Rocket stove mass heaters...

Discussion in 'Off Grid Living' started by Witch Doctor 01, Dec 6, 2011.

  1. Oddmar

    Oddmar Monkey+

    It's just a regular 55-gallon steel drum. Picked it up at the salvage yard for $5. I used a wire wheel on my right-angle grinder to take off the paint.

    Go to • View forum - Heating and Cooling to read alot of good threads by people who have built and used these stoves. Follow their footsteps and you'll have a good-running stove. Don't make the noob mistake of "Well, i don't have X so i'll make mine smaller here, and just run the exhaust out the window cause i don't wanna cut a hole through the roof", then complain cause it doesn't work right or it smokes up your house.

    Don't be afraid to ask me questions, i like to help people new to this technology.
    chelloveck likes this.
  2. chelloveck

    chelloveck Diabolus Causidicus

    Thanks for posting the link....that is one cool self sufficiency/sustainability website.

    Found this cool idea which would make for a nice project.

    Last edited: May 27, 2021
    Gopherman likes this.
  3. cjsloane

    cjsloane Monkey

    chelloveck likes this.
  4. Gopherman

    Gopherman Sometimes I Wish I Could Go Back to Sleep

    I posted this a while ago, their are clean outs located in the front of the burn chamber and the big drum can also be removed.
    The real beauty of this thing is, the burn is so hot and complete, that creosote is not an issue, and only pure white fly ash is left!
    I have one in my garage, a little prototype I built out of refractory clay and its amazing. It heats the main chamber so hot you can't touch it in a few minutes. I am currently building one in my green house to get ready for winter crops. I am also going to build a portable version for my house.
    I will make a detailed video of the build and post it along with supporting data.
    chelloveck and ghrit like this.
  5. Gopherman

    Gopherman Sometimes I Wish I Could Go Back to Sleep

    A T placed at the exhaust port and a 6" 9 volt fan place at the backside will create a very efficient draw and eliminate back flow of smoke into the house.It also eliminates the need to place a burning piece of paper in the flue to start the draft until the furnace comes up to temp.
    A secondary pipe coming into the house, and out by the intake will supply enough outside air to supply what is needed without creating a draft from a window.
  6. Oddmar

    Oddmar Monkey+

    If it's built properly, the stove creates it's own draft internally and no exhaust fan is required. I've thought of adding one for cold start-ups though. I've never needed a cold-air intake. The RMH will cook you out of the house if you let it run a little too long, so you'll have a window or a door open anyway.
  7. Gopherman

    Gopherman Sometimes I Wish I Could Go Back to Sleep

    As the fire begins to go out I have found that a temperature drop occurs, the draw slows or stops completely.
    The fan does not have to be left on continuously, definitely aids in the starting process but if you leave it unattended it's a good idea to turn it on.
    Its hard to get the smell of wood smoke out of everything in your house. It also insures that the fire burns out quickly.
  8. Oddmar

    Oddmar Monkey+

    I dunno what you built your RMH out of, or even if you have one, because...

    With the fire burning, the interior of the burn tunnel and heat riser is between 1500 and 2000 degrees fahrenheit. Even an hour after the fire has Completely gone out, the draw on ours is still strong enough to suck small pieces of paper through the tunnel.

    That's why when the fire goes out we cap the feed, to keep it from drawing air through all night and cooling the mass by convection. Even with the feed chamber capped all night, in the morning you can't put your hand on the top of the drum, because the heat riser is still so hot it's keeping the center top of the drum burning hot.
  9. Gopherman

    Gopherman Sometimes I Wish I Could Go Back to Sleep

    Mine is a 6" diameter made from refractory clay, that I poured into a mold. I do not have the cob bench set up yet, which may be causing some of my back draft problems
    Still in the testing phases of completion.
    We are building a cob structure on our property that will have one, and I will install one in my greenhouse as well, want to see if I can build a portable unit for inside as well but I think weight will be prohibitive.
    I will post the Video.
    Comments only intended to help troubleshoot problems I have seen others mention and how they dealt with theirs.
    The small fan cannot hurt and can definitely help increase the rate of burn when starting the fire by acting something like a bellow, I have been dropping lit paper into the chamber to start mine, very inefficient way to start the draft.
    I have seen videos where back draft has been a problem and that's how they dealt with it, I have been having that problem when starting my fires.
    If you have an up and running unit/ complete with the bench, your definitely a step ahead of me!
    This tech. is awesome and absolutely a must for any scenario, cooking, boiling water or just staying warm.
    The Gasification stove is awesome as well, I do have one of those up and running,Talk about efficient!
  10. Oddmar

    Oddmar Monkey+

    The only times i've seen major backdraft problems (with other people's RMH's) is when they make the interface too small (between the drum and the ducting through the mass). Our drum sits on a section of another drum and the whole side of that section is open feeding into the mass.

    Or when they run the exhaust out the side of the building (to some sort of vent cap or tee) instead of through and about 4' above the roof. Wind pressure on the side of the structure causes the backdraft. Wind flowing over the vent above the roof just increases draft.

    It's also important to decouple the burn tunnel/ heat riser from the floor, so the (concrete?) floor doesn't leach heat from the system and cause an incomplete burn.

    Another important thing is to insulate the exhaust stack. The thermal mass leaches so much heat from the exhaust sometimes the exhaust doesn't want to rise up out the stack. We put a 10" diameter piece of ducting around the 8" diameter exhaust stack and packed cellulose insulation in between them. This keeps the exhaust hot enough to rise up and out.

    Also the heat riser Must be a minimum of 2 times taller than the burn tunnel is long. My latest one is a 10" burn tunnel and a 42" tall heat riser. Next time i'll lengthen the burn tunnel to 14" or so.

    On my next build, i intend to use refractory cement and vermiculite mix for the burn tunnel and heat riser casting, with fireclay and vermiculite cast around the burn tunnel (to save money). Refractory cement is $27 for 3.5 gallons from Acme Brick in Malvern Arkansas. Vermiculite is $20 for a 4 cubic foot bag. We've got good enough red clay here on the property instead of buying fireclay.

    My previous 3 builds i've used 2"x4"x9" firebrick to construct the burn tunnel and heat riser. But that used 82 bricks at 1.98 ea.
    Gopherman likes this.
  11. Gopherman

    Gopherman Sometimes I Wish I Could Go Back to Sleep

    It's not always the destination that's most interesting, mostly it's the Journey!:)
  12. Gopherman

    Gopherman Sometimes I Wish I Could Go Back to Sleep

    OK! I found a way around having to be a welder to do the rocket stove. The burn chambers always burn out at the elboy and unless you build them out of firebrick (extremely heavy) burn out are a problem, so then your back to the welding issue!
    I bought a case of fire insulation board 12" x 36" I built it using screws and metal tape did a test burn for over an hour and It works Great!! Put the drum and exhaust on it and got temps so hot can't touch it!
    I still need to see how it holds up long term. Pic's coming tomorrow!
    I'm building a version out of Castable Refractory Clay as well tomorrow. I will film it and hopefully post that as well.
    kellory likes this.
  13. Gopherman

    Gopherman Sometimes I Wish I Could Go Back to Sleep

    I video taped the Castable Rocket Stove project, but, I ran out of Refractory Clay. So, I have enough now to pour my riser tube and will continue filming tomorrow. Hopefully I can have it up and running by Thursday.
    Test burn was awesome!!
    Dunerunner likes this.
  14. ghrit

    ghrit Bad company Administrator Founding Member

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