Experimental Wood Stove - Five years on...

This video is about the sideways burning, self feeding, experimental wood stove I made for the workshop five years ago. It's based loosely on rocket-stove principals. The burner is made from old scrap gas bottles and insulated refractory, it has a separate combustion unit and heat exchanger to maximise wood burning efficiency. One week spot is the difficulty in cleaning the heat exchanger, as you will see...
It is somewhat similar to a scaled up rocket stove, but uses a fan to drive the flue gasses, so that virtually all the heat can be removed with the heat exchanger without suffering the usual problems of creosote build up.
This stove has been awesome, but could use a few tweaks as discussed.
For more recent rocket stove griddle making experiments see my latter video here: goo.gl/XBy3cn
For more low-downs on past and present projects, subscribe to the Flowering Elbow channel: kzbin.info...
Original build articles about the woodstove on Flowering Elbow.org: www.floweringelbow.org/categor...
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Background music in order: Bustin Loose With Lead, SundaySpirit, Corruption, HillbillyBed, DogHouse, HiFiBrutality - audionautix.com:

[@creatorTWin]

Really interesting idea for a fireplace/stove. I liked the video.

[@TheProjectGuy194]

Go build man, plenty of info in your video, yours makes my stove look very basic. It's giving me a few idea's for my next build. Thumbs up from me.

[@richardsandwell2285]

Very interesting build.

[@panatrat]

That looks crazy😍......

[@mannurse7421]

❤ this is great

[@jamespeterson1148]

nice. like the use of venturi effect to preserve the fan.

[@FloweringElbow]

Thanks

[@mikeporter5421]

I like it!

[@indigodragon7129]

That's a lot of reused bits and bobs mate. Try gallium sealed in copper pipes with those fins on them has heat exchange with stirling hot gas pistons turning fans to pass air over gallium copper heat exchange pipes. 😊

[@clobbyhops]

Very ingenious thinking Frankensteinish looking heater you’ve created here, none the less, ( I like it 😍) What was your overall room temps during your winter months, I’m in Michigan and we don’t use the Celsius language here, sorry. 👍🤗

[@FloweringElbow]

shop temp range, but about 70f (22c) when 32f outside. Goes much hotter if I keep the stove at full tilt!

[@duggydugg3937]

nice piece. the fire must be intense doing so much damage

[@andrewyek]

wow. ur stove lasted 5 years.. wonderful work. what is the material you used at the burn chamber ? like perlite + water glass ? or something else. thanks.

[@FloweringElbow]

Andrew, it was castable refractory.

[@FloweringElbow]

Over insulated fire brick.

[@petrus4]

@15:30 - "Gee, that looks safe." ;)

[@clobbyhops]

So what were your average room temperature during winter months?

[@FloweringElbow]

22C

[@r8edrv4fun65]

Cool stove though

[@-powerband-gamer-6117]

how hard would it be to make a generator that makes its electricity from fire?

[@DeliciousDeBlair]

I take it there was no stainless steel used on the internal parts?

[@FloweringElbow]

Only stainless was on the hot plate on the top of the burn unit. Why do you ask?

[@badWithComputer]

If you block up that primary air intake and drill an intake above the wood feed right at the top i bet the draught would be loads better and consistent.

[@FloweringElbow]

Good afternoon BadWC, thanks for the comment. I have tried this and it was somewhat better mostly... but just occasionally back-draught, so I switched to the preheated pipe air, which I think makes it burn hotter anyway. Thanks again, Bongo.

[@badWithComputer]

@@FloweringElbow i've heard, not sure if true, that cold air contains more oxygen than warm/hot so odd that it burns hotter with heated intake.

[@gordtron]

really cool. what do you use the heat exchanger for?

[@FloweringElbow]

Hey there, thanks. The heat exchanger is air to air - it warms the room air.

[@gordtron]

@@FloweringElbow very cool stuff. been trying to plan a little furnace i could heat water with, just exploring other functions while the war against energy pipes up.

[@FloweringElbow]

@@gordtron yes wise! i could have gone the water heating / central heating rout with this and I think it would work well, but as it's essentially a big (well-insulated) one-room heater, getting good air-to-air transfer is better.

[@andrewyek]

i have to search for the make of this stove.. looks promising, although it is way too complicated. lol

[@FloweringElbow]

No vid of the making, but check my website for the complete build walk through with pics. link is in description.

