Blue Flames Are Good Flames - Rocket Stove Upgrades

I've been wanting to make a door for my rocket stove to control the primary and secondary air and find out what difference it makes. I lost a bunch of footage because the camera kept overheating, but I still think it looks pretty cool ;)
Time Stamps:
00:00 Why I'm Making A Door
00:26 Rocket Stove Door Design
01:36 Rocket Stove Upgrades
03:59 Rocket Stove Testing
09:40 What Worked Best

[@petert8931]

One of the most useful videos on rocket stoves on the internet. Thank you!

[@BitsOfInterest]

Thanks 👍 It has everything I wanted to know before I built it 😉 I figured other people have the same questions 😁

[@em20245]

Wow! Great tweaks!

[@quantumofconscience6538]

I think toward the end he said temps were actually going down with the secondary air. Once you reach absurdly high temps., as he did, there is no smoke that is not burned up as fuel. It's all gone inside the riser. Once that point is reached, the secondary air is actually "an air conditioner" that cools it all down a bit. The ideal amount of oxygen does not always mean the maximum amount of oxygen. Once the ideal 02 amount is reached, additional air added is like an air conditioner. Secondary air is ideal in, say, wood stove applications where the firebox is about 400 degrees colder than a rocket stove and some smoke (unused fuel) is about to enter the chimney and leave the house as smoke. The secondary injection removes it. In my opinion, most rocket stoves can reach such high temperatures where secondary air is not necessary, especially with this ceramic board or vermiculite. Even most "welded metal" rocket stoves have no smoke, and they are cold compared to this one, and have no secondary air. I am just speaking to people who want to make this, and see all these videos where they think secondary air is needed. It is not needed. It helps a bit but don't think you MUST have it. Also, rocket stoves like the riser small to radiate / contain the heat. If your riser gets too wide, most of the effect is lost. Error on the small side for everything, even the "batch box."

[@BitsOfInterest]

I think the conclusion should be that temperature went down when I blocked as much primary air as I could. When I captured the blue flames in the riser both primary and secondary were open as much as possible. I think I forgot to take a temperature reading because I was too amazed by what I was seeing 😜 I got the highest (measured) temperature when I moved the slider in front of the secondary air, but there's a significant gap between the door and those pipes, so I think if they want to suck in air they still can. Also the yellow flames didn't go away when I started blocking primary or secondary air, only when both were wide open. I have seen rocket stove videos where they do shut down primary air when it's up to temperature, but I guess my quick and easy build with 1 inch boards doesn't hold temperature that well and needs primary air. Maybe if you build another 1 inch layer around this one it works better, but then you're doubling cost also... Maybe then it's more efficient to just go straight to casting it 2 inch thick as recommended in the first place 😉 Edit: you can make the riser as wide as you want as long as you keep everything in proportion; it has to be taller and your fire box has to scale in all dimensions also. I would recommend a larger fire box so you don't have to fill it as often, but I didn't want to go taller than 2 ft on the riser.

[@SerenityOracle]

Saw you on vid iq :) I love this content! Thank you for sharing :)

[@BitsOfInterest]

Thanks! 👍 I don't follow all of the "KZbinr advice" because I just make videos about what I'm working on whenever that happens and what I'd watch myself 😜

[@rockcrusher4636]

Very nice, thanks for sharing. Cheers.

[@BitsOfInterest]

Thanks! 👍

[@ruszsiezbeti]

great job. and what to do with that energy 😈

[@BitsOfInterest]

For now mostly melt cameras, lol. I want to build a grill/oven some time with a rocket stove heat source, that's why I started experimenting with this one.

