New, starting first build, pics, *UPDATE*

I'm am new, currently residing in eastern Montana. I have started my first build after a ton of reading on here and my rocket looks promising, I did think a little out side the box on this one. The burn tunnel is flat and wide with a lip, I am unable to test burn it outside atm so i got the idea to light a hand full of tea lights and to see if i could get it to draw. It starting drawing correctly with 2 tea lights, no chimney yet, and I am gonna hopefully get the barrel today which is a small water heater tank. Measurements are
Feed tube depth: 7in
Burn tunnel widest part is 9in
Top of burn tunnel width 6in
Back of feed tube to back of burn tunnel 27in
Bottom of burn tunnel to top of riser 29in
I am using my phone atm so please excuse misspelling lol.

Been buring for 2 hours so far on a five gallon bucket of lodge pole pine.
will post video soon with changes made!

Welcome to permies, Roak! You have the start of a pretty nice rocket mass heater build going!

Dave Burton wrote:Welcome to permies, Roak! You have the start of a pretty nice rocket mass heater build going!

Thanks!

Hi Roak;  Welcome to the wonderful world of Rocket science !

 Have you acquired a copy of the builders guide from Ernie & Erica Wisner ?  It is highly recommended. Readily available from Amazon or from the Wisners directly. With it almost all your questions are answered.

The Mock chimney I see in your photo's. Is that flue liner ? If yes , you might want to consider other options. They are known to crack from the rapid heating and cooling of a rocket stove.

Keep us posted, with many pictures as you build. Ask any questions you like, we are always happy to share!

thomas rubino wrote:Hi Roak;  Welcome to the wonderful world of Rocket science !

 Have you acquired a copy of the builders guide from Ernie & Erica Wisner ?  It is highly recommended. Readily available from Amazon or from the Wisners directly. With it almost all your questions are answered.

The Mock chimney I see in your photo's. Is that flue liner ? If yes , you might want to consider other options. They are known to crack from the rapid heating and cooling of a rocket stove.

Keep us posted, with many pictures as you build. Ask any questions you like, we are always happy to share!

Thanks for the tip on the book!
Yes that is flat chimney liner, i did read somewhere about them possibly cracking. They were basicly free, and i think maybe them being 2 short pieces maybe they would be less likely to crack? I did buy plenty of fire brick, probably more than I need but who can say no to 50 cents a brick! Lol. If the chimney liner fails will report back with the rebuild using fire brick ;)

Howdy Roak,  

Your dimensions are certainly "outside of the box" - Certainly a great way to learn what works and what doesn't from first hand experience rather than just reading about it but I would still definitely suggest finding a way to experiment somewhere with a real burn (wood) with what you have before permanently building it into your final location.

Also know that when you add a barrel, then a bench or bell and then a chimney, it behaves differently with each new addition.
One thing I have experienced with a low and wide burn tunnel is that the coals from the fire will quickly fill this area thereby blocking the tunnel... then you not only get to see what smoke back is all about, but more dramatically, what its like to have the system run backwards!! I'm glad nobody was around when this happened to me!!!

Your heat riser is pretty short too for proper drafting.

As Thomas suggested, the Builders Guide will give you all the dimensions and proportions for a well tested RMH which you can then play with and modify if you choose....preferably outside with a fire extinguisher close by!

Good luck with your build!

If you can rotate the burn tunnel dimensions so it’s taller than wide it will help keep ashes from blocking air flow. Best to get it closer to square/round if you can.

Gerry Parent wrote:Howdy Roak,  

Your dimensions are certainly "outside of the box" - Certainly a great way to learn what works and what doesn't from first hand experience rather than just reading about it but I would still definitely suggest finding a way to experiment somewhere with a real burn (wood) with what you have before permanently building it into your final location.

Also know that when you add a barrel, then a bench or bell and then a chimney, it behaves differently with each new addition.
One thing I have experienced with a low and wide burn tunnel is that the coals from the fire will quickly fill this area thereby blocking the tunnel... then you not only get to see what smoke back is all about, but more dramatically, what its like to have the system run backwards!! I'm glad nobody was around when this happened to me!!!

Your heat riser is pretty short too for proper drafting.

As Thomas suggested, the Builders Guide will give you all the dimensions and proportions for a well tested RMH which you can then play with and modify if you choose....preferably outside with a fire extinguisher close by!

Good luck with your build!

Thanks for the info!
I did think about the ash blocking the air flow, time will tell on that one. Also i have been curious to what will happen when the air is partially directed around the fuel instead of thru the fuel, being my feed tube is narrower at the top than the bottom unlike a normal feed tube where air is completely pulled thru the fuel and coals. Will i get a poor burn? will i get a Leaner hotter burn? will it back fire?lol  i Hope this makes sense. :/
Forgot to add my chimney is going to be 8in

Tomorrow there is a small possibility there will be a test fire, if so will do a you tube vid and post here.

I think you have the right approach as the blocks can easily be reconfigured to refine your design as you see how it works.

Interesting project with a different approach than the norm.
I am more an armchair warrior than an expert but a nice bed of coals (not really ash) lying in the bottom of the fire box and tunnel is part of the way rocket stoves work and that is why a higher tunnel is normally recommended.
Not to say your design won’t work, in my own design I went the opposite way with the fire box design and made it wider at the feed end.
I did this because I find it makes the wood (sticks) lay toward a the centre rather than lean into the tunnel.
Keep the post coming......