[@billray1785]

Is it a bit complicated?

[@FloweringElbow]

Yes, but so was a camp fire when people didn't know about it.

[@billray1785]

I know what you are saying, but the fan on the roof, the chambers etc. and how well does it perform, I say this as I would like to build a rocket mass stove and I don't want to over complicate things and above all heat with very little wood and keep the heat longer. Also where I live the power goes out, so I want to heat with no electric. If it works for you great but I need a simple thing for a simple mind and looking for the best way to do it. No disrespect to you on your build.

[@FloweringElbow]

I agree with you that simple and elegant is something to be aimed for - having it use electric is a big consideration. I worked out that it was more that worth it given the benefits to burn efficiency and heat transfer (all or most of the heat can be extracted from the flue gasses without overly worrying about draw issues and creosote build up). As you see from the vid - it clearly isn't a perfect system... A rocket mass, wouldn't work so well for the workshop because it is used so inconsistently - the metal exchanger heats the place up much faster (but on the down side also cools down much quicker). It's all about finding the compromise that works.

[@thechumpsbeendumped.7797]

Did you ever find out what caused the pattern on the hot plate?

[@FloweringElbow]

We are sure it was something to do with the way I welded the two layers of the top plate together....

[@thechumpsbeendumped.7797]

@@FloweringElbow That makes sense if you spot welded it I guess. I was also wondering if the combustion in the hinged hopper was caused by the burnt through preheat tube blowing the flames in the wrong direction? From what I’ve seen of rocket style stoves, I’m wondering if having the air inlet in the hopper and blowing downwards would stop the flames traveling up the fuel and combusting in the wrong place?

[@FloweringElbow]

@@thechumpsbeendumped.7797 yeah that occurred to me also. Just haven't found the time to change it 🙃 . Though having jets of air close to combustion is the best for efficency...

[@victoryfirst2878]

This stove is very unique for sure. Maybe you should of used stainless steel pipe inside the burn chamber to keep corrosion at bay ?? I know the price is a bit salty but you would not have to replace the pipe.

[@FloweringElbow]

Yo VF. So right on the stainless pipe. All the air pipes have now mostly corroded/ burnt away. They lasted a few years, when I get round to it, I will replace. It gets exceptionally hot in the insulated combustion chamber, so finding something super heat resistant...cheers, Bongo

[@victoryfirst2878]

@@FloweringElbow Good day Bango. I can tell you I am slowly getting material for my wood stove. Got pipe's made of inconel. That is top dog material used in jet engines. Am sure this will not let me down. My problem is I cannot get the best of both worlds in a wood stove. I need long burn time 12 hours, high heat output 100K BTUs, super efficient too. Making this happen will be a challenge for sure. Can you tell me what you would do ??? Keep in touch Bongo and peace too.

[@FloweringElbow]

@@victoryfirst2878 not 100 % sure what I would do. Have you considered making a big batch burner and a thermal store?

[@victoryfirst2878]

@@FloweringElbow I would really like to stay away from a thermal store. Takes up to much space. I am figuring if I would make a real efficient stove that would not really matter. I get wood dropped off for free. So the wood is not a problem. Now to the big batchbox burner, I am thinking of making a combination ballergan rocket stove combination. This maybe the ticket for me. Right now I am still in the planning stages and have a lot to figure out. Peace Bango.

[@r8edrv4fun65]

Music is too loud.

[@coachgeo]

like the self feed potential in sideways burning.. hmmm

[@FloweringElbow]

Yep it's certainly one of the best features of the stove...

[@tommyt4062]

I'm certainly no Expert and if the stove works then great but it just seems over engineered in the wrong places to me. Is heating the primary air really necessary? I can fully understand heating the secondary air but is heating the primary air through such a long route not also restricting the amount of oxygen that can get into the burn chamber? Most of the cars I've owned for the past twenty years have had induction pipes that run right to the grill so the car can breath nice cold air which contains more oxygen and gives more power, I've not watched formula one for a long time but seem to remember they would have to adjust fuel mixtures not only for tracks at higher altitudes but also tracks in hotter climates for the same reason? As I said I'm no expert and this is a question not a condemnation, my initial thought was Wow a lot of work has gone into that but then I started to wonder how much you would actually gain from all that work and if putting a couple of slip joints or pipe spigots on the flue would have been better time spent?

