fuel

been playing with my small cores and burning everything that will fit. like i have read on here the bigger stuff don't burn as well as smaller stuff. the other day i burned some chunks, instead of long sticks. the chunks were bits of 2x4, about 2" square. they really seemed to be better. at least they gave off more flame in tunnel and didn't have anything for the fire to climb up on(like the sticks do sometimes). just tossed a couple in every 20min. had to watch that i didnt close off the the tunnel opening though.

Ronald Bush : Once you have a well made and super insulated combustion zone in your Rocket Mass Heater it only takes a few minutes of operation for that area to start
to visibly glow cherry red.

Once you reach that stage, The only rule that you need to follow is A large amount of surface area is ALL ways your friend. Three or 4 chunks of wood Nestled in your
Feed Tube, will all ways burn better than one Piece which has the same mass but less surface area !

If your Feed tube is full, it will work as well or better than the same feed Tube 1/2 full with bricks on top of the Feed tube to channel the air around the Fuel ! All this will
soon become Automatic, as you learn to judge when to fuel it based on the Sound of your Rocket Mass Heaters Roar ! For the Craft ! Big AL

i have noticed the "call of the roar" so to speak. when setting next to it, it automatically pulls you to poke when it gets quiet. lol thats half the fun while tinkering.

i busted a 4"er, i made from yellow clay, sand, perilite ,and weed/grass stalks. it was burnt maybe 40hrs over 6 weeks, (1-4hr burns) with lumber scraps/sticks. i wanted to see how it held up and how strong it was. the 4"thick areas of casting was really and still is very rugged! the areas where it was 2"thick not so much. i also used some fiberglass mess tape rubbed into the outer layer which added a lot of strength and didnt crack. over all i was impressed with the ruggedness the interesting thing was the fire mark in the cob. i can see now ill need a lot more perilite in the mix. at least for the first 4" around core/riser. there was about 2" of red colored(fired) clay around core. the core weighed about 25-30# and would give off heat for 2.5 hours, after fire was out! also raise temp in my kitchen 5* in that time. these are just cores mind you. i havent reached the point of building one with a barrel on top yet.


anyone try coal in one of these things? i have seen some used oil burning rigs on the net. dont see that as very clean but maybe it is at these temps?

can see now ill need a lot more perilite in the mix.

Perlite will weaken the cob so that it won't last very long as a burn tunnel. Check the threads about the shippable core.

anyone try coal in one of these things?

Yes, it didn't work very well. Coal might work better sitting on a grate; we haven't tested this.