i tried with 4.2m length 1.2m width 1.2 m depth the air circulation is not triggering inspite of forcing air from inlet hole .when air is blown from inlet hole near start point of fire smoke is coming out from outlet hole. After fire is picked up igniting the wood the lid sheets are closed. The fire did not last. It went off. Are the dimensions of pit necessary to follow. Do you have English video. Do you have text file giving guidelines?