How To Make A Cobb Rocket Stove Water Heater

This cobb rocket stove has a secret...it makes hot water. By adding a 3/8 inch copper coil to this mud-based rocket stove, I am able to circulate water using a thermal siphon to heat a bucket of water. Part 2 of the video will be the creation of an outdoor shower. The 5 gallon bucket got pretty fast...hotter than a shower would need to be. In this video I make the stove with a mixture of sand, clay and straw.
Check out the video that inspired my stove, by Off Grid Secrets:
• Clay Rocket Stove
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[@rosebudd1507]

Thank you for your videos, my 11 yr old grandson and I are going to be making a rocket stove!

[@worthlessprofessor6477]

Great project! I also really appreciated not having background music with everything. It had a good balance.

[@GreenShortzDIY]

Thanks for the feedback. I throw an audio track in when I need to. If my high-speed video goes over 1000%, the audio drops out of the render. So, I cover those spots with music. Plus, some sections just feel like they need a jam. :-) Thanks for watching.

[@imonlyhalfnutsreally2113]

@@GreenShortzDIY I do agree with Worthless Professor on this, I'd rather hear ambient sounds than a soundtrack. I realize many(not you) think they are making hollywood blockbusters rather than sharing the knowledge they have gained over a lifetime of experience. Which often comes with many failures and some great successes. Rather than the music some feel compelled to add I personally would rather hear the"oh sh** i screwed that up and i need to redo all this part" I'm a hands on guy who learns from others mistakes as well, at least when they share them. Not sure why people feel compelled to remove the not quite perfect projects. I've never started a youtube channel even though I've been making projects since i was a youngster, and that would be about 50 years ago (smiling face inserted here) keep up your great work, i enjoy it greatly. thanks again, halfnuts.

[@zachariahpoltergeist4516]

Sped-up construction noises is my new favorite sound!

[@leschab]

Nice proof of concept project. Okay for short term. Exposing that copper coil to the extreme heat will burn it rather quickly. You are spot on about cobb's versatility. If there is a fail, break it up , re-hydrate and use again. Wonderful.

[@daveborinski3021]

The “thermal” pump works better than I thought it would. Thanks for the education!

[@GreenShortzDIY]

Thanks for watching Dave. I was excited to see it flowing. A fun experiment for sure.

[@awaitingthetrumpetcall4529]

I'm working on making an animated 'explainer' video to share my ideas about off-grid electric power generation. My original goal in watching your videos was just to get a good rocket stove reference that didn't require welding. Instead, I've been binge watching for two days and then I subscribed. Your ideas are brilliant. If and when I complete my animation project I'll have to post a link to your videos.

[@perzperez6316]

Extreme knowledge! Thank you brother you are awesome!

[@tsukaharafarm]

Handmade rocket stove is good! In Japan, where I live, it has become cold in the fall. I use a clock-type stove. Warm tired body by boiling water and drinking coffee during breaks in farm work☕️

[@GreenShortzDIY]

私のビデオを見てくれてありがとう。 私は数回日本に行ったことがあります。 あなたの国が大好きです。 多くの素晴らしい人々と場所。 また素晴らしい食べ物。 冬に仙台に行ったことがありますが、寒さがどれほど寒いのか知っています。 あなたはどの町に住んでいますか？

[@tsukaharafarm]

Thank you for your reply! I live in Ibaraki Prefecture. Due to global warming, winter is getting warmer. Still, the area where I live is windy and winter farming is difficult. You went to Sendai! There was a big earthquake, but now it has recovered and returned to a bright town.🤝

[@seek2find]

I lived in Shimonoseki and almost froze while I tried sleeping under my kotatsu table and blankets in January and February, even though I am Canadian, I have never been colder! We only had a kerosene stove for the whole house.

[@wildflower746]

Awesome demonstration! The next part should answer so many questions i have. Thank you, much appreciated!

[@GreenShortzDIY]

Hi Amber. Send me your questions and I'll do my best to answer. :-) Thanks for watching.

[@janesanford2701]

Intreaguing, I really hope I can build something like this one day. Thanks.

[@bulletproofpepper2]

Thanks for sharing!

