Robert Johnson

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since Nov 14, 2013
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Recent posts by Robert Johnson

My kid walked into the rd and scared the crap out of me one day. As I am often broke I had to really think of something. I do my aunts yard and she had an area that i did not usually mow. So there were a bunch of saplings and cedars in an area that she wanted to eventually have a garden. So I had been thinking of a wattle fence and I saw my opportunity to to do it. Took about three days with a cane knife and a chainsaw. I didn't concrete the cedar posts in as the structure supports itself. It was a lot of fun. Gonna do my back yard too soon. Now everyone slows down and looks as they drive by, making the road safer in the process!
3 years ago
I tell ya I am addicted to this stuff now. I'm already trying to rationalize building another one now. Maybe one just for cooking now......
4 years ago
Maybe put a larger barrel over the bell and cut two holes for ducting. One on side towards bottom another on top and connect a fan blowing in to barrel from side through to the top transporting the hot air to wherever you need it. It could even be a 12v fan run off of batteries or solar. Only problem is it might make it burn less efficient by stealing heat before the re-burn.
4 years ago
Yeah I was pretty sure it wasn't a batch box but I didn't know what else to call it. L-tube didn't seem right at the time. The exhaust leaving the top of the mass is not hot. Warm is more like it. I can put my hand on it and keep it there without pulling away. So I think it's efficient enough for this little house. We are in Texas so it will be fine. Yes I agree that a J-tube works better but I'm a truck driver and am at work a lot and I need it to be as simple for my wife to use as possible. So far there has been zero back smoking. It was a very fun build and my wife says it looks like an old style steam engine. I was thinking of putting a scoop on the front to  accentuate that motif further.
  As for convection I believe the airflow travels up the length of the mass from floor to ceiling and then is pushed away along the ceiling until it dumps its energy and sinks down to floor again back towards the low pressure zone near the base of the mass and then repeats the process if I am thinking correctly. Been a long time since high school physics class though  L😂L
4 years ago
The original batch box was a 12" duct with the 8" duct connecting and going up through the riser. I think batch box may not be the right word. I think it was just not angled up enough and I found I didn't need that big a burn chamber anyway. When I converted it I just put a 8" elbow inside the 12" chamber and just filled it in with clay and perlite.
 No left over charcoal after burns. The core is perlite with enough clay to make it stick together well. The exhaust going from the core to the bell does indeed get hot but not dangerously hot. Still, I plan to insulate it with rock wool, but it just adds to the radiated heat. I don't have cad but I have attached a drawing of the system. Sorry it's crude. I'm at work.
 And yes that's a badass stainless lid I got off Ebay and I just keep a gap open at the bottom so that air comes in and cools the lid on its way to the fire. And yes it's just a coincidence that vent happens to be there.
 
4 years ago
I live in a mobile home and don't have a lot of room for a bench on my rocket stove. So I built this one with the mass standing up. It works better than I thought it would.  I think it actually works better because all sides of the mass is in contact with the air enabling a better convection throughout the room.  I made it like a batch box but it did not draft very well. So I reduced the mouth to an 8 inch.  Now it drafts like a beast! Absolutely zero smoke comes out my chimney now.  My mass is contained inside of 2 55 gallon drum's standing on top of each other. I have 2 15 gallon drums on the inside  with the 8 inch exhaust tube coming down the center all the way to the bottom. I have solid Clay between the 55 gallon drum's and the 15 gallon drums. No cob. The drums  contain the mass nicely. This is my first rocket mass heater. I built a rocket stove water heater last year and it still works like a beast.
4 years ago
I built one of those rocket water heaters. It works exceptionally well I do say. I used the pass through technique using 50 feet of 1/2" copper tubing running through a 40 gallon stainless steel kettle. There is no pressure to it. It has an over flow hose going to the outside. The core is a 30 gallon barrel turned on its side with 6" pipe holding the form and I have a clay perlite mixture filling the space. I insulated the outside of the whole thing with rockwool. Anyway here's some pictures.
5 years ago
Could you use ceramic tile instead?
6 years ago
This core is really solid. Been burning for 9 hours and the barrel is still cool. I don't think there will be a need of excessive perlite bed. I think the concrete blocks will suffice for now.
6 years ago
Well I cast my core last night! It turned out better than I expected! No leaks at all! I first caked the outside of the burn tubes with about 1/2" of 3000° refractory cement and then packed the barrel with clay/perlite/refractory cement mixture. Weighs about 150 lbs altogether. Gonna pack the riser and do tests tonight after work!
6 years ago