• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies living kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • raven ranson
  • paul wheaton
  • Jocelyn Campbell
  • Julia Winter
stewards:
  • Burra Maluca
  • Devaka Cooray
  • Bill Erickson
garden masters:
  • Joylynn Hardesty
  • Bryant RedHawk
  • Mike Jay
gardeners:
  • Joseph Lofthouse
  • Dan Boone
  • Daron Williams

I'm new around here  RSS feed

 
Posts: 13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I think a bit of history about how I got here might interest some people.

I am native to Atlanta Ga and currently live in Smyrna. I am a techie by nature and vocation. Much of what follows is a long tortuous path of doubt and discomfort that has lead me to a new view on how I think I should live my life. All the reading and research over the past year has lead me to believe I am not living life...only surviving it. I will change this for the better. I have to find a way to make it happen.

Over the past 15 years or so I have weathered maybe half a dozen ice storms. It seems I have had the misfortune to always live in an area where the power goes out. I can honestly tell you that any modern house these days is completely worthless when the power goes out. I lack the vocabulary to express how much I HATE being cold.

bare with me I have tons of ideas and thoughts ping ponging around my skull right now.

I started my journey by researching alternative housing methods. I found earthships, straw bale, earthbag ect... I then started thinking about these types of houses being off grid. My research lead me to finding different ways of heating an off grid house and that lead me to rocket mass heaters. Even as a little kid I never liked fireplaces as I viewed them as a total waste of a tree since all the heat goes right out the chimney. All of this lead me to permaculture and somewhere along the way I found a link to this site after watching one of the lectures by Paul.

So now here I am and convinced I want to live outside a large city off the grid on my own land with no building restrictions. I've never had much desire to live in a cave or anything but after watching tons and tons of videos on the subject it makes perfect since and I would only limited by my imagination and checkbook.

So there you go an abridged version of what has lead me to this forum.

This past weekend I made my first attempt to build a rocket mass heater.

Try #1 didn't go very well. I was using some left over concrete paver bricks, just the brick, I didn't sheath it in cob or anything yet. Anyway I created the base with the J tube with a 6" x 26" cast iron riser(without the insulated sheath ) , 30 gallon drum. I was not getting enough draw so the flame and the smoke were coming out the wood feed side.

Try #2 I changed the config of the brick to make the wood feed horizontal to the ground and the draw was much better and I didn't get any smoke or flame back.

I really want to the wood feed to be vertical because then I can put longer peaces of wood in and it will self feed. I am convinced I need to insulate the riser reducing the space inside the drum and play with the dimensions of the J-tube also. I've never done anything like this before so I will have to play around with it until I get it right. I'll get it to work because I will not stop fiddling with it until I do.


 
Posts: 128
Location: Sierra Blanca, TX
2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Sounds like you are not getting the draw you want because it leaks. Air should only have 2 paths. The opening in the feed tube and the exhaust pipe. Seal up everything and thermal dynamics should do the rest. once heat starts rising up into the chamber it should suck air into the J
 
gardener
Posts: 2580
Location: Upstate NY, zone 5
92
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
It is essential to have the heat riser and burn tunnel insulated, so they can get freaky hot and create the strong draft and complete combustion. Iron or steel will not stand up to such heat especially combined with the combusting atmosphere. You need masonry - ideally firebrick or cast refractory cement, but old red bricks will work reasonably well. Modern hard bricks, or concrete bricks, will not stand the heat stresses well. As Joseph mentioned, sealing the joints is also critical.

The vertical self-feeding aspect is nice, but be careful of using very long sticks. If they hang up, the fire can burn up and let the top fall over onto the floor. Inside a house it is strongly recommended to only use sticks cut to the same length as the height of your feed tube. This also allows you to slide a brick partly over the feed tube to control the air supply. Too much air will dilute the heat and cause less effective burning.

You also need a chimney going up from the end of the flue path for most situations, regardless of what you may have heard about a chimney not being necessary. If it works at all without a chimney, it will work much better with one.

There are dimensions and ratios that will give the best results, and you can find most all the essential information in "The Book", Rocket Mass Heaters by Ianto Evans and Leslie Jackson. http://www.cobcottage.com/rocket-mass-heaters-new-edition-iii
 
Frank Johnson
Posts: 13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks for the positive feedback.
 
Frank Johnson
Posts: 13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
As an FYI, I am a tech person by trade. I've never built anything like this before so this is a learning process for me. I know my materials are not ideal.

As I have been learning about RMHs that there are a good number of things you need to know about "fire brick":
Such as what grade of brick you might need. Soft, medium, hard.
Each of these have a diff range of temperatures they are suited for.

I think the fire brick you see in my photos are Hard as they are extremely heavy. Once I decide on my final arrangement I will line the hottest parts of the burn area with the few fire bricks I have. I don't get much time to fiddle with this project so am still learning what will work and what will not. Working on this thing outdoors can be a trial as the wind can create back drafts which is annoying. This RMH will be outdoors so I am not overly concerned about having everything exact.

