Rocket stove mass heaters...

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

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  1. BTPost
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    BTPost Old Fart Snow Monkey Moderator Site Supporter

    No use wasting Good Room Air, to feed a fire that is heating an Enclosed Space. Very counter-productive....
    NotSoSneaky likes this.
  2. Rabid
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    Rabid Monkey

    Any wood stove uses air from within the room, combustion air is rarely brought in from outside except for some sealed fireplaces. If you have a wood burner now and it is working properly then a rocket stove mass heater will work also. I have a friend who had his house so air tight that he couldn't burn his wood stove unless he cracked a window open. Most houses just aren't that air tight and one that is may not be very healthy. If you wanted you could run an air duck to the fuel opening in the mass heater and it will draw from outside. I would put a butterfly damper in it though. If your concern is controlling the burn of the mass heater there is no controll, it burns flat out there is no control. The idea is to burn it hot, hot is clean, and get as much heat off of the burn as possible. If you don't have a large enough heat sink then your exhaust will be hotter and that is wasted heat. There is comming a day when the government will no longer allow those smoldering, smoking wood burners and people will be caught off guard.
    kellory likes this.
  3. BTPost
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    BTPost Old Fart Snow Monkey Moderator Site Supporter

    Apparently you haven't been around the technology innovations in the last two decades of Wood Stove design. Any Good Wood Stove will have an External FireBox Air Intake, so that it does NOT use Internal Air from the room. This does two things. First it keeps the Draft at a constant level, that doesn't change as the in-room environment, changes. (Like opening a door to another room in the cabin) Second, It doesn't allow an Air Pressure change, as the combustion sucks the Oxygen out of the room, and forces the CO2 up the chimney. The results of a Negative Air Pressure inside the cabin is that Outside Cold AIR is sucked thru every crack, door, and window frame, which just makes the place all that more harder to heat, and burns more BTUs to hold the same room Temps. If you lived in Cold Country, and heated with Wood, this would be self-evifdent. Just Say'en.... YMMV.... but the Physics doesn't Lie......
    vegasrandall and NotSoSneaky like this.
  4. gunbunny
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    gunbunny Never Trust A Bunny

    Yup, an outside air source for the cumbustion is 10% more effecient than using the room air because the stove doesn't have to pull replacement air through the cracks in your walls. Here's some pictures of my pellet stove's air system.

    012 (903 x 1204). 011 (912 x 684). 010 (912 x 684).
    The top picture is the front of my stove, shown so you can understand the layout of the next two pictures. The middle picture shows the view down from the top of the stove, and the last picture is slightly to the side, looking down. The upper duct is fresh air, and the bottom duct is the exhaust. The picture makes everything look much dirtier than it actually is... ;)
    NotSoSneaky and kellory like this.
  5. Rabid
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    Rabid Monkey

    I guess the reason I'm so hot on the mass heaters is that I got burned on the wood stoves. (puns intended) After I bought my wood burner the town put a ban on them because of the nuisence smoke. Yes, I took a loss but a few years later I moved out of town and bought a place that just happened to be down wind of a smoldering black box. On nights when we had an inversion layer I thought I would die. No wonder I got the house on my first offer. I have not given wood stoves much consideration since those early years. I can't say I even know much about them. Now that I am looking to move to a more remote location I don't want to send up smoke signals to let everyone know where I am. Since the rocket mass heater only smokes a very little bit on start up It has caught my attention and I have been working on trying to figure out my own design. One of the things I plan to include in my design is an outside combustion air source. Thanks guys for pointing that out. I also have an idea for a rocket stove mass heater/ oven. I guess i had better get on the stick and find a piece of land.
  6. Motomom34
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    Motomom34 Monkey++ Site Supporter

    This is the most interesting thing. Due to fire danger I worry about sparks and plus the smoke would be an issue, also any time a neighbor lights their wood stove I get on high fire alert when I smell the smoke. This is something I think would be do'able. Occasionally there are no burn days but this rocket stove wouldn't really apply. Going to see if I can locate a book.
  7. Cruisin Sloth
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    Cruisin Sloth Special & Slow

    smouldering black box is ???

    I live with an Airtight (wood burning fire ) , Mine is hard to see smoke.

    Sloth
  8. Motomom34
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    Motomom34 Monkey++ Site Supporter

    I wonder how long the exhaust vent must be. I see that these seem to have long sitting areas but I wonder what the minimum would be.
  9. BTPost
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    BTPost Old Fart Snow Monkey Moderator Site Supporter

    The issue is how well the Exhast Stack DRAFTS, when the firebox is burning at temp. The longer a horizontal run and the more 90s in the flue, the worse it will draw, and the efficiency goes way down. So any design needs a long straight vertical Flue, connected, after the thermal Mass and the surface area between that thermal Mass, and the flue Gases needs to be as much as possible without constricting the flow of the Gases, up the flue. These are the design trade offs.
    Silversnake likes this.
  10. Rabid
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    Rabid Monkey

    The vertical flue doesn't seem to be an issue. I've seen many with only a two foot rise. There must be some kind of formula out there to figure the optimum run of stove pipe and amound of heas sink you would need.
    Here are a few vids that helped me understand rocket mass heaters

    Rocket Mass Heaters
    Rocket Stoves -- Home

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