[@siuolsretlaw8166]

To prevent kinks in your copper pipe you could try bending it around a piece of schedule 40 pvc or other pipe in the size that you want the coil to be. The trick is to keep the copper pipe close to the pipe used for the shaping and bend it a little at a time. It makes a perfect uniform coil without kinks if done right.

[@sosteve9113]

nicely build,i have made something similar for the swimming pool

[@GreenShortzDIY]

Cool. I bet that is a perfect use for it. Also guessing yours is bigger? Yes? Thanks for watching.

[@JosephJRyu]

Great video. Thank you so much!

[@GreenShortzDIY]

Thanks for watching Joseph. I appreciate the encouragement.

[@marymacfarlane4275]

TY for this sharing!

[@GreenShortzDIY]

Thanks for watching, Mary.

[@seamorebutts1594]

You can also fill the soft copper with water, then freeze it. To prevent kinkage.

[@tinasearcy4684]

Thank you

[@TheNorthwestForager]

Always enjoy your videos. Thank you!

[@GreenShortzDIY]

Thanks for watching Senor Forager. :-)

[@tomaszjaschke631]

Great my friend. Thank you so much. regards!!!:)

[@henrymestdagh6692]

You should stretch out the coil slightly and mount it inside a wire tube so the clay is not in contact with the copper tube. If there’s a slight space between the coils it should be more effective. You can even incorporate it in the side walls of the fire pit as well the lower it is the better. You should make a damper to slow down the burn. It burns too fast so you use more fuel. That would also be good for a home made hot tub in the yard. In summer I do all my cooking on one make of recycled bricks.

[@GreenShortzDIY]

Thanks for the damper tip. I need to learn about methods in that a little more, but I understand the concept. I do another coil in a bigger rocket stove, that is open inside the riser. Works better. I’m impressed that you do all your cooking on an rocket stove! Awesome!

[@edwilderness]

Another possibility is to wrap the copper tubing loosely around a short piece of PVC pipe of the desired diameter for the coil like 6 inch perhaps. This should keep it from kinking at all, although I've never tried it.

[@ghz24]

A damper is contrary to the operation of a rocket stove.

Hello Henry, would you have some link that shows what you are explaining? Thanks ahead.

[@Foreseeable1]

Pro Tip: Another way to curl copper tube is to fill it with water and put it in a freezer, the ice will support the tube wall which prevents kinking.

[@brad1201]

That's awesome!

[@michael_house]

Great video. Thanks!

[@orlandocavalcante]

Muito bom parabéns

[@kathrynkenyon785]

THIS IS AWESOME!!!

[@dadks5663]

Yea. I always enjoy your video. Making everything so simple and easy to apply 💯💯💯🤟🤟🤟👍👍👍

[@cvl85]

Wow.. It burns extremely clean

[@GreenShortzDIY]

Yeah. I need to capture some of that heat coming out the top. Thanks for watching.

[@duhhhh1723]

So awesome , thank you ,wow .

[@astanfartin1647]

nicely done

[@horsenoname7854]

Fill it with sand is a must 💜

[@maggysantana3878]

This project is good to do it outside because it needs a co2 pipe to bring the gases out. But it works nice outside. Thanks for sharing.

[@michiganporter]

Man the sounds around your place! Crazy sounding with the sped up recording!

[@sandramaher4243]

Excellent ! Thank you 🌹👏🌹👏🌹

[@GreenShortzDIY]

Thank you for watching, Sandra.

[@lindaowens2959]

I stumbled upon you and am so happy 😃 I love it! Thank you I look forward to seeing more

[@GreenShortzDIY]

Thanks for the encouragement, Linda. Thanks for watching.

[@davidhayes5382]

This is brilliant. There has to be Irish 🇮🇪in here somewhere 🤣

[@GreenShortzDIY]

🙌🏼 thank you for watching.

[@cpd833]

"Stoked"...no pun intended I am sure😎 Nicely done...I am interested in your follow up video. Thanks

[@GreenShortzDIY]

Was there a pun? 😂 Actually, all puns on this channel are fully and painfully intended. If you knew my father’s humor, you’d understand I had no chance. 😳 Thanks for the laugh and for watching.

[@DonnieBigBucks]

You could've used your pvc as a form for wrapping the copper coil. Cool video, thanks man!

