Prepper rocket stove

Hi everyone.  I live in an all electric home. If the big one happens, cascadia subduction zone earthquake, I could be without power for a year or more. I tried making a rocket stove out of a 5 gal metal paint can but it didn't work well.

Then I remembered I had some spare metalbestos stove pipe up in the shop. Here is how it looked. It worked very well. The firebox piece I had welded up for a different project. The clay I used between the firebox and the stove pipe was not fire clay so it didn't last. I have some woodstove door gasket material for next time.

Thanks for all of the great posts you made to this thread.

Great Job Dave!

That looks like it works perfect!  
As a rocket stove, that design will last a good long time.
As a mass heater it would have issues.

Nice work with materials you had on hand! I presume it works well. I think you could alter the proportions and have it work even better. The heat riser is plenty tall enough for a rocket stove, but the horizontal burn tunnel is quite a bit longer than optimum, and the feed tube is shorter than you could have given the riser you have. A taller feed tube would allow longer wood and more consistent burning.

You mentioned clay you had not being fireclay and failing... I don't see where clay would be in the photos. I have used native clay (very sandy and stony) in rocket stoves and it has worked fine; as it burns, the part of the clay that is exposed to fire turns into pottery and gets stronger. If yours crumbles, there is probably insufficient actual clay and too much silt in it. Do you know how to do simple hand tests for the quality of clay? Can you make a sausage or rope from it and bend it without it cracking apart?

I think you could improve the function of your rocket by replacing the steel feed and one of the sections of metalbestos with a 5 gallon metal bucket lined with clay for a feed tube, connected directly to the metalbestos pipe. You would want the total horizontal length from center of feed to center of riser to be a bit less than half the height of the riser from base to top. The feed from bottom to top should be not more than 1/3 the height of the riser. It looks like you have 8" metalbestos pipe (10" o.d.) and a 4" x 6" steel feed tube. Ideally a rocket core is consistent in internal cross section from start to end, and if any part is slightly smaller, it should be the burn tunnel.

Thank you Glen for your input and suggestions.

I have the book "Rocket Mass Heaters" by Ianto Evans and I attended a workshop where we built a rocket mass heater for a greenhouse.

This was just a cook stove for an emergency. The clay I used was gray modeling clay I got at amazon.

I really appreciate your data about the relationships between different parts of the stove. I will study what you suggested and will think about changes needed.

Thanks to Permies and all of you who offer opinions and advice on such a wide range of subjects. I feel like I am home here. 🙂

"Gray modeling clay" from Amazon... probably wasn't clay but a type of plasticine compound. That would be totally unsuited for anything involving heat.