# Rocket Stove Water Heater Build (pic heavy)



## biggkidd

Hi everyone I have just started building a new water heater for our off grid home. This is my first attempt at a rocket stove. My second go building a wood fired water heater. The first one lasted six years until I let the stove stay out several days in a row during the coldest weather we've had in years. 

Anyway this build will be using mostly recycled materials. 

Didn't get a lot done but am slowly making progress. This first pic is the assortment of tanks I am using to build with, well some of them. Along with a few of the tools I use to cut. I do own a cutting torch but rarely use it. I prefer clean cuts like a saw leaves. 



I started with the tank I thought would be the worst to cut which was the oxygen tank far left in the first pic. I started the cut with a skill saw and metal blade.




Then finished up with a sawzall. You can see I use a simple strap to hold the tank still.



The tank turned out to be a little shorter and fatter than I thought.



In that pic you can see a small hole I drilled in the tank before cutting. That"s there because I'm chicken a friend gave me that tank & said it was empty. The valve opened and nothing came out but I still wanted to be sure before I went throwing sparks while cutting it open. I haven't blown a tank yet nor do I want to !



I also got the top and bottom cut out of the propane tank 2nd from the left. I used a cut off wheel on a grinder to start the cut then a jig saw.



I don't know if you could tell but it was sitting on the other tank I had cut.



I also got one of the freon tanks cut but I am not sure its going to work for what I wanted. It's to big around at 9.5". I was looking for 9" for that inside baffle. That one I cut with the grinder and cutoff wheel. Cut like a hot knife through butter.

Here is a bad drawing of the idea I have in mind.



Its not to scale and leaves a lot of details out but gives you an idea. :stars:

That's all I've gotten done so far more tomorrow. 

If any of you have any ideas to improve this or any tips and tricks to make it easier please let me know.


Thanks


Larry


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## biggkidd

Wow 68 views and no comments I must be doing everything right. LOL Just kidding.

Guys I remembered the camera but forgot to take many pics. I did get a few. 

First up an old oil tank for more metal. Question 3/16" metal is what gauge? 8 maybe? Anyway this old tank I picked up a year ago for $20 has done a couple of projects. Heaviest dang tank I've ever seen.



I think that may be why I forgot to get many pics. I was rattled by the sawzall. lol Interesting side note made five 5 foot cuts on the same blade and still going.



Ok in that pic if you will notice the light shining through I started to cut it across then realized it would save cuts and metal to cut the circle in since I needed both sides of the cut.

Did get one side of the fire chamber welded up then stacked a few pieces as a mock up. Just to see how thiings were fitting so far.



I did change up the design a little as you can see from the mock up. Still going with the same basic principals. One other change the burn chamber made (upright cyl. last pick) the OD is 6.75" so now the fire box is also. So instead of 4x6 ID its now 4x6.375 ID I think. Some times just have to work with what I have. 
That's about all I got done today. People kept stopping in to talk witch is fine but cost me a couple hours.

Not sure if I will have time tomorrow to work on this a bunch of other stuff is taking priority. You know the type; fire wood, water, cleaning, washing clothes, grocery shopping etc. fun fun fun

Have a good night.


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## rusticfarmer

I like it. Can't wait to see it done. Do you think you might have some trouble cleaning it out?


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## biggkidd

rusticfarmer said:


> I like it. Can't wait to see it done. Do you think you might have some trouble cleaning it out?


Thanks 
I don't think cleaning will be an issue. I'm planning to make the top removable and the end of the fire box will have a door. From what I have read rocket designs hardly have any ash as most all goes up the chimney. 

Larry


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## dirtman

I believe 10 ga. is 1/8. So 3/16 Is probably less than 6 ga.


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## elkhound

outstanding...cant wait to see this as it goes along.


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## biggkidd

It's slow going working with old junk but at least the price was right. BTW I made a mistake on one of the earlier posts I had said the burn chamber was 4x6.375 that was wrong its 4x6.625 or 6 and 5/8. 

So I started off today by welding the old tank on which is now the burn or reburn chamber.



Then the top plate for the burn chamber.