[@o00oZu1o00o]

That was cool. Always super satisfying managing to build one of those devices that heat water with only super durable stuff. Now what I want to know is how this model compares in core temperature, gas emissions, and volume of BTUs transferred to water, to a model made with the same cob and the same heating chamber core surface area, but which has the coil in the place where you would put the barrel on this rocket stove : on the way out of the hot fumes, but not in the heat riser itself. Because in the rocket stoves DVD they say that the second is better. Hey I'm building one right now!! Maybe out of stainless steel if the shop say they can weld it for me at a reasonable price. It's just to hold the ceramic boards in place, it's not the actual rocket stove.

[@jimbarton1757]

Use salt for filler to bend it. Easier to get out being water soluble.

[@GreenShortzDIY]

Good tip, Jim. Thank you. Thanks for watching.

[@jimbarton1757]

@@GreenShortzDIY can get real tight bends and coils.

[@ilmisteroeservito6982]

...or sand

[@analleeban-eg8408]

@@GreenShortzDIY qq

[@mr.dalerobinson]

Or use a steel ‘spring’ that fits over the copper pipe. We used to sell one designed for this purpose at a plumbing supply I worked at. It’s coils are too tight to be a spring but it creates a bendable but circular pressure evenly over the copper. Quicker and easier than filling a length of copper. Move it along the pipe as you make each bend

[@alexcarmichael8946]

Thanks

[@GreenShortzDIY]

Thank you for watching.

[@cecilarchie4112]

That was cool, great video, keep'em coming

[@GreenShortzDIY]

Thanks for watching Cecil. I will keep them coming. :-)

[@lisafrequency55]

I love it good job!!

[@GreenShortzDIY]

Thanks for watching, Lisa :-)

[@OffgridSecrets]

Nice! You did it! I hope it works well for you.

[@GreenShortzDIY]

Thanks man. Thanks for the inspiration and for reaching out. I need to check out your shower video to see how you set it up. You ought to do a build video on your stove, even if you have make another one. I think it would do well for you. Thanks again.

Awesome video.

[@leloup7733]

Superbe merci

[@theword4501]

Perfect... Im going to build one 💪😎👍 but I'm going to shop around for hoses that can handle boiling water. Lol. What a great experiment. God blessed this One ❤❤❤

[@GreenShortzDIY]

Ha. Good point. I did switch to braided hoses on the follow up video. Thanks for the feedback. Good luck with your build. Thanks for watching.

[@duhhhh1723]

I'm so jealous of your unlimited access to Georgia clay 🤔 😉

[@GreenShortzDIY]

Lol. I can only dig my yard so deep before the house falls in. :-) Thank you for watching.

[@blackdog.6398]

Hey it turned out awesome dude !,,, love it and your video . Thank you..

[@bahramkashanian4252]

Tom ! Good job !

[@GreenShortzDIY]

Thanks for the encouragement and for watching.

[@raquelvillarvlog6497]

Good day my friend nice vedio god bless i hope stay connected

[@AngelHernandez-hh3rq]

Muy buena tu idea

[@GreenShortzDIY]

Gracias por mirar el video. Y por el cumplido. Gracias mi amigo.

[@godrow]

Very nice!!!

[@GreenShortzDIY]

Thanks for watching. :-)

[@Stephanie9959]

Love your videos.

[@GreenShortzDIY]

Thanks for watching, Stephanie.

[@table4glasses]

Watching you mix the clay looked like how the dough for a croissant is made, but on a larger scale! Cool video, thanks as always for the great content :)

[@GreenShortzDIY]

Ha. The anti-croissant. :-) Thanks for watching and for the encouragement.

[@col2959]

viddynovic I've never made a croissant

[@peggykelliher5698]

@@GreenShortzDIY 🤣😂

[@pawanshrestha5321]

U worked realy hard.

[@GreenShortzDIY]

Thank you Pawan. This was a fun project. Thanks for watching.

[@christophebroillet2867]

Great video. As you like challenge look about having a better heat exchange. Heating water with fire and copper inside and then cold water thru. Look at geoff Lawton rocket stove heating water first version you will love it.

[@GreenShortzDIY]

Thank you Christophe. I will check out the Geoff Lawton video. Thanks for watching.