Anyway here are a few photos of my current arrangement which I am going to change as I think the burn chamber is to big. In this arrangement it is around 10 inches.
IMG_0250.JPG
[Thumbnail for IMG_0250.JPG]
IMG_0252.JPG
[Thumbnail for IMG_0252.JPG]
IMG_0253.JPG
[Thumbnail for IMG_0253.JPG]
 
Posts: 217
Location: US, East Tennessee, north of Knoxville
13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Those dense firebrick, the ones measuring 4.5 x 9.0 x 2.5 (inches) and weighing in the neighborhood of 7 lbs. per each, are commonly available from refractory and some builders suppliers here in the US. Erica Wisner wrote a very informative post on the various types of firebrick and other suitable RMH materials. I'll post the link here in case you haven't seen it, check out post 15:

http://www.permies.com/t/30551/rocket-stoves/Fake-fire-brick

And once the Wisner's book rocket mass heater Builder's Guide is released early this year, it will be a must have for RMH enthusiast for sure:

http://www.amazon.com/Rocket-Heater-Builder%C2%92s-Guide-Step/dp/0865718237
 
Frank Johnson
Posts: 13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
This was my first full weekend off in two years so I spent most of it playing with the RMH brick arrangement. I decided to go ahead and try my hand at sealing the blocks with some homemade mud plaster. It may not look very good but it does have the rockety draw I was looking for. I did get the riser packed with mud also but forgot to get a photo of it. I used a peace of 10" duct as the outer casing. I have a couple of 15 second vids showing the draw and sound of the rockety goodness but the forum does not allow an MOV file to be uploaded. I'll have to look and see what sort of vid file is allowed and see about converting them.
IMG_0259.JPG
[Thumbnail for IMG_0259.JPG]
 
Glenn Herbert
gardener
Posts: 2580
Location: Upstate NY, zone 5
92
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Looking good so far! You will get even better draw if you make the heat riser taller, ideally 3 to 4 times the height of the feed tube from the burn tunnel floor. Laying the riser bricks up on edge will get you more height while reducing the mass that has to heat up before the draft gets to its best.
 
Frank Johnson
Posts: 13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Glenn Herbert wrote:Looking good so far! You will get even better draw if you make the heat riser taller, ideally 3 to 4 times the height of the feed tube from the burn tunnel floor. Laying the riser bricks up on edge will get you more height while reducing the mass that has to heat up before the draft gets to its best.



My riser which is not shown in it's finished state here, will add another 26" to the bricks you see in the photo above. I also need to cut one of the top bricks in half then adding another layer pf brick to the riser area so when I add the barrel I will have enough room to install the duct where the bench piping will connect.

So a couple of short vids showing the drafting without the riser.

 
Frank Johnson
Posts: 13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I had a few days off and dug into this RMH project and have it nearly complete.
 
Frank Johnson
Posts: 13
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Ok this project is on hold for the time being as my sister needs to make up her mind where in the yard she wants to put it. I still need to build the bench to attach to it. The bench will not happen though until the location is determined.
 
gardener
Posts: 1295
Location: Little Belt Mountains, MT
224
chicken dog hugelkultur hunting purity wofati
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I'm not sure which videos or books you've read on the subject, but there are a lot of great learning resources out there that you can just soak in to help you get through this project - I find the more I understand something, the easier time I have working on it.

ernie and erica just released their Rocket Mass Heater Builder's Guide, and Paul's brand new DVD set, Better Wood Heat: DIY Rocket Mass Heaters is also now available for preorder. That one's kind of nice, because it shows you both a cob and pebble style, and also goes into the inner workings of the core of the RMH a bit more.
 
Frank Johnson
Posts: 13
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Destiny Hagest wrote:I'm not sure which videos or books you've read on the subject, but there are a lot of great learning resources out there that you can just soak in to help you get through this project - I find the more I understand something, the easier time I have working on it.

Ernie and Erica just released their Rocket Mass Heater Builder's Guide, and Paul's brand new DVD set, Better Wood Heat: DIY Rocket Mass Heaters is also now available for preorder. That one's kind of nice, because it shows you both a cob and pebble style, and also goes into the inner workings of the core of the RMH a bit more.




Thanks for the links and info. I am familiar with Ernie and Erica and Paul's info. I have viewed maybe 200 videos about rocket mass heaters from all over the internet before building mine.

I will say that mixing mud by hand was allot harder than I thought it would be and when the time comes time to build the bench I will use a cement mixer.
 
Is that a spider in your hair? Here, threaten it with this tiny ad:
Two part roundwood timber framing workshop sep 24-29 and oct 1-5
https://permies.com/t/91267/permaculture-projects/part-roundwood-timber-framing-workshop
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!