I came across this recipe for castable perlite insulation and thought about giving it a try to insulate a heat riser made from stove pipe with in hopes that once the thin stove pipe burns up the cast refectory will be strong enough and last for many many years. I have my doubts that this mixture would be strong enough but maybe insulated fire bricks could be made for the burn tunnel as well. www.myheap.com/book/chapter-01/irc/irc.php
There are a lot of different recipes that i have found some contain calcium aluminate cement, I'm hoping to find a way to make insulating fire brick from clay i can find in the ground and sawdust. Some of the test bricks that i have made from clay and saw dust have good insulating properties but are quite fragile I'm making a rocket heater with a out of sawdust and dirt with a consumable liner, my hope is that the saw dust will burn out of the first inch or two which will provide enough insulation to prevent the rest of the sawdust from burning out so that there is still good strength to the outside of the stove. I'll post some pictures and stuff i don't think that the heater will be ready for at least a month tho because of how long it takes the sawdust and dirt to dry.
Last Edit: Mar 25, 2010 23:02:50 GMT -5 by spacevan
Right on spacevan! Donkey has done quite a bit of experimenting with this too. Have you seen his older threads on the subject? I seem to remember one called "tapered heat riser"? but check back through the threads and you'll find a bit of info he's shared.
I found an article describing the results of different home made fire brick using clay as a binder. The amounts used, there effectiveness of insulating and also the effect they have on the temperature of the fire are charted out. I found the article to be interesting and a good starting point for trying to come up with ways to make a durable rocket heater with out the use of fire brick. Where i am from fire brick is almost impossible to find except the 1.25"x4"x9" fire brick for lining wood burning stoves. Canadian tire charges $6.00 a brick so that is way to expensive the make a rocket heater core out of. The link for the article is www.hedon.info/InsulativeCeramicsForImprovedCookingStoves
Last Edit: Mar 30, 2010 17:54:15 GMT -5 by spacevan