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I'ld say, as with most dumpster fires, the combustibles buried beneath tons of rubble, were indeed oxygen starved, thus creating the same effect as an airtight wood burning stove.
Again, not rocket science, easily understood and acknowledge by the children in this home or most with a wood burning stove of this type.
look fool even in your quote it says air is added your a Prick thus not air tight is itslowly allows air to combine with the wood