The next thing was to get the sides on for the feed. That didn't go so well I messed up cut and tacked the front and back on the left and right. Then had to break them back off cut the angle off back to square ends. Then cut and installed the correct pieces for the sides. 



Ok here here not sure if I did right or not but I brought the rear wall of the feed down into the back of the burn tunnel. 



My thinking is the air will have to drop below this wall and be started back up as it enters the fire.


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## biggkidd

Also made a separate air chamber. Watching the youtube videos I noticed that the builds that reached the highest temps all had a separate air box. So I made the air box 1" by the width. There will be a cap or top for the feed that will stay closed so air has to draw through the air box. The top will also help keep any rain etc. out of the feed and burn areas.



In that pic the last wall is not in its just a piece I clamped in to show the actual size.



The feed is 15* from vertical the reburn is 2* the other way from vertical. I plan to raise the floor of the burn chamber enough under the reburn to make it vertical my thinking here is that it gives the fire and heat a nudge in the right direction. Okay it was an accident that I left once I realized it might just work in my favor. 

Still a long ways to go. Need to make a top and a clean out door along with that last air box wall. Then I'll be ready to think about mounting the bottom section of the heat exchange.

Still open for any suggestions. 

Larry


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## rusticfarmer

biggkidd said:


> The feed is 15* from vertical the reburn is 2* the other way from vertical. I plan to raise the floor of the burn chamber enough under the reburn to make it vertical my thinking here is that it gives the fire and heat a nudge in the right direction. Okay it was an accident that I left once I realized it might just work in my favor.
> 
> Still a long ways to go. Need to make a top and a clean out door along with that last air box wall. Then I'll be ready to think about mounting the bottom section of the heat exchange.
> 
> Still open for any suggestions.
> 
> Larry


I suggest you make some stainless slats or fire brick with grooves under the wood to keep it off the floor. Regular metal will just burn out. The key is major air at that cool air vent. I really like the way you are setting this up. I just wonder if you have the right sizes for burn tube and air intake. I always have to play with it when I make a rocket stove till it's right.


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## biggkidd

rusticfarmer said:


> I suggest you make some stainless slats or fire brick with grooves under the wood to keep it off the floor. Regular metal will just burn out. The key is major air at that cool air vent. I really like the way you are setting this up. I just wonder if you have the right sizes for burn tube and air intake. I always have to play with it when I make a rocket stove till it's right.



Thank you for the tip this is my first rocket stove. The air box may well be to small.

Larry


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## biggkidd

Well after being to feverish from my meds sunday to work yesterday I was able to get back to this today. 

I started off by finishing up the air box.



Next I cut notches in for hinges and made a top and door.







I also made a simple latch for the door but forgot to get a pic of that.


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## biggkidd

For some reason photo bucket is giving me a hard time tonight. It doesn't want to give me the link addresses for the pics.

Next I cut that 30 lb. propane tank in half at the original seam. 





May not have been the ideal place to have the split but with the lip it makes it easy to remove and reinstall. 

Before I went any farther I thought it would be a good idea to give this much a test run.





The amazing amount of heat quickly fogged my camera lens.

Larry


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## biggkidd

I stuck the bottom of the heat exchange on for another pic.



Even though I didn't catch a picture of it the flames got all up in the heat ex-changer. Not sure if thats a good idea. I still have quite a few pieces to make. 

Okay here's what I have learned so far. With just a handful of damp twigs off the ground and a small bit of ripped up cardboard this thing makes HUGE amounts of heat. Lights easy and burns fast. Now I also noticed that it burns a lot harder with either the door or top open. So I may have made the air box to small. But I am not sure at this time. I'll know more after a few true burns with a full load of wood after the stove gets fully up to temp. .

One thing I would change if I built another one is I would angle the fire tunnel up some (10-15*) to help encourage the flow of the flame and heat. I would also make the reburn chamber taller probably 24" instead of 18". 

One thing that it did tell me was that its burning incredibly HOT. It turned the clean steel blue like a set of chrome headers. Wish I had a thermal IR heat gun to see what the actual temp was. It also got hot faster than I expected.

Larry


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## partndn

Wow, nice job!


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## biggkidd

partndn said:


> Wow, nice job!


