by Rhett » Thu Apr 03, 2014 4:00 pm
Yeah I burned it again last night - crystal clear. Already so much better and I think it will get better still. There is still a lot of wet clay left. Man, I used too much clay. I am sure of it. The riser is breaking apart too now. When it comes to mixing, vermiculite != perlite. I used 2:1 verm to clay and I really think it was nowhere near enough. I am afraid when the pipe burns out the riser is just going to fall to pieces if I move it. So I need to get it placed where it is going to be and not touch it. It's insulating good, the propane tank outer shell doesn't remotely get warm after 30 minutes of burning so that's nice. Not too worried about the core either, I can patch it up and then brace with cob or steel as you said.
It's performing beautifully as far as I can tell, even with the wet clay left. I think that smoke must have been the stove as you said, I didn't realize new pipe would do that. One thing that surprises me is how easy this thing is to light. It wants to be on fire.
So adding up my materials, I have spent $75 on clay and have two of 5 bags left so that's $45, I spent $35 on two buckets of furnace cement and used that. I spent $70 on 8 cubic feet of vermiculite and have used about 7 of that, let's call it $60. I used about $3 worth of fiberglass. $14 for the riser stove pipe and another $12 for the elbows. So all in I am at $170. Not bad for an 8" system with a massive 47" heat riser and 3" of insulation all around it, but I really think it could be improved. For one thing the perlite costs the same and I am convinced I would have used half as much, I'll have to pay closer attention to the labeling next time. That would have saved me $35 and resulted in less cracking. I shouldnt really call it cracking, mine is breakage.
So now I am researching cob to see if it is a good option for me for using this thing as a firepit/bench. I have a mountain of soil I excavated when I built my house. I am going to do a soil test to see how usable it is for cob.