The general waterproof heating is to cover a small pot with a big pot, and the same is true of the principle of Yunnan gas pot. Just making some changes. The middle of the clay pot is designed as a crater to receive the steam in the lower boiling pot. There is a ditch next to it for cooking vegetables and meat, so that the cooking pot below can upload steam to the top. The gas tank has a lid that is stuffy, so the steam will circulate in it, which means that the steam evaporated from the pot will run up more or less. Why not use the ordinary clay pot in the square steamer? Because it can speed up the circulation and heat evenly. If only ordinary clay pots are placed on it, too little water in the pot will lead to the danger of dry-fired clay pots bursting. Basically, this is just to miss the wisdom of our ancestors. Practicality is not good at all, because unless a stainless steel inspection chart is developed, it is difficult to lift the ears of the steamer, and it is also dangerous to steam the dishes on the table.