Thank you still a long way to go. New materials would turn out a better end product.

Larry


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## partndn

Yeah, maybe, but you will have learned so much by doing this, without expense. Nothing wrong with repurpose!

I couldn't do it, but I have a friend with a welder and have thought about bartering stuff for his welding. :buds: You're inspiring me further.


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## biggkidd

partndn said:


> Yeah, maybe, but you will have learned so much by doing this, without expense. Nothing wrong with repurpose!
> 
> I couldn't do it, but I have a friend with a welder and have thought about bartering stuff for his welding. :buds: You're inspiring me further.


 Repurposed materials are about the only way I get to play with my crazy ideas. There is nothing wrong with it either. I just sometimes miss the days when I could call the suppliers and have what I needed delivered.

Thanks you know necessity is the mother of invention! 

You know welders have come down a whole lot and it really isn't that hard to do I bet you could pull it off.

Have a good night.

Larry


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## biggkidd

For todays update things went kind of slow. Did a lot of head scratching trying to figure then shape a collar.



You can see I clamped a strip of 11 gauge metal on the reburn chamber then tack welded it and worked the clamp around until I had a good fit.



Then I welded the seam closed and cut the tack welds loose.Then welded the collar to the bottom of the heat exchange. Now I can separate the pieces for cleaning or moving.





Once I got that done things were starting to get moving along.


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## biggkidd

Next I wanted to see if it would all fit in this old propane tank. 



As you can see it was a close fit or at least looks like it will be. So then I had to split that 100 lb tank like I did the other one. Once I had the two halves I cut a hole in the bottom and side for the base to slip in to. I don't know if the propane over the years had hardened that steel or what but that was some HARD metal to cut.



A test fit went well now I can insulate the reburn chamber and up from there.



You cant tell it from this angle but the base piece was on. 



The top outer cover was not on in that pic it is going to be a close fit. even if I can't get any insulation in the top section it will give a closed air space which will help some.


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## biggkidd

The base piece installed. 



I should have gotten a profile pic to show that the fire tunnel still needs to be insulated somehow. 

Well that was all I got done today. Another day or two should just about see this phase of this project finished. Then we get to test. Still debating about that as I already took the 50 gal water heater tank home. Our road and driveway are awful so not sure I want to make the extra trips required to bring it back to the shop for testing. I may just hook everything up in place and go from there. Our road and drive are so bad we had to park the new jeep and go back to driving the big jeep and its even having a hard time. If it gets stuck I don't know what we will do.

One thing I am still having a hard time figuring out is how to run the piping through the double wall. Any ideas? I still have to make up the center baffle and fit it. I've asked everyone I know for a pop rivet tool & everyone says yep I got one but have no idea where it is. Gee that sounds familiar.


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## biggkidd

Well I did get most of it finished today. Although it was an aggravating day and I am not real pleased with how I did this last part.

But this is what it looks like. 




The "look" is fine with me fairly clean even. This more important part inside is what I am not happy with. 



I trashed the one piece of sheet metal I was able to come up with. In all honesty it was a little small in the first place. Then I totally messed up trying to make the cones on the ends. So I went ahead and use one of the freon tanks as is other than cutting off the valve and placing a riser on the bottom. I am sure this will hurt performance but until I come up with something else to work with it will have to do. 

Here's a shot from the front.



All that's left to do at this point is to weld the chimney pipe adapter on and insulate / cover the fire tunnel. Oh yeah and stuff insulation around the reburn chamber. If theres time tomorrow I will try and hook up a 5 gallon bucket to test with. I have to make a trip into the city mid day though. 

Bending copper coil that's several years old and been bent many times as not nearly as easy as new stuff. But since it looked okay I used what I had. I do however have a nice shiny newly coiled 10' piece looking for a new home. (5" coil for 6" stove) But it's going to be a part of another one smaller and portable for the guy who gets me lots of old junk to play with. He's always going here and there with the boy scouts and needing a way to heat water. Thought I might make it so the coil removes easy and can also be used as a cooking stove. Still thinking that one through.

Y'all have a nice night!


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## Bret

A lot of skills going on there. Fun. Interesting. Good work.