[@simplyed9482]

Job done ✔ You inspired me 👍

[@CritterFritter]

The Hopi Indians in the SW USA built adobe dome dwellings called “hogan” that kinda remind me of your mud rocket stove. Doorways and Windows about the base with a central chimney. Fun project! Thx!

[@GreenShortzDIY]

Cool. I’ll have to look that up. Thanks for the info. Thanks for watching.

[@1charlastar886]

NAVAJO hogan, not Hopi. Find pics on

[@jorgedalua4156]

I love it how you make stove,..i living in france and brasil, make some stove here where i am,.would be funny vacations

[@judeevolves3347]

Excellent video. 🙏💗🙏

[@GreenShortzDIY]

Thank you for watching.

[@sophiepoint6270]

Good job with the coil👍

[@GreenShortzDIY]

Thanks 👍

[@olddanb1]

There's nothing to see here. These are not the Droids you're looking for. EXCELEEEEEEEENNNT.

[@GreenShortzDIY]

Thank you for watching.

[@TheFrogmeadows]

OMG I love you!

[@teslah2997]

nice job!

[@GreenShortzDIY]

Thank you. Thanks for watching.

[@felicitascastroaguilar5485]

Hola muy buen video gracias mu gusta su trabajo es muy interesante y genial saludos

[@GreenShortzDIY]

Muchas gracias por mirar y por los cumplidos. Lo aprecio. Mucho gusto.

[@user-kg1mv4ek8e]

Good

[@mvblitzyo]

super awesome ! great video !!

[@GreenShortzDIY]

I appreciate the encouragement. Thanks for watching.

[@daverdal1]

Cobb and Go !!

[@GreenShortzDIY]

Thank you for watching.

[@demesewmereid9147]

You are smart .I like you

[@bonguy3461]

i havent watched this channel in 2 years i forgot this existed. time to catch up on my fav

[@GreenShortzDIY]

Ha. You've got some catching up to do. Thanks for the encouragement and thanks for all the watching. :-)

[@bonguy3461]

@@GreenShortzDIY last video i watched was worm bin composting that was 3 years ago. love the cob works.

[@littlechestnutorchard]

You wasted so much hot gases and energy from short chimney, you must utilize chimney design either make it longer and longer copper coil or add extra heat absorbing material to the chimney.

[@GreenShortzDIY]

Su, you are right. I was surprised how short the coil was for a 10 foot piece of copper. This was an experiment, of course, but if I made this again, it would have a much longer cool and taller chimney. Thanks for the feedback and thanks for watching.

[@SpiritusBythos]

Do you have a design that you highly recommend? Thank you

[@jesuschristislordoflordsan427]

i thought it seemed like waste of energy too and it slipt my mind that instead of copper coil we could use some kind of water container right on the fire instead, sealed with input/output to larger container somewhere making use of " thermal siphon"??

[@kristoffer-robinlotze7273]

@@jesuschristislordoflordsan427 Hmm... a double walled chimney with water in it. 🤔 Now you got me going! 😀

[@thorman1089]

Jesus Christ is Lord of Lords and King of Kings the copper pipe has more surface area and therefore will heat quicker

[@nedrgr21]

Thanks 4 the vids - about to make one myself. What about making the j tube firebox since u r 1\2 way there anyway? May get a hotter burn.

[@imonlyhalfnutsreally2113]

Tom, great video as always !!! Can I share some terminology. You built a water heater, you did not build a hot water heater. If you built a hot water heater you would need a supply of hot water to feed your water heater to then get HOTTER water and that wouldn't make sense and it would be redundant 😁. You understand that and very few others can grasp that idea. Not sure what that says about the mental capacity of the rest of the world 😁. Keep up the great work and keep doing the videos, there is much to learn from this man.

[@GreenShortzDIY]

Thank you for the feedback. Thank you for watching.

[@aRAhandfamDaExplorer]

You know so many things my friend and this is cool:)

[@calmauric8218]

Interesting watching the cob being made! I Made a cement copper coil stove recently too. I also used 3/8 pipe but roughly 3x more. I found that it burnt so much better when I slipped in my flu extension. And it got much hotter. So far I've used it to heat 200l of water with success.

[@flamel397]

How much time did you to heat up 200lt of water?

