Bill Rust

Wow, what an interesting thread! Thanks.

Thanks for the honest replies; they are much more helpful than wind blown up my proverbial kilt. I expected some strong opinions about my use of concrete. Since this is my first RMH and because I live in the city and don't have access to clay soil without digging up my wife's beautiful, but tiny garden, I thought to start with concrete and go to clay if it doesn't work. It's not a complete show-stopper if my first effort doesn't work out. If it lasts even a season or 2 of light workshop use, I'll be happy and will have leaned a lot.

Thanks for the tips on right angle bends, packing cob tightly to my flue, and round holes. I think a 30 or 55 gallon barrel would facilitate a round hole better. The small (but 100% free) barrel made certain compromises necessary. Since I have found a source of dry clay powder for $10 a 40 lb. bag recently, I will try raising my barrel to 2" from the top of my heat riser using cob. I don't plan to cook on top of my barrel and will probably put some cob up there too.

Is there a thread on Permies.com that talks about making cob (50/50 clay sand mix) from dry powder fireclay? I can get straw here in the city, but how necessary is it for my application (e.g. covering the top of my cast core and barrel, and packing around my flue pipes, not likely more than 10-12" off the floor?)

Thanks again for the useful, if not brutally honest information!

Hi, I originally wanted to make something portable, but then the idea evolved into a mass heater. I have a hybrid design in part inspired by one of your members. Here is the construction (kind of a long video, just jump ahead if it gets to long in the tooth)

http://youtu.be/jLR8cAz1hTA?list=PL3AD33C058355581E

I made essentially a cast core that also routes the heat exhaust to my flue. I did my first burn yesterday and the sides of the cast core didn't even get warm! The flue got hotter than I really wanted and I have a couple of questions. First some details (as I remember them)

6" system
Feed tube depth (to bottom of channel) 10" + 4" of flue liner on top of core
Horizontal measure of channel from front wall to back wall 15-16"
Bottom of channel to top of heat riser 35.5"
Current gap between top of heat riser to inside of barrel top - 1.0"
Barrel 17 gallons (I think)
Flue is 6" diameter
Horizontal run of flue is about 11-12'
Vertical run of flue is roughly 17'

I'm still waiting for my infrared thermometer to arrive so if you want temps I should have them soon.

I plan to seal the drum with cob, but I think 1.0" gap is too small and was thinking 1.5-2.0" would be better?
I have some patio blocks surrounding, but not touching my horizontal run of flue, would packing in cob lower the output temp?
I think I may be getting too much ash, and it contained charcoal. Should it?

Love your information. I have read many threads here and done months of research before starting. Thanks for the help already even though this is my first post!