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## Harry Chickpea

How do you plan to clean off the creosote that will build up on the cold metal of the tank holding the water? That will act as an insulator.


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## biggkidd

Thanks Bret


Harry,

The only place water will be is in the copper coil. I also made it so the top can be removed for cleaning if needed. A rocket design burns so hot and fast I doubt there will be much if any build up.

Thanks for the comments. 

Larry


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## biggkidd

Well we gave it a tryout yesterday. It works! It's not as fast as I was hoping for but I still think it will work well. Of course it still needs some fine tuning and dry wood. What we burned yesterday was just cut last week.

First pic is the burn load for this test.



Fire burning nicely.



You can see in the pic that the water is flowing through the heater via therm-o-siphon. 



And last a short video hope it works. 



You should be able to click on pick to watch video.

It took about 10-15 minutes to warm that water from roughly 50* to 105* .
Turned out Pat had a temperature gauge we were able to check with. Water out of the hose was 50* bucket of water got to 105* before we put the fire out. The wood was about 1/2 burned.

Larry


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## rusticfarmer

That's some nice work and really great fabrication.


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## biggkidd

rusticfarmer said:


> That's some nice work and really great fabrication.


Thank you it was a lot of fun too. Making useful things out of junk is nearly a passion for me. Hopefully have it hooked up today. The weather hasn't been cooperating.

Larry


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## biggkidd

Well we got the hot water rocket stove in today, after cutting some firewood. It does work as advertised! I decided after finding gauges that only started reading @120 to drop that idea. I did come up with a way to know the temp though, sort of. Hook a LED to the thermostat that came with the heater tank. 

Overall it works real well from what I have seen so far. It has had a workout since it was hooked up. It has been burning the whole time. Through two baths and showers. A load of dishes, and general clean up. The water has steady gotten hotter. So it would also work as a on demand type of water heater I believe. 

I do see several things I would do differently. Mostly just to improve longevity and efficiency . The size of the hopper, burn chamber, and reburn seem to work pretty well. I would use more and larger coil, a lot more. A whole lot of heat is being wasted. 

If anyone decides to build one or if I build another. (which I probably will) These are the changes I would make. Make the fire box large enough to line completely with fire brick. Use a refractory coating inside the reburn chamber and up to the top of the coil or to the exhaust stack. Both on the walls and on the baffle. Using this basic size I would likely go up to a 3/4" X 60' coil, at minimum 1/2"x 60'. Like I stated a LOT of heat is being wasted. One other thing I might change if height isn't an issue. I would move the hopper in till you are loading the wood right in the bottom of the reburn chamber and do away with the fire box tunnel. The burn/reburn chamber would need to be taller by about a foot.

I will try and get some times from start up to hot to use and hot to cut off sometime when we are not using it. 


Larry

Have a nice night.


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## biggkidd

I haven't been burning this at dusk before. So I just noticed it looks like it gets warm.









 Have a nice night

Larry


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## biggkidd

After two years of hard use I finally had to pull it apart and clean it out. I was amazed as we have been burning wet green wood almost exclusively. The freon tank used as a diverter to make the hot gases go over and around the coils is about done. It and the 30lb propane tank both have rust and the metal is flaking in large 4+ inch pieces. Propane tank is not nearly as bad as the freon tank. Amazingly it all came apart and back together without trouble. Only took about an hour. I have no doubt this wouldn't have been necessary if we had been burning dry wood. The coil and freon tank were almost one clogged with buildup. The metal is showing considerable heat damage which is no surprise. Several places have buckled up and or warped. 


Lessons learned here are to line the inside with firebrick second I think getting rid of the freon tank and making concentric rings with a longer coil. Think a coil starting at 4" then 6 8 10 12 back to 4 and so on. It would still be a single run maybe twice or three times as long. A LOT of heat is still being wasted that should be being used. I expect this would cut the burn time in half and the fuel used as well. One other thing a rain cap is in order maybe a flapper style with a rod to open and close. I think the rain caused a bunch of the rusting along with the caustic residue from the wood.