[@calmauric8218]

@@flamel397 takes 3 hours to heat up

[@calmauric8218]

But that's not 100% of the tank. I only use the top quater as that's always the hottest part. Normally comes out at about 45c

[@flamel397]

@@calmauric8218 im asking cz im trying to build a greenhouse with this method to heat up the gh and to make sure that theobroma cacao has 23/25 C temperature all the year. Did you actually know if this method with heating the water cloud help me to do this? (I'll heat up approx 300lt of water in the cold night)

[@calmauric8218]

@@flamel397 ok. Look into "rocket mass heater" several people have successfully heated a greenhouse bed in Sub zero temperature. It's like a rocket stove. But even better

[@hikerx9366]

Incredible.....just want to be off grid so bad when I watch stuff like this. Thanks so much for informing us all how easy it can be with DIY projects my friend. I love the color of the red clay can a person buy it if they don't have access to this type of clay?

[@pauljs75]

If you can do anything with fired clay (not sure if you've got a kiln anywhere your setup), it might be neat to try making interlocking sleeved cylinders. Shouldn't be too different than making pottery around some forms. Then after firing those, you could stack those sleeves to be used as a chimney liner for something like this. Perhaps adding one or two feet to the height, since those would help support the surrounding clay/cob from deforming too much.

[@GreenShortzDIY]

Hi Paul. No kiln yet, but I have something that might work. I like the idea. I’ve been thinking about trying some clay mixed with sawdust to create a fire brick. Could do them in a cylinder form to do what you are suggesting. Thanks for the feedback and thanks for watching.

[@monicareid8858]

Really neat design! This could be incorporated with a shower house, a hot tub, an outdoor cookstove, or add to a spa-like environment Once this is finalized, I’d use copper pipes or pecs designed for heat for the hose. Also, wouldn’t it be better for the heated water to got the bottom of the bucket (instead to the top) and the cold water to come from the top? As hot water enters the bottom of the bucket, the heat would rise, causing a convection current so the entire water mass increased gently, instead of downward in layers. The cold water, being heavier, would lend to cycling faster from the top, as well. Once the cob dries and bakes, this will become much tighter and more efficient The way you have it now lends to maintaining temperature layering and would be harder to draw from with a spigot, as the first water you draw will be the coldest. Nice prototype experiment! Excellent explanation I like your long-fiber use of cob!

[@GreenShortzDIY]

Thank you, Monica. I agree there are many applications. I hadn’t considered your suggestion on switching the feeds. I’ll have to try that. Thank you for the feedback. Thank you for watching.

[@josephinehogg3629]

Great idea. I bet people in California are wishing they heard about this before their power was turned off

[@GreenShortzDIY]

Ha. True. Thanks for watching Josephine. Have a good day. :-)

[@obiecanobie919]

WE are watching ! the big one is just around the corner ..

[@eieio-mn9pm]

Californians deserve cold showers

[@charliem989]

@@eieio-mn9pm boomers should have never been allowed on the internet...

[@carlosgermansanchezlizarra9629]

GREATFULL IDEA FOR USES OUTDOR , CAMPING , ETC , THANK YOU MR GREENSHORTZ BE GOOD , I SEE YOU LATER

[@GreenShortzDIY]

Thank you, Carlos!

[@JohnDoe-ib3hr]

Love this build! would be interesting to see the difference between having a coil or just heating a boiler over the flame and letting that thermo-siphon into another container instead.

[@GreenShortzDIY]

Thank you, John. I think a pot on the top would have been more efficient, or gathered more heat. Of course, I wanted to try the coil. :-) Thank you for watching.

[@TheEmbrio]

The coil allows to cook something on top of the rocket stove and still prepare some hot water, for doing dishes or a shower later on...

[@macks9511]

Great project. The only thing you needed to do was change up the hosing. The top hose in your cob stove needs to go to the bottom of your bucket so that the convection heat can continue to rise and then run your top hose from your bucket into your cold water intake in the oven. We did this in alternative energy in college with a solar panel.

[@thomasbroking7943]

Instead of plumbing coil look at the AC copper coils. I was told they're easier to bend.

[@GreenShortzDIY]

Thanks for the feedback, Thomas. Thanks for watching.

