present for me :)

Nice ideas. Just one remark, you have to suck secondary air from outside in an independent way you suck primary air. It will give you more control of the fire. Also do not forget the air wash to keep the glass clean.

Nice design and love the double riser, never got time to build one and enclose it so looking forward to see how you get on. just one thing....Dont make the cut outs too small on the risers as it will drastically reduce the flow inside them.

Be interesting to see the effect of opposing vortx, will they cancel each other out when they exit the riser top?
Would two matched vortex merge at the top creating a stronger downward vortex?
Answers on a postcard please   

Well, the last week has been one of learning for me. A comedy of errors, but I love the learning process too, so it was pretty fun.

First, tried to mark out stuff with a white crayon, that was a bad idea. Ordered some welders pencils and soapstone which work really well.

Then the grinder arrived, and I decided to cut out some pieces. Had no idea how LOUD metal on metal would be. So I had to order some ear protection.

Finding a good way to clamp the stuff so I could grind on it was a trial as well. You gotta remember, I really had nothing but an idea a month ago, so I am really fumbling through this.

At any rate, finally got to cutting, and was finally able to get everything cut out! The metal can really heat up when grinding on it, grabbed stuff a time or two and learned that lesson.

Picked up a welder and some wire, will give that a whirl tomorrow. I do have good eye protection and gloves so I hope that will do.

@ppotty1 I am really torn on how big to make those cutouts on the risers. If I have a 4x4 burn tube that is 16sq inches that need to enter the risers. I have heard that you want to be no less than 90% of that number or things will not draft properly, but more than that and you wont get the acceleration from a venturi type effect. So in my plans I have the openings between the risers together totaling 14 sq inches. I plan on making them small and increasing them slightly, gathering data and documenting each jump.

Here is the result so far:

Looking good so far, the riser cut outs look to be about right for the size of the tube. I would tack just the risers and the feed together and have a quick test burn to see how it performs, no rules with this as you might be the first one to try it out.

I think you need to figure a way to control the #2 air flow. You may just end up with a bypass that cuts out #1 air. Also, You may learn to hate that feed tube. Wood loves to get hung up on any little projection and, certainly, can't stand to be compressed through a funnel. Squash that feed tube to match the burn chamber and you'll probably be happier.
Awaiting further vids.
Great looking concept!!
Kevin

ievolve wrote:

I'm a software engineer by trade, havent welded anything since Jr. High, so this should be an adventure :)

Welding  is a lot like learning how to riding a bike for the first time, It will come back to you with a little practice.  

Nice SS pipe ! Looking forward to seeing your RS when your done. 

Well, fabrication complete and first burn is in the books.  I got some video and will post it up later today.  Overall a pretty learning experience.  I have a whole bunch of questions now though, probably easier to explain in a screencast so I will follow with that video as well.

To save the suspense.  I did have brief moments of blowing flames out the top of the riser shortly after the heat risers were heated, about 4 mins, but that roaring flame only lasted for about 2 mins.  For the most part I was able to maintain about a 6-8 inch dual vortex, but just didnt feel like I was getting the full secondary burn happening, as a result I wasnt seeing an ultra clean burn like I have seen with other stoves.  It was about 15F outside last night at 1AM when we lit it up, the top 3/8 steel plate above the heat risers toped out at about 620F.

As other suspected, the 18" feed tube did create a bit of a chimney, midway through the burn I pulled it off and just fed wood in the top hole.

At any rate, more video, ideas, and tinkering to follow...

Looking good so far, you will get a big flame out when you first light the rocket, you will find they calm down when the riser gets hotter, if you do a big re-fuel it will flame out again I guess its something to do with the gas created from the fuel mass once it first starts burning. some air restriction on the feed chimney will probably stop it smoking out, although it is maybe a little bit long when compared to the riser.

ievolve wrote:

As other suspected, the 18" feed tube did create a bit of a chimney, midway through the burn I pulled it off and just fed wood in the top hole.

Nice stove you have got over there and for someone that is working with metal and fabricating metal stuff for the first time, it is very good indeed. About smoke coming out of the fuel feeder, it happens because you have no air control for primary air and air entrance is much bigger in area when compared to the riser pipes area. To test this idea, I suggest you make a new trial, reassemble the "feeder pipe" cover the bottom to be more or less air tight (pack soil or clay around the bottom for example), light the stove and cover partially the top of the feeder after you insert wood. You will see that for a certain opening, no smoke will come out and air is sucked in at a certain speed. This points me to another issue. Lets say that the stove works well with the feeder as you planned it, air controls work fine, very hot burn but will some smoke come out when you open the top of the feeder tube to load more wood? The answer is "probably". If you install a 6 inch chimney tall enough and when the stove is hot, probably there will be no smoke coming out. if you use a smaller diameter chimney, horizontal and not vertical, probably there will be smoke coming out from the feed tube. So, if you have to restrict air for you primary burn, how is secondary air going to arrive to the combustion?

Kevin Bacon wrote:

I think you need to figure a way to control the #2 air flow. You may just end up with a bypass that cuts out #1 air.
Kevin

I have to agree with Kevin on this detail. I suppose that you have to figure a way of getting the secondary air from the exterior and get it very hot when it reaches the combustion.

Ok guys, here is a vid of the first burn. Preparing another with some questions that likely wont come till tomorrow. I've already done a couple more burns today, having some fun "debugging" steel/fire   

The twin fire swirl is very nice. Looking forward to see the stove complete and working.

hi man! thats look really nice!

caotropheus wrote:

The twin fire swirl is very nice. Looking forward to see the stove complete and working.

I also like the looks of your twin swirl fire   Great job on your first RS build !  

Oh yeah......now that looks cracking! I absolutely love the 'rocket' sound from these stoves! I guess you are living the dream and getting it in a sort of stereo having two riser tubes  :lol: 

Nice work! You must be pleased if this is your first attempt at this sort of thing.

Thanks to everyone for the kind words and advice, I've had about as much fun fiddling with getting max performance as I had actually dreaming it up. I've now got 6 or 7 burns under my belt, learning as I go.

One thing that I can tell is going to be pretty critical for me is to come up with a way to make everything airtight. Perhaps it is just my design, but when I start it up from a cold start I can expect about 3 or 4 mins of massive amounts of smoke (as any fire would), if this thing were in my shop I would be all smoked out by the time things were rolling.

Yesterday I added a mesh screen to hold the coals off the bottom of the burn chamber and allow air to flow freely under. It seemed to make a pretty big difference for my stove, I had much better airflow, it burned hotter, and seemed like I had better re-burn in the heat riser too.

One other curious point is that during a burn, I can cover one of the barrels and it will increase flow in the open riser. The flow increase is to be expected. But what is odd is that according to my math, covering one of those risers should create a choke point, but it does not. Has me wondering if I can get away with smaller openings into my risers and perhaps create more of a venturi?

There are a couple things I will be trying this weekend.

First is I want to insulate my heat risers pretty significantly and see what side effect (if any) I get.

Second is I want to try a different secondary air strategy, I just dont feel like my secondary air is doing much of anything, whether I cover it or leave it open it really doesnt make any difference in the heat riser. Have any of you seen dramatic differences in your heat risers when you open/close the secondary air?

Below is a video of last nights burn, we are a bit buried in snow and the wood was very wet. But after about 8 or 9 mins it got rocking.