Trial and error teaches if we are smart enough to listen. lol 

All in all I am very happy with it.
Larry 

Turing Timberland to Homestead Since 2008


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## Bret

Interesting. Way To Stay With It. Thanks


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## partndn

I forgot about this and glad you posted to bring it back up!
Lots for people to benefit from your demo and results.


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## biggkidd

partndn said:


> I forgot about this and glad you posted to bring it back up!
> Lots for people to benefit from your demo and results.


Just thinking someone may benefit from seeing what works and what could be improved. Thanks for your comments.


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## Harry Chickpea

"The coil and freon tank were almost one clogged with buildup."

Expected. Got pics?


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## biggkidd

Sorry Harry I didn't think to take any.


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## AgrarianDr

Just had to say kudos. 
In one of your earlier posts you were wondering about the ashes. I suppose you have discovered by now that a rocket stove sucks in air like a vacuum cleaner, and as such, continues the burn until literally nothing is left. I have built a number of them. One I used to cook dinner and boil water at a (loosely organized) hunt club. Got to the point where I had to build another because everyone wanted to use mine with, as you said, a few sticks off the ground
Great job :clap:


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## JeepHammer

Version 2.0, maybe a little larger at the base and some fire brick inside to reduce thermal losses and glowing metal?
Refractory bricks are cheap...


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## Bearfootfarm

> Lessons learned here are to line the inside with firebrick second I think getting rid of the freon tank and making concentric rings with a longer coil. Think a coil starting at 4" then 6 8 10 12 back to 4 and so on. It would still be a single run maybe twice or three times as long. A LOT of heat is still being wasted that should be being used. I expect this would cut the burn time in half and the fuel used as well. One other thing a rain cap is in order maybe a flapper style with a rod to open and close. I think the rain caused a bunch of the rusting along with the caustic residue from the wood.


You can get "refractory cement" that pours just like concrete, or can be used like mortar to enclose metal exposed to extreme heat.

Using the proper sized pipes and some wooden forms you could enclose a coil of water line inside a hollow tube of refractory that the fire would pass through.


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## biggkidd

One thing to remember guy & gals is this project has worked for 2 years and was made from 99% recycled materials. IIRC I spent 3 bucks for a couple hinges. So 2 years of hot water for some time & junk plus 3 dollars. Not a bad deal in my mind. LOL :walk:

But now that the learning curve is more or less done I would spend some bucks. Point of fact when I do build another it WILL have all my stated improvements and maybe some poured refractory cement TOO. Possibly Along with one or more of the reflective coatings to help hold the heat where needed. 

I have always liked practicing with junk as if it doesn't work I'm not out much if anything. When I build another water heater I will spend maybe $200-300 for a lifetime waterheater. When I can swing it I do try and make or buy things that will last forever!


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## biggkidd

Decided that burning a 5 gallon bucket of split wood was to much for 50 gallons of hot water. So I broke down and bought a 60' coil of type K 1/2"ID copper tube. Fitting it all in the required space was tough. But it's done and cut the wood consumption down by about half. I do still plan to rebuild the burn chamber as the metal isn't standing up to the excessive heat well. It's going to be the same design just lined with firebrick and use a clay chimney liner in place of metal. The dimensions are actually a little better than what I first used. IMO 

http://www.homesteadingtoday.com/attachment.php?attachmentid=57508&stc=1&d=1477333355

http://www.homesteadingtoday.com/attachment.php?attachmentid=57509&stc=1&d=1477333355

http://www.homesteadingtoday.com/attachment.php?attachmentid=57510&stc=1&d=1477333355

Pics of the new coil and the jig I made to bend it on. Been so long since I've been on here I couldn't remember how to insert the pics like I did before.

The new coil is 3 times as long as the original and is pushing the limits almost turning the water to steam. I'll check back incase anyone has questions. 

One other thing several people have asked if I thought this would make enough heat to heat a home. There is no doubt in my mind that with a large enough storage tank this would work wonders heating a home. It would have to burn twice a day 24hrs I expect and heat a well insulated home just fine on a couple buckets of wood per day.


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## Bret

Keep notes. Keep building your success formula. Looks neat and efficient. You're on to something.

You've come from "afar."


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