[@FloweringElbow]

Hey Tommy thanks for your input. It was long enough ago now that I was messing about and experimenting with this stove that I have forgotten some of my research and reasons for doing it certain ways. I know what combustion wants is heat and oxygen. The hotter the better, that way if the give it too much oxygen it will not cool down the fire... I knew I wanted to pipe most of the air in from outside anyway and on days when the stoves needed it tends to be very cold (and sometimes very humid). I could have simply piped it in straighter but as I was building the stove at the same time it seemed easy to try that out. I don't remember it being a huge amount of extra work. With hindsight I should definitely have made a slip joint between the burn unit and heat exchanger - what I had free and to had was a straight insulated tube and I was keen to light it up so....

[@tommyt4062]

FloweringElbow Ok I understand what your saying, It was going to be sucking really cold, damp air from outside so the idea was to just pre heat it a bit. Have you ever tested it by controlling the air just by opening the window on the burn box? it would be interesting to see if or what the actual difference in temperature is between using ambient air and pre heated air?

[@FloweringElbow]

It makes a big, immediate and visible difference Tommy. With the door open it goes well enough, but gets too much air and burns 'softer'. With the door closed the incoming air is at much higher velocity, and you can see it blasting from the nozzles. It's much more fierce - which makes sense as the strong air currents are really mixing up the oxygen and combustion gasses, as well as exposing new surfaces for combustion (blasting away bits of char that can insulate parts of the wood from the heat). If I leave the door open it also slows down the warming of the workshop, as it is sucking out workshop air (which gets replaced with cold air from outside, which is drawn in through the small gaps round doors etc.

[@tommyt4062]

FloweringElbow is that with the door wide open or just cracked open? The reason I ask these questions is because I'm interested in making an outside kitchen so like a rocket powered oven and possibly a hot plate mainly just to keep as much heat out of the house in the summer months but I would also like to learn about rocket heaters. My family owns a house in Bulgaria has underfloor heating that is powered by log burners using a heat exchanger, I've been wondering about making a pellet feed rocket stove to be more efficient and which could burn for longer without needing so much attention.

[@FloweringElbow]

It is with it open anything more than a crack. Have you watched my latest ones on the rocket stove grill griddle? goo.gl/XBy3cn

[@jayedavies3686]

Try a piece of emery paper

[@FloweringElbow]

Jaye Davies for which bit?

[@peeegeee8397]

you are not getting a clean burn cause you fire is not hot enough. you also need multiple burning chambers you should have realized this the very first moment you realized there was creasode in the roof chimney exhaust

[@FloweringElbow]

Hey P Grant. Actually it is very clean burning! The amount of build up is very little given the five years of use it's had. I believe that that build up is only from the very start and end of the burn cycles. This is hard to avoid without some kind of propane burner going at those times.

[@Pwecko]

Sadly, it was too much like hard work trying to listen to you with that racket going on in the background.

[@murrayrunge5602]

i think you wasting lots of heat and also making something simple seem very complicated.

[@FloweringElbow]

Murray Runge the design is very much geared to extracting all the heat... where is the losses?

[@murrayrunge5602]

heat ex changers that lay horizontal intake one end and exhaust the other seem more efficient. your crud buildup should be an indicator that not burning hot enough right?

[@chrislloyd1505]

Murray Runge Firstly I’m not an expert and I can’t speak about heat exchanger efficiencies but having seen a few chimneys swept and the amount of crud that they can make even in a year burning wood between sweepings, this heater seems pretty ‘clean’ for five years worth of use between cleanings. Also the amount of metal erosion from the burning would seem to me that it is burning pretty hot.

[@FloweringElbow]

Chris, I couldn't have said it better. Thanks! Murray, I have measured the heat of the gasses leaving the flue, and they are usually less than 50C (!) even when the stove is at full tilt. This indicates to me that most heat is being extracted. Also after the first 10 mins or so, when the fire is just getting started, there is NO visible smoke, indicating very complete combustion.

[@murrayrunge5602]

Yes it doubtingly is getting up to gas burning tempts , just imagine if it were built with a horizontal heat exchanger ! Although my opinion refers to a simpler design , i did not mean to offend. If it works for you and doesn't pollute our atmosphere while capturing maximum fuel benefits is wonderful. But do you agree that it could have been constructed more simpler where there is no electrical fan in the exhausting process and the heat exchanger is easily accessable?