[@petergrassel3973]

Great job

[@AMUabdullah]

Nice and awesome

[@roosenlodewijkwiggers4594]

Nice work! I can give you a tip on the door system: use a glaspanneled flip up where the bottom is not sealing to let in air, then use a normal door on the front with a glass, where the opening are on the top, that way the primary air also get's preheated, going in at top, moving down the glass to the gap into the fire box. I saw this in another video. It works really well. Also it helps protecting to sparks from fire box. I love your experimenting. Also another tip could be to put the secondary air pipes at the top, where the air is hotter, especially when you load up the box, there it will heat up quicker, and also hotter.

[@BitsOfInterest]

Thanks for the tips 👍 I can see how that door design could maybe improve efficiency, but mostly safety if you want to use the stove inside. That said, I think it may be more complicated to fabricate without welding. I'm only using it outside and I only burn hardwood, so I haven't had a problem with sparks coming out. Still something to consider though if you are in a very dry area and don't want to start a forest fire...

[@raydreamer7566]

If you were to put a cooking pot on your stove with the low riser the bottom would become Blackened. After you extend the riser and put your cooking pot on the extended riser the bottom of your cooking pot will be almost clean because of the more complete combustion . Good build and I agree the door does make for better control. Usually on a rocket stove secondary air is used to reduce the output heat by cooling the flame . There are many rockets stoves that are certified for home heating that use secondary air to cool the output flame temperature and control the stove temperature to a cooler temp..

[@250tegra]

Thank you, that is looking so good! The analysis suggests (as you imply) that if you have _enough_ air, it matters less whether it is primary or secondary air . . . I would deduce that your mixing of air with wood gas is very good, with your rams horns making sure that the air gets properly mixed in. Well done! Blue flame, that is just awesome.... 🔥👍😁 ps: the water glass coating looks to be much harder, is it good?

[@BitsOfInterest]

Thanks! Part of my results could be that I don't have a perfect seal (or any seal at all) from the door to the secondary air pipes, but it seems to favor a mix of primary and secondary air. The rocket stove is pretty much self regulating, so you just have to give it what it wants :) As with most of the enhancements I experiment with, I probably should've applied the water glass when I first built it. I haven't seen any new damage and it appears to be much tougher. You can even hear it when I pull the secondary air pipes out; it sounds more like rock or sandpaper when there is friction, instead of a softer sound when you gouge the material. Where there was existing damage though it really soaked into the boards, so it would be easier to apply on new boards with their factory coating.

[@Danny-tp6xf]

Very cool! Thanks for the great vid! Are you also planning om making a firebox over the exhaust? Would be cool :)

[@BitsOfInterest]

Thanks! I'm not sure what you mean by a firebox over the exhaust but one day I want to build a grill/oven around it. I hope it doesn't get too hot for that 😁👍

[@Danny-tp6xf]

Oh I mean like a bell (I think it's called like that). Like what they did in this vid: kzbin.info/www/bejne/nXbaeZelnpeBmJY Do I hear some Dutch in your accent by the way?

[@BitsOfInterest]

Ah, yeah. That's what you would do if you're building a rocket mass heater. I don't have plans to heat my house with this one. It's too small anyway so it needs to be refilled quite often and is more for short use outside. PS That's correct. Not many people can figure out what accent that is ;) PS2 Sorry, your comment got blocked because of the link so I didn't see it until now.

[@Ed19601]

@@BitsOfInterest Niet een heel sterk accent maar toch wel duidelijk

[@thatcrazyguy1971]

Nice interesting videos, thanks for the upload. I can't find where you applied waterglass to your boards, and how you did it. I missed it?

[@BitsOfInterest]

Thanks 👍 I didn't film that because it looks exactly like painting something. So you use a regular paint brush and probably some gloves because all this high temp stuff is full of warnings how it will kill you 😉 Just let it dry overnight and fire it up to cure it. I got the cheapest container on Amazon, but didn't pay close attention to the size, so I got a tiny 4oz bottle and I only had enough for the inside of the burn chamber. I could've spent a little more and gotten a big bottle to maybe coat some more boards.

