How to build a rural fire kang?

Several key knowledge points: 1. Kang is built on concrete floor, which is not wet and easy to burn. 2. The kang cave is wide and deep, and there is little resistance and much ash when the smoke flows, so it is not necessary to clean the ash every few years. 3. The brick wall forming the flue is thick, which can store heat and transfer heat evenly. 4. The position where the smoke in the stove enters the kang hole is called the throat eye. The area of this place must be smaller than the sum of the actual air intake areas of the oven door and grate, and also smaller than the area of the chimney mouth. So the stove can smoke. You can try installing a hose on your own faucet. When running water, the pipe head is suddenly pinched, the outlet becomes smaller and the water flow becomes stronger. Sediments that have not moved before may be impactful. This is the principle that the local pumping force becomes larger, which can impact the flue gas. 5. The bottom of the chimney root is more than one foot lower than the bottom of the kang cave. To put it bluntly, there is a pit. This is the legendary "kennel" and wind tunnel. Its function is to prevent cold air and rain falling from the chimney mouth from directly flowing into the kang cave. 6. Don't care too much about the height of the chimney. A good chimney should be like an inverted horn, thin on the top and thick on the bottom, so that the root of the chimney can not only store more hot air, but also prevent too much cold air from being pressed into the chimney mouth. You can build the chimney as thick as the top and bottom, and add a small cement pipe on it in winter. It doesn't matter whether it is high or low. Some people in rural areas buckle a flat-bottomed basin. In this way, less cold air will be forced into the chimney. 7. A kind of health is popular in Northeast China now. To put it bluntly, one is to build a four-box pool on the concrete floor, which looks like a "mouth" shape, and there is no need to backfill the bottom of the kang, so that the hole in the kang will be deep. A wall is built in the middle to divide the kang into two parts, namely the flue entrance and the flue exit, which is equivalent to a word "Yue". The flue entrance is wide, the flue exit is narrow, and the middle is inclined horizontally. To put it bluntly, it is equivalent to being divided into two trapezoids, one large and one small, and the flue entrance is narrowed from wide to narrow. Some of these kangs say that they don't need to be dug once every seven or eight years, while others say that they don't need to be dug once every 10 years. With the transformation and relocation of shanty towns, many people's kang has been pulled open, and there is no windward stone, backfill soil and the like. The disadvantage is that the kang surface needs to be made of concrete and steel bars. In the internal space, there is no brick wall to store heat, so it is estimated that the ceasefire will soon cool down.