Thanks for the info!
I did think about the ash blocking the air flow, time will tell on that one. Also i have been curious to what will happen when the air is partially directed around the fuel instead of thru the fuel, being my feed tube is narrower at the top than the bottom unlike a normal feed tube where air is completely pulled thru the fuel and coals. Will i get a poor burn? will i get a Leaner hotter burn? will it back fire?lol  i Hope this makes sense. :/
Forgot to add my chimney is going to be 8in

Tomorrow there is a small possibility there will be a test fire, if so will do a you tube vid and post here.

When you do your test burn, all will be revealed! ...(sounds like something yoda would say)  

Your system with the low wide burn tunnel will likely either let much of the air bypass the wood around the sides, cooling the fire due to extra volume, or the low "wing" spaces will fill with ash as you use it and be tricky to clean out.  The low wide cross section works at a larger scale in kilns as it allows air to get to more of the wood without a thick bed of coals choking off oxygen to the bottom layer, but at this scale, you probably won't have enough critical mass of wood to use that effect.

You definitely want your feed tube to be as tall as the length of wood you plan to burn. If the wood sticks out of the top, you risk a reverse chimney effect if the draft is not strong enough, with no way of damping it off. (Don't ask how I know this.)

Your clay flue tiles will probably crack with heat cycles if you get a hot enough fire for full combustion, and I would advise you to leave them accessible for inspection and replacement. A heavy firebrick heat riser will take a long time to heat up and establish strong draft, and you will need to surround it with insulation so it doesn't conduct heat away from the core continually. A riser of thin "split" firebrick would be better if you want it heavy-duty, or insulating material will give the fastest, hottest burning results.

IT WORKS!!!

Changes: raised the chimney 2.5in

Here are my observations, keep in mind i was using damp wood lol.
For the fist 10 sec i was getting a back burn, so i shoved some lit paper down the tunnel and it was like someone flipped a switch and immediately the burn and rocket sound started. Burned awesome for about 5 min then the coals really got spread out in the wide burn tunnel and the fire became "lazy" , no rocket effect but continued to burn with no back burn. I am thinking once more coals establish the rocket effect will return after a longer burn. i am going to try a long burn tomorrow with good dry wood and i am thinking about raising the chimney another 2.5in.

Glenn Herbert wrote:Your system with the low wide burn tunnel will likely either let much of the air bypass the wood around the sides, cooling the fire due to extra volume, or the low "wing" spaces will fill with ash as you use it and be tricky to clean out.  The low wide cross section works at a larger scale in kilns as it allows air to get to more of the wood without a thick bed of coals choking off oxygen to the bottom layer, but at this scale, you probably won't have enough critical mass of wood to use that effect.

You definitely want your feed tube to be as tall as the length of wood you plan to burn. If the wood sticks out of the top, you risk a reverse chimney effect if the draft is not strong enough, with no way of damping it off. (Don't ask how I know this.)

Your clay flue tiles will probably crack with heat cycles if you get a hot enough fire for full combustion, and I would advise you to leave them accessible for inspection and replacement. A heavy firebrick heat riser will take a long time to heat up and establish strong draft, and you will need to surround it with insulation so it doesn't conduct heat away from the core continually. A riser of thin "split" firebrick would be better if you want it heavy-duty, or insulating material will give the fastest, hottest burning results.

thanks for the info!
i will defiantly add to the feed chamber a bit, long term goal to to run mostly pellets. Did manage a test burn today and will do a long burn hopefully tomorrow.
The clay chimney will defiantly be accessible, i am only using it because it was basically free,.i will take the gamble and happly report back if it fails. i do know they know to crack on a standard fireplace chimney on houses but it got me thinking that they are surrounded by brick most of the time and maybe they are prone to cracking due to lack of space for expansion and contraction. What i have done is got two short sections (about 16inch each) and just stacked them, i am not even gonna mortar them together and see what happens. I am going to be running an 8in chimney straight up thru my roof which i hope will help with any draft issues?  My main goal is to extract/store as much heat as i can get away with in the barrel because this stove is in a 70's trailer house and i am cautious about adding the weight from a mass to the floor. Hopefully after winter i will be building a small addition off the trailer to house a large rocket stove and Mass, then i will be able to go crazy lol.

Roak, your reminding me of my own 'first kiss' I had with my rocket. A pretty awesome experience and one I will never forget!
Keep experimenting and post your results.

Gerry Parent wrote:Roak, your reminding me of my own 'first kiss' I had with my rocket. A pretty awesome experience and one I will never forget!
Keep experimenting and post your results.

https://www.youtube.com/watch?v=6S5inEKBVwk

Look what i came across at the salvage yard, pretty sure thats stainless steel, if not i will find out when i put the heat to it.

Use a magnet?

Graham Chiu wrote:Use a magnet?

Very Magnetic so could be low grade stainless

ALL DONE!....For now

works awesome!!!

I can tell you are pleased to see it working
Is there a reason why you can’t make it a complete 6” system?

Fox James wrote:I can tell you are pleased to see it working
Is there a reason why you can’t make it a complete 6” system?

I could, but I like coloring outside the lines.  It seems to have paid off stepping up the size of the system as the gasses travel along, i got the idea from seeing that the larger stoves appear to function better and draw better so i thought about what would happen if the system was stepped up multiple times plus I wanted a 4 inch feed but the draw of an 8 inch stove.  The stove will get a tear down tomorrow and reassembled up on blocks because it is getting the hearth/floor uncomfortably hot. Plus i would like more instant heat out of the stove itself and I can do that by getting air under it and plus I cant have any real mass atm being this is in a trailer house and the floor is not great.

I have a feeling that once the fire has dried out and is performing at its best, you will just be continually feeding in wood to keep it going?