[@rhiantaylor3446]

Thank you for the video, i'm facinated by rocket and similar wood-burning stoves. I am particularly attracted to the heat efficiency and low-pollution achievable which I understand comes from having a very high temperature extended chimney above the fire to complete the burn. Having a pipe for water heating is attractive but being so close to the inside of the chimney, I think this must negate the high temp chimney objective. I presume this why we often see a cover over the chimney, forcing the exhaust back down and exhausting at the base. The area between the chimney and the cover is the area where heat could be harvested with the coil to heat water, without risking the "hot chimney" principle. Any thoughts - have you tried this sort of design ?

[@GreenShortzDIY]

Rhian Taylor Hi Rhian. I think what you are talking about is called a rocket mass heater. It’s related to a rocket stove, but usually has a taller chimney and a barrel or some over the top to provide complete combustion while forcing the warm exhaust through a “mass” to absorb the heat and radiate into a living space. The complete combustion relies partly on a very hot riser. It’s sort of the nozzle of the rocket. I do want to eventually make one of these, but I’m still in the learning phase. Paul Wheaton is a guru on the subject. You might enjoy some of his videos. Thanks for watching.

[@denisewilson8367]

@ Rhian Please check out Audiobro for a great rocket mass heater and cooking stove with optional hot water heater. he offers plans for the two versions with personal help if needed.

[@evandorco5193]

Nice video

[@frankenstein3163]

Great stuff as always. TY Is cob better for water heater ? Or is you's pear lit, sand, concrete mix better ? Heating water wies.

[@QueerVampire6969]

WHAT ABOUT A COB ROCKET STOVE OVEN / PIZZA OVEN??? I'D LOVE TO SEE THAT

[@GreenShortzDIY]

Now you are talking. :-)

[@peterbeyer5755]

Aprovechio have a great rocket pizza oven.

[@josephdupont]

any problems with the copper/ heated floors with copper get abraded by expansion and contraction.. But the cob will most likely be less of a problem.. Nice video.

[@FabiusPyromanus]

Awesome video! Subbed!

[@GreenShortzDIY]

Thanks for watching!!! And for the sub. :-)

[@thky7228]

Thankyou super, Dizayn kombi

[@1943L]

Conical shape of open coils in the chimney would pick up more heat perhaps.

[@CampTlangram]

Making 1-2inch gap between copper coil and sand will allows more flame to hit the coil.

[@kryl70kryl]

хорошая работа! молодец!

[@GreenShortzDIY]

Спасибо за комплимент. Спасибо за просмотр.

[@user-wh3md6si7q]

Всегда в иностранных роликах ищу коммент от наших: их мнение, итерес к теме для меня большой показатель.

[@fbksfrank4]

I want to make a heat battery, this is one way of heating it up!

[@916619jg]

You can also send a steel cable down the copper tube to prevent kinking. If you pull some cable out as you twist it it's less likely to get stuck. That is the best way to do brake lines btw... You can also fill it with water and freeze it

[@tisabelmartinez817]

Good attempt, although you should have the top coil from the stove going in to the bottom of the bucket, that way you heat all the water in your bucket. Remember heat rises!!!!

[@johnluquer]

Bend your pipe around your pvc chimney form.

[@GreenShortzDIY]

Good suggestion. I did like that bending the copper by hand allowed me to feel how it was moving...at least my first time at it. Thanks for the feedback.

[@jimkeegan6503]

Came to say this!

[@fraa888grindr7]

How long did it take to heat water? Why aren't you trapping heat with lid on bucket; how much faster would it heat with a lid?

[@DerekRoss1958]

The bucket was just a temporary test unit. It didn't matter how long it took to heat the water. So he didn't need a lid.

[@fraa888grindr7]

@@DerekRoss1958 interesting. That's one of the things I would be testing for.

[@grannyphoenix6520]

Damn, young man. Surely that train is early.

[@okmmauh]

Your Grandfather taught you. What a great legend of a man

[@robertmontgomery3186]

Instead of placing coil inside the near the fire. I would have encased the coil inside the mud. Still getting the heat from inside but would have given you a much larger coil ring for more water to be heated.

[@markthomasson5077]

Robert Montgomery agreed, I guess he will burn through that coil pretty quickly.