Batch Box Rocket Stove Secondary Air Discussion

Hey Gang! Here's a long overdue discussion of Secondary Air in a Batch Box Rocket. I go over materials and functions, and talk about my latest findings. Hope it's helpful!
Here's a link to my Pre-Port Secondary Air page. I share some Testo data and development info.
walkerstoves.com/
Secondary Air horizontal section: amzn.to/3NpAGPE
Secondary Air vertical section: amzn.to/3A4eyrd
Easy to follow Rocket Stove and Cook Stove plans available here:
walkerstoves.com/
My Clay/Sand Mortar Mix Recipe: 3 parts dry sharp sand by volume, 1 part dry ground fire clay by volume. Add water to desired consistency.
Fire clay: amzn.to/2ykT2B0
Sharp sand: amzn.to/2LJKqa9
Thanks for watching!

[@nickviney4912]

Thanks Matt. We are currently gathering all our materials to begin our Tiny stove build. Super excited . From DEVON sw UK

[@thomaswalz3515]

As always, enjoy your insights. I've a scrap yard nearby that retains stock it can sell by the pound. They have stainless... which I think would be more durable... I think melting temp is 2600°F. I may be wrong. Presently have a J tube, drawing plans for a batch... want to try my own design first,but will be designing it to be easily converted to Peter's should it not be what I expect. Thanks again... that 10% secondary info is HUGE.

[@live2av8]

That video got WAY more exciting than expected at 5m 30s! Lol! Thanks for the secondary info, good stuff.

[@MVSuances]

Hello from Madrid I ve build my batch box and I put a P Chanel above and I have not introduce any tube inside only the horizontal tube conducting to a hole of bricks just above the narrow betwen the primary and secondary chamber Is cleaner and It works

[@victoryfirst2878]

Thanks a bunch for this information. My stove is king right now cause of this item. Peace

[@johnwager6704]

Could you possibly make a video of you replacing the secondary air parts?

[@mervynshute880]

what is the wall thickness of the riser tube`? please.

[@lasaramicael3009]

Muchísimas gracias por toda la explicación del aire secundario y primario. ¿Y qué tal el cuello de una botella para tubo vertical del aire secundario? ¿Aguantaría la temperatura? Por el diámetro, sería para una bbr4. Probaré y te diré. Gracias, saludos desde Argentina 🇦🇷

[@Davidmc23]

Man you are a cool cucumber. I've had woodpiles fall and know the sheer "WTF???" I saw on your face but you didn't flinch. Also enjoy your work, thanks for making your vids.

[@w4447]

seems like you just need to find the right material. It's out there and it is cheaper then what you got. Call or better yet go down to your local metal company they'll be happy to help you. I was thinking a outside air supply that way the pipe stays cooler when air is drawn through it. And you only need a piece a foot long long or less. Also placement can help longevity, the rest can have a flange inside the pipe to close it and be galvanized or even plain steel tube to the outdoors.

[@Mike-rp6lb]

so how long did it last?

[@greganderson2932]

Do you can the end of the pipe or leave it open?

[@SnowyOwlPrepper]

Great video. There is another alloy of stainless steel (321) that has titanium atoms in the matrix. Some of the heat exchangers in outdoor wood furnace use it. The properties are very good for higher temps. 310s stainless is a good around high temperature and corrosion resistant stainless steal. Do you know what the nickel percentage is in yours.

[@broaudio]

The alloy I'm currently testing is Rolled Alloys RA330. You can read about it here: www.rolledalloys.com/alloys/nickel-alloys/ra330/en/ "35% nickel, 19% chromium, 1.25% silicon and controlled production techniques to ensure a product that has the optimal microstructure to withstand repeated thermal cycling." So far it seems to be holding up very well. Thanks for the comment!

[@joelhollingsworth1926]

How's the new RA330 steel lasting so far? Good news to report? :)

[@yourmommasbackdoor]

Hey Matt, just left a message for you on Permies, although I figured why not try here too so see how quickest to reach you. I just bought your book with plans from Amazon and am excited to build the 6" Peter van dam Berg batch box stove, looking for a link that shows the aluminum trim out process to complete the stove as well as what type of adhesive to use to assemble the unit. Cheers, shannon

[@victoryfirst2878]

Matt, do you ever have smoke come out of the secondary air tube since it is open ??? Thanks

[@broaudio]

No, as long as there is draft in the chimney there is negative pressure everywhere inside the stove, so it never smokes back.

[@victoryfirst2878]

@@broaudio I will be making a secondary air tube out of inconel with a stainless perforated floor on both sides of the air tube. Thanks for the information broaudio.

[@sarfraz6931]

Hi thank you for the great information, really helpful, can I ask what the exhaust pipe part is called?

[@broaudio]

I was using a turbo down pipe from a small car.

[@jamesglenn520]

The steel that they use for car exhaust is some of the weakest in the world. That's why people are getting new pipe put on their vehicles constantly. Schedule 40 steel pipe can be found in most any recycle scrap yard. The wall thickness is massive compared to exhaust tubing!

[@Boscovius]

Matt, what do you think would be the result of cutting the top of your port tube at a 45 degree angle so it slopes downward in the direction of flow? Would that not have the same Bernoulli effect and cause a low pressure draw through the pipe?

[@broaudio]

Thomas, I think it may be of slight benefit, but as I say about my slotted version, it's not worth the time since that detail will be gone in a few weeks of hard burning as the metal begins to deteriorate.

