rocket stove

hello. i'm building a rocket mass heater using a 55 gallon drum and 8"x 8" flue liner clay pipe. do i need to put a cylinder around the 8"x8" square and insulate it? thanks dan

Yes you need to insulate.

Rockwool batt, held by chickenwire works well for lightweight units. Not glass wool!

Danny Willis : By insulating the clay flue liner you will greatly speed up the rate at which the Clay Pipe heats up! If used as part of the feed tube, burn tunnel or
the heat riser, the clay pipe will heat up/expand unevenly and is likely to crack, The Good people at Dragon Heaters, have a couple of adaptations to the clay
tile they use, AND they split the tiles lengthwise and then hold the parts together with Stainless Steel Clamps !

If you are going to use the clay pipe after the barrel, I believe several people Have successfully used the clay tile you would like to use, however soft
red brick works well for me, I am planning on some further exploration of the heat sink qualities of 'Potsdam sand stone'. so I don't qualify as an expert with
clay tile Y. M. M. V. ! Hope this is timely and helps ! for the craft ! Big AL

where do i get rockwool batt? thanks dan

This is what you're looking for (other brand names exist too):

http://www.lowes.com/pl_Stone+Wool+Insulation_4294769460_4294937087_#!

http://www.homedepot.com/b/Building-Materials-Insulation-Rock-Wool/N-5yc1vZboco