[@thatcrazyguy1971]

@@BitsOfInterest Thank you for your reply. So just painting pure sodium silicate, does the trick? Have you experienced it with time? Decays, brittles?

[@BitsOfInterest]

@@thatcrazyguy1971 yeah, apparently that's all it needed. I should've painted that stuff on those boards as part of the initial build, but I didn't know any better at the time. I can't really speak to time, because I haven't fired it up in 6 or 7 months (too hot here) but with all those tests I did for the video and a few burns after I didn't see any new damage. It used to feel like poking a stick in dense wet sand when I gouged the boards. Now it feels and sounds like rock, tough and a gritty sound. I think you can hear it a little when I pull those pipes out somewhere before I do the test burns.

[@thatcrazyguy1971]

@@BitsOfInterest excellent! Thanks

[@jimfitzgibbon5492]

Could you be kind enough to post the size of your fire Chamber & heat riser ? The inside & Outside, length & high . I would love to build one. I can fabricate the rest, so don,t go to a lot of trouble. I truly would like to build one. Great videos .

[@BitsOfInterest]

I just replied to your other comment on the first video, so I'll just paste that reply here ;) If you are familiar with SketchUp (Free) I shared the 3D model from the video in the description. (Edit: it's in the description of the first video, the one where I show it in the beginning.) Just keep in mind the boards I used are 12"x12"x1" so most pieces are 6"x12" and some 8"x12" and 4"x12". You can think of it as two square tubes that fit inside each other. The heat riser or chimney is 4"x4" inside, 6"x6" outside. It's 2 boards or 24" high. The burn chamber is 8"x8"x18" outside, 6"x6"x17" inside. The 17" is because it's closed on the back, but not the front.

[@kignacio]

4:22 is that because of the (small amount of) thermal mass that the metal adds to the box?

[@BitsOfInterest]

No, it's much simpler. It's because fire needs air and when you have that metal grate in air can come in from the bottom. It helps a lot with lighting the fire and sustaining the fire later on. The ashes can also fall through so it doesn't starve the remaining wood from air. Without it it just turns into a pile of ashes with pieces of half burnt wood in it.

[@TensaSaigo]

Hello, I appreciate You are trying different aproach than others, just a little thing I noticed. When i play the playlist for rocket stove the videos are sorted backwards and 1st starts playing the last one with paint upgrades, than the 2nd with mesh and sec.air tubes and last one is the construction video. As a viewer I cannot change the the order of the playlist...

[@BitsOfInterest]

I understand your point. You should be able to change the order when you are playing the playlist. It just doesn't save it for you like that. Edit: it looks like that's a mobile only feature. Oh KZbin... The reason I have the latest video first is to highlight to viewers that there is more on the topic they are interested in. Most people that have watched my videos have seen the oldest video with the build and even today most people watch that old video first. If I then have a playlist that starts with what they've already seen they may not look at it.

[@scottweinberg3268]

So have you used this hard for at least one big burn everyday, to test your metal exposed to the full on heat on a daily basis. (few have made that work but perhaps you have got it)

[@BitsOfInterest]

For the video I burned it hard for only two hours two days in a row. For each test I refilled so the system warms up and then refill again for recording the test. Which metal are you talking about BTW? The door shouldn't be a problem because that's cooled from the outside. I considered lining the inside of the door with vermiculite but I concluded that's too complicated for my use case. I primarily wanted to test no door vs dedicated primary and secondary air. The metal on the inside (secondary air pipes and grate) I consider sacrificial. They will spall and eventually burn out. At that point I will replace them.

[@scottweinberg3268]

@@BitsOfInterest Ok, that is what I wanted to know, if this has been tested on a daily basis I mean, as far as the metal question goes, I was meaning the grate, and like wise would be surprised if it lasted long.. Always fun to test a few things though.