[@jamesglenn520]

I think by closing the top of the tube and drilling a series of holes in the back side of it might help with deterioration. By having the air jetting out the holes it should help keep the heat pushed away from the exposed edges. This is the purpose of the Combustion Air intake of the newer wood stoves. Just a thought!! Lol

[@Boscovius]

@@jamesglenn520 I like the way you're thinking. Any kind of coating that could survive those temperatures at that juncture that could protect the metal from the high temperature oxidation would eliminate having to replace the tube entirely. That's sort of been a Holy Grail for me since I began studying these stoves. I've learned a LOT from Matt.

[@rymalia]

Matt, what’s the thought on these metal wear parts getting vaporized over time - are there any concerns with harmful emissions? I don’t know enough about metals and chemistry, but I’m curious what you know about what might be getting released from those disintegrating metals? Thanks!

[@broaudio]

Hi, thanks for the great question. I do not believe there is any reason to be concerned, the metal gives up it's carbon to the combustion cycle and most of the rest of the elements end up as flakes in the wood ash. It's a similar process to rusting, just much, much quicker. Hope that helps!

[@rymalia]

broaudio thanks for the reply, (that was fast!), and yes that makes sense to me now. Thank you.

[@thomaswalz3515]

An addendum... I do have a J-tube. It's on my channel, my first build, which I have since made the burn chamber almost twice the size so I could burn cord wood. What I found is that cord wood does not burn well vertically unless the burn chamber is stuffed full, thus increasing the velocity of intake air since rockets DEMAND a certain CFM once burning. I installed a 3/4 inch secondary drawing cool exterior air. It does amp up the temps but the fire needs to be burning vigorously. I've also found that I get the best burn with wood cut into 4 inch lengths, stuffing the (new larger) burn chamber full... I'm getting barrel temps up to 800°F. I also changed to a coarser stone in my mass... but that's another conversation.

[@voidisyinyangvoidisyinyang885]

your feedback just demonstrates how finicky these stoves are. So for example when you say "burn chamber" - you mean the J feed tube or the horizontal "fire box"? Why does there even HAVE to be a horizontal fire box?

[@thomaswalz3515]

@@voidisyinyangvoidisyinyang885 I agree... i made a larger copy of one on YT, Zero Labs (check it out), it's my first and only one. So it does has a burn tunnel. What a learning experience this basic rocket has been. Like you, I really don't think a tunnel is necessary. Thanks for bringing it up. I think the elimination of the tunnel will facilitate easier starts since the riser must be heated first to get things flowing in the right direction. I'm reminded how often I had backflow in the beginning, filling the house with smoke. Duh... The cord wood firebox is made of 1/4 inch (6mm) steel plate. Temps are so high at its base that some of this firebox has melted away... astounding. Who'd think wood could melt steel? I am designing various rockets now, considering a horizontal firebox, all refractory, no metal, except the exterior. Back to the drawing board.

[@voidisyinyangvoidisyinyang885]

@@thomaswalz3515 New rocket heater riser tube - that upload? No firebox - just the feed tube and the heat riser. kzbin.info/www/bejne/e4HaenpqibyDl8U&ab_channel=LozHarrop

[@user-pq6uv2kk2f]

Дякую за ваші пояснення...

[@billwoehl3051]

Woodpile collapse: guessing from the hollow cavity, the grey hair on your head, the children been getting the firewood for the stove.

[@wiredforstereo]

I might be a little more concerned with the 19% chromium in the 330. Might be better to just stick with periodic replacement if the 330 wears out at any speed, but I haven't seen an update as to how this is working.

[@jeremiahshine]

I still think running the rectangular tube (or black pipe)through the back wall of the chamber and have it re-enter higher up would work. Insulate the bend outside of the core. There isn't anything to clog nor to deteriorate. Of course, that opens up the turn to clogging. Maybe a half brick or ceramic rod as the debris shield. Or stick to the Mitsubishi flange.

[@comptegoogle511]

If your secondary air tube goes through your stove to preheat the air then you won't cool down the air-fuel mix.

[@IanClarkOM]

i'm really curious how long this new material will last

[@thatswhatshesaid1]

If you don't mind a little spend, you could go to a fabrication shop and get these made from tungsten, much higher melting point and not as prone to distemper. Their melting point is 1000 degrees or more higher than steel

[@chrismarr2663]

Link is not working

[@comptegoogle511]

You can use a scrap car exhaust pipe elbow for very cheap.

[@chefbperez]

Soo....is the more expensive pipe worth it?

[@broaudio]

YES! It's holding up without issue after a few years of steady use.

[@andrewgervais3039]

Hi Matt! How has the RA330 been holding up so far? Thank you!

[@broaudio]

It's still perfect! I think it's the solution, it's looking like it hasn't deteriorated at all. I'll post an update before too much longer.

[@erike.weaver6027]

@@broaudio Sweet! :) Glad to hear it has been holding up well

[@russelmurry1564]

The difference between secondary burn n no secondary burn is huge difference

[@musicteacherbuilder]

Try a pipe with ceramic “lips”?

[@jamesglenn520]

I had a GF back in high-school that had a set of those!!🤣😜

[@ericaberger4133]

Lástima que no tengan subtítulos en español

[@Fersiope]

5:26 😂😂😂👍

[@quest_onchannel54]

Heads up, your amazon links are dead.