I'm about to start building a portable tandoor oven inside of a 30 gallon oil drum, kind of like what Grasshopp3r described in this tandoor oven ideas? thread.
I have most of the materials already. The interior dimensions of the 30 gallon drum is 18 inches diameter by 28.5 inches height. I have a supply of regular firebrick and split firebrick, and a terracotta flower pot to serve as the tandoor pot. The flower pot is about 16 inches tall and 16.5 inches in diameter at the top. 16 inches is a bit short for the walls of a tandoor oven, particularly since there will be a wood or charcoal fire built in the very bottom. That doesn't leave much wall space above for the naan, and puts the food too close to the coals.
So my plan is to build a firebrick floor in the bottom of the barrel, then put a vertical course of firebrick on top of the oven floor, and set the flowerpot on top of the vertical course. That'll lift the pot up another 9 inches over the fire.
With the bottom of the flowerpot cut off to make the top opening of the tandoor oven, the height of the pot will be 15 inches. The bricks are 9x4.5x2.5 inches. So the floor plus the vertical course around the periphery will be 11.5 inches. Add the 15 inch height of the flower pot for a total of 26.5 inches. That gives me two inches for insulation at the bottom of the barrel underneath the firebrick floor to bring the top of the oven even with the top of the barrel. I don't mind if it ends up a little above or below the rim.
I plan to use loose vermiculite around the outside of the flowerpot above the level of the firebrick course that it sits on top of to provide insulation. But I believe I need something more substantial below the floor and between the upper vertical brick course and the walls of the barrel. I don't want too much heat to transfer to the outside of the barrel.
So here are my questions:
1) Would ceramic blanket material work between the vertical firebrick and the steel drum wall. If so, how thick should it be? Does compressing it diminish its insulating properties? Where do you buy this stuff and what names does it go by? (The brickyard where I bought the firebrick did not sell it.)
2) Would 5 to 1 vermiculite to portland cement work effectively as an insulating layer below the floor and behind the vertical course against the barrel wall? Will two inches in the bottom of the barrel be sufficient? How thick should it be between the vertical firebrick course and the wall of the barrel? Would an inch be enough? I'm thinking that anything more than an inch thick would make the usable floor of the oven too small for an adequate fire. The barrel is only 18 inches inside diameter, and the firebricks are 2.5 inches thick. I could use thinner split brick for the vertical course, if necessary.
Thanks for any help or suggestions you can offer. I hope to record my build project with stills and video cam so I can post it later. If the video works out, I'll put it on YouTube.
I have most of the materials already. The interior dimensions of the 30 gallon drum is 18 inches diameter by 28.5 inches height. I have a supply of regular firebrick and split firebrick, and a terracotta flower pot to serve as the tandoor pot. The flower pot is about 16 inches tall and 16.5 inches in diameter at the top. 16 inches is a bit short for the walls of a tandoor oven, particularly since there will be a wood or charcoal fire built in the very bottom. That doesn't leave much wall space above for the naan, and puts the food too close to the coals.
So my plan is to build a firebrick floor in the bottom of the barrel, then put a vertical course of firebrick on top of the oven floor, and set the flowerpot on top of the vertical course. That'll lift the pot up another 9 inches over the fire.
With the bottom of the flowerpot cut off to make the top opening of the tandoor oven, the height of the pot will be 15 inches. The bricks are 9x4.5x2.5 inches. So the floor plus the vertical course around the periphery will be 11.5 inches. Add the 15 inch height of the flower pot for a total of 26.5 inches. That gives me two inches for insulation at the bottom of the barrel underneath the firebrick floor to bring the top of the oven even with the top of the barrel. I don't mind if it ends up a little above or below the rim.
I plan to use loose vermiculite around the outside of the flowerpot above the level of the firebrick course that it sits on top of to provide insulation. But I believe I need something more substantial below the floor and between the upper vertical brick course and the walls of the barrel. I don't want too much heat to transfer to the outside of the barrel.
So here are my questions:
1) Would ceramic blanket material work between the vertical firebrick and the steel drum wall. If so, how thick should it be? Does compressing it diminish its insulating properties? Where do you buy this stuff and what names does it go by? (The brickyard where I bought the firebrick did not sell it.)
2) Would 5 to 1 vermiculite to portland cement work effectively as an insulating layer below the floor and behind the vertical course against the barrel wall? Will two inches in the bottom of the barrel be sufficient? How thick should it be between the vertical firebrick course and the wall of the barrel? Would an inch be enough? I'm thinking that anything more than an inch thick would make the usable floor of the oven too small for an adequate fire. The barrel is only 18 inches inside diameter, and the firebricks are 2.5 inches thick. I could use thinner split brick for the vertical course, if necessary.
Thanks for any help or suggestions you can offer. I hope to record my build project with stills and video cam so I can post it later. If the video works out, I'll put it on YouTube.
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