[@BitsOfInterest]

Rocket stoves love metal, especially eating it ;) The grate I made last year and I used it about a dozen times or so for multiple hours each. It's still holding up structurally, but it's already spalling. If you'd use it on a daily basis maybe it will last one season (3-4 months) probably not more. The secondary air pipes may last longer because they are thicker metal. That said, there still is value in having something similar that allows air from underneath and ashes to fall through, you'll get a better/hotter fire from it.

[@timothyg967]

Line with aluminum flashing & loop chimney over firebox with a steel plate top = stove

[@BitsOfInterest]

If the melting point for aluminum is 1220F (660C) it won't survive anywhere in this rocket stove. You can put a barrel with an exhaust at the bottom over the core to use it as a heater. You can find a lot of videos from people that did that.

[@audiokees4045]

I think this metal pipes do burn away pretty quick. Also that basket will.

[@BitsOfInterest]

If you're going to use it daily during the heating season you'll probably have to replace them annually. They are worth the convenience of lighting the fire and added efficiency though. They are also pretty cheap and easy to make.

[@knightmare1015]

Can we please have a list of materials that's needed for this build?

[@BitsOfInterest]

I think this is it. I may have forgotten something, but then I'll edit it later. This is across all rocket stove videos up until now and multiple orders from different places. 8x vermiculite board 12"x12"x1" (300mm x 300mm x 25mm) 1x stove gasket cement (and a caulking gun) regular wood screws longer than 2" or 50mm 1x 12"x12" (300mm x 300mm) expanded carbon steel 2x 1" (25mm) carbon steel square tube 12" (300mm) long 6x 1"x1" (25mm x 25mm) carbon steel angle 36" (900mm) long 1x 1/16" (1.5mm) carbon steel sheet 2x high heat spray paint 1x sodium silicate (and a brush to apply it) 1x 1/4" (6mm) graphite impregnated wood stove gasket 1x 3"x6" (75mm x 150mm) mica glass some small bolts, washers and nuts to put the door together and a hinge.

[@knightmare1015]

@@BitsOfInterest thank you so much. Sorry it took me a while to respond. This so far has been the easiest build that I've seen to date on KZbin.

[@deanthornby2026]

I'm trying ...but just smoking out my house and green house ... before I build in my bed room I gotta get it right 🤣

[@BitsOfInterest]

Maybe you're already doing this, but it could help to push that first piece of paper (or whatever you're lighting with) slightly into the riser so that heats up first and gets the draft started. Hopefully you won't get smoke in your face that way 😁👍

[@JiffyDealer]

In the house?!?!

[@BitsOfInterest]

You can use the same principle/design to build a rocket mass heater for your house. You'd enclose the core (the only part I have) in brick and/or metal and add a chimney to the outside.

[@scottweinberg3268]

@@BitsOfInterest There is so much more to this, such as the sq ft of surface that this core can utilze, as well as all the factors that make a good stove set up.

[@hafsalinda]

The temps your running the stove at are in the range of diesel exhaust temperatures, therefore a thermacouple and guage can be installed to read constant temperature at the thermacouple install point. A 35 gallon barrel laid on its side would make a great heat collector and securing point for 4" single wall pipe to duct cooler gasses outside the space. The radiant heat would be tremendous. With the temps your working at. Why not add secondary air at the turn to verticle also?

[@BitsOfInterest]

Interesting idea about the thermocouple. For the video I was moving around a lot so I chose the IR thermometer. The laser also looks cool on camera ;) If I'd use a barrel I'd probably put it up so it can encapsulate the whole heat riser and I don't have to float it somehow. I'd also put some high temperature material like vermiculite either spaced off the top of the riser or attached to the underside of the barrel lid so it doesn't burn out as quickly. In my first rocket stove video I explained why the secondary air is right at the port, because it will suck in the air automatically. You can probably cut those pipes a little longer at an angle to get right in the middle of it, but it seems to be working already. Here's the video if you're interested. I explain the design in the first few minutes before the build starts: kzbin.info/www/bejne/eJS7aGp8oa-qZrM